Browse Prior Art Database

Digital Sensor for Robot Grippers

IP.com Disclosure Number: IPCOM000059874D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Barringer, WA: AUTHOR [+4]

Abstract

In the past, grip sensors in robot grippers have been limited to two basic types. For example, one commonly used grip sensor is a photosensor which detects the presence of objects independent of the forces applied to such objects. A second commonly used grip sensor is the strain gauge, an analog device which measures the force applied to the gripped object. Unfortunately, this latter device requires very sensitive amplifiers and analog-to-digital conversion before a usable signal is obtained. In many gripper applications, only touch sensing is required. That is, a digital sensor, which activates when a threshold force is detected, provides a sufficient indication when a part is positively held by gripper fingers. Use of the above-mentioned analog sensor is precluded in many applications due to weight and cost.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Digital Sensor for Robot Grippers

In the past, grip sensors in robot grippers have been limited to two basic types. For example, one commonly used grip sensor is a photosensor which detects the presence of objects independent of the forces applied to such objects. A second commonly used grip sensor is the strain gauge, an analog device which measures the force applied to the gripped object. Unfortunately, this latter device requires very sensitive amplifiers and analog-to-digital conversion before a usable signal is obtained. In many gripper applications, only touch sensing is required. That is, a digital sensor, which activates when a threshold force is detected, provides a sufficient indication when a part is positively held by gripper fingers. Use of the above-mentioned analog sensor is precluded in many applications due to weight and cost. A miniaturized, low-cost, digital force sensor is described below. As seen in Fig. 1, the sensor includes two main elements, namely, a flexure element 1 and a thin membrane switch 2. Forces are transmitted from the gripper actuator through the drive and guide links 3 to the fingers 4 of the gripper. When the gripper grips an object, a resistance force is generated in the fingers. As seen more clearly in Fig. 2, a small deformation of the flexure element activates the thin membrane switch. The switching stroke of the membrane switch is very small (e.g., 3 mils). Therefore, to activate the membrane switch, the deflection at finger tip is relatively small. For example, the deflection is approximately 9 mils when the L and YT parameters of Fig. 2 are 2.5 inches and .75 inch, respectively. As seen in Fig. 2, the flexure element is the undercut beam section "XT". The gripper finger m...