Abstract
Gait stability of the walking robot has great influence on the many functional features related to walking robots, from mechanical construction to control algorithms and generating steps. The goal of the presented research was a development of the concept of hexa-quad bimorph walking robot. Results of the performed static stability analysis allowed the initial verification of the mathematical model and provided information about the design adequacy and the possibilities of controlling the machine. The research involved analysing the characteristic postures of the robot focused on retaining static stability. To achieve this objective the mathematical model was made to determine the centre of gravity for the robot by using Denavit-Hartenberg notation. On this basis the simulation model was created in Matlab Simulink environment, where the described analyses were conducted. Based on the obtained results, the initial model error was determined at approximately 3%. It was also established that the centre of gravity for the design was not significantly different from the effective centre of gravity for the robot. This made it possible to achieve static stability through adequate alignment of the legs in nearly every robot configuration.
Highlights
Gait stability is one of the most important parameter, which has an influence on a number of functional features related to walking robots, from mechanical construction to control algorithms and generating steps
Support polygon is defined as a two-dimensional figure created from coordinates of tips of all supporting legs projected onto a horizontal plane
Longitudinal static stability margin is defined as the shorter one out of the distances between the projection of centre of gravity on the horizontal plane and the edge of the support polygon as measured along the direction of the walking robot's speed vector
Summary
Gait stability is one of the most important parameter, which has an influence on a number of functional features related to walking robots, from mechanical construction to control algorithms and generating steps. The measurement value used to determine stability margin can be either distance, angle, energy, moment or force. On their basis many stability criteria have been formulated. The main assumption of static stability of walking robots is retaining centre of gravity or its projection inside the support polygon. Longitudinal static stability margin is defined as the shorter one out of the distances between the projection of centre of gravity on the horizontal plane and the edge of the support polygon as measured along the direction of the walking robot's speed vector. Static stability margin is defined as the shortest distance between the aforementioned projection and the edge of the support polygon. Irregularities of the surface where the robot is moving around do not have influence on adequacy of results obtained by means of one of the above mentioned methods [5]
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