A computer-assisted device comprising: an actuator; an instrument (130, 200, 720) having an end effector located at a distal end of the instrument (130, 200, 720) and one or more drive mechanisms for coupling force or torque from the actuator to the end effector; and one or more processors configured to: set a velocity set point of the actuator to an initial velocity; monitor force or torque applied by the actuator; when the applied force or torque is above a first threshold, reduce the velocity set point; when the applied force or torque is below a second threshold, increase the velocity set point; when the applied force or torque is above a maximum threshold, decrease the velocity set point to zero; and drive the actuator based on the velocity set point; wherein the first and second thresholds are lower than the maximum threshold; wherein after decreasing the velocity set point to zero, the one or more processors are configured to: wait for a predetermined period of time; after the predetermined period of time has passed: set the velocity set point to a non-zero value; determine whether the applied force or torque continues to be above the maximum threshold while the velocity set point is set to the non-zero value; set the velocity set point back to zero and wait again when the applied force or torque continues to be above the maximum threshold; and indicate a failure after a predetermined number of wait cycles when the applied force or torque continues to be above the maximum threshold. an actuator; an instrument (130, 200, 720) having an end effector located at a distal end of the instrument (130, 200, 720) and one or more drive mechanisms for coupling force or torque from the actuator to the end effector; and one or more processors configured to: set a velocity set point of the actuator to an initial velocity; monitor force or torque applied by the actuator; when the applied force or torque is above a first threshold, reduce the velocity set point; when the applied force or torque is below a second threshold, increase the velocity set point; when the applied force or torque is above a maximum threshold, decrease the velocity set point to zero; and drive the actuator based on the velocity set point; set a velocity set point of the actuator to an initial velocity; monitor force or torque applied by the actuator; when the applied force or torque is above a first threshold, reduce the velocity set point; when the applied force or torque is below a second threshold, increase the velocity set point; when the applied force or torque is above a maximum threshold, decrease the velocity set point to zero; and drive the actuator based on the velocity set point; wherein the first and second thresholds are lower than the maximum threshold; wherein after decreasing the velocity set point to zero, the one or more processors are configured to: wait for a predetermined period of time; after the predetermined period of time has passed: set the velocity set point to a non-zero value; determine whether the applied force or torque continues to be above the maximum threshold while the velocity set point is set to the non-zero value; set the velocity set point back to zero and wait again when the applied force or torque continues to be above the maximum threshold; and indicate a failure after a predetermined number of wait cycles when the applied force or torque continues to be above the maximum threshold. wait for a predetermined period of time; after the predetermined period of time has passed: set the velocity set point to a non-zero value; determine whether the applied force or torque continues to be above the maximum threshold while the velocity set point is set to the non-zero value; set the velocity set point back to zero and wait again when the applied force or torque continues to be above the maximum threshold; and indicate a failure after a predetermined number of wait cycles when the applied force or torque continues to be above the maximum threshold. set the velocity set point to a non-zero value; determine whether the applied force or torque continues to be above the maximum threshold while the velocity set point is set to the non-zero value; set the velocity set point back to zero and wait again when the applied force or torque continues to be above the maximum threshold; and indicate a failure after a predetermined number of wait cycles when the applied force or torque continues to be above the maximum threshold.