ESR Pollmeier GmbH
Servo Drive Technology


Characteristics of a servo drive system

Machine parts usually have to be accelerated and decelerated quickly in order to arrive at a certain position in short time. At the same time the path of movement or the speed may be predetermined by the application. A servo drive system is capable to carry out these tasks (see also FAQ).

Important characteristics of ESR servo drive systems are
  • high dynamics
  • high accuracy
  • wide speed range
  • good control behavior

Fields of application

Both machinery manufacturer and end users who build their own machines use servo drive systems by ESR. Usually they are small and medium-sized businesses e. g. from the following fields

  • Handling and assembly systems
  • Optical discs production machinery (CDs, DVDs, ...)
  • Electronics production machinery
  • Semiconductor production machinery
  • Measuring and testing machinery
  • Machine tools and metal working machinery
  • Packaging machinery
  • Textile machinery
  • Plastics processing machines
  • Coiling machines
  • and many more

Modes of operation

Positioning: The classical field of servo drive usage – to accelerate to the rated speed within a few milliseconds only to decelerate a short time later just as quick. And of course the target position is to be reached exactly with an error of a few hundredths of a millimeter.

In profile position mode it is sufficient to transmit the desired target position to the digital ESR servo drive (e. g. by using a fieldbus interface) to let the drive move to that positon – in a way defined before with parameters like target velocity and acceleration and deceleration ramps. Additionally the integrated part program offers a complete positioning control in the device (servo drive integrated PLC).

If you rather let the higher-level controller do the position control, you can also use the ±10 volts interface of a speed controlled ESR servo drive (analog or digital).

Speed control: With their particularly good control behavior and the smooth motor run, complemented by the acceleration and deceleration ramps which can be defined exactly, both analog and digital servo drives by ESR are suitable for use as speed controlled drive.

By using the part program the digital servo drives can perform complete speed profiles on their own. These profiles are used e. g. in optical disc manufacturing, when the liquid coating is applied and then centrifuged. Special part program blocks for speed profiles make the definition of different ramp profiles and slopes easy. The part program can contain several such speed profiles and let the user choose e. g. via the digital inputs or a fieldbus interface which profile to apply.

Spindle positioning: In some applications the rotary motion has to be stopped occasionally and the axis has to be moved to a certain position, e. g. in order to change the workpiece or the tool.

ESR's digital servo drives are prepared for this use too. After setting all required parameters once, a signal at one of the digital inputs or via the fieldbus interface is sufficient to start the spindle positioning or to resume the rotary motion again.

Axis synchronization: In many machines the motion of one axis depends on the motion of another axis. Apart from the customary control of one ore more axes by a higher-level controller, ESR's synchronization unit for analog servo drives in 19" design can be used for increment-precise synchronization of two axes.

Digital servo drives are even more convenient and offer more possibilities. With the function "Electronic gearing", devices by ESR couple a master and a slave axis at an adjustable gear ratio.

Electronic cam disk: In some cases the gear ratio between master and slave axis is not a constant. The function "Electronis cam disk" is a smart solution for applications where mechanical cam disks have been used before. ESR's digital servo drives offer this function optionally. Use a software tool to adapt the "shape" of the electronic cam disk comfortably to the application (e. g. for packaging or punching machinery).

Flying shear: A special, repetitive motion profile is used when a continuous material flow must not be interrupted by cutting, printing, testing, or otherwise processing the material: While processing (e. g. cutting) the material the slave axis has to synchronize with the material flow, after that it has to run back to the starting position. This function, called "Flying shear" or "Flying saw", is already integrated in the digital servo drives by ESR (partly as an option) and requires only a small effort during parameterization (for cutting length, return velocity etc.).

Torque control: Compared to other controlled drives, ESR servo drive systems have the advantage of a very accurate and dynamic current control. They produce full torque even at standstill or low velocity (stall torque). The precise current control allows a sensitive torque control, as used e. g. in coil winding machines. The high stall torque is useful e. g. in presses.

PLC functions: Complete positioning control can be realized within the digital ESR servo drives by using the part program. The part program offers also access to all technology functions and the different interfaces of the servo drive. With this functionality it is sometimes even possible that no higher-level controller is required in applications with one or a few independent axes.

...and more: In our development department we continuously improve our devices – new functions are added, existing functions are extended and refined. Mostly it is our customers who challenge us, and we will put all our effort into satisfying you as our customer.

Communication with higher-level controllers

When choosing the appropriate servo drive system it is important to know how the drive shall be integrated into the automation system. The ±10 volts interface of all ESR servo drive systems offers an easy possibility for setpoint value transmission (current or speed). The digital inputs and outputs and the serial interface of the digital servo drives offer further ways of communication. These devices are optionally also available with a fieldbus interface (e. g. EtherCAT, CANopen, Profibus-DP, or Interbus), for further information see Products/Fieldbuses.

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