This paper is a study into the possibility to use a self-regulated pressure control valve as a way of realizing active steering into road vehicles by hydraulic means. From an actuator point of view, active steering refers to the possibility to control the assistance pressure via an external signal. From the steering system control loop, it is seen that the task of the steering system is to control the assistance pressure in each chamber of the assistance cylinder. A methodology is also derived for investigating the concept and finding a set of design parameters based on system requirements. This is based on a linear approach and later a simulation of the complete steering system with vehicle and driver. In order to assure good control accuracy during fast actuation of the valve a high gain is required. This would require an over damped valve with large proportions. This design was tested to verify the design methodology. A feasible design based on maximum available spool force was also tested. This design showed to large deviation in steering wheel torque compared to the original system.

Today’s passenger vehicles are becoming more and more safe as more steering related active safety functions are being introduced. As an example, lane keeping assist functions or even electronic vehicle stability with steering intervention can be mentioned. However, the same trend can yet not be witnessed for heavy vehicles, which is, among others, due to a lesser degree of controllability of the steering system. While electric power assisted steering has been introduced in passenger cars in recent years on a broader basis, electric power assisted steering is yet not suitable for heavy vehicles due to heavier loads on the steering rack. Heavy vehicles thus lack a freely programmable steering system.The purpose of this paper is to generate and evaluate the requirements of future hydraulic actuation concepts for heavy vehicles, where emphasis is put on the required steering actuator linearity and bandwidth. Both actuator response and linearity are decisive for transmitting a proper steering feel to the driver. In this study we provide a structured approach to derive the required bandwidth as a function of the system sizing and provide a simulation supported method for deriving the requirements of linearity and accuracy.

Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles. Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.

This paper presents a new automotive safety function called Emergency Lane Assist (ELA). ELA combines conventional lane guidance systems with a threat assessment module that tries to activate the lane guidance interventions according to the actual risk level of lane departure. The goal is to only prevent dangerous lane departure maneuvers. The ELA safety function is based on a statistical method that evaluates a list of safety concepts and tries to maximize the impact on accident statistics while minimizing development and hardware component costs. ELA runs in a demonstrator and successfully intervenes during lane changes that are likely to result in a collision and is also able to take control of the vehicle and return it to a safe position in the original lane. It has also been tested on 2000 km of roads in traffic without giving any false interventions

This paper presents a new automotive safety function called Emergency Lane Assist (ELA). ELA combines conventional lane guidance systems with a threat assessment module that tries to activate the lane guidance interventions according to the actual risk level of lane departure. The goal is to only prevent dangerous lane departure maneuvers. The ELA safety function is based on a statistical method that evaluates a list of safety concepts and tries to maximize the impact on accident statistics while minimizing development and hardware component costs. ELA. runs in a demonstrator and successfully intervenes during lane changes that are likely to result in a collision and is also able to take control of the vehicle and return it to a safe position in the original lane. It has also been tested on 2000 km of roads in traffic without giving any false interventions.

The performance of a parking system is dependent on many factors. One is the placement of the sensors. In this paper a system which uses ultrasonic ranging sensors is considered. The mounting of a ultrasonic sensor on a passenger vehicle is restricted by, among other factors, design, assembly process, enclosure cost and reliability. All of which must be considered when choosing optimal mounting locations.

The basis of this work includes a ray-trace based simulation environment which is used to capture the physical properties of sound traveling through air. The simulation environment together with sensor models, is used to evaluate the effect of different mounting positions on the accuracy of the detection of the parking space. The Hough transform is used here, as well as in the real system, in order to extract the confining lines of the parking space from the sensor measurements. The strength of these lines are then used to compare different sensor mounting locations.

The created simulation environment differs from other work in this area since it tries to capture the physical properties of the sound waves as opposed to the geometric-only approach. The emitted sound pulse is divided into a large number of rays, each with sound properties tied to them. These rays are then traced through a model of the parking space environment, reflections are calculated and finally the summarized echo into the listening sensor is calculated.

The simulation is implemented in 3D Studio MAX which make it relatively easy to create various realistic parking scenarios. An important factor for choosing 3D Studio MAX as the basis of the simulation environment was that it allowed for a new way of modeling ultrasonics using ray-tracing, and at the same time - using the same ray-tracing technology - excellent visualization capabilities.

Car parking has been, and still is, a growing problem, with increasing vehicle sizes in the luxury segment as well as sport-utility vehicles. This is especially true when bearing in mind the confined parking spaces in parking lots and cities. While damage during parking generally does not cause any injury to the passengers, it is costly and annoying. Park assist systems are by no means new on the market, since passive systems which provide longitudinal guidance using ultrasonic distance sensors have been available on the market for a number of years.

The system presented is a semi-automated approach to parallel parking problems, as they frequently occur in European and Asian cities. The challenge during the development of this system was to have as few components as possible added to a standard vehicle, seeking reuse of many of the already built-in functionalities. The result is a system that leaves the longitudinal control of the vehicle to the driver but automates the steering process, and even stops the vehicle when the final parking position is reached.

This paper describes a system for supporting the driver of a passenger car in different parking situations. Todays cars are getting larger in size and the drivers view in both forward and rearward direction is becoming more limited. This fact calls for a system of sensors and algorithms capable of supporting the driver through the parking maneuvre in a safe and smooth way.

The paper presents the development of some of the subsystems in a fully automatic parallel parking system, utilizing ultrasonic ranging sensors for environment mapping. In contrast to existing passive parking aid systems, the ultrasonic range sensors need to have a narrower aperture to be able to map the surroundings properly. This can be accomplished by either increased sensor size or by a higher number of sensors.

The emphasis of the paper is the signal conditioning in the parking system. The Hough-transform along with a statistical CUSUM test are used to find the properties of the target parking space.

The system makes use of hardware components already available in modern cars and a small number of added components. The resulting system is automated, from finding a suitable parking space to maneuvering the car into the parking space, while keeping the driver in authority since the longitudinal control, i.e. throttle and brakes, are still the drivers responsibilities.

The prototype system is implemented in a Volvo S60 which has been modified with an electric power steering unit and an ultrasonic sensor array consisting of a total of six sensors spread out around the vehicle. The electric power steering unit is used for steering wheel angle control when the system is active by adding an external torque to the assist torque normally applied.

The traditional way of assisting car drivers during steering is with the help of hydraulic power assisted steering (HPAS) systems, which were introduced in the 1960's. In these systems, the torque the driver applies to the steering wheel is used to open a spool valve, which then modulates the load pressure in a hydraulic piston in the steering gear, thus assisting the driver. Such systems are regarded as cost effective and robust, but at the same time associated with limited flexibility. Since the broad introduction of electric power assisted steering (EPAS) systems during past years, the possibility to freely control steering wheel torque has been achieved. Steering wheel torque control is utilized both by comfort and safety functions, such as park assist systems and lane keeping assist systems or the next generation of active yaw control functions. In this paper, a solution to the controllability problem is presented for conventional HPAS systems. The solution is based on a traditional hydraulic power steering unit with modification to the valve. Added to the valve is an extra pilot motor, which enables the valve to be actuated electrically without compromising the basic robust mechanical solution of a traditional hydraulic power steering unit. Control strategies for position control and offset torque control have been presented together with test results carried out in a hardware in the loop test rig. An important advantage of the proposed solution is its low electric energy consumption. The electric motor has to compensate for the tiny sealing friction in the hydraulic spool valve. In other respects it relies on the power gain capability of the hydraulic system. This concept is called Active Pinion.

This paper describes how a hydraulic power steering system with increased flexibility, Active Pinion, can be applied as the actuator to an automatic parking system, Parking Pilot. The requirements on the actuator from the parking system and how the actuator's performance translates into parking maneuver performance is studied. The system have been installed in a test rig and in a demonstrator car.