Design of a Lower-Limb Exoskeleton Drive Using an ArduinoBased Stepper Multimotor

Abstract

 Lower-limb exoskeleton is a walking aid and therapy for the lower part of the human body which is made for stroke or paralyzed sufferers. This tool is attached to the user’s waist and can help the movement of the user’s thighs, which in general, this tool is used for rehabilitation and assisting human work activities. Movement of the lower-limb exoskeleton consists of at least two degrees of freedom (DOF) or degrees of freedom motion, even in full it can be 6 to 12 DOF. In addition, the exoskeleton is used for therapy and is equipped with controls that really help the user to make movements, and the results can improve motor function. This movement control system generally uses a microcontroller and the drive system is a motor. Rehabilitation tools with the help of robots have been developed in many developed countries. Most of the designed rehabilitation aids have a large size and also have a heavy weight. So it requires a special place for rehabilitation. Therefore, an exoskeleton that is lightweight and also small in size is needed so that it can be used for other activities. The lower-limb exoskeleton is a combination of robotic technology and medical rehabilitation technology. In terms of design, the exoskeleton design should not only incorporate a rigid and flexible structure, but also have a high degree of resemblance to the movement of the human foot. However, there are still many problems with the lower-limb exoskeletons studied previously, which use a thick, bulky supporting frame with a low degree of freedom to partially support the wearer’s weight and mobility. If the rigid supporting frame and mechanical components are tightly attached to the body, it causes movement discomfort during rehabilitation training and may also cause secondary injury to the patient. Therefore in this study, the focus was on selecting the type of motor used so that the exoskeleton can support the medical rehabilitation of patients. The type of motor used was a stepper motor type 28BYJ-48 along with a ULN2003 motor driver and Arduino Uno as the controller. Furthermore, the propulsion system and controller are implemented in a prototype lower-limb exoskeleton with a 2:1 scale of human size. The tests carried out in this study were: movement of the thigh to the right and left, movement of the knee to the right and left, and movement of the ankle   to the front and back, by analyzing the rotation angle and maneuver time of the designed system. The test results show that the Stepper Motor produces better and smoother movements where the angle of rotation along with the time duration of the movement of the thighs, knees, and ankles makes the patient comfortable in making movements in the framework of rehabilitation