An Energy Efficient Manipulator Design Approach: Application to a Leg in Swing Phase

The importance of energy efficiency of a robotic manipulator is clearly evident when the manipulator has to use on-board power. With miniature machines, this issue is even more important since the size and the weight guides the performance of a design. In this paper, a design methodology is proposed which may allow a robot to follow desired trajectories approximately without actuator inputs. Actuator inputs are used to further modify the trajectories. The design philosophy has the following key elements: (i) the inertia matrix of the device is suitably altered using mass distribution; (ii) compliant elements are introduced to take away the gravity terms; and (iii) additional springs are used to create certain periodic gait motion. This design philosophy is applied on a two dof leg executing a swing motion. It is found that the passive motion of the designed leg is close to the desired trajectories but is not exact. Actuators are added to get the desired response fully. Power input for two legs with and without this design philosophy, are then compared.