Design and Testing of a Physical Therapy Device Controlled With Voice Commands

The world population is aging. Age-related disorders such as stroke and spinal cord injury are increasing rapidly, and such patients often suffer from mobility impairment. Wearable robotic exoskeletons are developed that serve as rehabilitation devices for these patients. In recent years, knee brace has attracted attention as an alternative for lost function and to extend the physical function of people who are forced into rehabilitation by injury or illness. An assistive knee brace is a simple wearable exoskeleton which is used to help people with mobility issues. This device enhances the strength of the user and also helps in providing locomotion. Many exoskeletons are currently available in the market that have different functions and use. It is believed that, to date, no voice activation-controlled knee brace device exists in an orthotic application, and that this project debuts a unique approach. This project presents the design of assistive bionic knee joint with a motor-based actuator. In our previous work, we have developed the pneumatic-based assistive bionic knee joint. This device has proven to be very effective for patients with a need of physical therapy. However, its design has several disadvantages. For example, it uses compressed air for actuation, but the compressed air is not easily refilled and portable. The complexity of tubing layout also restricts the mobility. Furthermore, the tubing system is hard to prevent air leakage in a long-term usage. In this paper, we present the design and prototyping of a new exoskeletal mechanism that mainly consist of a stepper motor, the ball screw and a set of spur gears. The ball screw provides a linear movement to behave stretching and retracting action on the assistive bionic knee joint as the human knee joint movement. The frame of the exoskeleton is modeled in SolidWorks to be modular and easy to assemble. To create a proof-of-concept of the design, 3D printing is used. A voice recognition system has been developed in-house to control the exoskeleton using simple voice commands. The motor is controlled using a motor driver and powered using an external battery source. The 3D printed prototype with integrated voice-controlled module is tested for its essential functions. The test setup is loaded on the leg of a mannequin and tested under no-load operation. The results show that the device is very effective in a no-load operation. The paper will describe the test setup and the preliminary characterization of the knee brace.