A Simplified Method for the Identification of Vehicle Suspension Parameters

To simulate vehicle dynamic performance, accurate parameters must be available to relate the vehicle differential equation model to the actual vehicle. This paper presents a simplified method to identify vehicle suspension spring rates, damping characteristics, and unsprung mass inertia properties. The method presented employs a digital computer algorithm to implement an equation error identification technique. A sequence of four laboratory tests was developed to obtain suspension input and response data required in the equation error technique. Each test is of a short duration (less than three seconds) and does not require vehicle disassembly. To verify the technique a test stand employing an electro-hydraulic position servosystem was constructed and the test sequence was applied to the rear suspension of a 1972 Pontiac Catalina. When the identified parameters were used to simulate the response of the vehicle suspension to the test input, agreement to within 13 percent of the actual maximum measured response resulted. The results presented in this paper show the potential of the technique to be an accurate, simplified method of obtaining vehicle suspension parameters.