Proposing the Safety Mechanism of Ankle Joint Pushing Machine to Prevent the Over Stretching

In this paper, an ankle joint pushing system concerning about the safety mechanism of preventing the over stretching was proposed, and the effect of the safety mechanism was examined in the system. The bending of the ankle joint is an important medical treatment that physical therapist (PT's) utilize to help their patients recover their ability to walk and to prevent contracture. Since the ankle treatment requires a large amount of force (nearly equal to the subject's weight) plus precise angle and power control, manual treatment by PTs has not been replaced by mechanical treatment systems. In order to realize the safety mechanism of the ankle joint pushing treatment, the developed system uses two features. (1) The proposed device can control the starting angle of the ankle joint pushing treatment by manual setting. (2) The proposed device can realize the over stretching prevention by proposing mechanical fuse using nylon wire. Above two mechanisms can realize to get shorter the total time of the treatment, and it can release the pushing force to the toe when the setting force is exceeded. The total time of the treatment was shortened to 56% compared with previously proposed our developed automatic ankle joint pushing system, and the developed overload prevention mechanism working force was measured as 36.5 ± 4.4 N when 58 N nylon wire used. The proposed two set of the safety mechanisms will effectively work to develop ankle joint treatment system.