Active control for rock grinding works of an underwater construction robot consisting of hydraulic rotary and linear actuators

The rock grinding, one of the purposes of the underwater construction robot, is done by the rotation torque of the rock grinding machine. The rotation torque of the rock grinding machine is proportional to the force that the robot arm applies to the rock grinding machine. If the robot arm applies excessive force the rock grinding machine halts. In contrast, unless the force is sufficient, the rock grinding machine bounces. Thus, the force applied to the rock grinding machine by the robot arm for rock grinding should always be adequate. When the underwater construction robot is remotely controlled, the operator has to repeatedly manipulate the proportional control valve to maintain an optimal torque, which requires advanced operating skills even on land and causes tiredness even for skilled operators. The present paper proposes an active control technique for maintaining the optimal torque and speed for the rock grinding machine. In order to evaluate the effect of the proposed control method, the simulations and experiments were performed.