It is important to minimize the energy dissipated by the reduction gears and motors in a three-jointed vertically articulated manipulator. This paper proposes an optimal design method for simultaneously determining eight design variables, which are three motor masses, three reduction gear ratios, a counterbalancer mass for the third link and an offset between the first and the second links. Using these design variables, the equation of motion and the dissipated energy can be expressed as functions of the moment of inertia and the Coulomb friction torque of the joints and the inertia matrix of the manipulator. Optimal design variables can be determined by minimizing the dissipated energy under the constraint conditions for the motors and the offset. The numbers of stages for the reduction gear trains are determined from the optimal gear ratios. Simulations show that the proposed design method can reduce the dissipated energy more effectively than the inertia matching method.

This paper describes a hammering robot with a flexible link which can hit an object from an arbitrary direction in a 3-D space. A dynamical equation of a flexible link hammer is presented by taking gravity into consideration. The conditions that the hammer can strike an object flatwise with only a normal velocity to its face are investigated, and a manipulating method to satisfy the hitting conditions is obtained.

This paper proposes a continuous hitting operation on objects with unknown coefficients of rebound by a flexible link hammer. This hammer system uses only the first mode of vibration for a desired hitting. The angular acceleration for a continuous hitting can be obtained from numerical calculations. However, this method is not useful for on-line processing Therefore, the multi-layered neural networks are applied to the calculation of the parameters of the angular acceleration. The outputs of the trained network agree well with the numerical solutions.

The paper deals with the motion control of a flexible link hammer within a vertical plane. The deflection of the flexible link hammer is analyzed in the condition that the hub actuator is excited by a single pulse acceleration and the head is subjected to gravity, Next, the flexible link hammer is attached to the end effector of a home robot. It is shown that the robot can tap a person on the shoulders to relieve them from stiff shoulders.