Sensing characteristics of an optical three-axis tactile sensor under combined loading

Procedia Computer Science

Tsunogai

Kayaba

et al. 2014

Self Cite

Although the three-axis tactile sensor is capable of delicate measurement, it is weak for heavy contact force. In order to enhance resistance to a high degree of applied force, we attached a rubber skin onto the sensor surface to protect the sensing element. FEM analyses found that sensitivity is not significantly reduced and that the skin induces subsidiary effects such as the disappearance of insensible areas and the enhancement of stability of the columnar feeler. If the skin is substantially softer than the columnar-conical feeler, the sensor can measure three-axis force without reduction of sensitivity. Based on these simulated results, we produced a columnar-conical feeler-type three-axis tactile sensor with rubber skin. The experimental results show, as demonstrated by FEM analyses, that the sensor possesses three-axis sensing capability and that the insensible area vanishes.

Section: Basic Sensing Principlementioning

confidence: 99%

Advanced Design of Columnar-conical Feeler-type Optical Three-axis Tactile Sensor

Procedia Computer Science

Tsunogai

Kayaba

et al. 2014

Self Cite

“…3) that can obtain not only normal force distribution but also tangential force distribution. We presented this sensor in previous articles [8][9][10], which are helpful for explanation. Although ordinary tactile sensors can only detect either normal or tangential force, since this tactile sensor can detect both, the robot can use the sensor information as an effective key to induce a specified behavior.…”

Section: Robot Hardwarementioning

confidence: 99%

“…Since robots' tactile sensing is important for performing any task [1][2][3], we are developing an optical three-axis tactile sensor that measures distributed tri-axial tactile data using the principle of a uni-axial optical tactile sensor [4][5][6][7]. If a robot is equipped with tactile sensors on its fingers, it can detect not only grasping force but also slippage caused on its hands [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Two-Hand-Arm Manipulation Based on Tri-axial Tactile Data

Abdullah

Wada

et al. 2011

Int J of Soc Robotics

Self Cite

Tactile sensing ability is important for social robots, which perform daily work instead of persons. The authors have developed a three-axis tactile sensor based on an optical measurement method. Since our optical three-axis tactile sensor can measure distributed tri-axial tactile data, a robot equipped with the tactile sensors can detect not only grasping force but also slippage from its hands. In this paper, the authors have two objectives: one of them is evaluation of the three-axis tactile sensor in actual robotic tasks; the other is to demonstrate effectiveness of tri-axial tactile data for motion control. To accomplish these objectives, the authors have developed a two-hand-arm robot equipped with three-axis tactile sensors. In the robot motion control, we implement a recurrent mechanism in which the next behavior is induced by the tactile data to make the robot accept intention embedded in the environment. Since this mechanism is based on the tactile data, it is easy to apply it to communication between the hand-arms to obtain the best timing for cooperative work. In a series of experiments, the twohand-arm robot performed object transfer and assembling tasks. Experimental results show that this tri-axial tactile base programming works well because appropriate behavior is induced according to slippage direction.

“…We produced a unique tactile sensor system based on an optical waveguide transduction method for an application to humanoid robot hands (Ohka et al 2004;Yussof et al 2010). The optical waveguide sensing principle used in this tactile sensor provides comparatively better sensing accuracy to detect contact phenomena from the acquisition of the three-axial directions of forces (Yussof et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Object Exploration Using a Three-Axis Tactile Sensing Information

Abdullah

Wada

Journal of Computer Science

et al. 2011

Problem statement: To advance the robust object recognition of robots, we present an algorithm for object exploration based on three-axis tactile data that is necessary and sufficient for the evaluation of contact phenomena. Approach: The object surface contour is acquired by controlling the finger position so that the normal force, measured by optical three-axis tactile sensors, remains constant as two fingertips slide along the object surface. In this algorithm, when the robot grasps an object, the tangential force increment is checked to judge the initial contact state because it is more sensitive than the normal force. After contact between the fingertips and the object, the normal force is adjusted to remain constant with a tolerant value between the upper and lower thresholds. Results: In the verification test, shape exploration experiments were conducted using a hand-arm robot equipped with our tactile sensor and a hard sinusoidal-shaped wooden object. Experimental results show that the hand-arm robot is capable of gathering the object contour having a concave or convex portion because its finger position controlled by three-axis tactile sensing information follows the object surface. Conclusion/Recommendations: We derive a control algorithm in robot fingers based on time tangential force increment and normal force detection to perform a shape exploration procedure.