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Robotic Gripper Slip Sensor for Large Objects, Using Doppler Shift At Ultrasound Frequencies

IP.com Disclosure Number: IPCOM000062269D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brennemann Jr, AE: AUTHOR

Abstract

Phase detection by distributed detectors permits slip sensing in the case where the object being grasped is larger than the gripper face, in one or two dimensions, with no unique emitting sound source.

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Robotic Gripper Slip Sensor for Large Objects, Using Doppler Shift At Ultrasound Frequencies

Phase detection by distributed detectors permits slip sensing in the case where the object being grasped is larger than the gripper face, in one or two dimensions, with no unique emitting sound source.

The figure shows two gripper fingers 1-2 grasping an object 3. Finger 1 is an ultrasonic transmitter and finger 2 has detectors 4 distributed around its edge. Detectors 4 supply inp to Doppler processor 5. Sound is propagated from ultrasonic emitter 6 through finger 1, through object 3, to ultrasonic detectors 4. The area of contact of the object 3 with finger 2 covers the entire width of finger 2; thus there is no unique location of a sound source. If object 3 moves in the Z direction, there is no basic change in the static phase informatio the set of detectors 4 on finger 2. However, there are transient changes in phase; these are observed as Doppler shifts in frequency while object 3 is in motion.

The Doppler shift is a function of the velocity of the moving material and the velocity of the sound. This can be expressed as: DF = Vm/Lambda where DF is the change in carrier frequency, Vm is the velocity of the moving material and Lambda is the wavelength of the carrier frequency. Lambda = velocity of sound/frequency. The velocity of sound in aluminum is about 5000 meters/second and the wavelength of the carrier at 1 MHz is 5 mm thus, if the material of object 3 is aluminum,...