Motion Control Design for an Economical Robotic Walking Support System: The Robotic Cane

This study aims at the development of a motion control design for controlling robotic walking support systems using a force-controlled motion command generator so that robotic walking support systems can provide smooth motions to users with desired motion speeds. The motion control laws are implemented with a low-pass filter that has adjustable gain and bandwidth. Through the cooperation of motion control laws and force-sensing results, the force-controlled motion command generator can generate smooth motion commands to smoothly drive robotic walking support systems. A simple and low-cost biaxial force-sensing device is developed in this study to estimate the equivalent interactive forces between the user and the robotic walking support system. A calibration procedure is also developed to obtain the virtual spring coefficient and to design an estimation method that can be used with the biaxial force-sensing device. A robotic walking support system, the robotic cane, is developed with two operation modes, autonomous motion mode (AMM) and manual motion mode (MMM), for testing the proposed motion control approach, and several tests and experimental results are presented to show the validity of the proposed approach.