Dynamic control of powered wheelchair with slip on an incline

Most people take freedom to move for granted. However, to physically disabled people who can only depends on wheelchair for their daily movements this freedom is out of reach. Ability of wheelchair users and the access methods used in driving these wheelchairs vary. Variety of users therefore requires systems that are adaptable for many types of access devices. Authors of this paper believe that safety of wheelchair users depends not only on the type of controller used, but also on the model used. As a result a real life wheelchair dynamic model that accounts for uphill and downhill gravitational disturbances, frictional forces and slipping effect is considered in this work. Euler Lagrange procedure is applied in the derivation of the equations of motion of the wheelchair model used in this paper. To imitate a normal wheelchair and develop a system that is adaptable to nearly every access device considered, input-output feedback linearization has been applied in tracking linear velocity and angular orientation and in the development of the control law applied in this model. The developed controller successfully tracks and maintains desired angular orientation and linear velocity of the wheelchair before and after slipping.