Abstract

We propose a navigational aid approach for the blind that relies on active optical profilometry with real-time electrotactile interfacing on the skin. Here we are concerned with the optical parts of this system. We point out the particular requirements the profilometer must meet to meet the needs of blind people. We show experimentally that an adequate compromise is possible that consists of a compact class I IR laser-diode triangulation profilometer with the following characteristics: 30-cm to 30-m range, 1-deg angular resolution, 20-ms acquisition time per measure of distance, 60° angular scanning field.

© 1996 Optical Society of America

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References

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  1. M. Jacquin, “What technical aids blind people need in the near future or computer access is not yet what it could be,” Newsletter 2 (Royal National Institute for the Blind, London, July1989), pp. 13–19.
  2. M. Adjouadi, “A man-machine vision interface for sensing the environment,”J. Rehabil. Res. Dev. 29, 57–76 (1992).
  3. P. Bach y Rita, “Tactile vision substitution, past and future,” Int. J. Neurosci. 19, 29–36 (1983).
  4. R. D. Easton, “Inherent problems of attempts to apply soar and vibrotactile sensory aid technology to the perceptual needs of the blind,” Optom. Vision Sci. 69, 3–14 (1992).
  5. K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).
  6. P. Bach y Rita, Brain Mechanisms in Sensory Substitution (Academic, New York, 1972).
  7. G. Janson, “Tactile guidance of movements,” Int. J. Neurosci. 19, 37–46 (1983).
  8. C. C. Collins, P. Bach y Rita, “Transmission of pictorial information through the skin,” Adv. Biol. Med. Phys. 14, 285–315 (1973).
  9. G. Seitz, G. John, H. J. Tiziani, “Triangulation sensoren für Roboteranwendungen,” in Proceeding of the Ninth International Congress, Laser 89, W. Waidelich, ed. (Springer-Verlag, Berlin, 1990), pp. 235–240.
  10. R. A. Jarvis, “A perspective on range finding techniques for computer vision,” IEEE Trans. Pattern Anal. Machine Intell. PAMI-5, 122–139 (1983).
  11. O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).
  12. D. Addleman, L. Addleman, “Rapid three dimensional surface digitizer,” U.S. International PatentWO 87/01194 (12February. 1987).
  13. J. Cornillaut, “Mesures industrielles par laser,” in Laser Principes et Technologies d’Applications, M. Maillet, ed. (Lavoisier, Paris, 1990), pp. 310–320.
  14. Hamamatsu Technical Data, 16-step Range Finder (Hamamatsu, Hamamatsu City, Japan, 1988).
  15. M. Rioux, “Laser range finder based on synchronized scanners,”Appl. Opt. 23, 3837–3844 (1984).
  16. Laser light apparatus safety, CEI 825, NFC 43–801 (November. 1985).

1992 (2)

R. D. Easton, “Inherent problems of attempts to apply soar and vibrotactile sensory aid technology to the perceptual needs of the blind,” Optom. Vision Sci. 69, 3–14 (1992).

M. Adjouadi, “A man-machine vision interface for sensing the environment,”J. Rehabil. Res. Dev. 29, 57–76 (1992).

1991 (1)

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

1984 (1)

1983 (3)

R. A. Jarvis, “A perspective on range finding techniques for computer vision,” IEEE Trans. Pattern Anal. Machine Intell. PAMI-5, 122–139 (1983).

P. Bach y Rita, “Tactile vision substitution, past and future,” Int. J. Neurosci. 19, 29–36 (1983).

G. Janson, “Tactile guidance of movements,” Int. J. Neurosci. 19, 37–46 (1983).

1973 (1)

C. C. Collins, P. Bach y Rita, “Transmission of pictorial information through the skin,” Adv. Biol. Med. Phys. 14, 285–315 (1973).

Addleman, D.

D. Addleman, L. Addleman, “Rapid three dimensional surface digitizer,” U.S. International PatentWO 87/01194 (12February. 1987).

Addleman, L.

D. Addleman, L. Addleman, “Rapid three dimensional surface digitizer,” U.S. International PatentWO 87/01194 (12February. 1987).

Adjouadi, M.

M. Adjouadi, “A man-machine vision interface for sensing the environment,”J. Rehabil. Res. Dev. 29, 57–76 (1992).

Bach y Rita, P.

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

P. Bach y Rita, “Tactile vision substitution, past and future,” Int. J. Neurosci. 19, 29–36 (1983).

C. C. Collins, P. Bach y Rita, “Transmission of pictorial information through the skin,” Adv. Biol. Med. Phys. 14, 285–315 (1973).

P. Bach y Rita, Brain Mechanisms in Sensory Substitution (Academic, New York, 1972).

Collins, C. C.

C. C. Collins, P. Bach y Rita, “Transmission of pictorial information through the skin,” Adv. Biol. Med. Phys. 14, 285–315 (1973).

Cornillaut, J.

J. Cornillaut, “Mesures industrielles par laser,” in Laser Principes et Technologies d’Applications, M. Maillet, ed. (Lavoisier, Paris, 1990), pp. 310–320.

Easton, R. D.

R. D. Easton, “Inherent problems of attempts to apply soar and vibrotactile sensory aid technology to the perceptual needs of the blind,” Optom. Vision Sci. 69, 3–14 (1992).

Hignette, O.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

Ho, M.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

Jacquin, M.

M. Jacquin, “What technical aids blind people need in the near future or computer access is not yet what it could be,” Newsletter 2 (Royal National Institute for the Blind, London, July1989), pp. 13–19.

Janson, G.

G. Janson, “Tactile guidance of movements,” Int. J. Neurosci. 19, 37–46 (1983).

Jarvis, R. A.

R. A. Jarvis, “A perspective on range finding techniques for computer vision,” IEEE Trans. Pattern Anal. Machine Intell. PAMI-5, 122–139 (1983).

John, G.

G. Seitz, G. John, H. J. Tiziani, “Triangulation sensoren für Roboteranwendungen,” in Proceeding of the Ninth International Congress, Laser 89, W. Waidelich, ed. (Springer-Verlag, Berlin, 1990), pp. 235–240.

Kaczmarek, K. A.

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

Midavaine, P.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

Noack, J. C.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

Rioux, M.

Seitz, G.

G. Seitz, G. John, H. J. Tiziani, “Triangulation sensoren für Roboteranwendungen,” in Proceeding of the Ninth International Congress, Laser 89, W. Waidelich, ed. (Springer-Verlag, Berlin, 1990), pp. 235–240.

Tiziani, H. J.

G. Seitz, G. John, H. J. Tiziani, “Triangulation sensoren für Roboteranwendungen,” in Proceeding of the Ninth International Congress, Laser 89, W. Waidelich, ed. (Springer-Verlag, Berlin, 1990), pp. 235–240.

Tompkins, W. J.

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

Volat, J. P.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

Webster, J. G.

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

Adv. Biol. Med. Phys. (1)

C. C. Collins, P. Bach y Rita, “Transmission of pictorial information through the skin,” Adv. Biol. Med. Phys. 14, 285–315 (1973).

Appl. Opt. (1)

IEEE Trans. Biomed. Eng. (1)

K. A. Kaczmarek, J. G. Webster, P. Bach y Rita, W. J. Tompkins, “Electrotactile and vibrotactile displays for sensory substitution systems,” IEEE Trans. Biomed. Eng. 38, 1–16 (1991).

IEEE Trans. Pattern Anal. Machine Intell. (1)

R. A. Jarvis, “A perspective on range finding techniques for computer vision,” IEEE Trans. Pattern Anal. Machine Intell. PAMI-5, 122–139 (1983).

Int. J. Neurosci. (2)

G. Janson, “Tactile guidance of movements,” Int. J. Neurosci. 19, 37–46 (1983).

P. Bach y Rita, “Tactile vision substitution, past and future,” Int. J. Neurosci. 19, 29–36 (1983).

J. Rehabil. Res. Dev (1)

M. Adjouadi, “A man-machine vision interface for sensing the environment,”J. Rehabil. Res. Dev. 29, 57–76 (1992).

Optom. Vision Sci. (1)

R. D. Easton, “Inherent problems of attempts to apply soar and vibrotactile sensory aid technology to the perceptual needs of the blind,” Optom. Vision Sci. 69, 3–14 (1992).

Other (8)

M. Jacquin, “What technical aids blind people need in the near future or computer access is not yet what it could be,” Newsletter 2 (Royal National Institute for the Blind, London, July1989), pp. 13–19.

P. Bach y Rita, Brain Mechanisms in Sensory Substitution (Academic, New York, 1972).

G. Seitz, G. John, H. J. Tiziani, “Triangulation sensoren für Roboteranwendungen,” in Proceeding of the Ninth International Congress, Laser 89, W. Waidelich, ed. (Springer-Verlag, Berlin, 1990), pp. 235–240.

O. Hignette, M. Ho, P. Midavaine, J. C. Noack, J. P. Volat, “Optoelectronic device for determining the distance and the shape of an object,” French patentWO 87/07942 (8December. 1987).

D. Addleman, L. Addleman, “Rapid three dimensional surface digitizer,” U.S. International PatentWO 87/01194 (12February. 1987).

J. Cornillaut, “Mesures industrielles par laser,” in Laser Principes et Technologies d’Applications, M. Maillet, ed. (Lavoisier, Paris, 1990), pp. 310–320.

Hamamatsu Technical Data, 16-step Range Finder (Hamamatsu, Hamamatsu City, Japan, 1988).

Laser light apparatus safety, CEI 825, NFC 43–801 (November. 1985).

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Figures (8)

Fig. 1
Fig. 1

Blind person walking down a sidewalk: G, flat ground; θ M , scanning angle of the laser beam; CL, cutting line; S, stone; H, hole. The scanning telemeter mounted on the cap of the blind person measures the distances of obstacles situated on the cutting surface (dashed curve).

Fig. 2
Fig. 2

Electrotactile interface. The cutting line (dotted curve) represents the electrotactile signal that moves on the skin in synchrony with the laser beam.

Fig. 3
Fig. 3

Basic scheme of the telemeter. The lighted zone A' of the CCD line of abscissa x' = OA' is related to the distance of the obstacle: D, distance to the obstacle; B, triangulation base; Ob, obstacle; LD, collimated laser diode; L, lens; CCD, CCD line; IF, interferential filter; oC, optical axis of L; f, focal length of the lens.

Fig. 4
Fig. 4

Uncertainty δD versus distance D as given in Eq. (3) with an experimental uncertainty of one pixel.

Fig. 5
Fig. 5

Scheme for a compact scanning telemeter: Ob, obstacle; B, base; M1,M2, mirrors with their rotational axis perpendicular to the figure plane; SM, step motor that draws both mirrors synchronously by a mechanism (not shown): CCD, CCD line; LD, collimated laser diode; L, lens; IF, interferential filter.

Fig. 6
Fig. 6

(a) Video output trace of the CCD line for an obstacle of black cotton tissue at 15 m; emission power of the laser diode, 4 mW. (b) Video output trace of the CCD line for an obstacle of white cotton tissue at 15 m; emission power of the laser diode, 4 mW.

Fig. 7
Fig. 7

(a) Video output trace of the CCD line for an obstacle of white cotton tissue at 2 m; emission power of the laser diode, 4 mW. (b) Video output trace of the CCD line for an obstacle of black cotton tissue at 2 m; emission power of the laser diode, 4 mW.

Fig. 8
Fig. 8

Video output trace of the CCD line for the case of 60-klx white-light competition on a white obstacle at 5 m; emission power of the laser diode, 4 mW.

Equations (12)

Equations on this page are rendered with MathJax. Learn more.

Δ θ = τ d θ / d t ,
D = ( f B / x ) + f ,
δ D = δ x ( D f ) 2 / ( B f ) .
Φ L = T L S Ω ,
π L S = P ρ,
Φ L = T P ρ S 1 / π D 2 ,
E P = Φ L τ 4 w 2 / ( π α 2 f 2 ) ,
370 ρ = D M
E M = 1.2 × 10 3 t 0.75 J for λ = 810 nm .
t = d / ( D d θ / d t ) .
P M t = E M .
D = 4.8 × 10 11 p M 4 d / ( d θ / d t ) .

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