Patent ID: 7402142
Filing Date: 2008-07-22
Classification: B62D

Abstract:
1. A method for obtaining in real time torques to be applied to joints of a leg of a biped walking system, the method being performed by modules and stored in a processor and comprising the steps of: deternmining which leg or legs are in contact with the ground by a leg-motion determining module that uses data from a hip vertical accelerometer; obtaining an attitude of the leg by a leg-attitude computing module that uses data from a hip horizontal accelerometer, a hip gyroscopic sensor and joint angle sensors; obtaining a position of a center of gravity of a whole body by a body center of gravity location computing module that uses an output of the leg-attitude computing module and data from a chest horizontal accelerometer, a chest gyroscopic sensor, the hip horizontal accelerometer, and the hip gyroscopic sensor; obtaining a vertical component of acceleration of the center of gravity of the whole body including the leg by a body center of gravity acceleration computing module that uses an output of the body center of gravity location computing module and data from the hip horizontal accelerometer, the hip vertical accelerometer and the hip gyroscopic sensor; obtaining a vertical component of an actual ground reaction force acting on the leg by a ground reaction force estimating module, based on which leg or legs are in contact with the ground, the attitude of the leg, the position of the center of gravity of the whole body and the vertical component of acceleration of the center of gravity of the whole body including the leg, the ground reaction force estimating module using outputs of the leg-motion determining module, the leg-attitude computing module, the body center of gravity location computing module and the body center of gravity acceleration computing module; obtaining an actual point of application of the ground reaction force by a module for estimating a point of application of a ground reaction force, based on the position of the center of gravity of the whole body, positions of ankle joints and positions of joints at front ends of feet under normal condition and based on positions of the joints at front ends of feet when going up or down stairs or going uphill or downhill, wherein it is determined based on positions of the ankle joints while the both legs are in contact with the ground whether the system is under normal condition or going up or down stairs or going uphill or downhill, the module for estimating a point of application of ground reaction force using outputs of the leg-attitude computing module and the body center of gravity location computing module; obtaining moments acting around the joints of the leg, by a joint moment estimating module, using the vertical component of the ground reaction force acting on the leg at the point of application of the ground reaction force, the vertical components of forces acting on the joints of the leg and a term of the acceleration of gravity and without using the horizontal components of the forces acting on the joints of the leg and a term of acceleration except the term of the acceleration of gravity; and obtaining the torques to be applied to the joints of the leg, by a gravity compensation torque computing module, based on the moments acting around the joints of the leg.