Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand

Abstract

It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

Contact Point Calculation on a Haptic Interface Utilizing Differentiated Force

“…The error range of P e x is 0-0.0026 m by using (15) and (16). Here, the error ranges of P e x and P e x were compared by using (13) and (15).…”

“…Then, the large error occurs. In the proposed method, if the differentiated force information is used for the contact point calculation, the value of the denominator of the equation become a large value as shown (15) and (16). If this value is as large as the value which does not become a minute value by the sensor noise amplified by the differentiation, using (16) prevents the occurrence of the error.…”

“…There are also methods using external force observer for sensorless tactile sensing, while the contact position is fixed (13) (14) . Furthermore, studies using a camera have been progressed (15) (16) . The usage of a camera reduces the number of required sensors.…”

A Mechatronic Perspective on Robotic Arms and End-Effectors

“…Load measurements through strain gages integrated in a Wheatstone bridge is a well established procedure, and thus is more cost effective in comparison to piezoelectricity and piezoresistivity (Hwang et al, 2007). Optical measurements on the other hand can provide significant accuracy in the readings (Sato et al, 2010). However this technology requires the implementation of a camera in the structure of the sensor and the incorporation of image processing techniques.…”

A framework for dynamic sensory substitution

“…In their paper [3], [4], [5], present a sensitive fingertip sensor that consists of a CCD camera mounted on one side of a clear silicon, and two rows of colored spherical markers that are located within the clear silicon. Based on the observed shifts between the two rows of the markers, the authors present an algorithm for three dimensional force distribution reconstruction.…”