Simplified Modelling of Legs Dynamics on Quadruped Robots' Force Control Approach

Abstract

The development of the service and intervention robotics has stimulated remarkable projects of mobile robots well adapted to different kinds of environment, including structured and non-structured terrains. On this context, several control system architectures have been proposed looking for the improvement of the robot autonomy, and of the tasks planning capabilities, as well reactive characteristics to deal with unexpected events (Medeiros et al., 1996; Martins-Filho & Prajoux, 2000). The proposed solutions to the locomotion on hazardous and strongly irregular soils include adapted wheels robots, rovers, robots equipped with caterpillar systems, and walking robots. Some of this robot designs are inspired on successful locomotion systems of mammals and insects. The legged robots have obtained promising results when dealing with terrains presenting high degrees of difficulty. This is quite curious to notice that ideas concerning this robotic locomotion system have been present since the first idealistic dreams of the robotics history, and nowadays this approach has gained the interest and attention of numerous researchers and laboratories. Let's mention some of the relevant works involving legged robots: Hirose et al. (1989) proposes an architecture for control and supervision of walking; Klein and Kittivatcharapong (1990) study optimal distribution of the feet-soil contact forces; Vukobratovic et al. (1990) work on the robot dynamics modelling and control; Pack and Kang (1995) discuss the strategies of walk control concerning the gaits; Perrin et al. (1997) propose a detailed platform and legs mechanisms modelling for the dynamics simulation; Tanie (2001) discusses the new perspectives and trends for the walking machines; Schneider and Schmucker (2001) work on force control of the complete robot mechanical system.