Experimental Estimation of Slipping in the Supporting Point of a Biped Robot

When developing a gait cycle on a low-friction surface, a biped robot eventually tends to slip. In general, it is common to overcome this problem by means of either slow movements or physical adaptations of the robot at the contact point with the walking surface in order to increase the frictional characteristics. In the case of slipping, several types of sensors have been used to identify the relative displacement at the contact point of the supporting leg with the walking surface for control purposes. This work is focused on the experimental implementation of a low-cost force sensor as a measurement system of the slipping phenomenon. It is shown how, supported on a suitable change of coordinates, the force measurement at the contact point is used to obtain the total displacement at the supporting point due to the low-friction conditions. This is an important issue when an accurate Cartesian task is required.