Walking machine leg design: The effect of leg geometry on knee torque

Abstract

The authors have been studying the fundamental mechanics of legged vehicles with the aim of establishing generic principles for their mechanical design. The approach to date has been to consider overall machine design and leg mechanism design separately. In leg design there is inevitably a trade-off between workspace (reach) and leg weight for given loading conditions. To understand this trade-off, the effects of leg geometry on both kinematic workspace and leg weight must be investigated. Leg weight is largely a function of the hip and knee design torques; the former is determined by the overall machine design which has been discussed elsewhere.

This paper considers the effect of leg geometry on the total design torque that the knee must support through both its structure and the knee actuator. The actuator design torque is also considered. The leg geometry varied includes link lengths and knee twist angles. The necessary mathematical analyses are developed and data presented showing the relationship between knee or actuator torque and leg geometry.

Keywords

leg design knee torque walking machine legged robot

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References

Pfeiffer

Etze

Weidemann

H. J.

Six-legged technical walking considering biological principles. Robotics and Autonomous Syst., 1995, 14 (2/3), 223–232.

Weidemann

H. J.

Pfeiffer

Etze

Design concept for legged robots derived from the walking stick insect. In Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems, Yokohama, Japan, 26–30 July 1993, pp. 545–552.

Song

S. M.

Waldron

K. J.

Kinzel

G. L.

Computer-aided geometric design of legs for a walking vehicle. Mechanism and Mach. Theory, 1985, 20 (6), 587–596.

Dhanadapani

Ogot

M. M.

Modelling of a leg system to illustrate the feasibility of energy recovery in walking machines. In Proceedings of 1994 ASME Design Technical Conferences, Minneapolis, Minnesota, 11–14 September 1994, Part 2 (of 2), Vol. 69–2, pp. 429–435.

Shieh

W. B.

Tsai

L. W.

Azarm

Tits

A. L.

Multi-objective optimisation of a leg mechanism with various spring configurations for force reduction. Trans. ASME, J. Mech. Des., 1996, 118, 179–185.

Zhang

S. J.

Howard

Sanger

D. J.

Miao

Multi-legged walking machine body design. Robotica, 1997, 15, 593–598.

Howard

Zhang

S. J.

Sanger

D. J.

Multi-legged walker design—the joint torque versus workspace compromise. Proc. Instn Mech. Engrs, Part C, Journal of Mechanical Engineering Science, 1997, 211 (C6), 477–488.