Abstract: Systems and methods are presented that enable a legged robot to maintain its balance when subjected to an unexpected force. In the reflex phase, the robot withstands the immediate effect of the force by yielding to it. In one embodiment, during the reflex phase, the control system determines an instruction that will cause the robot to perform a movement that generates a negative rate of change of the robot's angular momentum at its centroid in a magnitude large enough to compensate for the destabilizing effect of the force. In the recovery phase, the robot recovers its posture after having moved during the reflex phase. In one embodiment, the robot returns to a statically stable upright posture that maximizes the robot's potential energy. In one embodiment, during the recovery phase, the control system determines an instruction that will cause the robot to perform a movement that increases its potential energy.

Abstract: A robotic system includes a humanoid robot having a plurality of joints adapted for force control with respect to an object acted upon by the robot, a graphical user interface (GUI) for receiving an input signal from a user, and a controller. The GUI provides the user with intuitive programming access to the controller. The controller controls the joints using an impedance-based control framework, which provides object level, end-effector level, and/or joint space-level control of the robot in response to the input signal. A method for controlling the robotic system includes receiving the input signal via the GUI, e.g., a desired force, and then processing the input signal using a host machine to control the joints via an impedance-based control framework. The framework provides object level, end-effector level, and/or joint space-level control of the robot, and allows for functional-based GUI to simplify implementation of a myriad of operating modes.

Abstract: A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

Abstract: A robotic system includes a robot having manipulators for grasping an object using one of a plurality of grasp types during a primary task, and a controller. Hie controller controls the manipulators dining the primary task using a multiple-task control hierarchy, and automatically parameterizes the internal forces of the system for each grasp type in response to an input signal. The primary task is defined at an object-level of control e.g., using a closed-chain transformation, such that only select degrees of freedom are commanded for the object. A control system for the robotic system has a host machine and algorithm for controlling the manipulators using the above hierarchy. A method for controlling the system includes receiving and processing the input signal using the host machine, including defining the primary task at the object-level of control, e.g., using a closed-chain definition, and parameterizing the internal forces for each of grasp type.

Abstract: A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

Abstract: A system and method for providing multiple priority impedance control for a robot manipulator where impedance laws are realized simultaneously and with a given order of priority. The method includes a control scheme for realizing a Cartesian space impedance objective as a first priority while also realizing a joint space impedance objective as a second priority. The method also includes a control scheme for realizing two Cartesian space impedance objectives with different levels of priority. The method includes instances of the control schemes that use feedback from force sensors mounted at an end-effector and other instances of the control schemes that do not use this feedback.

Abstract: A system and method for controlling tendon-driven manipulators that provide a closed-loop control of joint torques or joint impedances without inducing dynamic coupling between joints. The method includes calculating tendon reference positions or motor commands by projecting a torque error into tendon position space using a single linear operation. The method calculates this torque error using sensed tendon tensions and a reference torque and internal tension. The method can be used to control joint impedance by calculating the reference torque based on a joint position error. The method limits minimum and maximum tendon tensions by projecting the torque error into the tendon tension space and then projecting ii back into joint space.

Abstract: A technique that determines the tension in a tendon using a conduit reaction force applied to an end of a conduit through which the tendon is threaded. Any suitable tendon tension sensor can be employed that uses the conduit reaction force for this purpose. In one non-limiting embodiment, the tendon tension sensor includes a cylindrical strain gauge element and a force member mounted to an end of the conduit. The force member includes a cylindrical portion having a bore and a plate portion, where the cylindrical portion is inserted into a bore in the strain gauge element. The tendon is threaded through the strain gauge element and the force member. A strain gauge is mounted to the strain gauge element and measures the reaction force when tension on the tendon causes the strain gauge element to be pushed against the force member.