Toward controlled passive actuation

Experts all over the world agree on the potential of legged locomotion for difficult terrain. As of now, there are several point on which legged machines have significantly lower performance than than wheeled or tracked ones. First of all, they have a higher number of actuators which makes them heavier. This is related to the mentioned ‿low payload to weight ratio‿ with is also related to the fact that any additional weight has to be supported by the legs. This (active) supporting of mass, together with the additional movement in the legs compared to wheels and tracks also results in higher energy consumption. This energy consumption is further increased due to the fact that energy is lost at every impact (say foot touch-down), which also increases the mechanical stress on the entire structure. In this work a novel, integral approach is presented which minimises the use of electric actuators and enables absorption and re-use of energy involved at impact. By do- ing this, the number and size of electric actuators is reduced, which reduces the weight. Furthermore, by offer- ing intrinsically passive gravity compensation, the pay- load capabilities is potentially increased. By minimising the energy flow trough electric actuators, one of the most significant energetic losses is minimised. Our approach uses a single spring to couple two degrees of freedom and therefore energy exchange between two CPA (Controlled Passive Actuation) actuated degrees of freedom.