JP2508072B2 - Position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a position detection device for detecting a traveling position of a mobile device such as a crane, and particularly, is intended to accurately correct a detection displacement. It is a thing.

B. SUMMARY OF THE INVENTION The present invention has a rotation sensor that detects the rotation of the wheels of a mobile device, and a limit switch that is turned on by contacting a striker installed in the middle of the movement path. In the position detecting device for correcting the detection value of the rotation sensor, the correction is performed only when the limit switch comes into contact with one of the both ends of the striker.

C. Conventional technology For large cranes that perform automatic operation, a position detection device may be used to know the absolute traveling position of the crane. A widely used position detecting device is a type of device that detects the amount of rotation (number of rotations or rotation angle), such as a potentiometer or encoder, on the axle of a wheel of a crane to detect the position. . The position detecting device of this type has an advantage that the mechanism such as the crane main body or the rail does not need to be touched, and the absolute position can be detected simply by attaching a potentiometer or the like.

By the way, in the position detection device of the type described above, since the measurement target is the rotation amount of the wheel and not the absolute traveling position of the crane itself, for example, when a situation occurs where the wheel slips on the rail without rotating, the detection is performed. There was an inconvenience that there was an error between the position and the actual position of the crane.

In order to correct the displacement of the position detection as described above, conventionally, a limit switch for position correction has been used. This technique will be described with reference to FIG. In FIG. 5, a crane 1, which is an example of a mobile device, travels on a rail 3 by rotationally driving its wheels 2. Although not shown,
A potentiometer is installed on the axle of the wheel 2,
The detected value of the potentiometer indicates the traveling position of the crane 1. The crane 1 is also provided with a limit switch 4. Further, a striker 5 is provided near the rail 3, and when the crane 1 travels, the movable contact of the limit switch 4 comes into contact with the striker 5 and the limit switch 4 is turned on (ON). .

The method of position detection when configured as shown in FIG. 5 is as follows. That is, when the crane 1 travels and the limit switch 4 turns on, the detected value P _{ON of the} potentiometer
Remember. Then, for example, when the crane 1 reaches the position P shown by the dotted line in the figure, the detected value of the potentiometer is P _X.
Then, the position P can be calculated by the following equation. However, the position of the striker 5 (the position converted to the detected value of the potentiometer) is P _S.

P = (P _X −P _ON ) + P _S Since the position is detected using the above formula in this way, the limit switch 4 is closed after the wheel 2 slips and the detected value P _ON is newly set. By updating to, the positional deviation can be corrected and the position can be detected thereafter.

D. Problems to be Solved by the Invention In the prior art shown in FIG. 5, the striker 5 has a constant width along the traveling direction of the crane 1. Therefore, from the left side of the striker 5, the crane 1
When the limit switch 4 turns on when the crane moves to the right, and when the limit switch 4 turns on when the crane 1 moves to the left from the right side of the striker 5, the detected value P _ON
A deviation in charge of the width of the striker 5 will occur in the value of. Specifically, if the width of the striker 5 is 100 [mm], a value corresponding to this 100 [mm] (100 [mm]
Is converted into the detected value of the potentiometer). Due to such an error, the position of the crane 1 cannot be precisely controlled in the related art.

In view of the above-mentioned conventional technique, the present invention provides a position detection device capable of accurately controlling the position of a mobile device such as a crane.

E. Means for Solving Problems The configuration of the present invention for solving the above problems is a position detection device that uses a rotation sensor that detects a rotation amount (rotation number or rotation angle) of a wheel of a mobile device. When a striker is installed at a predetermined location of the mobile device and the limit switch installed on the mobile device detects the position of the striker and corrects the position, the position correction is performed only when the mobile device moves from the specific direction toward the striker. It is characterized by doing so.

F. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. As shown in the figure, the crane 1 travels on the rail 3 by rotationally driving its wheels 2a and 2b. A stopper 10 is provided at the start point of the rail 3 and a stopper 11 is provided at the end point of the rail 3,
In this example, the fixed position of the crane 1 is when the wheels 2b are in contact with the stopper 10. The striker 5 is fixed near the fixed position and close to the rail 3.

The crane 1 travels based on a command from the controller 12, and generally starts from the fixed position and travels to a working position, and when the predetermined work is completed, returns to the fixed position again.

The potentiometer 13 installed on the crane 1 has wheels 2b.
When the crane 1 moves to the right and the wheels 2b rotate forward, the detected value of the potentiometer 13 increases in accordance with the amount of rotation of the wheels 2b. When the crane 1 moves to the left and the wheels 2b rotate in the reverse direction, the detected value of the potentiometer 13 is the wheel 2b.
It decreases according to the amount of rotation. When the movable contact 4a of the limit switch 4 installed on the crane 1 comes into contact with the striker 5, the limit switch 4 is turned on (ON) and outputs a closing signal L _ON .

The closing control signal L _ON of the limit switch 4 and the detection value P _X of the potentiometer 13 are calculated by the calculation control unit 20 in the controller 12.
Sent to As shown in FIG. 2, the arithmetic control unit 20 is composed of a peak hold circuit 21, a comparison circuit 22, a register 23, and a data output unit 24. Of these, the peak hold circuit 21 is reset when the closing signal L _ON is input, and holds the maximum detection value P _X output from the potentiometer 13 at other times. The maximum value held in this way is P _P. The comparison circuit 22 is
When the limit switch 4 changes from the open state to the closed state and the close signal L _ON is input, the maximum value P _P and the detected value P _X are compared, and when P _P > P _X , the control pulse C _P
Is output. Further, when the control pulse C _P is input, the register 23 stores the detected value P _X at this input time and updates the previously stored value. Then, the latest value stored in the register 23 is set as the register value P _ON . Further, the data output section 24
Calculates the calculated value P by the following equation. However, the position of the right end 5b of the striker 5 (the position converted to the detected value of the potentiometer) is preset as P _S.

P = (P _X −P _ON ) + P _S The calculated value P thus obtained is displayed on the display unit 25 of the controller 12. This display shows the traveling position of the crane 1.

Next, the traveling state of the crane 1 and the mode of position detection will be described. In Fig. 1, point A shows the fixed position of the crane 1, point B shows the position where the limit switch 4 is turned on by the left end 5a of the striker 5 when the crane 1 moves to the right, and point C shows the crane. When 1 goes left, the limit switch 4 is moved by the right end 5b of the striker 5.
It shows the position to be turned on, point D shows the end point of crane 1,
Point E indicates a predetermined work position between points C and D.

(A) When the crane 1 is working at point E, the detected value P _X of the potentiometer 13 is P _{X (E)} . E
As the crane 1 moves leftward from the point, the peak hold circuit 21 holds P _{X (E)} as the maximum value P _P. And
When the crane 1 reaches the point C, the detected value P _X becomes P _{X (C)} , and at this time point, the closing signal L _ON is output. Therefore, the comparison circuit 22 operates and compares P _{X (E)} , which is the maximum value P _P at this time, with P _{X (C)} that is the detected value P _X. In this case, since P _P (= P _{X (E)} )> P _X (= P _{X (C)} ), the comparison circuit 22 outputs the control pulse C _P.
Therefore, P _{X (C)} is registered as the registration value P _ON of the register 23. Therefore, the data output unit 24 performs an operation of P = (P _X −P _ON ) + P _S = (P _C −P _C ) + P _S = P _S. In this way, when the vehicle is located at the point C, the calculated value P becomes P _S , and the traveling position displayed on the display unit 25 matches the actual absolute position of the crane 1. Eventually, the position detection is corrected at the point C.

(B) When the crane 1 is stopped at the fixed position A, the detected value P _X of the potentiometer 13 is P _{X (A)} (=
0). When the crane 1 moves to the right from the point A, the detected value P _X increases in accordance with the rotation amount of the wheels 2b, and the gradually increasing detected value P _X is held in the peak hold circuit 21 as it is. When the crane 1 reaches point B, the detected value P _X becomes P
_{At X (B)} , the maximum value P _P also becomes P _{X (B)} , and the closing signal L _ON is output. The comparison circuit 22 is activated by the closing signal L _ON, but since P _P (= P _{X (B)} ) = P _X (= P _{X (B)} ), and P _P > P _X does not hold, the control pulse C _P Is not output. Therefore, the registration value P _ON stored in the register 23 is not updated and the previous value is retained. Then, the data output unit 24
Calculates the calculated value P using the previous register value P _ON, and the calculated value P is displayed on the display unit 25. After all, at the point B, the position detection is not corrected.

(C) When the crane 1 is located between the points B and C and the closing signal L _ON is continuously output from the limit switch 4, the peak hold circuit 21 is in the reset state and the maximum value P _P is 0. Becomes Therefore, P _P > P _X is not established,
The control pulse C _P is not output, but the calculated value P is output using the previous register value P _ON . That is, at this time, the position detection is not corrected.

As described above, in the embodiment shown in FIGS. 1 and 2, the position detection is corrected only when the limit switch 4 changes from the open state to the closed state by the right end 5b of the striker 5. That is, even if the striker 5 is wide, the correction is performed only at one point.

FIG. 3 shows the essential parts of the second embodiment of the present invention. In this embodiment, the comparison circuit 22 'of the arithmetic control unit 20' has a closing signal.
Control pulse C _P when P _P ≦ P _X when L _ON is input
Is output. Therefore, in the second embodiment, the striker 5
Only when the left end 5a of the limit switch 4 changes from the open state to the closed state, the position detection is corrected.

FIG. 4 is a plan view schematically showing a third embodiment of the present invention, in which the crane 1 has three limit switches 4, 4 ',
Along with the installation of 4 ", there are installed three strikers 5,5 ', 5" for inserting the limit switches 4,4', 4 "at intervals along the rail 3. And shown in FIG. There are three such arithmetic circuits 20. In this embodiment, in the section I, the limit switch 4 and the striker 5 and the first arithmetic control circuit are used, and in the section II, the limit switch 4 ', the striker 5'and the second. By the arithmetic control circuit,
In the section III, the limit switch 4 ″, the striker 5 ″, and the third arithmetic control circuit respectively correct the position detection. In this case, as the correction method in each section, the method of the first embodiment or the method of the second embodiment is used as it is.

Although the potentiometer is used as the rotation sensor in each of the above-described embodiments, another type such as an encoder may be used. Further, the present invention is not limited to a crane, but can be used for detecting the position of various mobile devices moving along a fixed tangle.

G. Effect of the Invention As specifically described above with the embodiments, according to the present invention, the position correction is performed only at one end of the striker, so the position correction is performed only at one point in the traveling direction, The accuracy of position detection is greatly improved without being affected by the width of the striker.

Further, the mobile device only needs to be provided with the rotation sensor and the limit switch, and the present invention can be easily implemented. Of course, the present invention can be realized by improving the position detecting device used conventionally.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention, and FIG.
FIG. 1 is a block diagram showing the essential parts of the first embodiment, FIG. 3 is a block diagram showing the essential parts of the second embodiment of the present invention, and FIG. 4 is a schematic view of the third embodiment of the present invention. The plan view shown in FIG. 5 and FIG. 5 are configuration diagrams showing the prior art. In the drawing, 1 is a crane, 2,2a, 2b are wheels, 3 is a rail, 4,4 ', 4 "are limit switches, 5,5', 5" is a striker, 13 is a potentiometer, 20 is an arithmetic control unit, 21 is a peak hold circuit, 22 is a comparison circuit, 23 is a register, and 24 is a data output section.

Claims (2)

(57) [Claims] 1. A mobile device traveling along a route, wherein when a wheel of the mobile device makes a forward rotation, a detected value increases in accordance with its rotation amount, and when the wheel rotates in a reverse direction, it is detected in accordance with its rotation amount. A rotation sensor whose value decreases, a striker installed in the vicinity of the path and having a constant width along the traveling direction of the mobile device, a limit switch installed in the mobile device and brought into a closed state by contacting the striker When the limit switch is in the closed state, it is reset, and in other cases, the peak hold circuit that holds the maximum value among the detection values output by the rotation sensor, and the limit switch changed from the open state to the closed state. At that time, the detected value output from the rotation sensor is compared with the maximum value held by the peak hold circuit, and the maximum value is the detected value. When the control signal is exceeded, a comparison circuit outputs the control signal, a register that receives the control signal and stores the detected value of the rotation sensor as the latest registration value, and the latest registration value from the detection value output from the rotation sensor. A position detection device comprising: an arithmetic control unit formed by a data output unit that outputs a value obtained by adding a preset value indicating the position of the striker to the value obtained by subtracting. 2. A mobile device traveling along a route, wherein when a wheel of the mobile device makes a forward rotation, a detected value increases in accordance with its rotation amount, and when a wheel rotates in a reverse direction, it is detected in accordance with its rotation amount. A rotation sensor whose value decreases, a striker installed in the vicinity of the path and having a constant width along the traveling direction of the mobile device, a limit switch installed in the mobile device and brought into a closed state by contacting the striker When the limit switch is in the closed state, it is reset, and in other cases, the peak hold circuit that holds the maximum value among the detection values output by the rotation sensor, and the limit switch changed from the open state to the closed state. At that time, the detected value output from the rotation sensor is compared with the maximum value held by the peak hold circuit, and the detected value is the maximum value. The comparator circuit that outputs the control signal when it is above, the register that stores the detection value of the rotation sensor at the time of inputting the control signal as the latest registration value, and the detection value that is output from the rotation sensor A position detecting device comprising: an arithmetic control unit formed by a data output unit that outputs a value obtained by adding a preset value indicating the position of the striker to a value obtained by subtracting the resist value.