Fuzzy PID control for sit-and-reach trainer based on magneto-rheological damper

The sit-and-reach exercise has consistently garnered popularity among adolescents. Not only does it play a pivotal role as a crucial element in stretching training, but it also contributes to enhancing the overall flexibility of the adolescent body. However, training processes often encounter challenges such as safety concerns and increased human time costs. Current auxiliary stretching training robots primarily target specific joints, such as the ankle and finger joints, leaving a gap for a comprehensive training device dedicated to sit-and-reach movements. This study introduces the design of a sit-and-reach and stretching trainer, incorporating magneto-rheological damper to address safety concerns. The device offers two distinct training methods to provide a solution to the aforementioned challenges. Then the control method of magneto-rheological damper is studied. Through a comparative analysis with the traditional PID control method, the study adopts a fuzzy PID control strategy for the device's various training modes. In conclusion, comparative verification experiments demonstrate the superiority of the fuzzy PID control strategy in both overshoot and steady-state error control.