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

 

J.A. Vázquez*, M. Velasco-Villa

 

Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN) Departamento de Ingeniería Eléctrica, Sección de Mecatrónica. Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, CP 07360 México DF, México, *javazquez@cinvestav.mx.

 

ABSTRACT

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.

Keywords: biped robot, slipping, walking cycle.

 

RESUMEN

Cuando un robot bípedo desarrolla ciclos de marcha en una superficie con baja fricción, eventualmente tiende a patinar; sin embargo es común evitar este problema mediante ejecuciones de movimientos de baja velocidad o bien, mediante adaptaciones físicas en el punto de contacto con la superficie para aumentar las caractersticas de fricción. Cuando este fenómeno se presenta, la existencia y magnitud del desplazamiento relativo en el punto de contacto puede ser identificada a partir de una gran variedad de sensores. Este trabajo se enfoca en la medición del patinado descrito anteriormente a través de un sensor de fuerza de bajo costo. Se muestra además cómo, a través de un cambio de coordenadas, la lectura de la fuerza en el punto de contacto es utilizada para conocer la magnitud del desplazamiento en el apoyo debido al patinado.

 

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