Installation and Commissioning

System DescriptionServo System3 Servo System3.1 Principle functionThe servo system is a complex system comprising several different interacting unitsand system parts – both hardware and software. The servo function comprises:• Digital regulation of the poses, velocity and motor current of the robot axes.• Synchronous AC operation of the robot motors.3.2 RegulationDuring execution, new data on the poses of the robot axes is continuously receivedfrom the serial measurement board. This data is input into the position regulator andthen compared with previous position data. After it has been compared and amplified,new references are given for the pose and velocity of the robot.The system also contains a model of the robot which continuously calculates the optimalregulator parameters for the gravitation, the moment of inertia and the interactionbetween axes. See Figure 11.3.3 Controlling the robotAn digital current reference for two phases is calculated on the basis of the resolver signaland a known relationship between the resolver angle and rotor angle. The thirdphase is created from the other two.The current of the phases is regulated in the drive unit in separate current regulators. Inthis way, three voltage references are returned which, by pulse-modulating the rectifiervoltage, are amplified to the working voltage of the motors.The serial measurement board receives resolver data from a maximum of six resolversand generates information on the position of the resolvers.Product Manual 13