Active tension optimal control for WT wheelchair robot by using a novel control law for holonomic or nonholonomic systems

The characteristics of interaction between WT wheelchair robot and stair environments is analyzed and possible patterns of WT wheelchair robot during the stair-climbing process are summarized, with criteria to determine the pattern of the wheelchair robot proposed. Aiming at the complicated mechanism of WT wheelchair robot with holonomic constraints and combining it with the dynamic programming, namely the Hamilton-Jacobi equation, a new control law called active tension optimal control is presented for holonomic or nonholonomic robotic systems, based on which one can make the wheelchair robot with a holonomic or nonholonomic mechanism track the expected reference input of constraint forces of holonomic or nonholinomic constraints as well as track the expected reference input of the generalized coordinate of each joint. The module STATEFLOW in MATLAB is used to simulate the entire stair-climbing process of WT wheelchair robot, and comparison is made between the output curves of each joint and the tension of the track and the expected reference input curves, which verifies the effectiveness of the proposed control law. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg