Controlling a surgical instrument

A control system configured to control manipulation of a surgical instrument in response to manipulation of a remote surgeon input device. The surgical instrument comprises opposable first and second end effector elements connected to a shaft by an articulated coupling. The articulated coupling comprises a first joint driveable by a first pair of driving elements so as to permit the first end effector element to rotate, and a second joint driveable by a second pair of driving elements so as to permit the second end effector element to rotate. The control system: responds to a closing motion of the surgeon input device by commanding maximum forces to be applied to the first and second pairs of driving elements, so as to cause the first and second end effector elements to rotate in opposing rotational directions towards each other with a maximum closing force; and on detecting that the closing motion of the surgeon input device has ceased, commanding a reduction in the force applied to the first and second pairs of driving elements, thereby enabling both the first and second end effector elements to be rotated in the same rotational direction in response to a yawing motion of the surgeon input device.