Robotic vibration-suppression control (Bächer).
A robot control method, and associated robot controllers and robots operating with such methods and controllers, providing computational vibration suppression. Given a desired animation cycle for a robotic system or robot, the control method uses a dynamic simulation of the physical robot, which takes into account the flexible components of the robot, to predict if vibrations will be seen in the physical robot. If vibrations are predicted with the input animation cycle, the control method optimizes the set of motor trajectories to return a set of trajectories that are as close as possible to the artistic or original intent of the provider of the animation cycle, while minimizing unwanted vibration. The new control method or design tool suppresses unwanted vibrations and allows a robot designer to use lighter and/or softer (less stiff) and, therefore, less expensive systems in new robots.
BACKGROUND 1. Field of the Description (1) The present description relates, in general, to robots (or “robotic systems” or “robotic characters”) and control systems and methods for such robots. More particularly, the description relates to a method of generating control signals for a robotic system or robot (and to controllers implementing such a method and robotic systems or robots with such controllers) that provides computational vibration suppression during the movements of the robotic system or robot. 2. Relevant Background (2) Audio-animatronic figures and other robotic systems often suffer from unwanted vibrations during their operations. In particular, robotic systems or robots often will experience undesirable vibrations when undergoing fast and dynamic motions such as may be useful in a robotic character to provide expressive animations. For example, a robot may have an arm or leg that they move quickly from one location to a second location to provide a desired movement or move to a new pose, and the robot's arm or leg may vibrate significantly upon stopping at the second location. This can be undesirable when trying to replicate a particular character's movements, when trying to provide human-like motions, and so on. (3) In general, robotic systems are designed to be as stiff as possible, but, unfortunately, the physical system is rarely sufficiently stiff to behave like an idealized mechanical system whose components are assumed to be perfectly rigid. Hence, in r
1. A system for suppressing vibration in a robotic system, comprising: memory storing a definition of a robot defining a plurality of components of the robot and storing an input animation for the robot specifying motion of the components of the robot over a time period; a processor communicatively linked to the memory; a simulator provided by the processor running software, wherein the simulator performs a dynamic simulation of the robot performing the input animation including modeling a first set of the components as flexible components and a second set of the components as rigid components, wherein each of the flexible components is coupled at opposite ends to differing ones of the rigid components, and wherein the dynamic simulation predicts vibrations for the robot in performing the defined motion; and an optimizer provided by the processor running software, wherein the optimizer generates a retargeted motion for the components by adjusting the defined motion, while retaining an overall speed of an optimized end effector trajectory for the robot provided in the defined motion, to suppress a portion of the vibrations predicted by the dynamic simulation, and wherein the optimizer generates the retargeted motion by minimizing differences between locations of a set of marker points on one or more of the rigid components in the defined motion and in the retargeted motion and by allowing vibrations in one or more of the flexible components disposed between the rigid components. ||
13. A system for suppressing vibration in a robotic system, comprising: memory storing parameters of a target robotic system and an input motion for the target robotic system, wherein the input motion is defined by a set of motor trajectories defining movement of components of the robotic system; an optimizer modifying the set of motor trajectories to selectively suppress low-frequency vibrations of a plurality of the components of the robotic system during operations to perform a retargeted motion based on the input motion while an overall speed of an end effector center of mass (COM) trajectory of the robotic system; and a differential dynamics simulator generating a simulation of the input motion by modeling the target robotic system by representing flexible parts of the components with deformable bodies and stiff parts of the components with rigid bodies, wherein the optimizer modifies the set of motor trajectories based on the simulation. ||
18. A method of suppressing vibration in a robotic systems, comprising: receiving a set of input motions for a robot; simulating the robot operating based on the set of input motions by representing, during replaying of the set of input motions, flexible components of the robot as deformable bodies and rigid components of the robot as rigid bodies and by enforcing two-way coupling constraints between ends of the deformable bodies and the rigid bodies; based on the simulating, identifying vibrations of the components of the robot; and optimizing the set of input motions to generate a retargeted motion for the components of the robot that suppresses the low-frequency vibrations, wherein the optimizing generates the retargeted motion by minimizing differences between locations and orientations of a set of marker points on one or more of the rigid components in the set of input motions and in the retargeted motion.