engleski

Stability Analysis of In-pipe Inspection Robot

The idea was to model the behaviour of the pipeline-testing robot as a system of rigid bodies, casings and its members that are interconnected by joints. However, the difference between such a mathematical model and the “classic” model of robot manipulators is in its base. Here, as with walking robots, the so-called floating base is used, because its configuration, in addition to the position of the joints, also depends on the configuration of the base in space. In accordance with the laws of centroid mechanics, the model of floating base is also observed as a rigid body whose configuration has six degrees of freedom of motion. The exact determination of the base configuration requires data on its position and orientation. Furthermore, its kinematic and dynamic equations are modelled. Spatial vectors that are 6-dimensional vectors that combine the linear and angular motion component and forces of rigid bodies are used to describe the equations. Their use allows for a more compact record of rigid body motion equations, and consequently a more compact record of rigid body dynamics algorithms. Control algorithm of in-pipe inspection robot is based on so-called hybrid compliance control system, including its passive and active parts. At joint between leg jackets and at joint between housing (on driving and driven robot part) and upper leg jacket is mounted active actuator (serial elastic actuator) as active part. The method used for testing the system stability for certain robot system architectures was the so- called direct method or the second Lyapunov method. Depending on the nature of Lyapunov’s function, conclusions can be inferred on the stability of the equilibrium state of the system (stable state and asymptotic stability, and unstable state). To observe stability, we need to observe a linear unactivated system, invariant in regards to time.

in-pipe inspection robot, hybrid compliance control system, Lyapunov stability

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