Resource-constrained control systems
Master thesisTopic
Control design is usually performed assuming idealized timing assumptions, including sampling without jitter and negligible delay from controller input (sensing) to output (actuation). Of course, each ECU does not only execute a single control application but several at the same time. Each of them is developed under the above stated assumptions. In the case of a single processor system, these control applications compete for processor time. Since only one controller can execute at the same time, a real-time kernel arbitrates the access to the processor according to a scheduling policy. This of course leads to preemptions and, in the case of shared resources, blocking effects, etc. Obviously, the above stated idealized assumptions do not hold under such circumstances.
Therefore, the question arises how computation time may systematically be included within the design of discrete-time control systems [1] and how such a time-structured approach influences scheduling. From a control engineering perspective, this question concerns on the one hand side the derivation of the controller in combination with the determination of the sampling rate. On the other hand side, new technologies such as timed-programming make new degrees of freedom with respect to time-structuring accessible, e.g. the fast approximation of direct feedthrough leading to multirate systems [2]. In this work, the theoretical relations between linear sampled discrete-time control systems and scheduling shall be explored.
Goals and tasks
The above discussed aspects yield to the following work packages:
- Theoretical examination of linear sampled discrete-time systems concerning the systematic incorporation of time delay due to computation time.
- Discussion of possible transformations (such as e.g. discretization schemes) between different types of control design models (continuous, single-rate, multi-rate). What is their influence on the control design procedure?
- Reformulation of the control design task for the case of a multi-rate treatment based on the scheduled computation times.
- Examination of the above questions by means of the use-case electromechanical brake.
- Report in LaTeX
- High motivation
- Strong background in control theory
- Knowledge in real-time and embedded systems
- Strong autonomy and fast independent learning
[2] Winkelhake, J.: Entwurf digitaler Multiraten-Abtastregelungen.
Fortschritt-Berichte Nr. 8/1063, VDI-Verlag Düsseldorf, 2005.
The thesis is intended to be conducted partially at Bosch (Schwieberdingen) and at the RCS (Munich)
Begin: on appointment
Supervisors
