Control of a surgical robot arm

A surgical system comprising a surgical robot arm and a control unit for controlling motion of the surgical robot arm, the control unit being configured to receive an input signal from a surgeon input device for controlling the surgical robot arm and send an output signal to the surgical robot arm to cause motion of the surgical robot arm, the control unit being further configured to:

• detect a clash in respect of the surgical robot arm;
• in response to detecting the clash, place a limitation on the motion of the surgical robot arm;
• and
• receive an input signal from the surgeon input device for controlling the surgical robot arm and send an output signal to the surgical robot arm so as to control motion of the surgical robot arm in accordance with the limitation.

A method for controlling motion of a surgical robot arm, the method comprising:

• detecting a clash in respect of the surgical robot arm;
• in response to detecting the clash, placing a limitation on the motion of the robot arm;
• and
• receiving an input signal from a surgeon input device for controlling the surgical robot arm and sending an output signal to the surgical robot arm so as to control motion of the surgical robot arm in accordance with the limitation.