Kinematic and sensitivity analysis and optimization of planar rack-and-pinion steering linkages

In this paper, the combined kinematic and sensitivity optimization of a rack-and-pinion steering linkage is performed. This steering linkage is the most common steering system used in passenger cars. Although, the steering linkage has received a lot of attention for the minimization of the steering errors, no attempt has been made so far to investigate the sensitivities of optimum dimensions relative to variation of link lengths. The kinematic optimization of the linkage is carried out using three homogenous design parameters. The objective of the proposed optimization is to minimize maximum steering error during cornering. This is followed by a sensitivity analysis to predict how the steering error is affected by manufacturing tolerances, assembly errors, and clearances resulting due to wear. Since the optimized kinematic error is very sensitive to the variations of the linkage parameters, the kinematic and post-optimal sensitivity optimization of the steering linkage is performed in an integrated manner. The methodology proposed in this work helps the designers of rack-and-pinion steering linkage to choose the linkage parameters whose maximum steering error (MSE) and sensitivity are minimum.