US 5,399,870 AGranted

Position detecting method and apparatus for laser sensor

AssigneeFanuc Corporation

InventorsNobitoshi Torii, Ryo Nihei, Yasuo Naito, Hiroshi Wakio, Takashi Iwamoto

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Abstract

The present invention relates to a position detecting method and its apparatus that is capable of improving detecting accuracy in a laser sensor using a Charged Coupled Device (CCD) as a light receiving element. A sum of products of an output C.sub.i of each cell in a light receiving element and a cell position X.sub.i is obtained, and the cell outputs C.sub.i are added. When the cell output C.sub.i exceeds a predetermined threshold value, a counter is reset. When the cell output C.sub.i decreases down below the threshold value, the sample hold signal SH is counted. When the counted value of the counter becomes a predetermined value, a division circuit divides the above-obtained sum of products by the above addition value to obtain a center of gravity of the sum of products as a light receiving position. Then, thus obtained value is stored in a latch buffer. When a plurality of light receiving positions are obtained, the control unit picks out only the light receiving position of primary reflection beam from among them to identify the object position. Accordingly, the accuracy of the position detecting operation can be improved, since resolution in position detecting according to the invention is not determined on the unit of cell, but a light receiving position between adjacent cells in CCD can also be detected.

Claims17

Dependent claims

A position detecting apparatus for a laser sensor comprising:

a light receiving cell consisting of a Charged Coupled Device that contains a plurality of cells, each generating an output C.sub.i in accordance with an electric charge stored in proportion to a light quantity received on a cell surface;
timing signal generating means for generating a gate signal and generating a sample hold signal to successively scan respective cells from the beginning after the gate signal is outputted;
cell counter capable of being reset by said gate signal, for counting said sample hold signals to output a value x.sub.i of cell position in the light receiving element;
adder means capable of being reset by said gate signal and successively adding the output C.sub.i of each cell in the light receiving element to be scanned in response to said sample hold signal to obtain an addition value .SIGMA.C.sub.i ;
sum of products calculating means capable of being reset by said gate signal, for multiplying the output C.sub.i of each cell in the light receiving element to be scanned in response to the sample hold signal by said value x.sub.i of each cell position outputted from the cell counter and successively summing up these multiplied values to obtain a summed-up value .SIGMA.C.sub.i .multidot.x.sub.i ;
and
division means for dividing said summed-up value .SIGMA.C.sub.i .multidot.x.sub.i obtained by the sum of products calculating means by said addition value .SIGMA.C.sub.i obtained by the adder means to calculate a center of gravity position .SIGMA.C.sub.i .multidot.x.sub.i /.SIGMA.C.sub.i of receiving beams and outputting the center of gravity position as the light receiving position.

4 more elements

A position detecting method for a laser sensor comprising a Charged Coupled Device functioning as a light receiving element for detecting an object position, said Charged Coupled Device receiving light from scanning an array of cells, each cell having a corresponding position value and outputting a corresponding cell output value, said position detecting method comprising the steps of:

initializing a sum of products value to a preselected value;
multiplying a corresponding cell output value by a corresponding position value of one cell of the array of cells to obtain a multiplied cell value;
adding the multiplied cell value to the sum of products value;
repeating the multiplying and adding for each selected cell of the array of cells, to obtain a final value of the sum of products value;
initializing a sum of cell outputs value to a preselected value;
adding the corresponding cell output value for each of the selected cells of the array of cells to the sum of cell outputs value;
and
dividing the final sum of products value by the sum of cell output value to obtain a light receiving position.

5 more elements

Dependencies are inferred from the claim text.