Driver muscle fatigue analysis based on monorail crane operating environment biomechanical coupling model and surface electromyography signal

To quantitatively analyze and evaluate the driving fatigue of monorail crane drivers, this research established a biomechanical coupling model of the cab-driver operation environment within the Anybody. Muscle activation and muscle force were utilized as evaluation indicators to analyze the driving fatigue characteristics of monorail crane drivers. The research revealed that during the driving process, the biceps brachii displays the most pronounced variation for muscle activation and muscle force. In contrast, the trapezius and latissimus dorsi show less force and activation, with smoother curve changes. The extensor digitorum significantly exerts force during driving times of 1∼2, 12∼15.8, and 27∼30 s, with minimal activity otherwise. The rectus femoris, gastrocnemius, and soleus exhibit a cyclical pattern of increasing and then decreasing muscle force and activation. Peak durations for these muscles are 3∼21 and 27∼39 s, while the biceps femoris has the lowest muscle force and activation with minimal variation. A comprehensive analysis indicated that the overall fatigue of the lower limbs showed a continuous increase, with the fatigue being greater for lower limbs than upper limbs. Subsequently, surface electromyography experiment was conducted to validate the model by testing muscle electrical signal during maximum voluntary contraction (MVC). The results demonstrated that the relative error between the model and the experimental data was less than 15%, and the correlation coefficients were all greater than 0.966 ( p < 0.05), indicating a strong consistency between the model and the experimental data. Finally, EMG was employed to calculate and analyze the changes in muscle activity during the driving process. The findings from this research can serve as a theoretical foundation and provide data references for the optimization design of monorail crane.