JPH0361808A - Position detector - Google Patents

Abstract

PURPOSE:To secure high detection accuracy by a method wherein output of an increment encoder and a potentiometer are compared with each other to detect motion of a movable body during inoperative period and position data is calibrated. CONSTITUTION:Respective movable units of an increment encoder 10 and a potentiometer 14 are attached to a movable body being an object to be detected while a main position data memory 22 of a CPU 20 holds increment encoder output DEN. When the movable body moves, the increment encoder output DEN and potentiometer output DPT are compared with each other by a comparator 24. If the difference at this time is outside a predetermined dead zone as well as such data caused during inoperative period, motion of the movable body during the inoperative period is identified as well as position data according to the output data of the increment encoder 10 or the output data of the potentiometer 14 is calibrated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a position detection device that detects the position of a movable body using an incremental encoder or a potentiometer.

(Prior Art) As this type of position detection device, there is one using an incremental encoder or a potentiometer.

In a position detection device using an incremental encoder,
The detected amount is not an absolute value but a relative value. For this reason,
It was not possible to detect the movement of the movable object, which was the object to be detected, when it was inactive (no power was supplied).

In addition, position detection devices using potentiometers have physical limits in resolution and linearity due to the characteristics of the potentiometer, so a certain amount of error occurs, and the detection accuracy is lower than that of position detection devices using incremental encoders. It was not as good as a detection device.

Furthermore, in any of the above configurations, if a failure occurs in the incremental encoder or the potentiometer itself or an abnormality occurs in the wiring, an incorrect detected value will be output, which is a problem.

(Problems to be Solved by the Invention) As described above, in a position detection device using an incremental encoder or potentiometer, high detection accuracy and
There are advantages and disadvantages in detecting movement of the movable body during non-operation, and it has not been possible to have a satisfactory function.

SUMMARY OF THE INVENTION An object of the present invention is to provide a position detection device that can ensure high detection accuracy and detect movement of a movable body even when it is not in operation.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.

That is, the present invention provides an incremental encoder and a potentiometer for detecting the position of a movable body, and a difference between the output data of the incremental encoder and the output data of the potentiometer is outside a predetermined dead zone, and when inactive. When the data is generated data, the movable body is moved during non-operation, and the movable body is moved during non-operation. do.

(Function) According to such a configuration, high detection accuracy can be ensured by the output data of the incremental encoder, which is one of the two detection elements, and the first means allows the movable This makes it possible to detect the presence of body movement.

(Example) An example of the position detection device according to the present invention is shown in Figs.
This will be explained with reference to FIG.

Fig. 1 is a hardware configuration diagram of the position detection device of this embodiment, Fig. 2 is a flowchart of the main routine of the software installed in the position detection device of this embodiment, and Fig. 3 is the main routine in Fig. 2. 2 is a flowchart of an initialization routine in FIG.

As shown in FIG. 1, the position detection device of this embodiment is an incremental encoder (EN) 10 whose movable part is attached to a movable body (not shown) to be detected. A counter 12 that counts the pulse train that is the output, a potentiometer (PT) 14 whose movable part is attached to the movable body, and an A/D converter that converts the analog output (voltage value) of the potentiometer (PT) 14 into a digital output. 16. It has a sensor 18 that detects whether or not it is at the initial position using 0N10FF. This sensor 18 is an incremental encoder (E
N) The movable part is attached to the movable body so that the detection range of the potentiometer (PT) 10 and the potentiometer (PT) 14 is divided into two by OFF and ON. As this sensor 18, a contact sensor such as a limit switch or a non-contact sensor such as an optical switch is used.

Further, the position detection device of this embodiment has an output D IIN of the counter 12 and outputs D and T of the A/D converter 16.

and a CPU 20 that receives a preset signal that is the output of the sensor 18 and performs predetermined signal processing. The CPU 20 also includes a memory 30 that holds dead zone data and correction data necessary for the signal processing. Here, the CPU 20 is a normal digital computer and includes at least a main position data memory 22 and a data comparator 24. In addition, the means 12 for holding the dead zone data and correction data can set the dead zone data and the correction data by a switch such as a digital switch instead of the memory 3o, and can also provide the data to the CPU 20. It is.

The main position data memory 22 of the CPU 20 holds the incremental encoder output line, and this data ultimately becomes the detection data of this device.
It is preset by the preset signal. In other words,
When the movable body is moved to turn the sensor 18 from OFF to ON and a preset signal is given to the main position data memory 22, the main position data memory 22 is preset so that the new incremental encoder output DF:N is held. It has become.

The data comparator 24 then performs the comparison process described below.

Hereinafter, the detection procedure when the movable body moves in this embodiment will be explained. That is, the procedure shown in FIG. 2 is executed, and in step Sl, the incremental encoder output DIIN is set in the main position data memory 22, and for the set data (incremental encoder output Dgs) and potentiometer output DPT, Signal processing (formula (1)) is executed.

D RN”' D PT − to 1 ・D PT+ K
2... (1) Kl is a change rate correction coefficient (gain), K2 is an offset correction amount, and DPT is a potentiometer output corrected for change characteristics.

Next, in step S2, DEN and Dp〒 are compared,
In step S3, it is determined whether the difference value in step S2 is within a predetermined dead zone (outside the dead zone).

If it is determined in this determination that the difference value is within the dead zone, the process advances to step S4, and the incremental encoder output DE
Let N be the detection output of this device. Further, if it is determined in the above determination that the difference value is outside the dead zone, the process proceeds to step S5. If the difference value is outside the dead band, that is, if the difference value exceeds the dead band, it is considered abnormal data due to the following two factors (a) and (b), and DIIN is not used as the detection output of this device.

(,・B) Since the movable object to be detected moved when the power was turned off, the incremental encoder output D8N becomes incorrect.

(b) At least one of the incremental encoder (EN) 10 and the potentiometer (PT) 14 has failed, so either incorrect data or no data is output.

The above-mentioned or later-described steps determine the cases (a) and (b) above by signal processing. In step S5, it is determined whether or not it is in operation, that is, when the power is turned on;
If it is determined that the difference value is outside the dead band when the power is not ON, that is, when the power is OFF, the incremental encoder (E
N) It is determined that the potentiometer (PT) 10 or the potentiometer (PT) 14 is at fault, and a failure indication is output to that effect as Stella 1S. Further, if it is determined that the difference value is outside the dead zone when the power is turned on, an initial setting routine is executed as step S6.

This initial setting routine is executed according to the procedure shown in FIG. That is, in step Pl, the sensor 18 is
It is determined whether the sensor 18 is in the N state, and if it is determined that the sensor 18 is in the ON state, the process proceeds to step P3 via step P2.
If it is determined that the sensor 18 is not in the ON state, that is, in the OFF state, the process directly advances to step P3. In step P2, the operator moves the movable body to turn the sensor 18 from ON to OFF.

Here, in step P3, the sensor 18 is turned on by the operator.
The movable body is moved to change from FF to ON, and as a result, a preset signal from the sensor 18 is given to the main position data memory 22, the main position data memory 22 is brissed and sorted, and step P5, which will be described later, is performed. The counter 12 is operated to set an initial value. Note that the action of the sensor 18 is schematically shown in FIG. 4.

Next, after step P3, it is determined again in step P4 whether or not the sensor 18 is in the ON state.
At the moment when it is determined that the sensor 18 is in the ON state, the initial value is set in step P5, and the process ends.
If it is determined that the state is not N, that is, the state is OFF, the process returns to step P2.

As described above, according to this embodiment, high detection accuracy can be ensured by the output data DBH of the incremental encoder (EN) 10, which is one of the two detection elements, and
It is possible to detect the movement of the movable body while it is not in operation, that is, while the power is off, and furthermore, it is possible to grasp the failure state.

Further, a procedure capable of improving the failure detection ability is realized by inserting the routine of step S8 between step St and step S2 in the procedure shown in FIG. 2, as shown in FIG. 4. The routine of step S8 compares the upper and lower limits of the incremental encoder output DEN and the potentiometer a meter output DPT to obtain
It is possible to detect failure states in detail, and is realized by the procedure shown in FIG.

That is, in step R1, the incremental encoder output Di! N and the potentiometer output DPa, and it is determined in step R2 whether DENI D PT exceeds the upper limit value. Here, DRN + D PT
When it is determined that ε exceeds the upper limit value, it is determined in step R3 that the incremental encoder (EN) 10 or the potentiometer (PT) 14 is malfunctioning, and a display to that effect is displayed. Also, here, D ENI D P
If it is determined that T does not exceed the upper limit, step R
In step 4, it is determined whether DEN and DPT exceed the lower limit. Here, D+! If it is determined that N+DPT does not exceed the lower limit value, the incremental encoder (EN) 10 or the potentiometer (P
T) 14 is determined to be malfunctioning, and a display to that effect is displayed. Also, if it is determined that D ENI D PT exceeds the lower limit value, the incremental encoder (EN)
10 or potentiometer (PT) 14 is normal,
The data D ENI D PT is also determined to be normal.

In addition, various modifications (
7.

[Effects of the Invention] As described above, the position detection device according to the present invention uses an incremental encoder and a potentiometer for detecting a device of a movable body, and the output data of the incremental encoder and the output data of the L potentiometer. If the difference when compared is outside the predetermined dead zone and the data is generated during non-operation, it is determined that the movable body has moved during non-operation, and the output data of the front height C incremental encoder or the output of the potentiometer is determined. According to this configuration, high detection accuracy is ensured by the output data of the incremental encoder, which is one of the two detection elements, and Furthermore, it is possible to detect movement of the movable body even when the movable body is not in operation.

Therefore, according to the present invention, it is possible to provide a position detection device that can ensure high detection accuracy and can detect the movement ε of a movable body during non-operation.

[Brief explanation of drawings]

FIG. 1 is a hardware configuration diagram of the position detection device of this embodiment, FIG. 2 is a flowchart of an example of the main routine of the software installed in the position detection device of this embodiment, and FIG. A flowchart of the initial setting routine in the main routine, FIG. 4 is a diagram showing the action of the initial setting sensor,
FIG. 5 is a flowchart showing a modification of the routine in FIG. 2;
The figure is a flowchart of the comparison routine in FIG. 10... Incremental encoder (EN) counter... Counter, 14... Potentiometer (PT)
, 16... A/D converter, 18... Initial setting sensor, 20... CPU, 22... Main position data memory,
24...Data comparator, 30...Memory. Figure 2 Figure 6

Claims (1)

[Claims] An incremental encoder and a potentiometer that detect the position of a movable body, and when the difference when comparing the output data of the incremental encoder and the output data of the potentiometer is outside a predetermined dead zone and is data generated during non-operation. A position detection device characterized by comprising means for determining that the movable body has moved when it is not in operation, and for calibrating position data based on the output data of the incremental encoder or the output data of the potentiometer.