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Compact servos give integrated position control

Edited by the Engineeringtalk editorial team Apr 16, 2001

The Compax digital servo controller from Unimatic combines a powerful servo amplifier with a full position controller to enable single unit control of motion, speed and position

The Compax digital servo controller from Unimatic combines a powerful servo amplifier with a full position controller to enable control of motion and peripherals, control of speed and/or torque, and control of position from a single compact unit.

Power outputs from 1 to 35kW are available, and the fully digital design allows almost any type of synchronous or asynchronous motor to be operated with either resolver or SinCos feedback.

The design of the Compax takes integrated servo and positioning technology a stage forward by recognising that whilst position, speed and torque control are often separate functions in servo controllers, they actually belong together.

In the Compax unit, one processor system has access to all system-related parameters, such as motor type, DC bus voltage, motor current, external moment of inertia and output stage temperature.

This permits fully automatic parameter setting, as well as the use of advanced feedback concepts such as observer control and adaptive control.

The information obtained by integrating the motion control and the entire control system into one unit is used for fine tuning between closed loop and open loop elements of the system.

This leads to increased dynamic performance and greater stability, with reduced peak currents and torques.

A special signal process for control of the motor current ensures a fast response, giving the drive unit the best possible servo characteristics with regard to dynamic performance, stiffness and available peak torque.

Setting up of the controller is simplified by an automatic parameter calculation function.

All the data needed to set the controller � such as external moments of inertia, motor type, and transmission ratio � is entered directly in the servo control unit, and this data is then used to automatically calculate the optimum controller parameters.

Gone is the time consuming and tedious process of comparing large numbers of controller parameters, and overshooting or oscillating axes are now a thing of the past.

Only stiffness and damping parameters ever require modification for special control requirements, and the automated parameter setup ensures that these two parameters now operate entirely independently of each other.

In many applications, once the parameters have been set, it is possible for the system to operate virtually independently.

For simple integration, the Compax servo controller is built on an 'open control' philosophy, providing a range of communications options.

An RS232 interface is provided for setting parameters and controlling motion, and the Compax also offers Profibus, CANbus/CANopen and Interbus S interfaces, as well as HEDA real-time drive bus and CS31 system bus options.

In addition, the Compax provides a universal PLC data interface using binary inputs and outputs, enabling a cost-effective interface to any PLC to be implemented, regardless of manufacturer or country of origin.

Sixteen binary inputs and outputs are provided for status and programming control, and a 3-digit, 7-segment display is provided for error and status information.