Omniwheel Touchdown Characteristics and Adaptive Saturated Control for a Human Support Robot

Abstract

With population aging, increasing numbers of people who are elderly are losing the ability to walk and therefore are experiencing difficulties caring for themselves. This prompted the designing of a sitting-type walking-assistance robot named the human support robot (HSR), which can move accurately in narrow indoor environments and act as a person’s legs to assist her/him with activities of daily living. With the construction of a dynamic model of the HSR, a saturated control algorithm guarantees the safety of the omniwheels and the HSR supporting process. Analysis of the omniwheel touchdown characteristics improves the accuracy of the dynamic HSR model. Under trajectory tracking control with adaptive technology, the HSR tracking performance is improved, and the vibration in the orientation angle caused by the omniwheel touchdown characteristics is eliminated. The exponential practical stability of the tracking error system is derived, and the effectiveness of the proposed methods is confirmed in simulations.