Co-handling robot having a mixed-force control law providing high effector sensitivity and enabling interaction with the body of the robot

A co-handling robot comprising:

• a kinematic chain of mechanical elements comprising a proximal-end element forming a base of the robot and a distal-end element, the elements being mounted with the ability to move relative to one another so that the distal-end element is able to move with respect to the proximal-end element;
• a tool and/or a gripper, which is configured to be manipulated by a human operator, the tool and/or the gripper being connected to the distal-end element in such a way that the tool and/or the gripper has the same degrees of freedom as the distal-end element;
• means for controlling at least part of the first chain of elements, comprising:
• actuators arranged on the chain to perform all the movements of the various elements of the chain relative to one another and/or to apply a force between them,
• means for measuring displacement of the elements with respect to one another,
• a single multiaxis force sensor, arranged between the distal-end element and the tool and/or the gripper, so as to measure forces applied to the distal-end element and the tool and/or the gripper, and
• a controller for controlling the actuators on the basis of the measurements taken by the means for measuring displacement and by the measurements from the multiaxis force sensor, according to a control law implemented in the controller,
• said control law comprising:
• a force-increasing loop configured to amplify, at joints of the robot, forces applied to the tool and/or the gripper and measured by the multiaxis force sensor, this being in respect of at least some of the degrees of freedom of the distal end, the force-increasing loop comprising a comparator to subtract, from an integral gain Ki of the loop, an anti-windup gain Kaw, and an integrator which receives a result from the comparator to supply setpoint speeds for the various elements of the chain,
• an internal speed loop with proportional gain Kv which receives the speed setpoint from the force-increasing loop to supply non-saturation reference torques for the various actuators,
• an internal speed loop saturation function, a saturation term τsat being chosen to be greater than or equal to a vector τf0 of dry friction coefficients of the actuators, and
• an anti-windup component fed back to an input of the integrator of the force-amplification loop, and obtained from a force correction applied by the saturation function and the gain Kaw so that as soon as saturation comes into effect, the integrator of the force-increasing loop interrupts its integration.