Servo Joint Safety Position Monitoring Apparatus and Method

Apparatus for monitoring a servo joint controlled by a servo driver coupled to a servo motor having armature windings and a rotor over powerlines having multiple phases, the apparatus comprising:

• measurement circuitry configured to detect an electric signal on the powerlines;
• and
• one or more processors are configured to
• convert the electric signal detected by the measurement circuitry into a digitized signal group,
• convert the digitized signal group into an estimated rotor position of the servo motor,
• perform a digitized signal diagnostic procedure based on the digitized signal group that diagnoses whether the digitized signal includes a fault,
• perform a motor synchronization diagnostic procedure based on the electric signal detected by the measurement circuitry that diagnoses whether the servo motor is in a synchronized state,
• convert the estimated rotor position into a confident rotor position when the digitized signal diagnostic procedure diagnoses that the digitized signal is fault-free and the motor synchronization diagnostic procedure diagnoses that the servo motor is in the synchronized state, and
• generate a signal to cut power to the servo motor when the digitized signal diagnostic procedure diagnoses that the digitized signal includes the fault or when the motor synchronization diagnostic procedure diagnoses that the servo motor is in an unsynchronized state.

A method of operating some or all of a robot system, the method comprising:

• with a servo driver, driving a servo motor over powerlines to move two or more components of a robot about a joint, the powerlines having multiple phases;
• with measurement circuitry, detecting an electric signal on the power lines;
• converting the electric signal detected by the measurement circuitry into a digitized signal group;
• determining whether the servo motor is in a synchronized state based on the electric signal detected by the measurement circuitry;
• cutting power to the servo motor when the servo motor is determined to be in an unsynchronized state;
• determining whether the digitized signal group includes a fault under an assumption that the servo driver is in the synchronized state;
• and
• cutting power to the servo motor when the digitized signal group is determined to include the fault.