Mechatronics

Chapter 7

Intelligent Assistive Knee Exoskeleton ¹

This chapter explores the modeling, control, and implementation of pneumatic artificial muscles as actuators for a lower limb exoskeleton. The exoskeleton is aimed to serve as an assistive device to aid disabled persons. The intelligence of the exoskeleton is derived from the user’s own myoelectric signals. These signals are processed and used as the reference for the motion controller.

7.1. Introduction

7.1.1. Background on assistive devices

The percentage of elderly people in the present world is increasing at an alarming rate. As Table 7.1 shows, in many developed countries the percentage of people over 65 years is close to 20% [STA 10]. As the population of a country ages, there is a corresponding increase in the number of people with physical disabilities. As an example, Japan, the world’s third largest economy, is experiencing a phenomenon that is the first of its kind in the world. In 2005 the elderly made up 20% of its total population and it is predicted that by 2030 this percentage will grow to about 30% [OHN 06]. The immense strain that this situation will place on the economy can only be alleviated if active participation of the elderly in society could be prolonged.

Another leading cause of adult disability is cerebrovascular accidents, otherwise known as a stroke. In the United States it is the leading cause of permanent disability. According to the 2010 report from the American Heart Association, on average every ...