David Vaes

Optimal decoupling for improved multivariable controller design, applied on an automotive vibration test rig

Within the framework of tracking controller design for an automotive vibration test rig, a new control strategy is developed which is applicable to square multiple-input-multiple-output systems (MIMO-systems) with a certain degree of symmetry. Classical MIMO-controller design is a three step procedure: response measurement, MIMO-identification and MIMO-controller design. The latter two steps are often very cumbersome due to the multivariable character of the problem. In. this paper, a new procedure is proposed which replaces the second step with: (1) almost decoupling of the MIMO-system into multiple single-input-single-output systems (SISO-systems) by transformations of the inputs and the outputs; and (2) SISO-identifications of the decoupled systems. Thereby simplifying the control-design step to multiple SISO-controller designs. This paper also discusses the successful application of this new procedure on an industrial automotive vibration test rig.

Experimental H/sub /spl infin// control to improve an industrial off-line tracking control scheme on an automotive suspension test rig

This paper discusses the improvement of the tracking accuracy on an automotive suspension test rig by extending the available industrial off-line controller with a H/sub /spl infin// feedback controller. To reach a prescribed accuracy level in a bandwidth between 0 and 20 Hz, the off-line controller needs 7 iterations on a 2-axial durability suspension test rig to determine the correct control inputs. The extended scheme employs H/sub /spl infin// control techniques to achieve the same result in only 3 iterations. This approach takes forward the process of durability testing to a point where the required accuracy can be achieved in significantly less time.

Comparison of Different Multivariable Control Design Methods Applied on Half Car Test Setup

The multivariable tracking accuracy on an automotive vibration test rig can be improved by extending the current industrial off-line iterative feedforward procedure with a real time feedback controller. This article compares three MIMO feedback control design procedures with respect to design complexity and obtained performance: (1) DK-iteration, the most common μ-synthesis method to design robust MIMO-controllers, (2) a control design based on static decoupling, which is a combination of a static input – output transformation to decouple the system, and independent SISO-controllers designed for the diagonal elements of the transformed system and (3) an inverse-based control design, which is also based on a decoupling transformation, but the decoupling is performed by a dynamic precompensator. The performance of these controllers is compared experimentally on a half car test setup. The tracking performance of the controller designs based on static or dynamic decoupling is comparable with the performance of the controller based on μ-synthesis. The decoupling-based controller designs, using standard SISO H∞ techniques, are however much simpler and more straightforward.

Multivariable control for reference tracking on half car test rig

The multivariable tracking accuracy on an automotive vibration test rig can be improved by extending the current industrial off-line iterative feedforward procedure with a real time feedback controller. This paper compares two MIMO feedback controller design procedures in practice. First DK-iteration is used. This is the most common μ-synthesis method to design robust MIMO-controllers. Secondly a controller based on decoupling design is tested. This is a two step procedure. Step one is the calculation of a transformation of the inputs and the outputs to decouple the system as accurately as possible. Step two is the design of a decentralized controller (combination of independent SISO-controllers) for the transformed system. While the control design based on decoupling, using standard SISO H∞techniques is much simpler and more straightforward, the performance is comparable to that of the controller based on μ-synthesis.