Wataru Fukui

Development of multi-fingered universal robot hand with torque limiter mechanism

A multi-fingered universal robot hand has been developed in order to construct the platform of humanoid hand study. We also have developed a small and five-fingered robot hand. The robot hand is designed to protect the small driving system from a large external force. This protection mechanism is small enough to be installed in the joint driving mechanism and adaptable enough to deal with various load. This paper describes basic and unique specifications of the robot hand, and the effectiveness is confirmed by fundamental experiments.

Two-Fingered Haptic Device for Robot Hand Teleoperation

A haptic feedback system is required to assist telerehabilitation with robot hand. The system should provide the reaction force measured in the robot hand to an operator. In this paper, we have developed a force feedback device that presents a reaction force to the distal segment of the operators thumb, middle finger, and basipodite of the middle finger when the robot hand grasps an object. The device uses a shape memory alloy as an actuator, which affords a very compact, lightweight, and accurate device.

Shape classification based on tactile information by Universal Robot Hand

We propose a shape classification in continuous rotational manipulation by a multi-fingered robot hand. Our robot hand has five fingers equipped with tactile sensors. Each tactile sensor can measure a pressure distribution once every 10 ms while the robot hand rotates an object continuously. Our proposal classification method consists of the following processes: A kurtosis is calculated from each pressure distribution, and it quantifies the shape of the current contact surface. By rotating an object and measuring a time-series pressure distribution, the hand obtains a time-series kurtosis. An evaluated value is calculated from the time-series kurtosis and reference patterns using continuous dynamic programming (CDP) matching scheme. The contact shape is classified whether the evaluated value is lower than a given threshold. Experiments using three symmetrical objects and an asymmetrical object demonstrate the effectiveness of our proposal shape classification.

Slip detection using robot fingertip with 6-axis force/torque sensor

Slip detection is a essential and important function for dexterous manipulation. Many slip sensors have been proposed. However, many robotic hands have no slip sensor on their fingertips. We have proposed the slip detection method with 6-axis force torque sensor. This method detects a slip along only a fingertip. In this paper, we expand this method to detect a slip along a fingertip and a circumferential direction of the finger. Some experimental results confirm that the method is able to detect slips independently of slip directions, velocities and pressing forces.

Multiple joints reference for robot finger control in robot hand teleoperation

The multi-fingered robot hand has much attention in various fields. Many robot hands have been proposed so far. However, the robot hand cannot execute any tasks autonomously because the robot hand does not have enough motion and sensing ability to task complexities. Therefore, we have developed a robot hand teleoperation system with the motion capture data glove CyberGlove. Here, each joint of the robot hand is controlled according to the corresponding joint of the human hand. In this paper, we develop the teleoperation method that the robot hand joint is controlled to the multiple human hand joints. The positional error of the fingertips can be decrease by using the multiple joints reference. We show the effectiveness of the developed method through some experiments.

Fingertip force and position control using force sensor and tactile sensor for Universal Robot Hand II

Various humanoid robots and multi-fingered robot hands are used in research and development. As these robot hands grasp and manipulate an object, the control phase is divided into an “approach phase” and a “manipulation phase.” In the approach phase, a position control method is necessary to control the posture of the robot hand. In the manipulation phase, a force control method is necessary to control the fingertip force of the robot hand. However, it is difficult to control both the force and position of these hands at the same time. In this paper, we propose a grasping force control method based on position control for manipulation. In this proposed method, the finger position is controlled in the direction of the force vector. With this control method, any external force is cancelled and the initial force is kept constant, or the setting force is applied to an object.

High-Speed Tactile Sensing for Array-Type Tactile Sensor and Object Manipulation Based on Tactile Information

We have developed a universal robot hand with tactile and other sensors. An array-type tactile sensor is crucial for dexterous manipulation of objects using a robotic hand, since this sensor can measure the pressure distribution on finger pads. The sensor has a very high resolution, and the shape of a grasped object can be classified by using this sensor. The more the number of measurement points provided, the higher the accuracy of the classification, but with a corresponding lengthening of the measurement cycle. In this paper, the problem of slow response time is resolved by using software for an array-type tactile sensor with high resolution that emulates the human sensor system. The validity of the proposed method is demonstrated through experiments.

Multipoint haptic device for robot hand teleoperation

A haptic feedback system is required to assist teleoperation with robot hand. The system should provide the reaction force measured in the robot hand to an operator. In this paper, we have developed a force feedback device that presents a reaction force to operators multiple finger knuckles. The device uses a shape memory alloy as an actuator, which affords a very compact, lightweight, and accurate device.

Outer shape classification in rotation manipulation by Universal Robot Hand

We propose a method for shape classification in continuous rotation manipulation by a multi-fingered robot hand. Our robot hand has five fingers equipped with tactile sensors. Each tactile sensor can measure a pressure distribution once every 10(ms) while the robot hand rotates the object continuously. Our proposed classification method consists of the following processes: A kurtosis is calculated from each pressure distribution, and it quantifies shape of the current contact surface. By rotating an object and measuring a time-series pressure distribution, the hand obtains a time-series kurtosis. Finally, a evaluated value is calculated between the time-series kurtosis and reference patterns through a continuous dynamic programming (CDP) matching scheme. The contact shape is classified if the evaluated value is lower than a threshold. We show the effectiveness of our method through experiments.