Displacement Controlled Steer-by-Wire System

Xiaofan Guo, Purdue University

Abstract

The power steering system heavily rely on hydraulic system to transmit power. However, current power steering systems normally use valve control, which introduces high power loss due to throttling of the flow. Displacement control (DC) is proven to be a great alternative for hydraulic system to cut power loss. Ongoing research has shown great potential of energy savings and productivity increases of DC systems. Therefore, displacement control will be a very good fit for the steering system in order to increase system efficiency. Furthermore, steer-by-wire systems are currently investigated to replace traditional steering systems in vehicles. Steer-by-wire systems allow implementing advanced controller, such as required for autonomous driving and active safety functions. A novel displacement controlled steer-by-wire system with emergency system function is proposed in this thesis. In order to demonstrate the performance of the proposed displacement controlled steer-by-wire system, the hydraulic and mechanical system has been modeled through MATLAB/Simulink® . Most of the physics are captured in the model, such as the pump dynamics and system power loss, system pressure buildup, steering system load force calculation, etc. The novel DC steer-by-wire system is proposed for a combine harvester. Experimental data has been used to validate the model. Then, the validated model has been used to demonstrate system performance. From the result, the proposed system shows a very good tracking of command signal. Above that, the proposed system saved 80% of the pump output energy to the steering system by eliminating the valve-throttling loss. The overall system efficiency is very good. In addition, a simplified simulation model is built to cut simulation time for basic function demonstration only.

Degree

M.S.M.E.

Advisors

Ivantysynova, Purdue University.

Subject Area

Mechanical engineering

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