Kazuo Tani

Measurement of Slip, Force and Deformation Using Hybrid Tactile Sensor System for Robot Hand Gripping an Object

A hybrid tactile sensor system is proposed for a robot hand to hold and grip an object adaptively as the sensor system measures the slip of an object, the gripping force, and the deformation of its silicon rubber sensor element. A hybrid tactile sensor system consists of a Carbon Micro-Coil (CMC) touch sensor and a force sensor. The CMC sensor element is made of silicon rubber containing CMCs several micrometres in diameter. It is considered that the sensor element constitutes an LCR circuit, and the CMC touch sensor, deformed mechanically, produces signals due to the modification of the circuit. In this study, a dome-shaped CMC sensor element similar to the shape of a human fingertip was used. This paper first examines the characteristics of the CMC sensor in terms of slip detection when the sensor system held and released an object. Next, the characteristics of the CMC element are clarified with respect to the compression force and deformation when the CMC element was compressed vertically. Finally, methods using the hybrid tactile sensor system are developed to detect the slip of an object and estimate the magnitude of deformation of the CMC element.

Effect of touching manner and motion direction of human finger on human tactile recognition

The purpose of this paper is to investigate the effects of the touching manners and the motion directions of human finger in recognizing fine surface texture. The authors developed a measurement system to present a step-height of 10 to 1000 µm to the finger of the human subject to measure the human tactile sensation capability. The presentation device can control four parameters of the presentation, which are the step-height, the presentation velocity, the presentation angle, and the presentation temperature. Human subjects actively and passively touched and distinguished the step-heights to determine the different thresholds for step-heights. Also they passively touched and distinguished the step-heights with different motion directions of their fingers to determine the difference thresholds. As the results of the psychophysical experiments, it was found that the distinctive sensitivities of human tactile sensation in active-touch and passive-touch manners are different in discriminating between fine step-heights and that the directions of finger motion have little effect on the human tactile recognition of fine step-heights.

Directionality of human tactile sensation capability in discriminating fine step-heights

In this paper, the authors conducted psychophysical tests to investigate the effect of the directionality of human tactile sensation capability in discriminating fine step-heights. We evaluated the capability of human finger to discriminate the step-heights of 0 to 20 µm moving at the angle of 0°, 45° and 90°. The results suggest that the different directions of touching motion affect the human tactile sensation for recognizing step-heights.

Proximity and Force Characteristics of CMC Touch Sensor with Square/Dome-shaped Sensor Elements

A tactile sensor called Carbon Micro Coil (CMC) touch sensor was developed by CMC Technology Development Co., Ltd. The sensors elements used in the experiments of this paper are made of silicon rubber containing CMCs several micrometers in diameter. One of the elements is molded into a square 30 mm on a side and 3 mm thick; the other is a dome 16 mm in diameter and 2 mm height. CMCs in the sensor element contribute to the electrical conductivity and the sensor element is considered to constitute an LCR circuit. When an object approaches to the sensor element or the sensor element is deformed mechanically, the impedance changes, and the CMC sensor detects the impedance changes by measuring the modulation of amplitude and phase of an input excitation signal to the sensor element. The CMC sensor also creates voltage signals of the R- and LC-components separately according to the amplitude and phase modulation. In this paper, the characteristics of the CMC sensor with respect to its proximity and force senses are investigated. First, the output of the CMC sensor with the square-shaped sensor element is measured when an object approaches to the sensor element. Next, the output of the CMC sensor with the dome-shaped sensor element is measured when fine deformations of 1 to 5 μm are applied to the sensor element under variable compression force. The results suggest that the CMC sensor can measure the force variance applied to the sensor element as well as the distance between the sensor element and an object.

Modelling of Total System by Integrating Identified Models for Subsystems

Abstract System identification is difficult when the object system is too unstable to allow open loop control. To solve this problem we propose a method in which the total system is divided into subsystems, identified models are built for the subsystems, and the subsystem models are integrated into a total model of the system. We evaluated this method by applying it to making the observer of a wheeled inverted pendulum.

Task Programming for Robots Using Multi-mode Control – Preparation of Modes to Generate Motions for Disassembly Task –

Abstract Based on the consideration of tasks and motions and their relations, a method called “multi-mode control” is proposed to facilitate programming of robot tasks that require sensorimotor control. In this method, a mode defines a specific relation of sensor information and robot motion. A string of modes which correspond to the interactions of robot and environment constitutes a task program. Modes useful for disassembly tasks, beside others, are implemented. Tasks such as peg extraction are programmed using these modes and performed successfully.

Experimental investigation on integral cognition by multiple senses

Humans cognize images of events by perceiving through senses the stimuli generated by events. VR started the idea to let an artifact event generate the stimulation equal to that generated by the original event. For further generalization, we investigated the possibility of letting a human cognize an equivalent image from non-equal stimulation. In the experiment, variable integral stimuli of force, visual, and auditory senses are presented to a subject and integral cognition is compared in the measure of integral intensity. This will hopefully lead to a broader region of cognition possible using limited equipment for presenting stimulation.