The Balance: An energy management task

摘要

The balance has been widely studied over the last decades due to its importance in people independence. This allowed formulating models of human balance strategies. They are mainly based on inverted pendulum dynamical model stabilized with a feedback controller that keeps the Centre of Mass (CoM) within a stable trajectory within the Base of Stability (BoS). When a perturbation is applied the controller applies the force needed to keep the CoM along the defined trajectory. However, that describes very well one-foot standing situations cannot be generalized in double feet standing posture. This brought to the development of models like the Extrapolated Centre of Mass (XCoM) in order to manage the transaction between one foot and the other. It uses the ballistic of the pendulum in order to identify the landing of the opposite foot in order to phase the two pendula and have a smooth transaction between the two postures. We propose a generalized inverted pendulum model which accounts both feet accounting them as a pair of coupled pendula, describing all the different phases of both standing and gait. This also allows designing a semiautonomous hierarchical control which has a stronger parallel with the physiological counterpart. Where we have a feedforward controller coming for the motion planning, a slow feedback controller which generate the motor-commands and a fast feedback controller correcting the motor commands in order to stabilize the motion on the desired trajectory. This work presents a preliminary study which presents the model formulation and a basic evaluation of its ability to describe balance. Moreover, we identified a possible control architecture to implement in order to use this model in balance control.