A
control system and a method for controlling a surgical robotic
system are provided. The surgical robotic
system comprises a
surgical robot arm. The
surgical robot arm comprises a plurality of joints by which its configuration can be altered. An input is received which indicates a desired motion of the
surgical robot arm when the surgical robotic
system is operating in a mode in which the surgical
robot arm is controlled in accordance with an objective. The objective is to control a particular part of the surgical
robot arm to have a desired position and / or orientation. The
control system determines that the desired motion of the surgical
robot arm would cause a limit to be exceeded. In response to determining that the desired motion of the surgical robot arm would cause the limit to be exceeded, a
control signal is generated for controlling the surgical robot arm, and the generated
control signal is sent to the surgical robot arm in order to control the surgical robot arm. The
control signal is generated, in response to determining that the desired motion of the surgical robot arm would cause the limit to be exceeded, such that: (i) movement of a first set of one or more of the joints of the surgical robot arm is restricted, and (ii) movement of a second set of one or more of the joints of the surgical robot arm is not restricted.