Abstract: A system and method is disclosed for controlling a robot having at least two legs, the robot subjected to an event such as a push that requires the robot to take a step to prevent a fall. In one embodiment, a current capture point is determined, where the current capture point indicates a location on a ground surface that is the current best estimate of a stepping location for avoiding a fall and for reaching a stopped state. The robot is controlled to take a step toward the current capture point. After taking the step, if the robot fails to reach a stopped state without taking any additional steps, an updated current capture point is determined based on the state of the robot after taking the step. The current capture points can be stored in a capture point memory and initialized based on a model of the robot.

Abstract: A legged robot subjected to a force is controlled by determining an instantaneous capture point where the robot will step with a swing leg to reach a balanced home position, the balanced home position being a state in which the Center of Mass remains substantially over the Center of Pressure and the robot is able to maintain its balance indefinitely. The capture point can be determined using a Linear Inverted Pendulum Plus Flywheel (LIPPF) model of the robot. The LIPPF model includes a flywheel with a mass and a rotational inertia, and a variable length leg link. A torque profile is applied to the flywheel and a set of capture points is determined based on this torque profile An experimentally determined error value can be added to a capture point that is determined based on the model to account for differences between an actual robot and the model.

Abstract: A system and method is disclosed for controlling a robot having at least two legs, the robot subjected to an event such as a push that requires the robot to take a step to prevent a fall. In one embodiment, a current capture point is determined, where the current capture point indicates a location on a ground surface that is the current best estimate of a stepping location for avoiding a fall and for reaching a stopped state. The robot is controlled to take a step toward the current capture point. After taking the step, if the robot fails to reach a stopped state without taking any additional steps, an updated current capture point is determined based on the state of the robot after taking the step. The current capture points can be stored in a capture point memory and initialized based on a model of the robot.

Abstract: A legged robot subjected to a force is controlled by determining an instantaneous capture point where the robot will step with a swing leg to reach a balanced home position, the balanced home position being a state in which the Center of Mass remains substantially over the Center of Pressure and the robot is able to maintain its balance indefinitely. The capture point can be determined using a Linear Inverted Pendulum Plus Flywheel (LIPPF) model of the robot. The LIPPF model includes a flywheel with a mass and a rotational inertia, and a variable length leg link. A torque profile is applied to the flywheel and a set of capture points is determined based on this torque profile An experimentally determined error value can be added to a capture point that is determined based on the model to account for differences between an actual robot and the model.