Abstract: A method of testing a motor of a robot arm for a fault during a start-up procedure of the robot arm. The robot arm comprises a first link connected to a second link by a joint, the joint permitting the second link to move relative to the first link. The motor is for driving the joint and is a multiple-phase motor, each phase of the motor comprising a motor winding and a motor drive circuit for applying power to the motor winding from a power supply rail and for applying drive signals to the motor winding.

Abstract: A surgical robot comprising a surgical robot arm and a surgical robot arm controller. The surgical robot arm comprises a set of joints and a joint controller. The joint controller is configured to drive a joint of the set of joints. The surgical robot arm controller comprises a processor and watchdog circuitry. The processor is configured to send joint driving signals to the joint controller on a communication link. The watchdog circuitry is configured to: receive sequence values from the processor; determine whether each received sequence value matches a next expected value of a predetermined sequence; and if the received sequence value does not match the next expected value of the predetermined sequence, disable the communication link between the processor and the joint controller.

Abstract: A surgical robotic system for identifying the triggering of a condition in the system, the system comprising: a first robot arm; a controller; and a first wiring arrangement configured to provide an electrical connection between the first robot arm and the controller, the first wiring arrangement comprising: a first electrical coupling comprising circuitry configured to generate a selective electrical disconnect; a second electrical coupling; a first sensor configured to measure a first electrical output from the first electrical coupling; and a second sensor configured to measure a second electrical output from the second electrical coupling; wherein the controller is configured to detect the triggering of the condition by comparing the first electrical output and the second electrical output.