Bending moment-based force control of flexible arm under gravity

We discuss the force control problem for a constrained one-link flexible arm with the effect of gravity, based on a distributed parameter model. To solve the force control problem, we propose a simple controller constructed using only the bending moment at the root of the flexible arm. Information about the force and rotational angle of the motor is not necessary for implementation of the controller, and thus a force sensor and encoder are not needed. Several numerical simulations were carried out to determine the performance of the proposed controller, and we found that it works well for force control.