Bag-shaped actuator system, gripping device using the same, robotic hand, and usage method of robotic hand

A usage method of a robotic hand, the robotic hand comprising:

• a robotic hand body;
• a gripping mechanism placed in a distal end portion of the robotic hand body, and
• a force sensor configured to detect an external force applied to gripping members of the gripping mechanism;
• the gripping mechanism comprising a plurality of gripping members, the gripping mechanism being configured to grip a workpiece by moving at least any of the gripping members;
• a plurality of bag-shaped actuator systems, each bag-shaped actuator system comprising:
• a bag-shaped actuator including an airtight bag member made of a film material having a flexibility, and flowable particulates filled in the bag member;
• a bag-member communication pipe configured to communicate with an inside of the bag member of the bag-shaped actuator;
• a low-air-pressure-source communication pipe configured to communicate with a low air pressure source having an air pressure lower than external air;
• a high-air-pressure-source communication pipe configured to communicate with a high air pressure source having an air pressure higher than the external air;
• a switching mechanism configured to perform switching between communication destinations of the bag member of the bag-shaped actuator such that the inside of the bag member communicates with any of the external air, the low-air-pressure-source communication pipe, and the high-air-pressure-source communication pipe via the bag-member communication pipe;
• and
• a switching controlling portion configured to control the switching between the communication destinations by the switching mechanism;
• wherein the gripping members include respective abutment gripping portions configured to grip the workpiece by abutting with the workpiece;
• and
• at least any of the gripping members is configured such that the abutment gripping portion and a base-end-side abutment portion are constituted by respective bag-shaped actuators of the bag-shaped actuator systems, the base-end-side abutment portion being placed closer to a base end side of the at least any of the gripping members than the abutment gripping portion, the base-end-side abutment portion being configured to abut with the workpiece from the base end side of the at least any of the gripping members;
• the method comprising:
• a gripping step of gripping the workpiece by the abutment gripping portions of the gripping members of the gripping mechanism;
• an insertion step of inserting the gripped workpiece into an insertion hole of an insertion target workpiece;
• and
• a release step of releasing the workpiece inserted into the insertion hole from gripping by the gripping members, wherein the insertion step includes
• a moving step of moving the gripping mechanism gripping the workpiece toward the insertion hole of the insertion target workpiece along a hole axis of the insertion hole while an external force applied to the gripping mechanism via the workpiece is detected by the force sensor,
• an abnormal external force monitoring step of monitoring, in the moving step, whether or not an abnormal external force in the external force becomes larger than a predetermined abnormal external force threshold, the abnormal external force being along a direction different from a direction of an advancing-direction external force, the advancing-direction external force being along a direction reverse to an advancing direction of the gripping mechanism,
• a moving stop step of temporarily stopping a movement in the moving step when the abnormal external force becomes larger than the abnormal external force threshold,
• a posture changing step of changing a posture of the workpiece such that, after the movement is stopped in the moving stop step, the bag member of at least one of the bag-shaped actuators constituting the abutment gripping portions or the base-end-side abutment portions abutting with the workpiece is inflated by causing the inside of the bag member to communicate with the high-air-pressure-source communication pipe via the bag-member communication pipe such that, when the movement in the advancing direction is restarted, a magnitude of an abnormal external force applied to the gripping members via the workpiece after the restart becomes smaller than a magnitude of the abnormal external force before the stop,
• a re-gripping step of gripping the workpiece again by the gripping members, and
• a restart step of restarting the movement in the advancing direction, the movement being temporarily stopped.