CONCEPTUAL AND MECHANICAL DESIGN OF AN ANTHROPOMETRIC-SCALED BIPED ROBOT FOR REPRODUCING NORMAL AND PATHOLOGICAL HUMAN GAIT

Abstract

This paper presents some preliminary results concerning the conceptual and mechanical design, as well as the primary hardware and software development, of a biped robot able to reproduce human gait patterns as recorded from a gait analysis laboratory. Robot dimensions followed the same mean proportions between the segments observed in human subjects. In this way, geometrical and kinematical similarity between the robot and humans were sought, although the kinetical parameters of the robot (weight and moment of inertia) were kept as light as possible, minimizing the nominal torque requirements of the servo-actuators. The robot was designed and built using 10 PWM-controlled servo-actuators. For the ankle and hip joints, parallel three-dimensional mechanical linkages were used, with the advantage of almost doubling the nominal torque-generation capacity of the servoacutators, as the two servos are employed in the generation of the movements. However, this linkage has a complex kinematics, and it was necessary to derive a mathematical model to find the servo input angles that generates the desired joint angles for the gait cycle. The control of the robot is performed by MS-Windows dedicated software, that controls the PWM (Pulse Width Modulation) signals to the servo actuators. Keyworks. biped robot, biomechanics, control, human gait