Computation with mechanically coupled springs for compliant robots

We introduce a simple model of human's musculoskeletal system to identify the computation that a compliant physical body can achieve. A one-joint system driven by actuation of the springs around the joint is used as a computational device to compute the temporal integration and nonlinear combination of an input signal. Only a linear and static readout unit is needed to extract the output of the computation. The results of computer simulations indicate that the network of mechanically coupled springs can emulate several nonlinear combinations which need temporal integration. The simulation with a two-joint system also shows that, thanks to mechanical connection between the joints, a distant part of a compliant body can serve as a computational device driven by the indirect input. Finally, computational capability of antagonistic muscles and information transfer through mechanical couplings are discussed.