An optimized sensor configuration is proposed for a magnetorheological damping seat, in which a four-bar linkage mechanism is employed to achieve high-precision displacement measurement through angular sensing. To formulate the linkage optimization problem, the closed-vector constraint equations of the mechanism are established, proportional relationships between link lengths and installation positions are introduced, and a comprehensive optimization scheme for both link dimensions and mounting configuration is developed. Based on this formulation, an enhanced simulated annealing (SA) algorithm is implemented, incorporating adaptive temperature decay, dynamic step-size adjustment, and a controlled reheating mechanism to efficiently solve the optimization problem. Simulation results demonstrate that the proposed approach significantly refines the linkage geometry, yielding improved sensor linearity, higher measurement sensitivity, and enhanced overall robustness. Experimental validation on a scissor-type seat verifies that the optimized sensor design, integrated with geometry-based parameter fitting, delivers accurate displacement reconstruction and robust practical performance.