Development of a Passive Dynamic Walker with a Novel Knee Design

Abstract

Despite of the astonishing technology developed so far, bipedal systems have seen little success in practical applications. With the advent of rapid automation the need for bipedal robots to carry out complex tasks is only a matter of time. Designing this system based on human morphology permits the easy adoption of such systems in our society. These robots could access places deemed too dangerous for humans or carry out tasks that would reduce the mechanical effort from humans. The study of passive dynamic walkers is a field in robotics that aims to solve the problem of stability, energy efficiency, and naturalness lacking in the current robots. It aims to do this by exploiting the passive nature of human walking and hence designing an inherently stable system. A considerable research in this field has been done to analyse the effects of the shape of the feet or other variables such as the location of the centre of mass of the robot have on the walker’s gait. However, so far there has been a lack of research in the effects of adopting knees on the gait of such passive walkers. This research drew inspiration from the field of lower limb prosthetics and was able to demonstrate a stable kneed-gait, albeit for a small degree of activation. The bipedal walker with knees took an average 30.6 steps under its best configurations. An analysis of the various variables affecting the gait was successfully tested and analysed. Four different springs with various configurations were tested under three angles. The spring with a stiffness of 1430 N/m demonstrated the best performance for all three sets Moreover the most drastic improvement in the walker’s performance was observed with an increase of the angle. The walker showed the most stable gait when the initial angle was set to > 2°. It is proposed that the design of future passive dynamic walkers with knees include toes in order to resemble the human gait. Moreover, it is advised that a simple mechanism that promotes flexion should be added around the knee and ankle joint in order to achieve full flexion during the gait cycle.

Date of Award	31 Dec 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Zhenmin Zou (Supervisor) & Lei Ren (Supervisor)