Design of h-infinity tracking controller for application in autonomous steering of mobile machines

Abstract

The purpose of the designed H ∞ controller is to drive effectively the hydraulic system and to make it follow the desired trajectory, which is commanded by a joystick, steering wheel or geographic based data. To design the controller we used the experimentally identified SIMO linear mathematical model. The identification procedure is based on random excitation signals and prediction error methods for regressive discrete-time equations. The input of the mathematical model is the voltage applied to the spool driver EH module (PVE) and the outputs of the model are the spool position of the proportional valve in the steering unit, flow rate and the cylinder piston position. These output variables carry important information about the state of the system and can be used to increase performance in respect to the case, when using only the cylinder piston position or pressure signals. We have already experimented with various control strategies for the identified mathematical model. Experimental studies are performed on a laboratory test rig for electrohydraulic steering systems based on the 32-bit microcontroller and taking into account the technical specifications of mobile machine manufacturers and standards. In addition to the requirements of the safety standards, new advantages are achieved in terms of precise tracking control and providing a variable steering ratio between the steering wheel and the steering cylinder supported by the designed H ∞ controller.

Robustness Analysis of an Electrohydraulic Steering Control System Based on the Estimated Uncertainty Model

“…The developed real time Simulink ® structure used for experiments with LQG and H ∞ controllers is presented in Figure 20 [14]. The main block in the model is the MATLAB ® function block which realizes the communication on the CAN channel between the microcontroller MC012-022 [25] and the workstation.…”

“…Model ( 2) is used to design the LQG and H ∞ controllers. A detailed description of the procedure for LQG and H ∞ controllers synthesis is presented in [13,14]. The main proposition of this article is the investigation of robust stability and robust performance of the developed embedded electrohydraulic power steering system based on the new uncertainty model.…”

“…The methodology should be used after controller design and before implementation of the control algorithm into an actual control device. It was performed on two embedded control systems that were designed in our previous works [13,14]. They were based on a linear-quadratic Gaussian (LQG) controller and an H ∞ controller.…”

Developing magnetic sensor for spool-sleeve displacement of hydrostatic steering unit

“…Its dynamic characteristics directly affect the stability and reliability of the driving. Sensors for the positions of the proportional valve and the steering wheel are used as input for controlling of the vehicles [2], [3]. Direct measurement from sensors provides valuable insights for the dynamics and control of the OSP.…”