This concept paper focuses on integrating the Hydraulic Infinite Linear Actuator - Multi Rod (HILA-MR) technology into Variable Camber Continuous Trailing Edge Flap (VCCTEF) systems for Blended Wing Body (BWB) aircraft. HILA-MR is a novel actuator design enabling precise control of multiple flap segments in a VCCTEF via shared pistons. The HILA-MR/VCCTEF system demonstrates significantly lower power requirements compared to traditional simple flap systems and promotes a more optimal use of force and speed potential of hydraulic actuation throughout the flight envelope, reducing power requirements and contributing to overall efficiency and lower fuel burn. The system offers potential for drag reduction, improved efficiency, and reduced weight and volume for actuation and secondary power components in BWB aircraft. The aim of this paper is to give a comprehensive presentation of the HILA-MR system in a VCCTEF application, evaluate different aspects, design issues and benchmark the technology against present solutions.   

New technologies and innovations to reduce carbon dioxide emissions in the aeronautics industry are essential. The morphing wing concept is an excellent method to increase aircraft performance and reduce fuel consumption and may now become re-applied using a new actuation technology. Nevertheless, for the moment, several showstoppers inhibit the commercial introduction of morphing systems. A morphing wing design's structural skeleton, actuator and sensor network are characterized by an extensive and multi-branched network of actuators and sensors and many mechanical and electrical components that reduce reliability, availability, flight safety and maintainability. It also dramatically impacts weight, volume, complexity and costs. Therefore, less complex and more robust solutions are desired for the morphing wing technology to become a realistic alternative for the aeronautics industry.  Future morphing wing systems in aircraft can be improved significantly by utilizing a new type of hydraulic linear actuator invention, the Hydraulic Infinite Linear Actuator with Multiple Rods (HILA MR). A single HILA MR actuator has the potential to replace the whole actuator and sensor network in a morphing wing, enabling substantial rationalization in several ways and facilitating certification and commercial introduction.  Furthermore, compared to conventional actuating technologies, a HILA MR architecture allows for controlling the morphing structure using reduced mass and volume, enabling a power consumption reduction. With HILA MR, the mechanical actuation of the control surfaces may be embedded into the aircraft's fuselage in a bio-mimicking fashion similar to the human hand, where the muscles that control the fingers of the hand are located in the forearm. Light Dyneema fibre cables with high tensile strength are used to distribute actuator motions in the fuselage to the control surface, similar to how they are used in cable robots. In addition, the location of the actuator facilitates a slender wing design.  The HILA MR technology enables a novel way to generate and distribute linear mechanical movement for flight control and wing morphing. It mimics the characteristics of hydraulic servo cylinders, but the piston actuates several multiple rods in a switching fashion, using clamping elements. The HILA technology acts according to a timing-controlled shifting of operating modes between continuous and discrete incremental actuator positioning steps. Each rod actuates one part of the wings morphing mechanical structure. The application of this technology in aviation is also characterized by the following: a reduced number of servo valves, well-known clamping technology used for both stepping and locking functionality, a reduced number of position feedback sensors and a local hydraulic system in the fuselage or situated in the wing box with a small oil reservoir volume.  This paper aims to evaluate different aspects and design issues of the HILA MR system in a morphing wing application (actuator, sensor, control system and structural skeleton) and compare the technology against present electromechanical solutions. In addition, a simplified morphing wing system simulation model based on HILA MR is presented. Results from initial simulations show that the concept is attainable and will have the required response timings. 

In forestry and agriculture industry, robust and power-dense hydraulics have long played an important role for a rational and cost-effective logistics. In these fields there is a trend towards longer, larger and heavier vehicles and machines. Within the forestry business there is a need to develop transport vehicles with lower energy consumption. This can be done by improving the vehicles' aerodynamics. The air resistance of unloaded timber trucks and timber trains will be significantly reduced if stakes and banks are put together. Furthermore, there is a need to place banks and stakes at individual distances individually to accomplish different load combinations. In agriculture when sowing, it is an advantage to be able to flexibly position row units on a seed drill in optimal distances from each other to secure productive and sustainable farming. However, most present seed drills have fixed row distances and thus have a low adaptability for different crops or soil conditions. There is also a need for a faster transport of the seed drill between different fields.  Future actuation systems for forestry and agricultural vehicles and machines can be improved by utilizing a new sort of hydraulic linear actuator technology, the Hydraulic Infinite Linear Actuator (HILA). HILA technology also has an impact on heavy and dangerous manual steps when changing banks and stakes on timber vehicles. The adjustment can be controlled from the cabin, thus eliminating manual steps. Heavy bank elements on a timber vehicle can be positioned individually with high locking force. In the agricultural context, it is possible to quickly change between different inter-row spacing on a seed drill when using HILA technology, enabling a multi-purpose seed drill and inter-row cultivator. HILA long stroke capability also facilitates a smooth folding into a compact transport position. With the bills are gathered, a low center of gravity will be accomplished. This enables a more stable vehicle dynamics and enables a higher speed. HILA is based on a well-known hydraulic clamping element technology, where the piston and the piston rod can be coupled and uncoupled by means of the clamping element. The HILA invention, in its simplest usage, provides new features to hydraulic cylinders, such as providing very long strokes and small chamber volumes, which means high stiffness and low capacitance. However, the invention also enables lower weight and volume of the actuator when compared to conventional hydraulic cylinders. This is a new way to generate and distribute mechanical linear movement and force by using hydraulic actuators in a cost effective way. The technology also represents a new sort of digital hydraulics. The technology is best suited for relatively slow dynamics and where the movement pattern is well-known. 

SICFP2017

This is the proceedings of the 15th Scandinavian International Conference on Fluid Power held at Linköping University in Sweden on 7-9 June 2017. The theme of the conference was “Fluid Power in the Digital Age”. The contributions are well aligned with this theme, and are indeed reflecting the great developments. We are very grateful to the effort put in by the authors to produce such high quality papers, and also to those taking time to review papers to further enhance the quality. The contributions clearly shows that the fluid power industry, and academia, have both challenges as well as opportunities in keeping up with the evolving capabilities provided by the digitalization. It was with great joy to see old and new colleagues and friends attending our conference and the division of Fluid and mechatronic systems, at Linköping University. The conference is a bi-annual event, with alternating localization between Linköping in Sweden and Tampere in Finland. The process of hosting such an event is a great effort for our organization and I would like to thank all those involved in organizing this conference, and wish good luck with the next one to our Finnish colleagues. Thank you!

Prof. Petter Krus

Head of Division

Fluid and Mechatronic Systems

Review Process

Each author attending the conference days had the opportunity to select from three different ways of presenting their contribution. Firstly, a reviewed process with at least two international reviewers of each contribution. The process resulted in most cases with feedback from the reviewers with comments spanning everything between diagram legends to scientific methods. Some proposed papers where rejected upon recommendations from reviewers. Secondly contributions where also presented in industry sessions where the review process where internal only by the staff of the division. A third extended abstract presentation format where also presented during the conference.

This proceedings contain all presented contributions from the reviewed papers in the first section and thereafter the non-reviewed papers in second section. All reviewed papers are marked in the footer by the acceptance date.

Future hydraulic actuation systems can be significantly improved by utilisation of a new type of hydraulic linear actuator technology. By enabling multiple actuating elements, integrated in a compact and lightweight single unit controlled by ordinary directional valves it is possible to achieve a high position accuracy. This is a new way to generate and distribute mechanical linear movement and force by using hydraulic actuators in a cost effective way, in less responsive closed loop systems. This is a variant on the Hydraulic Infinite Linear Actuator, HILA, invention. The technology also represents a new sort of digital hydraulics. The presented technology provides typical hydraulic actuator characteristics with high system pressure and potentially no external oil leakage. It is based on a well-known hydraulic clamping element technology used in a new way, where the piston and the piston rod can quickly be coupled and uncoupled by means of the clamping element in a failsafe way by using well defined incremental steps. HILA in its simplest usage, provides new features to hydraulic cylinders such as providing very long strokes, high rod speed, and small chamber volumes which means high stiffness and low capacitance. The aim of this study is to present a fundamentally new way of using hydraulic actuators. The invention is called the Hydraulic Infinite Linear Actuator with Multiple Rods, HILA MR. The study presents the idea, principles and feasible combinations of the technology. Also applications in the aircraft and robotic field will be presented. 

Digital hydraulics is an ongoing trend that offers many interesting advantages and possibilities. Digital refers to that the system output is discrete, e.g. using an on/off valve with only discrete values or a finite amount of flow steps available. The advantages mentioned when compared to analogue systems are better performance, robust and fault tolerant, and amplitude independent bandwidth. On the other side noise and pressure pulsations must be handled, the physical size can be a problem, and the system requires complicated control. When considering control of linear motion, there are mainly two branches, controlling the flow with several parallel connected on/off valves, which generates discrete output flow values, or switching valves, which in theory can generate any mean output flow. The latter only requires one valve for each flow path but the demand for fast valves is very high, while the former requires many valves but avoids high frequent switching. With the introduction of a multi-chamber cylinder, secondary control is now also possible for linear motion. This paper is a first step in the investigation of the system applied to an excavator arm. The cylinder has four chambers, each with different area. Three pressure lines are used and a valve-pack of 27 on/off valves. The valve-pack connects the three pressure lines with each chamber generating 81 available force steps. The scope has been to start out with relative simple control of the velocity of the cylinder. To handle unnecessary switching of valves, different penalty strategies were tested. The results are promising where relatively smooth control could be achieved at the same time challenges with the system were identified. Next step is to investigate the force transients due to different capacitance in all four chambers as well as mode control for better accuracy. Energy potential compared to original system remains to investigate as well.

The main performance characteristics of a heli- copter is its fuel consumption. This paper re- ports the current state in an ongoing project seeking a fast and approximative implementa- tion of mathematical models for helicopter per- formance predictions, primarily in terms of fuel consumption. The model is limited to a subset of the normal operation modes, only including hover, climb and forward. Also, the focus is on smaller rotors, i.e. sub-scale rotors in the range of 1.5m to 4.0m in diameter as used in unmanned airborne vehicles (VTOL-UAV). The presented work consists of three parts; the heli- copter performance mathematical model and the numerical optimization method used for dealing with its implicit nature, the approximation grid scheme and the simulation of flight paths. The overall objective of the project is to establish an computational efficient approximative model us- able for onboard condition monitoring of the he- licopter performance and fuel consumption. 

Neuro mechanical network (NMN) is a new concept of adaptronic character. The governing idea is to include geometry, topology, load carrying, energy transfer, actuating, sensing and control of a machine in one single mathematical state model and, thereby, enable a formulation of the design and configuration problem as an optimization problem. We have focused our attention on a type of NMN consisting of what we call active trusses. For these, we have established a state model and given a design optimization problem from which we have obtained numerical solutions. These solutions show that the approach has the possibility to suggest new families of designs that are superior to those of classical passive trusses. We also indicate how activation may result in singularities, the treatment of which is, so far, essentially an open problem.

Simulation is a great tool to help the development of products. For simulation to be a validtool there are high demands on the models, where they need to be accurate and fast, regardingcomputational time.  This work is a first step to model and implement a 4 wheel drive system.The system is electronically controlled and the torque transferred by the system is dependenton the pressure built up by the hydraulic system. This work focuses primary on the develop-ment of the solenoid pressure control valve model. In order to perform simulations, the valvemodel needs to be connected to the rest of the system. The supply pressure is provided froma piston accumulator, that is implemented only to provide the right functionality at this stage.The load in this system is composed of a wet multiplate clutch, that is implemented only as astatic model based on measurements. The modeling of the valve was divided into studying theelectromagnetical part and hydromechanical part separately. The electromagnetical part, i.e.the solenoid, is modeled as a resistor in series with a nonlinear inductor. The electromagneticcharacteristics is modeled with the help of a curve fitting technique. A testbench was developedfor this purpose. The simulation results of the solenoid agrees well with measured results. Alinearized analysis of the hydromechanical part was performed in order to better understand thedynamics of the valve and see the most dominant effects. Two valve configurations resultedfrom this work. One includes more dynamics and has the possibility to change more param-eters in order to study different effects. The other configuration was based on the linearizedanalysis and therefore includes only the most dominant dynamics. This model is much fasterto simulate. Both configuration shows accurate results when compared to measurements of thesystem.