A combination electric tool includes a main body and at least one working part drivable via and separably attachable to the main body. The main body includes an electric motor and a control circuit with a signal recognition module having a microcontroller. The working part includes an identification module, the signal recognition module and the identification module being communicable such that the microcontroller can recognize the working part. A control method includes attaching the main body to the working part; judging which kind of working part is attached and selecting corresponding preset programs; sampling a working parameter value of the electric motor; comparing the sampled working parameter value of the electric motor with a corresponding preset value, and judging whether the electric motor is at an abnormal working state; and if yes, powering off the electric motor, and if no, returning to the previous step.

A power supply current monitoring device is used for a load drive apparatus with two systems to drive a load. Each system includes a drive circuit connected in parallel with a battery, a capacitor connected between the battery and the drive circuit, and a relay connected between the drive circuit and a point at which power of the battery is divided between the systems. When overcurrent is detected once in one system, a repetitive monitoring process is performed. The monitoring process finally determines that the overcurrent actually occurs when a predetermined condition is satisfied after repeating a monitoring cycle in which an overcurrent time during which the overcurrent continues after the relay is turned ON is accumulated. The condition is satisfied when the monitoring cycle in which the overcurrent time reaches a predetermined threshold is repeated a predetermined consecutive number of times.

An electronic circuit for a surgical robotic system includes a central power node, a first voltage bus that electrically couples a first power source to the node, a second voltage bus that electrically couples a second power source to the node, and several robotic arms, each arm is electrically coupled to the node via an output circuit breaker and is arranged to draw power from the node. Each bus is arranged to provide power from a respective power source to the node and each bus has an input circuit breaker that is arranged to limit a first output current flow from the node and into the bus. Each breaker that is arranged to limit a second output current flow from the node and into a respective arm. A breaker is arranged to open in response to a fault occurring within the respective arm, while the other breakers remain closed.

An electronic circuit for a surgical robotic system includes a central power node, a first voltage bus that electrically couples a first power source to the node, a second voltage bus that electrically couples a second power source to the node, and several robotic arms, each arm is electrically coupled to the node via an output circuit breaker and is arranged to draw power from the node. Each bus is arranged to provide power from a respective power source to the node and each bus has an input circuit breaker that is arranged to limit a first output current flow from the node and into the bus. Each breaker that is arranged to limit a second output current flow from the node and into a respective arm. A breaker is arranged to open in response to a fault occurring within the respective arm, while the other breakers remain closed.