Optimal Track Mixing with U·SimOpt

Optimizing Schedules on a Proving Ground or Collections of Standard Load Cases

Having derived a design load for the vehicle development process (e.g., with U·Sim), one often wants to map it to a schedule on the proving ground. There are three main reasons for doing this:

  • The resulting signals contain the durability relevant loading in a more condensed and shortened way.
  • The schedule to be derived can be applied not only to exactly the vehicle of the measurement campaign, but also to variants.
  • Measuring the loads can be easily repeated.

The Basic Approach – Optimize a Test Schedule

Besides the design load, input data for the tool are measurements on different test tracks (lanes) of a proving ground or in customer operation, from which a test scenario is to be compiled. These data include pseudo-damages for all relevant measured channels, properties of the tracks (length, duration, etc.), restrictions on the use of the tracks and the reference loads itself. The goal is to optimize a test schedule (find the optimum number of repetitions for each track) such that the combined load deviates as little as possible from the specified design loads.

Multi Criteria Optimization

As this needs to be fulfilled for many measured channels at the same time, the user interactively solves a multi-criteria optimisation problem and finds a good compromise. To be as flexible as possible with respect to the compromise, there are several objective functions available for optimisation:

  • Minimum runtime of the test schedule
  • Minimum deviation from the reference loads (left, right, or symmetrical)
  • Maximum quality of the test schedule relative to a quality function, which assigns an individual weighting to each channel
  • Minimum number of used test tracks

Different Constraints Can Be Considered:

  • Maximum permissible deviation from the design load
  • Minimum and maximum repetition factors of individual tracks
  • Restrictions on tracks in terms of time and length
  • Dependencies between different tracks (e.g., if track A is used, track B must also be used)
Quality of the solution and its decomposition into different lanes of the proving ground
© Fraunhofer ITWM
Quality of the solution and its decomposition into different lanes of the proving ground

More Features:

  • Graphical analysis of data, tracks, and test schedules
  • Modification of constraints and iterative adaptation of the solution
  • Microsoft Excel interface for data import and export