Two Techniques of Geometrical Modelization for an Hexapod Robot

Abstract : this paper presents two techniques of geometric modelization in 3D-space for an hexapod robot. The direct and inverse models involving an alternating tripod walking pattern are described. The strategy of the first method consists in solving the problem in the plane of the body platform and then integrating the solution in the 3D analysis. The second method relies on an analytic approach and appears more mathematical. We test both modelizations thanks to computer simulation and implement them for real with success on our first six-legged machine called RHEA. The modelization assumes that the positions of the leg extremities are known at each time with respect to a stationary reference frame. Several control commands are based on the direct and inverse 3D models and emphasis has been focused on how to smooth the body motion when changing propulsive tripod.