Akio Namiki

A tactile sensor sheet using pressure conductive rubber with electrical-wires stitched method

A new type of tactile sensor using pressure-conductive rubber with stitched electrical wires is presented. The sensor is thin and flexible and can cover three-dimensional objects. Since the sensor adopts a single-layer composite structure, the sensor is durable with respect to external force. In order to verify the effectiveness of this tactile sensor, we performed an experiment in which a four-fingered robot hand equipped with tactile sensors grasped sphere and column. The sensor structure, electrical circuit, and characteristics are described. The sensor control system and experimental results are also described.

Development of a high-speed multifingered hand system and its application to catching

In this paper we introduce a newly developed high-speed multi-fingered robotic hand. The hand has 8-joints and 3-fingers. A newly developed small harmonic drive gear and a high-power mini actuator are fitted in each finger link, and a strain gauge sensor is in each joint. The weight of the hand module is only 0.8 kg, but high-speed motion and high-power grasping are possible. The hand can close its joints at 180 deg per 0.1 s, and the fingertips have an output force of about 28 N. The hand system is controlled by a massively parallel vision system. Experimental results are shown in which a falling object was caught by the high-speed hand.

Dynamic regrasping using a high-speed multifingered hand and a high-speed vision system

In most previous studies, it has been difficult for a robot hand to regrasp a target quickly because its motion was static or quasi-static, in a constant contact state. In order to achieve high-speed regrasping, we propose a new strategy which we call dynamic regrasping. In this strategy, the regrasping task is achieved by throwing a target up and by catching it. In this paper, a regrasping strategy based on visual feedback is presented and experimental results using a high-speed multifingered robot hand and a high-speed vision system are shown. A cylinder is chosen as a specific example of target for dynamic regrasping, with which successful dynamic regrasping tasks are experimentally achieved

The 100 G capturing robot - too fast to see

This paper discusses the capturing robot with the maximum acceleration of 100 G in design specification. We aim find the combination of the arm with a mass of 0.1 kg and the spring capable of producing the initial compressed force of 100 N, in order to achieve the 100 G. To reduce the total capturing time, we propose an arm/gripper coupling mechanism where the spring energy initially accumulated in the arm is transferred to the kinetic energy of the arm and continuously to the kinetic energy for closing the gripper at the capturing point without any time lag. The experimental results show the maximum acceleration of 91 G and the capturing time of 25 ms were achieved. Experiments on capturing a dropping ball were also executed with the assistance of the 1 ms-vision.

Grasping force control of multi-fingered robot hand based on slip detection using tactile sensor

To achieve a human like grasping with a multi- fingered robot hand, the grasping force should be controlled without using information from the grasped object such as its weight and friction coefficient. In this study, we propose a method for detecting the slip of a grasped object using the force output of Center of Pressure (CoP) tactile sensors. CoP sensors can measure the center position of a distributed load and the total load applied on the surface of the sensor, within 1 ms. These sensors are arranged on the fingers of the robot hand, and their effectiveness as slip detecting sensors is confirmed in tests of slip detection during grasping. Finally, we propose a method for controlling grasping force to resist tangential force applied to the grasped object using a feedback control system with the CoP sensor force output.

High-speed batting using a multi-jointed manipulator

In this paper a robotic batting algorithm using a high-speed arm and high-speed stereo vision is proposed. With this strategy, the desired trajectory of the manipulator is generated so that both high-speed swing motion and tracking motion combine to meet the ball squarely with the bat. As a result the manipulator can follow the ball while swinging the bat at high speed even if it is difficult to predict the trajectory of a ball. Experimental results are shown in which a high-speed manipulator hits a ball thrown by a human.

High speed grasping using visual and force feedback

In most conventional manipulation systems, changes in the environment cannot be observed in real time because the vision sensor is too slow. As a result the system is powerless under dynamic changes or sudden accidents. To solve this problem we have developed a grasping system using high-speed visual and force feedback. This is a multi-fingered hand-arm with a hierarchical parallel processing system and a high-speed vision system called SPE-256. The most important feature of the system is the ability to process sensory feedback at high speed, that is, in about 1 ms. By using an algorithm with parallel sensory feedback in this system, grasping with high responsiveness and adaptivity to dynamic changes in the environment is realized.

Ball control in high-speed batting motion using hybrid trajectory generator

Speeding up robot motion provides not only improvement in operating efficiency but also improves dexterous manipulation by taking advantage of an unstable state or noncontact state. In this paper we describe a hybrid trajectory generator that produces high-speed manipulation. This algorithm produces both mechanical high-speed motion and sensor-based reactive motion. As an example of high-speed manipulation, a robotic ball control in a batting task has been achieved. Performance evaluation is also analyzed

High-speed throwing motion based on kinetic chain approach

In this paper the robotic throwing task is considered with the goal of achieving high-speed dynamic manipulation. We propose a kinetic chain approach for swing motion focused on torque transmission. In addition the release method using a robotic hand is analyzed for ball control. Experimental results are shown in which a high-speed manipulator throws a ball toward a target.

Design of the 100G Capturing Robot Based on Dynamic Preshaping

In this paper we discuss the design of the 100G capturing robot from the point of view of dynamic pre-shaping where all finger links make contact with the target object simultaneously. After briefly explaining the overview of the 100G capturing robot, we mathematically formulate the dynamic pre-shaping problem where we discuss how to determine the mechanical parameters, such as pulley positions, pulley radius, mass of finger link, and spring constant. We show a couple of experiments where the robot parameter is determined based on the dynamic pre-shaping problem.