In order for leading industrial companies to remain competitive, the process of product developement constantly needs to improve. In order to shorten development time -- that is the time from idea to product -- simulations of products in-house is becoming a popular method. This method saves money and time since expensive prototypes become unnecessary. Today the calibration of steering gears is done in test vehicles by experienced test drivers. This is a time consuming process that is very costly because of expensive test vehicles. This report investigates possibilities and difficulties with transfering the calibrations from field to rig. A steering rig has been integrated with a car simulation program. Comparisons between simulation in the loop (SIL) and hardware in the loop (HIL) have been made and differences between different configurations of steering gears have been evaluated. An automatic process including calibration of parameters, testing and analysis of the test results has been implemented. The work laid the foundation of calibration of steering parameters and showed correlation between calibration parameters and objective metrics.

No / This paper presents a method of designing a full electrical power steering system to replace a hydraulic power-assisted steering system with improved performance and benefits including energy saving, improved steering 'feel', simpler construction and environmental gain. The designed performance of the electrical power steering system represented an ideal hydraulic power-assisted steering power boost curve which was mathematically modelled to provide the required control characteristic for the electrical power steering system, including variation in the perceived power assistance with the vehicle's forward speed. A full electrical power steering system provides all the torque necessary to steer the wheels, and the steering feel is artificially generated by an electric 'feedback' motor which provides resistance to the driver's input. The performance of the electrical power steering system described in this paper was enhanced by manipulating the reactive torque to the driver's input at the steering wheel so that it depended upon the driving conditions. Full-vehicle software models were generated using ADAMS/car software based on an actual car fitted with hydraulic power-assisted steering and full electrical power steering. The simulation results from both models were compared, and it is concluded that the steering performances of both systems were similar but the steering feel of the full electrical power steering system could be tuned to provide improved feedback to the driver in use. The performance of the full electrical power steering system could be further improved with the introduction of a controller to manipulate the steering feel during undesired conditions.

<p>This is a thesis for a Bachelor Degree Project, performed in the subject Mechanical</p><p>Engineering. The students Roger Malmberg and Simon Hagberg have carried out a</p><p>design project on behalf of the recently established company J&D Assisting systems,</p><p>located in Halmstad.</p><p>The project consisted in developing J&D's first prototype of a power assisting solution</p><p>for wheelchairs. A power assisted wheelchair combines human power, which is delivered</p><p>by the arms through the pushrims, with electrical motors, which are powered by a battery.</p><p>The power assisted wheelchair is aimed at customers, who have used a regular</p><p>wheelchair for a long time, but who have become weaker or just need additional power</p><p>when driving uphill. This kind of wheelchair will provide additional power for users,</p><p>which will spare their wrists, elbow and shoulders. The product is torque sensor free and</p><p>instead it relies on the velocity. Engines and gearboxes from the company All motion was</p><p>a requirement. The construction could not impair the wheelchair's trafficability and the</p><p>performance would at least match up with the performance of the first prototype. To build</p><p>a working prototype was a part of the task. The work was early focused on the specific</p><p>wheelchair Etac Next. At the same time, the result should be, as much as possible,</p><p>suitable for the most common wheelchairs.</p><p>The result is a design where the engine packet is assembled in a 90° angle towards the</p><p>wheelaxle. In the angle, the power is transferred by bevel gears, assembled on shafts</p><p>supported by ball bearings. Then, the force is transmitted via a modified wheel axle to a</p><p>structure mounted outside the hub. Eight stokes transfers the force to the hand rims.</p><p>An operational prototype has been built and then been assembled on the wheelchair Etac</p><p>Next. The part mounted outside of the wheel has got a plastic hood to cover up and to</p><p>protect the inner parts. The plastic hood has been produced with SLS technology.</p>

This is a thesis for a Bachelor Degree Project, performed in the subject Mechanical Engineering. The students Roger Malmberg and Simon Hagberg have carried out a design project on behalf of the recently established company J&D Assisting systems, located in Halmstad. The project consisted in developing J&D's first prototype of a power assisting solution for wheelchairs. A power assisted wheelchair combines human power, which is delivered by the arms through the pushrims, with electrical motors, which are powered by a battery. The power assisted wheelchair is aimed at customers, who have used a regular wheelchair for a long time, but who have become weaker or just need additional power when driving uphill. This kind of wheelchair will provide additional power for users, which will spare their wrists, elbow and shoulders. The product is torque sensor free and instead it relies on the velocity. Engines and gearboxes from the company All motion was a requirement. The construction could not impair the wheelchair's trafficability and the performance would at least match up with the performance of the first prototype. To build a working prototype was a part of the task. The work was early focused on the specific wheelchair Etac Next. At the same time, the result should be, as much as possible, suitable for the most common wheelchairs. The result is a design where the engine packet is assembled in a 90° angle towards the wheelaxle. In the angle, the power is transferred by bevel gears, assembled on shafts supported by ball bearings. Then, the force is transmitted via a modified wheel axle to a structure mounted outside the hub. Eight stokes transfers the force to the hand rims. An operational prototype has been built and then been assembled on the wheelchair Etac Next. The part mounted outside of the wheel has got a plastic hood to cover up and to protect the inner parts. The plastic hood has been produced with SLS technology.

La commande du système de Direction Assistée Electrique (DAE) est un défi majeur en raison de ses multiples objectifs et de la nécessitée de réaliser plusieurs mesures pour la mettre en oeuvre. La commande doit assurer : le suivi du couple d’assistance de référence tout en assurant la stabilité du système et sans introduire des retards, l’atténuation des vibrations provoquées par chacune des entrées du système, la transmission des informations de la route au conducteur pour un bon confort et une meilleure sensation de conduite, l’amélioration de la performance de retour au centre. La commande doit également être robuste vis-à-vis des erreurs de modélisation, des incertitudes des paramètres, et des perturbations extérieures. En outre, la mise en oeuvre de la commande nécessite plusieurs mesures telles que : l’angle au volant, l’angle du moteur, la vitesse du moteur, le couple conducteur et le couple de réaction de la route. / The control of Electric Power Assisted Steering (EPAS) system is a challengingproblem due to the multiple objectives and the need of several pieces of information to implement the control. The control objectives are to generate assist torque with fast responses to driver’s torque commands, insure system stability, attenuate vibrations, transmit the road information to the driver, and improve the steering wheel returnability and free control performance. The control must also be robust against modeling errors and parameter uncertainties. In addition, several pieces of information are required to implement the control, such as steering wheel angle, motor velocity, driver torque and road reaction torque.

<p>A power assisted wheelchair combines human power, which is delivered by the arms through the pushrims, with electrical motors, which are powered by a battery. Today’s electric power assisted wheelchairs use force sensors to measure the torque exerted on the pushrims by the user. The force sensors in the pushrims are rather expensive and this approach also makes the wheels a little bit clumsy. The objective with this project is to find a new, better and cheaper solution that does not use expensive force sensors in the pushrims. The new power assisted wheelchair will instead only rely on its velocity, which is measured with rotational encoders, as feedback signal and thereby the project name “Torque Sensor Free Power Assisted Wheelchair”. </p><p> </p><p>The project consisted of two main parts; an extensive construction part, where an ordinary joystick controlled motorized wheelchair has been rebuild to the new power assisted wheelchair without torque sensors and a development part, where different torque sensor free controllers has been designed, simulated, programmed and tested.</p><p>The project resulted in a torque sensor free power assisted wheelchair, where the final implemented design is a proportional derivative controller, which gives a very good assisting system that is robust and insensitive to measurement noise. The proportional derivative control design gives two adjustable parameters, which can be tuned to fit a certain user; one parameter is used to adjust the amplification of the user’s force and the other one is used to change the lasting time of the propulsion influence.</p><p>Since the new assisting control system only relies on the velocity, the torque sensor free power assisted wheelchair will besides giving the user assisting power also give an assistant, which pushes the wheelchair, additional power. This is a big advantage compared to the pushrim activated one, where this benefit for the assistant is not possible.</p>

A power assisted wheelchair combines human power, which is delivered by the arms through the pushrims, with electrical motors, which are powered by a battery. Today’s electric power assisted wheelchairs use force sensors to measure the torque exerted on the pushrims by the user. The force sensors in the pushrims are rather expensive and this approach also makes the wheels a little bit clumsy. The objective with this project is to find a new, better and cheaper solution that does not use expensive force sensors in the pushrims. The new power assisted wheelchair will instead only rely on its velocity, which is measured with rotational encoders, as feedback signal and thereby the project name “Torque Sensor Free Power Assisted Wheelchair”. The project consisted of two main parts; an extensive construction part, where an ordinary joystick controlled motorized wheelchair has been rebuild to the new power assisted wheelchair without torque sensors and a development part, where different torque sensor free controllers has been designed, simulated, programmed and tested. The project resulted in a torque sensor free power assisted wheelchair, where the final implemented design is a proportional derivative controller, which gives a very good assisting system that is robust and insensitive to measurement noise. The proportional derivative control design gives two adjustable parameters, which can be tuned to fit a certain user; one parameter is used to adjust the amplification of the user’s force and the other one is used to change the lasting time of the propulsion influence. Since the new assisting control system only relies on the velocity, the torque sensor free power assisted wheelchair will besides giving the user assisting power also give an assistant, which pushes the wheelchair, additional power. This is a big advantage compared to the pushrim activated one, where this benefit for the assistant is not possible.