Three-dimensional measuring apparatus having improved speed and resolution

• US 5,509,090 A
• Filed: 08/04/1994
• Issued: 04/16/1996
• Est. Priority Date: 06/19/1990
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Maruyama, Tsugito, Kanda, Shinji, Wakitani, Jun
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Tran, Phuoc
• Application Number:
  US08/285,441
• Time in Patent Office: 621 Days
• Field of Search: 382/25, 382/67, 382/44, 382/41, 382/154, 382/203, 382/276, 382/285, 382/291, 382/293, 382/294, 356/376, 356/379, 395/119, 395/126, 395/94
• US Class Current: 382/276
• CPC Class Codes: G01B 11/2527 with phase change by in-plane movement of the patern
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

A three-dimensional measuring apparatus including a multi-slit projector has an actuator for displacing at least one of first and second diffraction gratings by only a minute distance in a direction perpendicular to the slit lights. An image recognizing apparatus includes an image arithmetic unit for changing, each time a coded multi-slit light pattern is changed, weights assigned to the binarized image signals, and for summing up the last weighted binarized image signals or the image signals of the last added results read out from an image memory, with newly weighted binarized image signals. This improves the image resolution reduces the memory capacity and increases the processing speed.

Claims

1. A three-dimensional measuring apparatus comprising a multi-slit projector for projecting coded multi-slit light patterns onto an object to be measured and an image recognizing apparatus, said image recognizing apparatus comprising:

an image pick up unit for picking up said coded multi-slit light patterns projected onto said object;

an image processor comprising;

a binarization circuit for binarizing, weighing and storing, image signals from said image pick up unit;

a plurality of image memories for storing the weighted, binarized image signals corresponding to the coded multi-slit light patterns as image signals, adding image signals stored in at least two of said plurality of image memories and storing the added result in another one of said image memories; and

an image arithmetic unit for changing, each time different coded multi-slit light is projected by the multi-slit projector, weights assigned to the binarized image signals obtained by said binarization circuit, and for summing the added result read out from one of said image memories with one of said weighted, binarized image signals from one of said image memories and obtaining final results;

decoding means for decoding a coded multi-slit light number from the final results of said image arithmetic unit and outputting a decoded multi-slit light number;

a coded pattern irradiated point memory for storing coordinates of coded pattern irradiated points of said object as memory addresses, and said decoded multi-slit light number which is output as the final result from said image arithmetic unit, said binarization circuit, said image memories, said image arithmetic unit and said coded pattern irradiated point memory are operative at a video rate of said image pick up unit; and

a three-dimensional distance calculating unit for receiving each of the memory addresses of said coded pattern irradiated point memory and said coded multi-slit light number and for calculating a three-dimensional position of said coded pattern irradiated points stored as coordinates in said coded pattern irradiated point memory, the projection of the coded multi-slit light, the binarization of the image signals and the calculation of coordinates of the coded pattern irradiated points are all performed simultaneously.

2. A three-dimensional measuring apparatus as claimed in claim 1,

wherein said multi-slit projector and said image pick up unit are arranged on a surface which crosses each of the multi-slit lights at a right angle, and said image pick up unit and said multi-slit projector are aligned along the same axis such that the image pick up unit is arranged to have the same X axis extending parallel to the direction of the array of the multi-slit lights, and wherein said distance calculating unit comprises:

read-only memories, ROMs, connected to said coded pattern irradiated point memory, for storing coordinates of three-dimensional positions of said object, said coordinates of the three-dimensional positions corresponding to said coordinates of the coded pattern irradiated points; and

a selector, connected to said read-only memories, selecting a respective one of said ROMS corresponding to an X axis coordinate, a respective one of said ROMs corresponding to a Y axis coordinate, and a respective one of said ROMS corresponding to a Z axis coordinate.

3. A three-dimensional measuring apparatus comprising a multi-slit projector for projecting coded multi-slit light patterns onto an object to be measured and an image recognizing apparatus, said image recognizing apparatus, said image recognizing apparatus comprising:

an image pick up unit for obtaining an image of said coded multi-slit light patterns projected onto said object to be measured;

a binarization circuit for binarizing image signals from said image pick up unit;

a plurality of image memories for sequentially storing binary image signals from said binarization circuit, said binary image signals respectively corresponding to said coded multi-slit light patterns;

an address generation circuit, connected to said plurality of image memories, for generating address signals for said plurality of image memories, said plurality of image memories simultaneously perform data read operations by the address signal to output respective read data, said binarization circuit said image memories, and said address generation circuit are operative at a video rate of said image pick up unit;

a decision control unit, connected to said plurality of image memories, for receiving the read data and outputting a slit light number based on the read data; and

a distance calculation unit, connected to said decision control unit and said address generation circuit, for determining three dimensional positions of the object to be measured, based on the address signals from said address generation circuit and the slit light number having a bit configuration composed of said binary image signals simultaneously read out from said plurality of image memories by said address signals.

4. A three-dimensional measuring apparatus as claimed in claim 3, further comprising:

a table, connected between said distance calculation unit and said plurality of image memories, storing the slit light numbers and the address signals from said address generation circuit and outputting the slit light numbers and the address signals to said distance calculation unit; and

said decision control circuit, connected between said plurality of image memories and said table, for determining the existence of "0s" included in a bit configuration of said binary image signals simultaneously read-out from said plurality of image memories and outputting only the bit configuration except for the configuration of all "0s" as said table, while generating a control signal for inhibiting the application of said address signals from said address generation circuit to said table if the bit configuration includes the determination of all "0s".

5. A three-dimensional measuring apparatus comprising a multi-slit projector for projecting coded multi-slit light patterns onto an object to be measured, and an image recognizing apparatus, said image recognizing apparatus comprising:

an image pick up unit including a plurality of light receiving elements each for picking up said coded multi-slit light patterns projected onto said object to be measured;

a plurality of binarization circuits, operatively connected to respective ones of said light receiving elements, for binarizing a corresponding output of said light receiving elements and outputting output signals;

a plurality of serial-in/parallel-out shift registers, operatively connected to respective ones of said binarization circuits, for performing a shifting operation and for storing the output signals of said binarization circuits corresponding to said light receiving elements each time different coded multi-slit light is projected by the multi-slit projector;

an address generation circuit for producing address signals specifying the shift registers corresponding to said light receiving elements; and

a distance calculation unit for determining three-dimensional positions of coded pattern irradiated points of said object to be measured, based on the address signals from said address generation circuit, and a slit light number having a bit configuration read out in parallel from said shift registers corresponding to said light receiving elements specified by said address signals.