A numerical dynamic behaviour model for 3D contact problems with friction

This paper proposes a novel algorithm for the condition detection in which the slip state transitions in a stick-slip motion, or the solution breaks down and also to study the state transition of nodes belonging to the contact area: stick, slip or open contact state. We designed a Matlab Simulink program to simulate the occurrence conditions for the slip-stick transition analysing three types of contact surface materials, with respectively 0.5, 0.75 and 0.9 friction coefficients, using finite element contact. The proposed method is able to detect the stick-slip motion and implicit the numerical instability of the model. By applying this method to control walking robots on uncertain, unknown and unstructured surfaces, the occurrence conditions for the slip-stick transition depending on the friction coefficient of contact material were determined. The presented simulations demonstrates through a numeric modelling of the dynamic behaviour of 3D contact problems with friction we can detect the slip/stick phenomenon for a walking robot motion on a uneven terrain, so it can improve the real time control in order to predict and avoid robot overthrow.