An optimization model of tractor clutch pedal design parameters based on lower limb biomechanical characteristics

The design of tractor pedal affects operator's comfort, working efficiency, and occupational health. To optimize tractor clutch pedal design parameters, we conducted a single-factor experiment and a response surface experiment based on a biomechanical model. The experimental indicators included the biomechanical loads of major activated muscles and joints of the lower limb, and the experimental factors comprised pedal-seat horizontal distance L, pedal-seat vertical distance H, and pedal spring stiffness k. The results indicate that L and H mainly influence the loads of semitendinosus and hip. Semitendinosus activity and hip torque first decreased and then increased with increasing L (or H), reaching the lowest level at 82 cm of L (or 42 cm of H). The increase in k led to gradual decreases in iliopsoas activity and increases in semitendinosus, rectus femoris, soleus activities, and ankle torque, as well as a first decreasing and then increasing trend of hip and knee torques. The overall biomechanical loads of the lower limb first declined and then grew with increasing L, H, and k. The optimal range of clutch pedal design parameters was calculated to be {(L, H, k) | 36≤L ≤ 40, 72≤H ≤ 76, 14≤k ≤ 22} when using the response surface method. Within this range, muscle activity and joint torque were reduced by 14.2% and 51.6%, respectively, indicating effective alleviation of the lower limb biomechanical loads. This study provides important implications for the biomechanical analysis of tractor operator-pedal interaction system and lays a foundation for improving the design and comfort of tractors.