Good Vibrations: Measuring the Vibrations of TouchR. Dey, B. Henson.

School of Mechanical Engineering, University of Leeds, LS2 9JT, UK.mn11rd@leeds.ac.uk, b.henson@leeds.ac.uk

Introduction Theory and Procedure

Experimental Setup

Future Work and Expected Results Conclusion

iMBE

• Quality of a packaging material can be detected by surveying it with one’s finger-tip.

• A particular emotion is generated when the ridges present on the finger comes in contact with the surface of the packaging material.

• Additional information about the quality of the product present inside can also be gathered.

• The actual reason behind the generation of the feel-good factor remains unknown.

• The aim of this project is to quantify the good vibrations induced in a finger when it slides on any packaging material.

Fig 1. A shopper using her finger-tips to sense the quality of a product.

http://www.telegraph.co.uk/news/uknews/2609556/Supermarket-price-comparison-Middle-classes-face-their-Ocado-moment.html

Shampoo

Crisps Note Book

Fig 2. Commodities that are generally scanned by finger-tips.

1.http://mrsduffsclassroom.weebly.com/the-writers-notebook.html. 2.http://www.dkimages.com/discover/home/health-and-beauty/hair-care/Shampoo/Shampoo-11.html. 3. http://vegan.fm/2011/02/walkers-crisps/

Sensors of a finger• Meissner’s corpuscle is a

superficial pressure sensor. It can sense vibrations having a frequency of 20-50 Hz.

• Ruffini endings is able to pick up vibrations between 100-500 Hz.

• Pacinian corpusle lies deep under the skin and is very sensitive to vibrations of 200-300 Hz.

• Merkel disks detects vibrations between 1-16 Hz frequency.

Fig 3. Different sensory receptors present under the finger-tip skin.

http://candacewalraven.wikispaces.com/K.++Sensory+Organs.

Sensor Stand

Load Cell

Stimulus

• The sensor used is a type 8230 load cell.• Works on piezoelectric effect of quartz

and possesses a sensitivity of 110mV/N.• Perfect for measurement of compressive

and tensile forces.• Provides a low impedance output.

• Casing materials of shampoo are used as stimulus.

• They are attached to the 9cm long aluminium bar with the help of double faced tape.

• The stimuli that are to be used in this study are:

1. Polyvinyl Chloride.2. High Density Polyethylene.3. Poly-propylene.4. Poly-styrene.5. Polyethylene Tetraphthalate.6. Low Density Polyethylene.7. PET/MET.

• Made of aluminium.• Holds the load cell in the

central groove.• The aluminium bar with

the stimuli is placed on the top.

• Efficient force transfer is obtained. Fig 4. SolidWorks model of the sensor stand.

Fig 5. Bruel and Kjaer load cell (8230). [2].

Fig 6. Dimensions of the load cell. [2].

• Interactions between the finger print and the texture of the material activates the underlying sensors in a finger.

• Static contact activates the ruffini endings and the merkell discs, while sliding contact activates the rest of the organelles.

• The small changes in forces is picked up by the piezoelectric load cell.

• Fourier transformation of the signal obtained from the load cell will provide a frequency distribution of the induced vibrations.

• Comparing the subjective opinions from the subjects with the obtained FFT signals will be helpful in segregating the good vibrations form the others.

• Transfer functions of the fingers will also be obtained.

• To take readings and individual opinions from subjects of various age groups.

• Compare and analyse the results to find the good vibrations and the finger transfer function.

• Along with visionary perception, the sensation of touch is very important in judging the quality of a packaging material.

• This study is designed to find out the texture induced vibration of any material into a human finger.

• The outcomes of this study will be helpful to the product designing industry, virtual reality and robotics.

• Developing products only for a particular age group in the society will be possible.

HDPE

REFERENCES

• Analysis of the finger transfer function will provide a method to find out variances in different fingers. Fig 7. Expected Finite Fourier Transform Output. [4].

1. Childs, T.H.C. and Henson, B. “Human tactile perception of screen printed surfaces: Self-report and contact mechanics experiments.” Journal of Engineering Tribology 221; (2007); 427-441.

2. Deltatron ® Force Transducer 8230 Data Sheet.3. Fagiani, R., Massi, F., Chatelet, E., Berthier, Y. and Akay, A. “Tactile perception by friction induced vibrations.” Tribology International 44; (2011); 1100-1110.4. Fagiani, R., Massi, F., Chatelet, E., Berthier, Y. and Sestieri, A. “Experimental analysis of friction-induced vibrations at the finger contact surface.” Journal of

Engineering Tribology 224; (2010); 1027-1035.5. Hollins, M. and Risner, S.R. “Evidence for the duplex theory of tactile texture perception.” Perception & Psychophysics 62(4); (2000); 695-705.