Optical range finder for 15–10-m distances

The available guide tools of the orientation and mobility for a blind are the cane, guide dog and electronic guide devices. A cane is easy to detect the hindrance that is in front of the user but not for the hindrance above the user waist. That's why a cane user of a blind sometimes will be hit by the upper hindrance. Guide dog is a very powerful mobility guider but expensive and the training and living care for the dogs are difficult. Hence, guide dog is not popular in many countries. The electronic devices for blind guide tools such as laser cane; sonic glasses, sonic guide etc. can only detect a single point at a time and not for a whole view. In our system, a machine vision blind guide system is proposed. A CCD grabbed the image of front view and divided the image into nine blocks. Each block is calculated to get the distance message, which is multipoint data to guide the blind by the converted voice signal.

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“…14 No. 2 April 2002 comprehendible distance measurement unit transmitted the voice message by an earphone [3,4].…”

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confidence: 99%

The Machine Vision Blind Guide System

Lay

Chen

Yang

2002

Biomed. Eng. Appl. Basis Commun.

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“…"SI (x) = I(x)sin(2if0x) (3) = A(x) sln(271f0x) + B(x) sin[4f0x + 0(x)]-B(x) sin 0(x) 's2 (x) = I(x)cos(2if0x) (4) = A(x)cos(2f0x) + B(x) cos [4,f0x + Ø(x)]+ B(x)sin 0(x) Design digital filter, deal I'51(x), I'52(x) with low-pass filter, filtratefo 2fo, then we can get:…”

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confidence: 99%

<title>Error analysis and correcting 3D profilometry based on quadrature demodulation</title>

Su¹,

Zhang²

2002

SPIE Proceedings

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In this paper, the errors of three-dimensioned profilometry based on quadrature demodulation are analyzed, and the corrected results are present. We found the method had three primary errors: the error that is caused by speckle of laser interference system, the error that is caused by mixing in quadrature demodulation and the error that is caused by the cosine fringe distortion in the structure light. We analyzed these three errors by experiment and theory. At last, we gave the corrected results.

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“…(x,y) arctan((I 3 -I 1 )/(I 0 -I 2 ))-2 x/p; (6) According the expression (6) we can get phase distribution which is modulated by the height of the detected object. But the value is between and .After phase unwrapping, we can get the true value of the phase distribution., then the value of the height we need.…”

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confidence: 99%

Three-dimensional shape measurement system with digital light projector

Zhong¹,

Zhao²

2002

Interferometry XI: Applications

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A new experiment system of three-dimentional shape measurement is presented. The advantages and the disadvantages are analyzed. In this experiment system, using digital light projector replaces traditional mode of projecting, and electronical grating replaces traditional grating. Obviously, the system has many advantages such as higher precise, easier to realize, etc. But there still are some disadvantages because of the characteristic of the system. We create different direction electronical gratings with different period in the system and use the four-step phase-measuring profilometry to get the phase and height of the detected object. According the experiment result, we analyze the errors introduced by the system. Then decrease such errors as much as possible. From the last result, we can conclude that the system has high practical value.

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Optical range finder for 15–10-m distances

Cited by 42 publications

References 2 publications

The Machine Vision Blind Guide System

The Machine Vision Blind Guide System

<title>Error analysis and correcting 3D profilometry based on quadrature demodulation</title>

Three-dimensional shape measurement system with digital light projector

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