Model of a Slip Sensor

Sensors and Actuators A: Physical

Crowder

2006

Certain photoelastic materials exhibit birefringent characteristics at a very low level of strain. This property of material may be suitable for dynamic or wave propagation studies, which can be exploited for designing tactile sensors. This paper presents the design, construction and testing of a novel dynamic sensor based on photoelastic effect, which is capable of detecting object slip as well as providing normal force information. The paper investigates the mechanics of object slip, and develops an approximate model of the sensor. This allows visualization of various parameters involved in the sensor design. The model also explains design improvements necessary to obtain continuous signal during object slip. The developed sensor has been compared with other existing sensors and experimental results from the sensor have been discussed. The sensor is calibrated for normal force which is in addition to the dynamic signal that it provides from the same contact location. The sensor has a simple design and is of a small size allowing it to be incorporated into robotic fingers, and it provides output signals which are largely unaffected by external disturbances.

Section: Slip Sensor Designmentioning

confidence: 99%

A dynamic tactile sensor on photoelastic effect

Sensors and Actuators A: Physical

Crowder

2006

“…The arrow on the sensing area (Fig. 8) shows the direction of object slip and should be kept perpendicular to the optical fiber alignment to have the photoelastic effect [26]. The light source used is a high radiance emitter of peak spectral output of 850 nm and the receiver is a PIN photodiode to match the emitter.…”

Section: Sensor Constructionmentioning

confidence: 99%

Photoelasticity Based Dynamic Tactile Sensor

Volume 4a: ASME/IEEE Conference on Mechatronic and Embedded Systems and Applications

Crowder

2005

The paper presents design, construction and testing of a photoelasticity based dynamic sensor which is capable of detecting slip as well as providing normal force information. Starting with investigations into mechanism of slip, an approximate model of the sensor has been developed. This model explains the design improvements necessary to provide continuous signal during slip. The theoretical model also helps identify various sensor parameters to characterize the sensor. The developed sensor has been compared with other existing sensors and the experimental results from the sensor have been discussed for the type of signal the sensor provides. The sensor is also calibrated for normal force. The sensor is novel in the sense that it offers dynamic slip signal as well as the normal force information from a single contact location, it provides continuous signal during slip, and it has small size which can be easily incorporated into robotic fingers. The sensor has an edge over other existing sensors that its design is simple yet it provides strong signals which are largely unaffected by external disturbances.

“…For example, in order to obtain imprint of foot loading condition, low modulus material has to be used and loading has to be applied in the direction of the light travel. This is atypical of conventional photoelasticity, where loading is applied across the light travel for pronounced photoelastic effect [5]. This paper considers application of conventional photoelastic techniques under unconventional loading situations and discusses their limitations when applied to sensing applications and proposes alternative approaches that may be necessary to extract the load information.…”

Section: Introductionmentioning

confidence: 99%

Photoelastic Stress Analysis Under Unconventional Loading

Volume 4: ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications and the 19th Reliability, STR

Grewal

2007

This paper presents use of conventional photoelastic techniques under unconventional loading situations to evaluate their efficacy in sensing applications. The loading is unconventional in the sense that low modulus photoelastic material is deformed under vertical load in the direction of light travel to induce the photoelastic effect. This is atypical of conventional methods where loading is across the light travel. Both RGB calibration and phase shifting techniques have been used to study the characteristics of fringe patterns obtained under vertical and shear loads. The results obtained under these conditions are discussed with their limitations specially when this is applied for sensing applications. Finally a case study has been conducted to analyze the foot image and conclusions drawn from this have been presented.