A safety apparatus and method for monitoring the position of a servo joint in a servo joint driving system are introduced. The safety apparatus includes modules for measuring powerline signals to determine a servo motor position and/or speed safely. By analyzing the synchronization between the motor and powerline signals, loss of synchronization, unexpected resistance experienced by the motor, and other fault conditions are detected so that power can be cut from the servo motor for safety. The safety apparatus and method achieve a functional safety position and/or speed generating and monitoring and reduce reliance on expensive position sensors and encoders. Robots utilizing the safety apparatus and a method of its use are also disclosed.

A safety apparatus and method for monitoring the position of a servo joint in a servo joint driving system are introduced. The safety apparatus includes modules for measuring powerline signals to determine a servo motor position and/or speed safely. By analyzing the synchronization between the motor and powerline signals, loss of synchronization, unexpected resistance experienced by the motor, and other fault conditions are detected so that power can be cut from the servo motor for safety. The safety apparatus and method achieve a functional safety position and/or speed generating and monitoring and reduce reliance on expensive position sensors and encoders. Robots utilizing the safety apparatus and a method of its use are also disclosed.