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  • 1.
    Björkman, Mattias
    et al.
    ABB, Sweden.
    Brogårdh, Torgny
    ABB, Sweden.
    Hanssen, Sven
    ABB, Sweden.
    Lindström, Sven-Erik
    ABB, Sweden.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Norrlöf, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    A New Concept for Motion Control of Industrial Robots2008Ingår i: Proceedings of the 17th IFAC World Congress, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper gives a short summary of an industrial development work on model-based motion control. This development has resultet in high robot motion performance simultaneously with an efficient use of the installed drive system of the robot.

  • 2.
    Björkman, Mattias
    et al.
    ABB, Sweden.
    Brogårdh, Torgny
    ABB, Sweden.
    Hanssen, Sven
    ABB, Sweden.
    Lindström, Sven-Erik
    ABB, Sweden.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Norrlöf, Mikael
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A New Concept for Motion Control of Industrial Robots2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This paper gives a short summary of an industrial development work on model-based motion control. This development has resultet in high robot motion performance simultaneously with an efficient use of the installed drive system of the robot.

  • 3.
    Hedberg, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Norrlöf, Mikael
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Comparing Feedback Linearization and Jacobian Linearization for LQ Control of an Industrial Manipulator2018Ingår i: Proccedings of the 12TH IFAC SYMPOSIUM ON ROBOT CONTROL, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Feedback linearization is compared to Jacobian linearization for LQ control of atwo-link industrial manipulator. A method for obtaining equivalent nominal performance forboth control designs is introduced. An experimentally verified benchmark model with industrialrelevance is used for comparing the designs. Results do not show any conclusive advantages ofFeedback linearization.

  • 4.
    Henriksson, Robert
    et al.
    McKinsey & Company, Sweden.
    Norrlöf, Mikael
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wernholt, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Schön, Thomas
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Experimental Comparison of Observers for Tool Position Estimation of Industrial Robots2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This paper investigates methods for tool position estimation of industrial robots. It is assumed that the motor angular position and the tool acceleration are measured. The considered observers are different versions of the extended Kalman filter as well as a deterministic observer. A method for tuning the observers is suggested and the robustness of the methods is investigated. The observers are evaluated experimentally on a commercial industrial robot.

  • 5.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Modeling and Control of Flexible Manipulators2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Industrial robot manipulators are general-purpose machines used for industrial automation in order to increase productivity, flexibility, and product quality. Other reasons for using industrial robots are cost saving, and elimination of hazardous and unpleasant work. Robot motion control is a key competence for robot manufacturers, and the current development is focused on increasing the robot performance, reducing the robot cost, improving safety, and introducing new functionalities.  Therefore, there is a need to continuously improve the mathematical models and control methods in order to fulfil conflicting requirements, such as increased performance of a weight-reduced robot, with lower mechanical stiffness and more complicated vibration modes. One reason for this development of the robot mechanical structure is of course cost-reduction, but other benefits are also obtained, such as lower environmental impact, lower power consumption, improved dexterity, and higher safety.

    This thesis deals with different aspects of modeling and control of flexible, i.e., elastic, manipulators. For an accurate description of a modern industrial manipulator, this thesis shows that the traditional flexible joint model, described in literature, is not sufficient. An improved model where the elasticity is described by a number of localized multidimensional spring-damper pairs is therefore proposed. This model is called the extended flexible joint model. The main contributions of this work are the design and analysis of identification methods, and of inverse dynamics control methods, for the extended flexible joint model.

    The proposed identification method is a frequency-domain non-linear gray-box method, which is evaluated by the identification of a modern six-axes robot manipulator. The identified model gives a good description of the global behavior of this robot.

    The inverse dynamics problem is discussed, and a solution methodology is proposed. This methodology is based on the solution of a differential algebraic equation (DAE). The inverse dynamics solution is then used for feedforward control of both a simulated manipulator and of a real robot manipulator.

    The last part of this work concerns feedback control. First, a model-based nonlinear feedback control (feedback linearization) is evaluated and compared to a model-based feedforward control algorithm. Finally, two benchmark problems for robust feedback control of a flexible manipulator are presented and some proposed solutions are analyzed.

    Delarbeten
    1. Modeling and Parameter Estimation of Robot Manipulators using Extended Flexible Joint Models
    Öppna denna publikation i ny flik eller fönster >>Modeling and Parameter Estimation of Robot Manipulators using Extended Flexible Joint Models
    2014 (Engelska)Ingår i: Journal of Dynamic Systems Measurement, and Control, ISSN 0022-0434, E-ISSN 1528-9028, Vol. 136, nr 3, s. 031005-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This paper considers the problem of dynamic modeling and identification of robot manipulators with respect to their elasticities. The so-called flexible joint model, modeling only the torsional gearbox elasticity, is shown to be insufficient for modeling a modern industrial manipulator accurately. The extended flexible joint model, where non-actuated joints are added to model the elasticity of the links and bearings, is used to improve the model accuracy. The unknown elasticity parameters are estimated using a frequency domain gray-box identification method. The conclusion is that the obtained model describes the movements of the motors and the tool mounted on the robot with significantly higher accuracy. Similar elasticity model parameters are obtained when using two different output variables for the identification, the motor position and the tool acceleration.

    Nyckelord
    Modeling, flexible arms, calibration and identification, motion control, robot manipulator.
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-61667 (URN)10.1115/1.4026300 (DOI)000333588100005 ()
    Tillgänglig från: 2010-11-17 Skapad: 2010-11-17 Senast uppdaterad: 2017-12-12
    2. Nonlinear Gray-Box Identification Using Local Models Applied to Industrial Robots
    Öppna denna publikation i ny flik eller fönster >>Nonlinear Gray-Box Identification Using Local Models Applied to Industrial Robots
    2011 (Engelska)Ingår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 47, nr 4, s. 650-660Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In this paper, we study the problem of estimating unknown parameters in nonlinear gray-box models that may be multivariable, nonlinear, unstable, and resonant at the same time. A straightforward use of time-domain predication-error methods for this type of problem easily ends up in a large and numerically stiff optimization problem. We therefore propose an identification procedure that uses intermediate local models that allow for data compression and a less complex optimization problem. The procedure is based on the estimation of the nonparametric frequency response function (FRF) in a number of operating points. The nonlinear gray-box model is linearized in the same operating points, resulting in parametric FRFs. The optimal parameters are finally obtained by minimizing the discrepancy between the nonparametric and parametric FRFs. The procedure is illustrated by estimating elasticity parameters in a six-axes industrial robot. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest for robot control.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2011
    Nyckelord
    System identification, Multivariable systems, Nonlinear systems, Closed-loop identification, Frequency response methods, Industrial robots
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-61670 (URN)10.1016/j.automatica.2011.01.021 (DOI)000289968500002 ()
    Tillgänglig från: 2010-11-17 Skapad: 2010-11-17 Senast uppdaterad: 2017-12-12
    3. Inverse Dynamics of Flexible Manipulators
    Öppna denna publikation i ny flik eller fönster >>Inverse Dynamics of Flexible Manipulators
    2009 (Engelska)Ingår i: Proceedings of the 2009 Conference on Multibody Dynamics, 2009, s. 1-20Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    High performance robot manipulators, in terms of cycle time and accuracy, require well designed control methods, based on accurate dynamic models. Robot manipulators are traditionally described by the flexible joint model or the flexible link model. These models only consider elasticity in the rotational direction. When these models are used for control or simulation, the accuracy can be limited due to the model simplifications, since a real manipulator has a distributed flexibility inall directions. This work investigates different methods for the inverse dynamics of a more general manipulator model, called the extended flexible joint model. The inverse dynamics solution is needed for feedforward control, which is often used for high-precision robot manipulator control.

    The inverse dynamics of the extended flexible joint model can be computed as the solution of a high-index differential algebraic equation (DAE). One method is to solve the discretized DAE using a constant stepsize constant-order backwards differentiation formula (BDF). This work shows that there is only a small difference between solving theoriginal high-index DAE and the index-reduced DAE. It is also concluded that scaling of the algebraic equations and their derivatives is important.

    The inverse dynamics can be solved as an initial-value problem if the zero dynamics of the system is stable, i.e., minimum phase. For unstable zero dynamics, an optimization approach based on the discretized DAE is suggested. An optimization method, using a continuous DAE formulation, is also suggested and evaluated. The solvers are illustrated by simulation, using a manipulator with two actuators and five degrees-of-freedom.

    Nyckelord
    Manipulator, Control, Differential algebraic equation, Flexible multibody dynamics, Non-minimum phase, Inverse dynamics
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-61326 (URN)
    Konferens
    2009 Conference on Multibody Dynamics, Warsaw, Poland, 29th June - 2nd July, 2009
    Forskningsfinansiär
    Vetenskapsrådet
    Tillgänglig från: 2010-11-12 Skapad: 2010-11-12 Senast uppdaterad: 2013-09-16
    4. Inverse Dynamics of Robot Manipulators Using Extended Flexible Joint Models
    Öppna denna publikation i ny flik eller fönster >>Inverse Dynamics of Robot Manipulators Using Extended Flexible Joint Models
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    High performance robot manipulators, in terms of cycle time and accuracy, require well designed control methods, based on accurate dynamic models. This work investigates different methods for the inverse dynamics of a general manipulator model, called the extended flexible joint model. This model can describe elasticity in all directions, unlike the traditionally used robot models. The inverse dynamics solution is needed for feedforward control, which is often used for high-precision robot manipulator control. The inverse dynamics of the extended flexible joint model can be computed as the solution of a high index differential algebraic equation (DAE). The obtained DAE is analyzed, and solvers for both minimum phase and nonminimum phase systems are suggested. The solvers are evaluated by simulation, using a manipulator with two actuators and five degrees-of-freedom. Finally, the suggested concept for inverse dynamics is experimentally evaluated using an industrial robot manipulator. In this experimental evalution, an identified model is used in the inverse dynamics computation. Simulations using the same identified model are in good agreement with the experimental results. The conclusion is that the extended flexible joint inverse dynamics method can improve the accuracy for manipulators with significant elasticities,

    Nyckelord
    Modeling, flexible arms, calibration and identification, motion control, robot manipulator
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-61594 (URN)
    Tillgänglig från: 2010-11-17 Skapad: 2010-11-17 Senast uppdaterad: 2010-11-18
    5. On Feedback Linearization for Robust Tracking Control of Flexible Joint Robots
    Öppna denna publikation i ny flik eller fönster >>On Feedback Linearization for Robust Tracking Control of Flexible Joint Robots
    2008 (Engelska)Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 12218-12223Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Feedback linearization is one of the major academic approaches for controlling flexible joint robots. This contribution investigates the discrete-time implementation of the feedback linearization approach for a realistic three-axis robot model. A simulation study of high speed tracking with model uncertainty is performed. It is assumed that full state measurements of the linearizing states are available. The feedback linearization approach is compared to a feedforward approach.

    Nyckelord
    Robotics, Manipulation, Control, Feedforward, Feedback linearization, Discrete-time, Flexible joints
    Nationell ämneskategori
    Teknik och teknologier Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-43055 (URN)10.3182/20080706-5-KR-1001.02069 (DOI)71180 (Lokalt ID)978-3-902661-00-5 (ISBN)71180 (Arkivnummer)71180 (OAI)
    Konferens
    17th IFAC World Congress, Seoul, South Korea, July, 2008
    Tillgänglig från: 2009-10-10 Skapad: 2009-10-10 Senast uppdaterad: 2013-02-23Bibliografiskt granskad
    6. A Benchmark Problem for Robust Feedback Control of a Flexible Manipulator
    Öppna denna publikation i ny flik eller fönster >>A Benchmark Problem for Robust Feedback Control of a Flexible Manipulator
    2009 (Engelska)Ingår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 17, nr 6, s. 1398-1405Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A benchmark problem for robust feedback control of a flexible manipulator is presented. The system to be controlled is a four-mass system subject to input saturation, nonlinear gear elasticity, model uncertainties, and load disturbances affecting both the motor and the arm. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. Four suggested solutions are presented, and even though the solutions are based on different design methods, they give comparable results.

    Nyckelord
    Flexible structures, Manipulators, Position control, Robots, Robustness
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-51596 (URN)10.1109/TCST.2008.2006755 (DOI)
    Tillgänglig från: 2009-11-09 Skapad: 2009-11-09 Senast uppdaterad: 2017-12-12
    7. A Benchmark Problem for Robust Control of a Multivariable Nonlinear Flexible Manipulator
    Öppna denna publikation i ny flik eller fönster >>A Benchmark Problem for Robust Control of a Multivariable Nonlinear Flexible Manipulator
    2008 (Engelska)Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 1206-1211Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    A benchmark problem for robust feedback control of a manipulator is presented. The system to be controlled is an uncertain nonlinear two link manipulator with elastic gear transmissions. The gear transmission is described by nonlinear friction and elasticity. The system is uncertain according to a parametric uncertainty description and due to uncertain disturbances affecting both the motors and the tool. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only disturbance rejection. The proposed model is validated by experiments on a real industrial manipulator.

    Nyckelord
    Robust control, Control, Benchmark examples, Manipulators, Disturbance rejection, Flexible arms, Robotics
    Nationell ämneskategori
    Teknik och teknologier Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-43053 (URN)10.3182/20080706-5-KR-1001.00208 (DOI)71168 (Lokalt ID)978-3-902661-00-5 (ISBN)71168 (Arkivnummer)71168 (OAI)
    Konferens
    17th IFAC World Congress, Seoul, South Korea, July, 2008
    Tillgänglig från: 2009-10-10 Skapad: 2009-10-10 Senast uppdaterad: 2013-02-23
  • 6.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    On Modeling and Control of Flexible Manipulators2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Industrial robot manipulators are general-purpose machines used for industrial automation in order to increase productivity, flexibility, and quality. Other reasons for using industrial robots are cost saving, and elimination of heavy and health-hazardous work. Robot motion control is a key competence for robot manufacturers, and the current development is focused on increasing the robot performance, reducing the robot cost, improving safety, and introducing new functionalities. Therefore, there is a need to continuously improve the models and control methods in order to fulfil all conflicting requirements, such as increased performance for a robot with lower weight, and thus lower mechanical stiffness and more complicated vibration modes. One reason for this development of the robot mechanical structure is of course cost-reduction, but other benefits are lower power consumption, improved dexterity, safety issues, and low environmental impact.

    This thesis deals with three different aspects of modeling and control of flexible, i.e., elastic, manipulators. For an accurate description of a modern industrial manipulator, the traditional flexible joint model, described in literature, is not sufficient. An improved model where the elasticity is described by a number of localized multidimensional spring-damper pairs is therefore proposed. This model is called the extended flexible joint model. This work describes identification, feedforward control, and feedback control, using this model.

    The proposed identification method is a frequency-domain non-linear gray-box method, which is evaluated by the identification of a modern six-axes robot manipulator. The identified model gives a good description of the global behavior of this robot.

    The inverse dynamics control problem is discussed, and a solution methodology is proposed. This methodology is based on a differential algebraic equation (DAE) formulation of the problem. Feedforward control of a two-axes manipulator is then studied using this DAE approach.

    Finally, a benchmark problem for robust feedback control of a single-axis extended flexible joint model is presented and some proposed solutions are analyzed.

    Delarbeten
    1. Frequency-Domain Gray-Box Identification of Industrial Robots
    Öppna denna publikation i ny flik eller fönster >>Frequency-Domain Gray-Box Identification of Industrial Robots
    2008 (Engelska)Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 15372-15380Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper considers identification of unknown parameters in elastic dynamic models of industrial robots. Identifying such models is a challenging task since an industrial robot is a multivariable, nonlinear, resonant, and unstable system. Unknown parameters (mainly spring-damper pairs) in a physically parameterized nonlinear dynamic model are identified in the frequency domain, using estimates of the nonparametric frequency response function (FRF) in different robot configurations/positions. The nonlinear parametric robot model is linearized in the same positions and the optimal parameters are obtained by minimizing the discrepancy between the nonparametric FRFs and the parametric FRFs (the FRFs of the linearized parametric robot model). In order to accurately estimate the nonparametric FRFs, the experiments must be carefully designed. The selection of optimal robot configurations for the experiments is also part of the design. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest.

    Nyckelord
    System identification, Multivariable systems, Nonlinear systems, closed-loop identification, frequency response methods
    Nationell ämneskategori
    Teknik och teknologier Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-12711 (URN)10.3182/20080706-5-KR-1001.02600 (DOI)978-3-902661-00-5 (ISBN)
    Konferens
    17th IFAC World Congress, Seoul, South Korea, July, 2008
    Tillgänglig från: 2007-10-30 Skapad: 2007-10-30 Senast uppdaterad: 2013-02-23
    2. A DAE Approach to Feedforward Control of Flexible Manipulators
    Öppna denna publikation i ny flik eller fönster >>A DAE Approach to Feedforward Control of Flexible Manipulators
    2007 (Engelska)Ingår i: Proceedings of the 2007 IEEE International Conference on Robotics and Automation, IEEE , 2007, s. 3439-3444Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This work investigates feedforward control of elastic robot structures. A general serial link elastic robot model which can describe a modern industrial robot in a realistic way is presented. The feedforward control problem is discussed and a solution method for the inverse dynamics problem is proposed. This method involves solving a differential algebraic equation (DAE). A simulation example for an elastic two axis planar robot is also included and shows promising results.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2007
    Nyckelord
    Differential algebraic equations, Feedforward, Flexible manipulators, Industrial robots, Inverse problems
    Nationell ämneskategori
    Teknik och teknologier Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-12853 (URN)10.1109/ROBOT.2007.364004 (DOI)1-4244-0602-1 (ISBN)1-4244-0601-3 (ISBN)
    Konferens
    2007 IEEE International Conference on Robotics and Automation, Roma, Italy, April, 2007
    Tillgänglig från: 2008-01-07 Skapad: 2008-01-07 Senast uppdaterad: 2013-12-04
    3. A Benchmark Problem for Robust Feedback Control of a Flexible ManipulatorA benchmark problem for robust feedback control of a flexible manipulator
    Öppna denna publikation i ny flik eller fönster >>A Benchmark Problem for Robust Feedback Control of a Flexible ManipulatorA benchmark problem for robust feedback control of a flexible manipulator
    2007 (Engelska)Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    A benchmark problem for robust feedback control of a flexible manipulator is presented. The system to be controlled is a four-mass system subject to input saturation, nonlinear gear elasticity, model uncertainties, and load disturbances affecting both the motor and the arm. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. Four suggested solutions are presented, and even though the solutions are based on different design methods, they give comparable results.

    Ort, förlag, år, upplaga, sidor
    Linköping: Linköping University Electronic Press, 2007. s. 12
    Serie
    LiTH-ISY-R, ISSN 1400-3902 ; 2820
    Nyckelord
    Robots, manipulators, flexible structures, robustness, position control
    Nationell ämneskategori
    Reglerteknik
    Identifikatorer
    urn:nbn:se:liu:diva-12854 (URN)LiTH-ISY-R-2820 (ISRN)
    Tillgänglig från: 2008-01-07 Skapad: 2008-01-07 Senast uppdaterad: 2014-10-08Bibliografiskt granskad
  • 7.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    ABB, Sweden.
    A DAE Approach to Feedforward Control of Flexible Manipulators2007Ingår i: Proceedings of the 2007 IEEE International Conference on Robotics and Automation, IEEE , 2007, s. 3439-3444Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work investigates feedforward control of elastic robot structures. A general serial link elastic robot model which can describe a modern industrial robot in a realistic way is presented. The feedforward control problem is discussed and a solution method for the inverse dynamics problem is proposed. This method involves solving a differential algebraic equation (DAE). A simulation example for an elastic two axis planar robot is also included and shows promising results.

  • 8.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A New Approach to Modelling and Control of Flexible Manipulators2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This work investigates feedforward control of elastic robot structures. A general serial link elastic robot model which can describe a modern industrial robot in a realistic way is presented. The feedforward control problem is discussed and a solution method for the inverse dynamics problem is proposed. This method involves solving a differential algebraic equation (DAE). A simulation example for an elastic two axis planar robot is also included and shows promising results.

  • 9.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Royal Institute of Technology, Sweden.
    Inverse Dynamics of Flexible Manipulators2009Ingår i: Proceedings of the 2009 Conference on Multibody Dynamics, 2009, s. 1-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    High performance robot manipulators, in terms of cycle time and accuracy, require well designed control methods, based on accurate dynamic models. Robot manipulators are traditionally described by the flexible joint model or the flexible link model. These models only consider elasticity in the rotational direction. When these models are used for control or simulation, the accuracy can be limited due to the model simplifications, since a real manipulator has a distributed flexibility inall directions. This work investigates different methods for the inverse dynamics of a more general manipulator model, called the extended flexible joint model. The inverse dynamics solution is needed for feedforward control, which is often used for high-precision robot manipulator control.

    The inverse dynamics of the extended flexible joint model can be computed as the solution of a high-index differential algebraic equation (DAE). One method is to solve the discretized DAE using a constant stepsize constant-order backwards differentiation formula (BDF). This work shows that there is only a small difference between solving theoriginal high-index DAE and the index-reduced DAE. It is also concluded that scaling of the algebraic equations and their derivatives is important.

    The inverse dynamics can be solved as an initial-value problem if the zero dynamics of the system is stable, i.e., minimum phase. For unstable zero dynamics, an optimization approach based on the discretized DAE is suggested. An optimization method, using a continuous DAE formulation, is also suggested and evaluated. The solvers are illustrated by simulation, using a manipulator with two actuators and five degrees-of-freedom.

  • 10.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Royal Institute of Technology, Sweden.
    Inverse Dynamics of Flexible Manipulators - A DAE Approach2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The inverse dynamics for a flexible manipulator can be formulated as a differential-algebraic equation (DAE). The the inverse dynamics is, e.g., used for feedforward control. This work investigates different methods for analyzing and solving these equations.

  • 11.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Department of Solid Mechanics, Royal Institute of Technology, Stockholm, Sweden.
    Inverse Dynamics of Robot Manipulators Using Extended Flexible Joint ModelsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    High performance robot manipulators, in terms of cycle time and accuracy, require well designed control methods, based on accurate dynamic models. This work investigates different methods for the inverse dynamics of a general manipulator model, called the extended flexible joint model. This model can describe elasticity in all directions, unlike the traditionally used robot models. The inverse dynamics solution is needed for feedforward control, which is often used for high-precision robot manipulator control. The inverse dynamics of the extended flexible joint model can be computed as the solution of a high index differential algebraic equation (DAE). The obtained DAE is analyzed, and solvers for both minimum phase and nonminimum phase systems are suggested. The solvers are evaluated by simulation, using a manipulator with two actuators and five degrees-of-freedom. Finally, the suggested concept for inverse dynamics is experimentally evaluated using an industrial robot manipulator. In this experimental evalution, an identified model is used in the inverse dynamics computation. Simulations using the same identified model are in good agreement with the experimental results. The conclusion is that the extended flexible joint inverse dynamics method can improve the accuracy for manipulators with significant elasticities,

  • 12.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Royal Institute of Technology, Sweden.
    On Feedback Linearization for Robust Tracking Control of Flexible Joint Robots2008Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 12218-12223Konferensbidrag (Refereegranskat)
    Abstract [en]

    Feedback linearization is one of the major academic approaches for controlling flexible joint robots. This contribution investigates the discrete-time implementation of the feedback linearization approach for a realistic three-axis robot model. A simulation study of high speed tracking with model uncertainty is performed. It is assumed that full state measurements of the linearizing states are available. The feedback linearization approach is compared to a feedforward approach.

  • 13.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Royal Institute of Technology, Sweden.
    On Feedback Linearization for Robust Tracking Control of Flexible Joint Robots2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Feedback linearization is one of the major academic approaches for controlling flexible joint robots. This contribution investigates the discrete-time implementation of the feedback linearization approach for a realistic three-axis robot model. A simulation study of high speed tracking with model uncertainty is performed. It is assumed that full state measurements of the linearizing states are available. The feedback linearization approach is compared to a feedforward approach.

  • 14.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wernholt, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    Royal Institute of Technology, Department of Solid Mechanics.
    Brogårdh, Torgny
    ABB AB, Sweden.
    Modeling and Parameter Estimation of Robot Manipulators using Extended Flexible Joint Models2014Ingår i: Journal of Dynamic Systems Measurement, and Control, ISSN 0022-0434, E-ISSN 1528-9028, Vol. 136, nr 3, s. 031005-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper considers the problem of dynamic modeling and identification of robot manipulators with respect to their elasticities. The so-called flexible joint model, modeling only the torsional gearbox elasticity, is shown to be insufficient for modeling a modern industrial manipulator accurately. The extended flexible joint model, where non-actuated joints are added to model the elasticity of the links and bearings, is used to improve the model accuracy. The unknown elasticity parameters are estimated using a frequency domain gray-box identification method. The conclusion is that the obtained model describes the movements of the motors and the tool mounted on the robot with significantly higher accuracy. Similar elasticity model parameters are obtained when using two different output variables for the identification, the motor position and the tool acceleration.

  • 15.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB Corporate Research, Sweden.
    Robust Control Of A Flexible Manipulator Arm: A Benchmark Problem2005Ingår i: Proceedings of the 16th IFAC World Congress, 2005, s. 966-966Konferensbidrag (Refereegranskat)
    Abstract [en]

    A control engineering benchmark problem with industrial relevance is presented. The process is a simulation model of a nonlinear four-mass system, which should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only the so-called regulator problem.

  • 16.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB Corporate Research, Sweden.
    Robust Control Of A Flexible Manipulator Arm: A Benchmark Problem2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A control engineering benchmark problem with industrial relevance is presented. The process is a simulation model of a nonlinear four-mass system, which should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only the so-called regulator problem.

  • 17.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB AB, Crane Systems, Sweden.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A Benchmark Problem for Robust Control of a Multivariable Nonlinear Flexible Manipulator2008Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 1206-1211Konferensbidrag (Refereegranskat)
    Abstract [en]

    A benchmark problem for robust feedback control of a manipulator is presented. The system to be controlled is an uncertain nonlinear two link manipulator with elastic gear transmissions. The gear transmission is described by nonlinear friction and elasticity. The system is uncertain according to a parametric uncertainty description and due to uncertain disturbances affecting both the motors and the tool. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only disturbance rejection. The proposed model is validated by experiments on a real industrial manipulator.

  • 18.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB AB, Crane Systems, Sweden.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A Benchmark Problem for Robust Control of a Multivariable Nonlinear Flexible Manipulator2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A benchmark problem for robust feedback control of a manipulator is presented. The system to be controlled is an uncertain nonlinear two link manipulator with elastic gear transmissions. The gear transmission is described by nonlinear friction and elasticity. The system is uncertain according to a parametric uncertainty description and due to uncertain disturbances affecting both the motors and the tool. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. The control problem concerns only disturbance rejection. The proposed model is validated by experiments on a real industrial manipulator.

  • 19.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB AB, Sweden.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A Benchmark Problem for Robust Feedback Control of a Flexible Manipulator2009Ingår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 17, nr 6, s. 1398-1405Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A benchmark problem for robust feedback control of a flexible manipulator is presented. The system to be controlled is a four-mass system subject to input saturation, nonlinear gear elasticity, model uncertainties, and load disturbances affecting both the motor and the arm. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. Four suggested solutions are presented, and even though the solutions are based on different design methods, they give comparable results.

  • 20.
    Moberg, Stig
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Öhr, Jonas
    ABB AB, Sweden.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    A Benchmark Problem for Robust Feedback Control of a Flexible ManipulatorA benchmark problem for robust feedback control of a flexible manipulator2007Rapport (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    A benchmark problem for robust feedback control of a flexible manipulator is presented. The system to be controlled is a four-mass system subject to input saturation, nonlinear gear elasticity, model uncertainties, and load disturbances affecting both the motor and the arm. The system should be controlled by a discrete-time controller that optimizes performance for given robustness requirements. Four suggested solutions are presented, and even though the solutions are based on different design methods, they give comparable results.

  • 21.
    Norrlöf, Mikael
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Henriksson, Robert
    McKinsey & Company, Sweden.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wernholt, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Schön, Thomas
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Experimental Comparison of Observers for Tool Position Estimation of Industrial Robots2009Ingår i: Proceedings of the 48th IEEE Conference on Decision and Control, 2009, s. 8065-8070Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates methods for tool position estimation of industrial robots. It is assumed that the motor angular position and the tool acceleration are measured. The considered observers are different versions of the extended Kalman filter as well as a deterministic observer. A method for tuning the observers is suggested and the robustness of the methods is investigated. The observers are evaluated experimentally on a commercial industrial robot.

  • 22.
    Wallén, Johanna
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Henriksson, Robert
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Norrlöf, Mikael
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    ILC Applied to a Flexible Two-Link Robot Model using Sensor-Fusion-Based Estimates2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Estimates from an extended Kalman filter (EKF) is used in an Iterative Learning Control (ILC) algorithm applied to a realistic two-link robot model with flexible joints. The angles seen from the arm side of the joints (arm angles) are estimated by an EKF in two ways: 1) using  measurements of angles seen from the motor side of the joints (motor angles), which normally  are the only measurements available in commercial industrial robot systems, 2) using both motor- angle and tool-acceleration measurements. The estimates are then used in an ILC algorithm. The results show that the actual arm angles are clearly improved compared to when only motor angles are used in the ILC update, even though model errors are introduced.

  • 23.
    Wallén, Johanna
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Gunnarsson, Svante
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Norrlöf, Mikael
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Henriksson, Robert
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    ILC Applied to a Flexible Two-Link Robot Model using Sensor-Fusion-Based Estimates2009Ingår i: Proceedings of 48th IEEE Conference on Decision and Control, IEEE , 2009, s. 458-463Konferensbidrag (Refereegranskat)
    Abstract [en]

    Estimates from an extended Kalman filter (EKF) is used in an Iterative Learning Control (ILC) algorithm applied to a realistic two-link robot model with flexible joints. The angles seen from the arm side of the joints (arm angles) are estimated by an EKF in two ways: 1) using  measurements of angles seen from the motor side of the joints (motor angles), which normally  are the only measurements available in commercial industrial robot systems, 2) using both motor- angle and tool-acceleration measurements. The estimates are then used in an ILC algorithm. The results show that the actual arm angles are clearly improved compared to when only motor angles are used in the ILC update, even though model errors are introduced.

  • 24.
    Wernholt, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Experimental Comparison of Methods for Multivariable Frequency Response Function Estimation2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Nonparametric estimation methods for the multivariable frequency response function are experimentally evaluated using closed-loop data from an industrial robot. Three classical estimators (H1, joint input-output, arithmetic mean) and two estimators based on nonlinear averaging techniques (harmonic mean, geometric/logarithmic mean) are considered. The estimators based on nonlinear averaging give the best results, followed by the arithmetic mean estimator, which gives a slightly larger bias. The joint input-output estimator, which is asymptotically unbiased in theory, turns out to give large bias errors for low frequencies. Finally, the H1 estimator gives the largest bias for all frequencies.

  • 25.
    Wernholt, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Experimental Comparison of Methods for Multivariable Frequency Response Function Estimation2008Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 15359-15366Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nonparametric estimation methods for the multivariable frequency response function are experimentally evaluated using closed-loop data from an industrial robot. Three classical estimators (H1, joint input-output, arithmetic mean) and two estimators based on nonlinear averaging techniques (harmonic mean, geometric/logarithmic mean) are considered. The estimators based on nonlinear averaging give the best results, followed by the arithmetic mean estimator, which gives a slightly larger bias. The joint input-output estimator, which is asymptotically unbiased in theory, turns out to give large bias errors for low frequencies. Finally, the H1 estimator gives the largest bias for all frequencies.

  • 26.
    Wernholt, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Frequency-Domain Gray-Box Identification of Industrial Robots2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This paper considers identification of unknown parameters in elastic dynamic models of industrial robots. Identifying such models is a challenging task since an industrial robot is a multivariable, nonlinear, resonant, and unstable system. Unknown parameters (mainly spring-damper pairs) in a physically parameterized nonlinear dynamic model are identified in the frequency domain, using estimates of the nonparametric frequency response function (FRF) in different robot configurations/positions. The nonlinear parametric robot model is linearized in the same positions and the optimal parameters are obtained by minimizing the discrepancy between the nonparametric FRFs and the parametric FRFs (the FRFs of the linearized parametric robot model). In order to accurately estimate the nonparametric FRFs, the experiments must be carefully designed. The selection of optimal robot configurations for the experiments is also part of the design. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest.

  • 27.
    Wernholt, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Frequency-Domain Gray-Box Identification of Industrial Robots2008Ingår i: Proceedings of the 17th IFAC World Congress, 2008, s. 15372-15380Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper considers identification of unknown parameters in elastic dynamic models of industrial robots. Identifying such models is a challenging task since an industrial robot is a multivariable, nonlinear, resonant, and unstable system. Unknown parameters (mainly spring-damper pairs) in a physically parameterized nonlinear dynamic model are identified in the frequency domain, using estimates of the nonparametric frequency response function (FRF) in different robot configurations/positions. The nonlinear parametric robot model is linearized in the same positions and the optimal parameters are obtained by minimizing the discrepancy between the nonparametric FRFs and the parametric FRFs (the FRFs of the linearized parametric robot model). In order to accurately estimate the nonparametric FRFs, the experiments must be carefully designed. The selection of optimal robot configurations for the experiments is also part of the design. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest.

  • 28.
    Wernholt, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Nonlinear Gray-Box Identification Using Local Models Applied to Industrial Robots2011Ingår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 47, nr 4, s. 650-660Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we study the problem of estimating unknown parameters in nonlinear gray-box models that may be multivariable, nonlinear, unstable, and resonant at the same time. A straightforward use of time-domain predication-error methods for this type of problem easily ends up in a large and numerically stiff optimization problem. We therefore propose an identification procedure that uses intermediate local models that allow for data compression and a less complex optimization problem. The procedure is based on the estimation of the nonparametric frequency response function (FRF) in a number of operating points. The nonlinear gray-box model is linearized in the same operating points, resulting in parametric FRFs. The optimal parameters are finally obtained by minimizing the discrepancy between the nonparametric and parametric FRFs. The procedure is illustrated by estimating elasticity parameters in a six-axes industrial robot. Different parameter estimators are compared and experimental results show the usefulness of the proposed identification procedure. The weighted logarithmic least squares estimator achieves the best result and the identified model gives a good global description of the dynamics in the frequency range of interest for robot control.

  • 29.
    Öhr, Jonas
    et al.
    ABB, Sweden.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wernholt, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    ABB, Sweden.
    Pettersson, Jens
    ABB, Sweden.
    Persson, Sofie
    ABB, Sweden.
    Sander-Tavallaey, Shiva
    ABB, Sweden.
    Identification of Flexibility Parameters of 6-axis Industrial Manipulator Models2006Ingår i: Proceedings of the 2006 International Conference on Noise and Vibration Engineering, 2006, s. 3305-Konferensbidrag (Refereegranskat)
    Abstract [en]

    A method for identification of flexibility parameters of a 18 DOF (degrees offreedom) robot prototype model is proposed. Experiments show the strengthof the method and the results indicates that flexibilities in the bearings and thearms, taken together, are of the same order as the flexibilities in the gears.

  • 30.
    Öhr, Jonas
    et al.
    ABB, Sweden.
    Moberg, Stig
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wernholt, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hanssen, Sven
    ABB, Sweden.
    Pettersson, Jens
    ABB, Sweden.
    Persson, Sofie
    ABB, Sweden.
    Sander-Tavallaey, Shiva
    ABB, Sweden.
    Identification of Flexibility Parameters of 6-axis Industrial Manipulator Models2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A method for identification of flexibility parameters of a 18 DOF (degrees offreedom) robot prototype model is proposed. Experiments show the strengthof the method and the results indicates that flexibilities in the bearings and thearms, taken together, are of the same order as the flexibilities in the gears.

1 - 30 av 30
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