JPH0625922B2 - How to save the current position of the controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for storing the current position of a control device that detects the position of a movable part of an automatic machine by using an incremental encoder.

2. Description of the Related Art In order to move a movable part of an automatic machine, for example, an industrial robot according to a preset program, it is necessary to detect the current position of the movable part. In general, an incremental encoder that outputs a pulse at a constant rotation angle is used to detect the position of the movable part, and the counter counts the number of pulses of the pulse signal output from the incremental encoder along with the movement of the movable part, and calculates the position. Thus, the current position of the movable part is detected.

FIG. 2 is a block diagram showing an example of a control device (A) used when detecting the current position of the movable part using the incremental encoder and controlling the movement of the movable part.
In the figure, (1) is a motor which is a drive source of the movable part,
(2) is a tacho-generator for detecting the rotation speed of the motor (1), (3) is an output signal from the tacho-generator (2) and a speed command signal from a CPU (6) which will be described later. ) Is a motor driver for controlling the rotation speed. (4) is an incremental encoder that outputs a pulse signal in conjunction with the rotation of the motor (1),
(5) is a counter that counts the number of pulses of the pulse signal output from the incremental encoder (4),
In (6), the current position of the movable part is calculated based on the count number output from the counter (5), and at the same time, this value is compared with previously input data regarding the movement of the movable part, and the movable part is moved to a predetermined position. It is a CPU that calculates the rotation speed of the motor (1) currently required to move the motor to (1) and outputs a speed command signal to the motor driver (3) via the D / A converter (7).

Then, since the movable part is moved to a predetermined position based on the data previously input to the CPU (6), when the motor (1) is started, the incremental encoder (4) is rotated along with the rotation of the motor (1). A pulse signal is output, the number of pulses of this pulse signal is counted by the counter (5), and the value is input to the CPU (6). Then, the CPU (6) calculates the current position of the movable part from the count number of the counter (5), compares this value with the previously input data regarding the movement of the movable part, and moves the movable part to a predetermined position. Calculates the rotation speed of the motor (1) currently required for the D / A converter (7)
To the motor driver (3). Then, the motor driver (3) controls the rotation speed of the motor (1) to a predetermined value by the output signal from the tachogenerator (2) and the speed command signal, so that the movable portion is directed to a predetermined position. And move at a predetermined speed. When the movable part reaches a predetermined position, the motor (1) is stopped by the speed command signal from the CPU (6), and the movable part is stopped at the predetermined position.

Further, in the case where a power failure accident occurs during the operation of the control device (A), the motor (1) is stopped and at the same time, the number of pulses counted by the counter (5) at this time is set to one day. By storing the current position in the storage device, a current position storage device (B) is incorporated for restarting the moving part from the state immediately before the occurrence of the power failure accident after the power failure accident. This current position storage device (B) is a control device (A).
In the initial state of the power failure, the power supply voltage supplied to the power supply voltage detector (8) detects when the power supply voltage drops by 5% from the reference voltage value, and the power supply voltage detector (8) lowers the power supply voltage. When a reset signal is detected, a reset device (9) that outputs a reset signal to the CPU (6) and the counter (5) and the count number in the counter (5) are temporarily stored when the reset device (9) is activated. Storage for (1
0) and.

Then, when the power supply voltage detector (8) detects the decrease in the power supply voltage, the reset device (9) is activated, and when the reset signal is output toward the CPU (6) and the counter (5), the CPU ( 6) stops the motor (1), and at the same time, stores the number of pulses corresponding to the current position of the movable part, which is counted by the counter (5) at this time, in the storage device (10).
The data regarding the current position of the movable part before the power failure value is stored by storing the data in the. After that, when the movable part is restarted, the movable part is restarted from the state immediately before the power failure based on the count number stored in the storage device (10).

Problems to be Solved by the Invention As described above, by incorporating the current position storage device (B) in the control device (A), even if a power outage accident occurs during the operation of the control device (A), a power outage accident will occur. Since the data related to the current position of the moving part immediately before the occurrence can be saved, when the control device (A) is restarted after the power supply voltage returns to the normal value, the moving part is restarted from the state immediately before the power failure. It is possible to start. However, if the current position storage device (B) is configured as described above, when the reset device (9) is activated due to the decrease in the power supply voltage, the reset signal is almost sent to the CPU (6) and the counter (5). Output at the same time. Therefore, depending on the state of electrical connection between the devices when the reset signal is output from the reset device (9), the reset signal may be input to the counter (5) before the CPU (6), and the CPU ( 6) The storage device (10) stores the number of pulses counted by the counter (5).
The data in the counter (5) has already been reset when it is sent to the storage device (10) and may be stored in the storage device (10) as the current position 0 pulse of the movable part. In this way, if the current position 0 pulse is stored in the storage device (10), when the movable part is restarted,
The actual current position of the moving part is completely unknown,
Eventually, the movable part had to be restarted after being returned to the initial state, that is, to the origin, and there was a problem that there was no point in incorporating the current position storage device.

Means for Solving the Problems An incremental encoder is used to detect the position of the moving part of the mechanical system, the number of pulses output from the incremental encoder is counted by a counter, and based on this counted number of pulses, the current part of the moving part in the CPU is detected. When the position is calculated and a reset signal is input to the CPU and the counter due to the drop in the power supply voltage, the count number counted by the counter is sent to the storage device at this time, and data regarding the current position of the movable part is stored. In this case, the count number counted by the counter is always set to be a positive pulse number over the entire moving range of the movable part, and the pulse number counted by the counter is sequentially stored in the CPU at a predetermined timing. read, and the current number of counts _{P 1,} the previous count the number of _{P 0} Comparison, when both are coincident, rereads the count number P _1, In the case where both are a value of mismatch, if the number of pulses P ₁ is not zero pulses, number of pulses P ₁
Is the current position, and the number of pulses P ₁ is 0 due to the reset signal.
When reset to the pulse, the number of pulses P ₀ is set as the current position.

Action As described above, the number of pulses counted by the counter is set as a positive number of pulses, the number of pulses counted by the counter is sequentially read into the CPU at a predetermined timing, and the current count number P ₁ and the previous count number are read. comparing the P _0, in the state where both are a value of mismatch, if the number of pulses P ₁ is not zero pulses, the pulse number P ₁ and the current position, the pulse number P ₁ by a reset signal
When the pulse number is reset to 0 pulse, the pulse number P _{0 is set} to the current position. Therefore, the reset signal output due to the decrease of the power supply voltage causes the pulse number in the counter to be 0 pulse before the data transfer to the storage device. Even if it is reset to 0, the number of pulses immediately before the number of 0 pulses can be stored in the storage device.

Example FIG. 1 shows that the current position of the movable part is always controlled by the control device (A) incorporating the current position storage device (B) shown in FIG. 2 when the power supply voltage drops due to the occurrence of a power failure accident or the like. It is a flowchart for explaining a current position storing method for accurately storing, and the present invention will be described below according to this flowchart.

As a precondition of the present invention, the movable part moves within a movable range around the origin, and a pulse signal is output from the incremental encoder (A) along with this movement, and the number of pulses is counted by the counter (5). When counting, the pulse number to be counted is programmed in advance so that it is always counted as a positive pulse number over the entire moving range of the movable part as long as the device is operating normally. That is, the number of pulses when the movable portion is located at the origin is not 0 pulse but is set in advance in the counter (5) so as to be a positive value such as 1000 or 10000, and the movable portion is centered on the origin. Even if the incremental encoder (4) is rotated in the normal direction or the reverse direction by moving in the movable range and the pulse number of the pulse signal output from the incremental encoder (4) is added or subtracted to the above value in the counter (5). , The count number counted by the counter (5) is always a positive value.

Under the above-mentioned precondition, the control device (A) operates, the pulse signal output from the incremental encoder (4) is counted by the counter (5), and the counted number of pulses is read by the CPU (6) to move. When calculating the current position of the copy, first step in the CPU (6)
At (20), input the number of pulses P ₀ corresponding to the current position of the movable part. Next, in step (21), it is detected whether or not this pulse number P ₀ is a positive value, and if it is not a positive value, step (22)
Then, it is judged that the counter (5) is abnormal. When the number of pulses P ₀ is a positive value, the process proceeds to step (23) and the number of pulses P ₁ corresponding to the current position of the movable part is input again. Next, in step (24), the number of pulses P ₀ and P ₁ are compared,
If there is no difference between the two, that is, from step (20) to step (2
If the number of pulses has not changed during the transition to 3), return to step (23) again and set the number of pulses P corresponding to the current position.
Enter ₁ again. If there is a difference between the pulse numbers P ₀ and P ₁ , that is, if the pulse number changes during the transition from step (20) to step (23), the process proceeds to step (24) and the pulse It is determined whether or not the number P ₁ is reset by the reset signal output from the reset device (9) and becomes 0 pulse. When the pulse number P ₁ is a positive pulse number, the process proceeds to step (26), and the pulse number P ₁
The subsequent control operation is performed with the pulse number corresponding to the current position of the movable part. When the number of pulses P ₁ is reset to 0 pulse, the process proceeds to step (27), after determining that there is a timing error in the reset signal, the process proceeds to step (28) and is input before the number of pulses P ₁ is input. Number of pulses P
_The subsequent control operation is performed with ₀ as the number of pulses corresponding to the current position of the movable part.

If the program for determining the current position of the movable part by reading the count number counted by the counter (5) by the CPU (6) is set as described above, the power supply voltage decreases during the operation of the control device, and the CPU ( By inputting a reset signal to 6) and the counter (5), CP
When the U (6) sends the number of pulses counted by the counter (5) to the storage device (10), the reset signal is input to the CPU (6) earlier than the counter (5), and at this point, the counter (5) When the number of pulses of P is not reset, the number of pulses P ₁ is set at the current position of the movable part and the storage device (10)
Send to. When the reset signal is input to the counter (5) earlier than the CPU (6) due to the timing error of the reset signal, and the CPU (6) tries to send the pulse number to the storage device (10), the counter (5 The number of pulses in) is 0
When it is a pulse, the immediately preceding pulse number P ₀ can be sent to the storage device (10) as the current position of the movable part. Therefore, the reset signal is input to the counter (5) before the CPU (6), and the number of pulses in the counter (5) is reset to 0 before the number of pulses is stored in the storage device (10). Even if the number of pulses immediately before the counter (5) is reset can be sent to the storage device (10), the data regarding the current position of the movable part at the time of a power failure accident can be reliably saved. .

As described above, according to the present invention, the number of pulses counted by the counter is set as a positive number of pulses, the number of pulses counted by the counter is sequentially read into the CPU at a predetermined timing, and the current number of counts P ₁ is set. , The previous count number P ₀ is compared, and in the state where the two values do not match, if the pulse number P ₁ is not 0 pulse, the pulse number P ₁ is set as the current position, and the pulse is generated by the reset signal. When the number P ₁ is reset to 0 pulse, the pulse number P _{0 is set} to the current position, so that the reset signal is input to the CPU and the counter due to the decrease in the power supply voltage, and the number of pulses counted by the counter is stored. When sending the data to the device and storing the data related to the current position of the movable part, the reset signal is sent to the counter before the CPU. If the number of pulses in the counter has already become 0 before the number of pulses counted by the counter is transferred to the storage device,
The number of pulses immediately before being reset to a pulse can be stored in a storage device. Therefore, when the reset signal is output due to the decrease of the power supply voltage, the number of pulses immediately before the reset signal is output can always be stored in the storage device regardless of which of the CPU and the counter receives the reset signal first. It becomes possible, and it becomes possible to surely save the data regarding the current position of the movable part.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining a present position saving method of a control device according to the present invention, and FIG. 2 is a block diagram showing an example of a control device having a present position saving device. (A) ... Control device, (B) ... Current position storage device, (1) ... Motor, (4) ... Incremental encoder, (5) ... Counter, (6) ... CPU, (8) ...... Power supply voltage detector, (9) …… Reset device, (10) …… Memory device.

Claims (1)

[Claims] 1. An incremental encoder is used to detect the position of a movable part of a mechanical system, the number of pulses output from the incremental encoder is counted by a counter, and the current position of the movable part is calculated in the CPU based on the counted number of pulses. In addition, when a reset signal is input to the CPU and the counter due to the drop in the power supply voltage, the count number counted by the counter is sent to the storage device at this time, and data relating to the current position of the movable part is stored. , The number of counts counted by the counter is always a positive number of pulses over the entire moving range of the movable part, and the number of pulses counted by the counter is sequentially read into the CPU at a predetermined timing, and this time the count number P _1, compared with the previous count number P _0, both When it matches, rereads the count number P _1, In the case where both are a value of mismatch, if the number of pulses P ₁ is not zero pulses, the pulse number P ₁ and the current position , Number of pulses P by reset signal
_{When the 1} is reset to 0 pulse, the current position saving method of the control device is characterized in that the number of pulses P ₀ is set as the current position.