Kinematic analysis of legged system locomotion on smooth horizontal surfaces

This thesis presents a model of legged locomotion in which position and velocity of body are directly controlled by positions and velocities of feet. One central relationship between foot acceleration, leg stroke and body velocity is developed. Procedures for determining all parameters of a step sequence including periods of constant body velocity (steady state) and constant linear acceleration of body (transient state) are presented. The following assumptions are used. Symmetrical trapezoidal velocity profiles are used for body and feet. Transient period is longer than or equal to one step time and a multiple of half step time. Step time and duty factor are constant during each locomotion stage. Stepping movements of a pair of legs are 180° out of phase and successive prints of one foot are symmetrically placed relative to the other foot. Starting and stopping occur with feet on a line perpendicular to the direction of body motion. Locomotion starts by lifting one foot and ends with one foot on the ground and the other being placed. When analyzing walking, designing a walking machine or designing a stepping sequence for an existing walking machine, it is important to understand constraints placed on body motion by motion of a single leg. Two dimensionless numbers which describe foot velocity profile are developed. Two additional dimensionless numbers result from constraint of leg workspace by foot acceleration and body velocity during steady state. These numbers provide useful relationships for design procedures. Defining a walking sequence requires transformation of objectives from global to body coordinates and continuously accounting for the relationship between these two systems. The technique described does this when body acceleration is non-zero as well as when body velocity is constant. Relationship between body and global coordinates is tracked for one leg pair using two diagrams: 1) position of feet relative to body versus time; 2) distances moved by feet and body in the global frame. A closed form inverse kinematic solution and an algorithm to find workspace for general three-revolute manipulator are presented

Synthesis of Robots/manipulators for a Prescribed Working Space

Mechanical Engineerin