Design of Information Acquisition and Control System for the Exoskeleton Robot

Hindawi Publishing Corporation Journal of Electrical and Computer Engineering Volume 2014, Article ID 309814, 7 pages http://dx.doi.org/10.1155/2014/309814 Research Article Design of Information Acquisition and Control System for the Exoskeleton Robot Huan Gou,1 Jialiu Wang,1 Hongfang Wu,1 Chao Wang,2 Lei Yan,1 and Jiang Xiao1 1 2 School of Technology, Beijing Forestry University, Beijing 100083, China Columbia University, NY 10027, USA Correspondence should be addressed to Lei Yan; Received 12 November 2013; Accepted 24 December 2013; Published 11 February 2014 Academic Editor: Xudong Zhu Copyright © 2014 Huan Gou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper puts forward an information acquisition and control system for the exoskeleton robot, which can collect movement and location information of the robot timely through a variety of sensors. The information is preprocessed by the microcontroller firstly and then transmitted to the host computer for data analysis and processing by ZigBee wireless transmission module to analyze the movement intention of human by virtue of the monitoring software on the host computer. To achieve assistance, the motor drive will be controlled by the robot through CAN bus, and the robot can effectively analyze human’s intention and monitor the operation status of the assisted robot in practical applications, finally enhancing the body’s walking ability. 1. Introduction The original meaning of exoskeleton is the shell structure of arthropod body which provides support for the animal’s movement and protection. This conception can be extended to exoskeleton robot, which is an integrated mechanism of human and machine. It combines human intelligence with robot body, controls the robot relying on human intelligence, and finally completes the task which cannot be accomplished by human intelligence or robot body alone. General Electric Company and Cornell University developed a wearable and individual equipment named Hardiman-1 in 1960. As the world’s first conceptual exoskeleton robot, Hardiman-1 was composed of 30 hydraulic power suppliers and servo hinges, and had 30 degrees-offreedom. This equipment used the master-slave control mode and was hydraulically driven to provide impetus for the upper and lower limbs. Unfortunately, the research was terminated because of the huge size and operation complexity of the equipment [1]. Japan University of Tsukuba designed the power-assisted “Robot Suit” named HAL (Hybrid Assist Legs) [2], which was mainly composed of wireless LAN (Local Area Network) system, battery pack, motor, reducer, sensor, and actuating mechanism. HAL used the angular transducer, the electromyography sensor, the reaction force sensor, and other sensors to obtain the state information of the exoskeleton and the operator, and then the power transmission adopted the method of motor-reducerexoskeleton mechanism to provide power for the robot body [3]. University of California, Berkeley developed Berkeley Lower Extremity (BLEEX), which was composed of fuel supply and engine system, control and detection system, hydraulic transmission system, and exoskeleton mechanism. The sensor system of BLEEX included the inclinometers, force sensors, gyroscopes, and plantar pressure sensors, of which inclinometers and force sensors were used to measure the joint force and limb inclination of robot, plantar pressure sensors took the role of the measuring apparatus of plantar pressure distribution when people walked, and gyroscopes were used to measure the center and inclination of the upper body. Based on the information collected by the sensors, the control system would ensure that the robot’s center of gravity was always on the user’s feet. After that, the control system would use the mechanical structure of the hydraulic drive to provide assistance for the exoskeleton mechanism [4]. Nanyang Technological University in Singapore also developed their exoskeleton system [5], which was composed of medial exoskeleton and outer exoskeleton. The medial 2 exoskeleton was bundled on the lower extremity and used joints of the encoder to measure the joint angle signal when walking, while the outer exoskeleton was to provide power for the system by the motor based on the joint angle signal from the medial exoskeleton. In addition, the prototype system used the point of zero moment (ZMP) theory to survey the walking stability of exoskeleton. In order to develop a wearable booster device for nurses, Japan Kanagawa University of Engineering designed a set of freestanding wearable booster jackets to move patients. The jacket selected micropump, portable nickel-tin battery, and embedded microprocessor as the components, which miniaturized the power supply and control system obviously. The joint drive of elbow, waist, and knee adopted new rotational displacement pneumatic drive, and the muscle strength signal was gained by muscle hardness sensors mounted on the upper arm, thigh, and waist. When the microprocessor receive the output signal of sensors, it would calculate the joint torque required to maintain a posture and then output the corresponding control signal to tell the PWM driving circuit to drive rotating cylinder [6]. Based on the above work, it can be seen that how to enhance the body’s ability to walk is the key to the design of new exoskeleton robot. Now exoskeleton robot is of still many problems, including the robot’s cooperation with human body and multisensor information collection and integration. In view of this, this paper tries to put forward an information acquisition and control system design which are based on ZigBee wireless sensor network and CAN bus. This system can combine human intelligence with exoskeleton robot, analyze the intention of human movement, and monitor the operating state of exoskeleton assisted robot. The rest of the paper is organized as follows. Section 2 presents the design of the exoskeleton structure. And then the establishment process of the information acquisition and control system is described detailedly in Section 3. Finally, some conclusions are given in Section 4. 2. Design of Structure 2.1. The Selection of Driving Mode. A reasonable choice of driving mode has a great influence on the structure and performance of exoskeleton robot. In addition, it also influences the information collection deeply. So the appropriate driving mode and driver must be selected in order to ensure the feasibility and accuracy of the information collection. Lower limb exoskeleton is usually driven in three ways: motor drive, hydraulic drive, and pneumatic drive. They have advantages and disadvantages. Motor drive control mode is simple, direct, easy to guarantee the control precision, and convenient to maintenance and use. But if greater p (...truncated)