Servo-drives and motion control

Without electronics and firmware modern motion control just would not exist. Behind any servo or stepper motor we use there is an amplifier and positioning controller. We differentiate between central and decentral (intelligence at each axis, connected with a communications bus system) topology. Central control structure is a concept where the control unit is centralized and takes over the entire machine control. This means that all control tasks are performed by a central controller. The central controller receives commands from the higher-level control or the operator, processes them, and sends the corresponding signals to the individual motors. This concept provides high flexibility and control over the entire machine but may require complex wiring and a powerful control unit. In contrast, decentralized control structure consists of multiple independent control units placed near the motors. Each control unit is responsible for controlling an individual motor or a group of motors. This decentralized arrangement allows for efficient wiring and reduces signal propagation delays as the control units are located in close proximity to the motors. This results in faster response times and improved machine control performance. Additionally, the decentralized structure offers increased fault tolerance since a single failure of a control unit does not render the entire machine inoperable. Both central and decentralized control structures require powerful firmware to fulfill the control tasks. Firmware is specialized software that runs on the control units and implements the necessary algorithms and functions for motion control. It enables communication with the higher-level control, interprets control signals, and translates them into precise motor movements. Firmware plays a crucial role in achieving positioning accuracy, dynamics, and stability in motion control applications.

Overall, electronics and firmware are essential for modern motion control. They enable precise motor control, accurate positioning of machines, and efficient management of motion sequences. Whether central or decentralized control structures are employed depends on the application requirements and system design preferences. Both approaches have their own advantages and disadvantages, but they rely on robust electronics and optimized firmware, which form the core of modern motion control.

Centralised motion control architectures

In the central control topology all the intelligence is centralised into one dedicated processor (the brain), which is responsible for all tasks regarding axis coordination (including interpolation), path calculation and generation and the position control. Depending on the exact configuration the controller may also be able to do the speed and current control; the command usually is an analog +/-10V signal or a digital PWM or pulse/direction signal.

 

UV commanded values

Some controllers are able to take over responsibility for the motor commutation also, which has the advantage that the feedback needs to be connected to the controller only. The command is provided by two analog +/-10V signals (UV commutation commands) or by two digital PWM signals (digital UV commutation commands). Some controllers can even provide the switching commands for the power ICs directly, so that the power electronics only consists of the semiconductors and some protective circuit.

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Decentralised motion control architectures

In the decentralised topology the motion control intelligence is provided by the single axis controllers, to take away the motion control specific tasks from the central processor; the amplifiers in this case are responsible for the motion tasks like path planning etc. For the communication several bus systems like CANopen, Profibus, EtherCAT etc. are available.

The most digital amplifiers today have already quite some intelligence on board (e.g. to provide a very comfortable setup tool) so that they also provide a fieldbus connection in addition to the classical +/-10V interface and therefore they are ideally suited for decentralised motion control architecture. 

Since every application has its own specific requirements we supply a variety of amplifiers and controllers to be able to offer the best solution for your application. Please click on any of the menu items on the right-hand side for detailed information on your area of interest.

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Functional safety

Functional safety requires a culture applying appropriate techniques over the full development cycle, starting with requirements engineering, keeping full traceability until project completion. Various intermediate accompanying steps ensure high quality and reliability and help to early detect and solve
problems. In particular, the following steps are crucial:

  • Identification of required safety functions
  • SIL determination
  • Hazard analyses (FMEA/FMEDA/FMECA)
  • SIL conformance verification (MTBF/SFF)
  • Functional safety audits

We and our partners support our customers in their development of safety-critical applications in various markets with different (though similar) standards:

  • DO-178B/C (Avionics)
  • IEC 61508 with derived standards
  • ISO 26262 (Automotive)
  • IEC 60601-1 (Medical Equipment)
  • EN 5012x (Rail Transport)
  • IEC 62304 (Medical Devices)
  • MISRA-C (Automotive)