Power Demand of Actively Controlled Multibody Systems

Abstract
Flexible manufacturing systems are characterized by machines and mechanisms with some or all mechanical degrees of freedom actively controlled resulting in the prescribed motion necessary for the production process or rheonomic constraints, respectively. Due to the high nonlinearity of large displacement motions inverse dynamics is a standard control concept well established in manufacturing, robotics and walking machines. It is shown that inverse dynamics results in high energy consumption and requires large power supply. For autonomous robots and walking machines the power supply adds to the weight, and additional weight needs more power again. Finally, actively controlled walking machines are very heavy devices not comparable to the light weight design of passive walking mechanisms. It is proposed to use local energy storage by springs to overcome the drawback of inverse dynamics. The design principles for reduced energy consumption are outlined with simple mechanical models and include nonlinear characteristics of the springs, too, to improve further the local energy storage capacity.