Legged Robot Research

HECTOR (HExapodal CTacc demonstratOR) has three body segments, each with its own Transputer, sensors and leg pairs. A head segment has 'feelers', 'hearing' and IR 'sight'. Each segment is a 'robot' in its own right. As the segments are connected together, then the overall functionality of the robot increases.

MAX (Mobile Autonomous heXapod) can walk over uneven terrain whilst maintaining a desired ride height and body attitude. His gait being determined either by the desired velocity, or by the weight of a load placed upon him. MAX is controlled by a novel hybrid conventional control and combined reactionary and CPG system.

HECTOR Research Funding and Selected Publications:

• Barnes D.P., Downes C.G., and Gray J.O., A parallel distributed control architecture for a hexapodal robot. In Proc. P. D. COM '91, IMACS - IFAC International Symposium on Parallel and Distributed Computing in Engineering Systems. Corfu, Greece, pp. 270 - 275. Edited by S Tzafestas, P Borne and L Grantinaid. Amsterdam: Elsevier Science, June 1991.
• Barnes D.P., Downes C.G., and Gray J.O., The real time control of a hexapodal robot using multiple transputers. In Proc. of the Third International Conference on Applications of Transputers. Glasgow, UK. Vol. 2, pp. 400 - 405. Edited by T S Durrani, W A Sandham, J J Soraghan, S M Forbes, 105 Press, August 1991.
• Downes C.G., Barnes D.P., and Gray J.O., Zespotige 'insect'- robot kan goed uit de voeten. In Electronica. NOTU, Nederlands, March and April 1993.

MAX Research Funding and Selected Publications:

This project involved building a six-legged robot. Gait control was achieved using six coupled non-linear oscillators that were driven via a central pattern generator (CPG). A dynamically variable gait was achieved via the entrainment of the coupled oscillators, and with the aid of an inverse kinematic model for the leg servos, and appropriate sensing, the body 'ride' height and attitude could also be controlled.

The research is aimed at extending our co-operating robot work, from wheeled mobile robots on a flat surface to legged locomotion over uneven terrain. This has involved building MAX (Mobile Autonomous heXapod), a six-legged robot, which can walk over smooth or rough ground. The robot has been biologically inspired by the cockroach. Each leg is powered by three model servos, allowing three degrees of freedom per leg. The leg movements are controlled by a Motorola 6811 microcontroller sitting on-board MAX. This sends position information to each of the servos, as instructed by a remote PC computer. The PC acts as a high level leg coordinator providing overall control and is connected to MAX using a serial communications link. The control software running on the PC is an analogue based neural architecture implemented in C++. The neural control mechanisms have been inspired by insect nervous systems. MAX is able to mimic an insect walking and demonstrates a continually variable gait between the slow wave gait and the much faster tripod gait. Sensors on MAX also measure his body attitude and height relative to the ground surface, and his control architecture is able to ensure that a fixed attitude and height are maintained while MAX negotiates uneven terrain. MAX can be steered, rotate on the spot and move in a crab-like fashion so as to maintain a fixed forward orientation. MAX's gait, body attitude and steering control means that he is highly manoeuvrable over difficult uneven terrain. We hope soon to have a small colony of these robot insects.

• Barnes D.P., Hexapodal Robot Locomotion Over Uneven Terrain. In Proc. IEEE Conf. on Control Applications. Trieste, Italy, September, pp. 441 - 445, Sept. 1998. PDF version available.

The information provided on this and other pages by me, Dave Barnes, is under my own personal responsibility and not that of Aberystwyth University. Similarly, any opinions expressed are my own and are in no way to be taken as those of Aberystwyth University.