A 1-d.o.f. Dynamic Pitching Robot That Independently Controls Velocity, Angular Velocity and Direction of a Ball

This paper demonstrates that a 1-d.o.f. planar ball-throwing robot has the capability of controlling three kinematic variables of a ball independently: translational velocity, angular velocity and direction. The throwing motion is modeled using two underactuated contact dynamics, called a finger-link contact model and a fingertip contact model, with a unidirectional transition from one model to another. A combination of a preliminary global search method and a search algorithm based on a simulated annealing algorithm provides joint torque commands for this highly nonlinear system. An experimental system with a 1-d.o.f. planer manipulator has been developed that throws a disk (ball) in a frictionless plane. The experimental results confirm the validity of the contact models and the feasibility of independent control of the three kinematic variables.