Interview: Mechanical Testing

Matthias Deter is Group Manager Engineering, responsible for customer projects with mechanical test benches, at dSPACE in Paderborn, Germany.

In some hardware-in-the-loop (HIL) test cases, it is not possible to access the electronic control unit (ECU) only by its electric interfaces. Mechanical access is also indispensable for tasks such as:

  • Applying mechanical loads to an electric drive
  • Physically stimulating the integrated sensors for mechatronics ECUs
  • Mechanically stimulating human-machine interfaces

Typical applications:

  • Testing/developing functions
  • Automated software release/acceptance
  • Examining error-case behavior
  • Concept validation
  • Mechanical endurance tests
  • Measuring the unit under test

With HIL technology, it is no problem to integrate and test ECUs (such as steering ECUs with all their interfaces) and vehicle buses. The reference values for the load machines are provided in real time by real-time simulation models. Genuine closed-loop operation between the test bench components, the ECUs and the simulation is achieved via suitable I/O interfaces. Thus, realistic load scenarios for the electronic and mechanical components can be created by coupling the test bench with a HIL simulator. Different load machines are used for different requirements and applications: rotary drives, spindle actuators, highly dynamic linear motors, etc.

These are typical test bench application areas:

  • Steering systems, such as:
    • Electric power steering
    • Superposition steering
    • Controlled electric pumps, e.g., fuel and hydraulic
  • Mechatronic ECUs with integrated sensors and actuators, such as:
    • Gear control units with integrated speed sensors
    • Parking brake ECU with integrated inclination sensor
    • ESP with integrated rotation rate and acceleration sensor
    • Pedal actuation for testing electric brake boosters
    • Force feedback control in driving simulator applications

Depending on the use case, the requirements comprise:

  • Powerful and dynamic actuators
  • Fast coupling between the actuator and the HIL system, e.g., the dSPACE Twin Sync Solution couples an LTi Servo One converter with a dSPACE HIL Simulator
  • The relevant sensors combined with suitable control algorithms for achieving high control quality and accuracy
  • Coupling between the test bench and the simulation model
  • Haptic requirements, e.g., for combining the test bench and a driving simulator

  • Pre-sales consulting
  • Modular, turnkey, custom test benches including Automotive Simulation Models, mechanics, sensors, electric motors, and control engineering
  • Integrating customer´s real components or simulation models into the test system
  • Test bench maintenance

Designing, constructing and controlling test benches with the following main application areas:

  • Electric power steering test bench; testing an EPS control unit and motor, as well as the complete electric steering system
  • ESP with integrated sensors
  • Electric parking brake
  • Rear axle steering
  • Load motor integration depending on the use case
  • Rotary load simulation with motors in various power classes
  • Translational load simulation via linear motors and ball screw actuators
  • Scalable systems from small rotary test benches (e.g., integrated in 19” cabinet) to large test benches for testing a complete steering system

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