A medical device comprising: a control input; an instrument manipulator configured to receive a surgical instrument (520, 900, 1000, 1100, 1200), the instrument manipulator including a first teleoperated actuator and a second teleoperated actuator, the first teleoperated actuator being configured to actuate a first mechanical degree of freedom of the surgical instrument (520, 900, 1000, 1100, 1200) and the second teleoperated actuator being configured to actuate a second mechanical degree of freedom of the surgical instrument (520, 900, 1000, 1100, 1200); and a controller configured to control movement of the surgical instrument (520, 900, 1000, 1100, 1200) installed for use on the instrument manipulator, in response to movement of the control input, wherein the controller is further configured to: detect, while the first teleoperated actuator is being commanded to maintain its current position, an application of external force to the first teleoperated actuator that is in excess of a first force threshold; detect, while the second teleoperated actuator is being commanded to maintain its current position, that the second teleoperated actuator is not experiencing external force that is in excess of a second force threshold, characterised by terminating, in response to detecting that an application of external force to the first teleoperated actuator that is in excess of the first force threshold and detecting that the second teleoperated actuator is not experiencing external force that is in excess of the second force threshold, the command to the first teleoperated actuator to maintain its current position. a control input; an instrument manipulator configured to receive a surgical instrument (520, 900, 1000, 1100, 1200), the instrument manipulator including a first teleoperated actuator and a second teleoperated actuator, the first teleoperated actuator being configured to actuate a first mechanical degree of freedom of the surgical instrument (520, 900, 1000, 1100, 1200) and the second teleoperated actuator being configured to actuate a second mechanical degree of freedom of the surgical instrument (520, 900, 1000, 1100, 1200); and a controller configured to control movement of the surgical instrument (520, 900, 1000, 1100, 1200) installed for use on the instrument manipulator, in response to movement of the control input, wherein the controller is further configured to: detect, while the first teleoperated actuator is being commanded to maintain its current position, an application of external force to the first teleoperated actuator that is in excess of a first force threshold; detect, while the second teleoperated actuator is being commanded to maintain its current position, that the second teleoperated actuator is not experiencing external force that is in excess of a second force threshold, characterised by terminating, in response to detecting that an application of external force to the first teleoperated actuator that is in excess of the first force threshold and detecting that the second teleoperated actuator is not experiencing external force that is in excess of the second force threshold, the command to the first teleoperated actuator to maintain its current position. detect, while the first teleoperated actuator is being commanded to maintain its current position, an application of external force to the first teleoperated actuator that is in excess of a first force threshold; detect, while the second teleoperated actuator is being commanded to maintain its current position, that the second teleoperated actuator is not experiencing external force that is in excess of a second force threshold, characterised by terminating, in response to detecting that an application of external force to the first teleoperated actuator that is in excess of the first force threshold and detecting that the second teleoperated actuator is not experiencing external force that is in excess of the second force threshold, the command to the first teleoperated actuator to maintain its current position.