Control device for link mechanism

摘要

Provided is a control device for a link mechanism capable of preventing a damage of joint mechanisms even in the case of a collision of a movable part against an external object. The control device 30 includes: a characteristic determination unit 34 which determines desired stiffness k_cmd_i of an elastic element 5 of each joint mechanism Ji so as to be within a range of first stiffness k1_i wherein the joint maximum elastic energy is equal to or more than joint collision kinetic energy to second stiffness k2_i wherein a first time is equal to or longer than a second time; and a characteristic control unit 35 which controls stiffness k_i of the elastic element 5 of each joint mechanism Ji to be the desired stiffness k_cmd_i.

主权项

1. A control device for a link mechanism having one or more joint mechanisms provided between a base body and a movable part which is movable relative to the base body and an actuator outputting a driving force for displacing the one or more joint mechanisms, in which each of the one or more joint mechanisms is configured to transmit motive power via an elastically deformable elastic element adapted to have variably controllable stiffness, the control device comprising:
a relative displacement speed determination unit configured to determine a relative displacement speed of each of the one or more joint mechanisms corresponding to a relative speed between the movable part and an external object in a case where the movable part collides with the object; a characteristic determination unit configured to determine a stiffness of the elastic element of each of the one or more joint mechanisms in the case where the movable part collides with the object so that the stiffness is within a range between first stiffness or more and second stiffness or less determined for each of the one or more joint mechanisms; and a characteristic control unit configured to control the stiffness of the elastic element of each of the one or more joint mechanisms in the case where the movable part collides with the object so as to be the stiffness determined by the characteristic determination unit; wherein: the characteristic determination unit determines the first stiffness so that elastic energy of the elastic element of the joint mechanism concerned in a case where an elastic deformation amount of the elastic element of the joint mechanism is a maximum deformation amount of the elastic element of the joint mechanism is equal to or more than kinetic energy of the joint mechanism which is obtained when the joint mechanism is displaced at a displacement speed of the joint mechanism determined by the relative displacement speed determination unit in each of the one or more joint mechanisms; and the characteristic determination unit determines the second stiffness so that a time interval from a time point of starting the displacement of the joint mechanism caused by the collision of the movable part against the object to a time point of starting the displacement of the joint mechanism caused by the elastic energy of the elastic element of the joint mechanism accumulated by the displacement of the joint mechanism caused by the collision is equal to or longer than a minimum time achievable in the joint mechanism in a case of changing the displacement speed of the joint mechanism by a speed obtained by inverting a direction of the relative displacement speed of the joint mechanism determined by the relative displacement speed determination unit by displacing the joint mechanism by using the actuator in each of the one or more joint mechanisms.