CHARACTERISTIC CURVES OF PNEUMATIC MUSCLE FOR THE USE IN THE UFMG EXOESKELETON Danilo Alves Pinto NAGEM dapin@ufmg.br Breno Gontijo NASCIMENTO brenognascimento@yahoo.com.br Claysson Bruno Santos VIMIEIRO, clayssonvimi@hotmail.com Henrique Resende MARTINS, henriquelabbio@hotmail.com Olival Fernando Lima SCHULTZ, schultztor@yahoo.com.br Márcio Drumond Costa FERREIRA marciodcferreira@hotmail.com Marcos PINOTTI Laboratório de Bioengenharia Departamento de Engenharia Mecânica Universidade Federal de Minas Gerais – UFMG Av. Antonio Carlos, 6627 31270-901 Belo Horizonte - MG pinotti@ufmg.br Abstract. This work is about the development of technology for accessibility projects, with the main objective to reduce the difficulty deficiency bearer has to walk and to realize routine tasks. Nowadays, there is a great demand for the development of low cost equipments used in the treatment to recover the walk movement as well as in sessions of physiotherapy. Recently, the Laboratory of Bioengineering at the Federal University of Minas Gerais (UFMG) has developed an artificial pneumatic muscle, DGP. In this work the relationships among pressure, volume and load required for DGP positioning control were established. It has also been developed an electronic circuit capable of triggering an electro-mechanical pneumatic valve using the myoeletric signal as an activate factor. The methodology to determine the flow required in a DGP, adapted to an exoskeleton, to auxiliary in the recover of the walk pattern is also presented. The walk pattern is determined by analyzing the position, speed and acceleration of hip and knee joints. This pattern is used in the calculation of the force, pressure and volume required in the DGP to recover and control the movement. Keywords: Bioengineering, artificial pneumatic muscle, walk pattern, dynamics of the walk, myoeletric signal, movement recovery, accessibility. 1. Introduction The walking is the most important function for the human autonomy. When the human movement is impaired, the use of mechanical equipment can aid to the functional motion and greatly improve human walking ability after neurological injuries. Traditionally the electric actuators used to restore the walking movement are big, heavy and presents some unsafeness characteristics. Hence the DGP (NAGEM, 2002; PINOTTI et all, 2004) an artificial pneumatic muscle was developed as a specific actuator to be used in functional orthesis and prosthesis. The use of pneumatic actuators to control the movement in the whole range is a recent technology. These actuators are usually used to control the starting and the ending positions of the movement (MCDONELL, 1997; BOBROW e MCDONELL, 1998; CHOU e HANNAFORD, 1996). The pneumatic actuators have characteristics that difficult his control, like the non-linear movement with a pressure variation, the air compressibility, and the friction in low velocities (MCDONELL, 1997; BOBROW e MCDONELL, 1998; RICHER, 2000; XIANG, 2004). However, the developments in control methods and equipments turned these pneumatic actuators capable to control robots movement with high precision (GUILHARD e GORCE, 2000; RICHARDSON, 2003; RICHARDSON, 2004). Flexible pneumatic actuators are an alternative feasible if compare with an electrical or hydraulic actuators for some applications in prosthesis and orthosis. Because this actuator behaves like the human muscle (KLUTE, 1999;