JPH0215171B2 - - Google Patents

Description

Detailed Description of the Invention <Technical field to which the invention relates> This invention measures the height of the cutting section of a combine harvester using a non-contact distance sensor such as an ultrasonic sensor, and determines the cutting height based on the measured height. The present invention relates to a method for automatically controlling cutting height.

<Prior art and its disadvantages> The distance sensor used for automatic cutting height control is usually a contact distance sensor using an actuator that contacts the ground, or an ultrasonic sensor using an ultrasonic oscillator and receiver. A non-contact distance sensor such as a distance sensor is used. However, with contact-type distance sensors, there is a risk of damage to the actuator when the inclination of the aircraft suddenly increases, and furthermore, the actuator may become buried in wet fields and become unusable, resulting in poor reliability and stability. From this point of view, non-contact distance sensors such as ultrasonic sensors have come into use.

The conventional mowing height control method using such a non-contact distance sensor compares a preset reference height with height data measured at regular intervals, and adjusts the mowing section at a constant speed according to the difference. I was trying to move it up and down.

However, for example, if ultrasonic waves are emitted against soft straw on the ground, or if a divider is broken into a stump and ultrasonic waves are emitted between the stumps, the received signal will drop significantly, making it difficult for the sensor to function normally. Despite this, accurate measurements are no longer possible.
As a result, there was a drawback in that the reaping section was forced to move up and down unnecessarily.

<Object of the invention> An object of the invention is to prevent the reaping section from operating when the measured height data is abnormal, and to prevent the reaping section from operating when the abnormal state of the measured height data is likely to be caused by a sensor abnormality. An object of the present invention is to provide a cutting height control method using a non-contact distance sensor that notifies abnormalities.

<Configuration and Effects of the Invention> To summarize, the present invention obtains measured average height data from a plurality of measured height data, and calculates the cutting height based on the deviation between the measured average height data and target height data. In this control method, when measured height data is above a certain value, that data is discarded as invalid data, and the contents of an invalid data counter that counts the number of consecutive occurrences of invalid data is counted up and the An abnormality in the non-contact distance sensor is notified when the count reaches a predetermined value.

According to this invention, if the measured data becomes abnormal due to straw, stumps, etc. on the ground, the abnormal operation of the reaping section can be prevented in order to invalidate the data. Also, when the contents of the invalid data counter that counts the number of consecutive occurrences of invalid data reaches a predetermined value,
In other words, sensor abnormality is reported only when abnormal data is received a certain number of times in a row.
Abnormality notification is performed only when it is almost certain that there is an abnormality in the sensor, which increases the reliability of sensor operation management.

<Description of Embodiments> FIG. 1 is a block diagram of a cutting height control device implementing the method of the present invention.

In the figure, an ultrasonic sensor (hereinafter referred to as USS) control circuit 1 drives a transmitter 2 every 60 milliseconds to emit a burst signal. The receiver 3 receives the reflected wave and sends the received signal to the USS control circuit 1. The received signal at this time is a negative logic pulse, and the pulse width corresponds to the time from transmission to reception, that is, the height of the reaping section. If there is no received signal within a specified period of time after transmission, the USS
The control circuit 1 forces the pulse to rise.
This time is set to 14 milliseconds. After waveform shaping, the received signal is guided as a received pulse to an exclusive OR gate 4 whose other input terminal is grounded. From the output of this exclusive or gate 4, exclusive or gate 5 and R1,
A differentiated pulse is formed by a differentiating circuit composed of C1 and C1, and is further guided to the interrupt port IRQ of the microcomputer 7 via the exclusive OR gate 6. Further, the output of the exclusive OR gate 4 is sent to the microcomputer 7.
input port R11. This input port R11 is used as a signal for determining whether the interrupt pulse input to port IRQ is based on the USS control circuit 1. The input terminal of the exclusive OR gate 6 is connected together with the output terminal of the exclusive OR gate 5 to the output terminal of a waveform shaping circuit 8 that shapes the waveform of the signal from the dynamo. The microcomputer 7 measures the engine speed based on the interrupt signal from the waveform shaping circuit 8.

Port R10 of microcomputer 7 has
The output terminal of the cutting height fine adjuster VR is connected. The microcomputer 7 has a built-in A/D converter, and converts the analog data obtained from the cutting height fine adjuster into digital quantities via the port R10 to obtain data for cutting height control. I have to.

The microcomputer 7 has a built-in ROM that stores a cutting height control program, and a RAM that stores preset data and further has flags and various work areas. In Figure 2
A configuration diagram of RAM is shown. Area A1 includes four types of flag areas. The flag F0 is the reaping part rising flag, the flag F1 is the reaping part lowering flag, and the flag F2 is the port R10 during engine rotation speed measurement processing.
When the input pulse rises or falls, the data invalidation flag is used to invalidate the current measurement data, and the flag F3 is a height data update flag. Area A2 stores the measured average height.
That is, average height data of past measured height data is stored. The data to be averaged is a total of 8 pieces of data, including the height data averaged last time and each of the past seven measurement data, or the height data averaged last time and the past measurement data. This is a total of two pieces of data including one measurement data. This distinction is determined by whether or not the current measurement data has a height above a certain level, as will be described later. Area A3 is
Stores the height data measured last time. Area A4
stores the previously measured height data. Similarly, areas A5 to A9 store five pieces of previously measured height data in descending order. Area A10 stores fine adjustment height data set by the cutting height fine adjuster VR. Area A11 stores target height data set in advance. Area A12 is an area that combines the average height data of area A2 and the target height data of area A11.
Store the difference from the value added with the fine adjustment height data of A10, that is, the deviation. Area A13 stores a reference height for determining whether eight pieces of data or two pieces of data are used to calculate the average height data stored in area A2. As described later, if the measured data is smaller than this height, the area A2~
While calculating the average height data from the 8 data of A9, if the measured data is H0 or higher, the area
The average height data is calculated from only the two data stored in A2 and A3. This reference height H0 is 522 mm. Area A14 provides intermittent drive pulses to the solenoid valve for vertically moving the reaping section based on the calculated average height data, or
The reference height for applying continuous drive pulses is memorized. The calculated average height data Ha is this reference height
If it is H1 or higher, give continuous pulses. On the other hand, if the average height data Ha is smaller than this reference height data H1, intermittent pulses are given. Area A15 stores the current on/off duty ratio of the solenoid valve based on the table of area A19, which predetermines the on-time period of the drive pulse corresponding to the deviation of area A12. As shown in FIG. 3, when the deviation is less than 260 millimeters, intermittent pulses are applied whose on-time becomes longer depending on the magnitude of the deviation.
Note that the off time is set to a fixed value of 150 milliseconds. Therefore, for example, if the deviation is 21 mm, the duty ratio is 1/16. Area A16 constitutes a sensing error counter to be described later.
Regardless of whether the sensor is normal, this counter is incremented when no reception is received within a predetermined period of time (6 milliseconds) after transmission, and is decremented if reception is received within a predetermined time period (6 milliseconds)16 It is an up-down counter. Area A17
stores the engine speed calculated by the interrupt from the dynamo. Area A18 stores 10 milliseconds, which is the reference cycle for cutting height control. As described above, the area A19 stores a table representing the relationship between the deviation and the on-time of the drive pulse (see FIG. 3).

Next, the operation of the cutting height control device having the above structure will be explained with reference to the flowcharts shown in FIGS. 4A to 4D.

FIG. 4A is a flowchart of the main routine for controlling the cutting height.

Step n1 (hereinafter step ni is simply referred to as ni)
performs initial settings for various registers and flags.
n2 checks the set state of flag F3.
This flag F3 is set when an interrupt is generated by a received pulse from the USS control circuit 1, as will be described later. If the flag F3 has been set, the program proceeds to n3 to reset the flag F3, and then proceeds to n4 to proceed to the height data update subroutine. In this height data update subroutine, the average height data Ha of area A2 is obtained, and the data of areas A3 to A9 and A16
The sensing error counter of is updated. Next, proceed to n5 and execute the cutting height control subroutine. In this cutting height control subroutine,
Based on the average height data obtained in the height data update subroutine of n4, the duty ratio of the drive pulse of the solenoid valve is determined, and the vertical drive control of the reaping section is performed. n6 is a step for determining the counter value of the sensing error counter. If this counter value overflows, that is, if the measured height data exceeds a certain value, 16
When the number of consecutive times occurs, a USS failure alarm is activated at n7. If the sensing error counter is not in an overflow state, proceed from n6 to n8. If the reference cycle times up at n8, the process returns to n2 and the state of flag F3 is determined again. As described above, height data update, cutting height control, and sensing error counter checking are executed every reference cycle.

In the main routine, the process proceeds from n2 to n3 when an interrupt is received from the USS control circuit 1, as described above. For interrupts use this
There are three types of interrupts: interrupts from the USS control circuit 1, clock interrupts, and interrupts from the dynamo. FIG. 4B shows an interrupt routine that is executed when an interrupt occurs.

When an interrupt occurs from the USS control circuit 1, dynamo, or internal clock, the contents of various registers are first saved in n10. If the interrupt is a clock interrupt, proceed from n11 to n12; otherwise, proceed from n11 to n13. At n13, the signal state of port R11 of microcomputer 7 is checked. If it is a falling edge of the USS control circuit output, the interrupt should occur at the beginning of the received pulse, so initialize the internal timer data that measures the height data (n14), and then n15
The timer is started at On the other hand, the interrupt
If it was performed at the rising edge of the USS control circuit output, it will proceed to n13 → n17 → n18, and n15
Stop the internal timer started at
Flag F3 is set at n19. and
At n20, restore the contents of the register and return to the main routine. By the above operation, the internal timer stores the pulse width of the received pulse which is proportional to the height of the cutting section. That is, the internal timer data will normally correspond to the measured height. If a received signal does not arrive within a predetermined time (6 milliseconds), this internal timer data has overflowed. This overflow condition is checked in the height data update subroutine described later.
When there is an overflow, the data is discarded as invalid data. Furthermore, if the interrupt is from the engine dynamo,
Proceed to n17 → n21, and here the engine rotation speed measurement process is performed. Furthermore, in this case, when performing the engine rotation speed measurement process, the US
S. Since this is the falling or rising timing of the control circuit output, in this case an error will occur in the next measured height data, so the data invalid flag F2 is set at n24. Therefore, the current measured height data is discarded as invalid data, as will be described later, since the flag F2 is set.

When flag F3 is set at n19 as described above, n2→n3→n4 is set in the main routine.
Then, the height data update subroutine is executed.

FIG. 4C is a flowchart of this height data update subroutine.

First, in n30, the state of the sensor invalidation flag F2 is determined. If the timing of the rise or fall of the USS control circuit output matches when the engine rotation speed measurement process is performed as described above, the data invalid flag F2 is set at n24. Therefore, the next time this height data update subroutine is executed, it will proceed from n30 to n38.
This subroutine is not executed and returns to the main routine. In other words, the height data is no longer updated. If the data invalid flag F2 is not set, the process next proceeds to n31, where it is determined whether the internal timer has overflowed. The internal timer consists of 8 bits, and the maximum scale is
The clock pulse width is determined so that it can measure up to 1044 millimeters. Therefore, the internal timer overflows when the measured data
This is when the diameter exceeds 1044 mm. This condition actually corresponds to the absence of a received signal within 6 milliseconds after transmission, as described above. In this case, the process advances to n39, increments the sensing error counter in area A16, and returns to the main routine. If the internal timer has not overflowed, the process advances to n32 and stores the internal timer data, that is, the measured height data, in Hn of area A3. Subsequently, the stored measured height data is compared with predetermined reference height data H0 of area A13. If data Hn is larger than data H0, execute n34. And if not,
Run n35. At n34, the average value of two pieces of data, the previously calculated average height data Ha of the area A2 and the previously measured measured height data Hn, is calculated as the current average height data Ha. At n35, the average value of the previously calculated average height data Ha and the past seven measurement data from data Hn to data Hn-6 is set as the current average height data Ha. That is, when the current measurement data is equal to or higher than the reference height data H0, the average of two pieces of data is taken, and when the data Hn is smaller than the data H0, the average of eight pieces of data is taken. When obtaining measurement data by sampling at appropriate intervals from a state where the height of the cutting section is very high, as more data is used to calculate the average height data, the weight of older data becomes larger and the actual height becomes larger. The difference in average height data increases. For this reason, overshoot is likely to occur. On the other hand, when the height of the reaping part approaches the target height from a relatively low height, even if a large amount of measurement data is used to calculate the average height data, the weight of old data will not become large. Rather, fluctuations in the average height data are eliminated, increasing stability. Therefore,
In this way, if the current measurement data is greater than a certain standard height data, the average of only two pieces of data is taken in n34, and if the same measured height data is smaller than the same standard height data, eight pieces of data are taken. By averaging the data, overshoot can be prevented and the stability of the cutting section around the target height can be achieved. N34 or N35 or above
When the average height data Ha is stored in area A2 in step n36, data in areas A4 to A9 are updated one by one to older data. Further, at n31, since the measured data is below a certain height, the sensing error counter is decremented and the process returns to the main routine. In this way, in the height data update subroutine, an operation is performed to obtain average height data Ha, which will be reference data for performing the next cutting height control.

When the height data update subroutine is executed in n4 of the main routine, the cutting height control subroutine is executed next. FIG. 4D is a flowchart of this cutting height control subroutine.

First, in n40, data on the set position of the cutting height fine adjuster VR is stored in ΔH of area A10. This data of ΔH is added to the target height data preset in area A11, and the addition result is subtracted from the average height data obtained in the above-mentioned cutting height data update subroutine. Then, the subtraction result is stored as a deviation in area A12. If the deviation is positive, the reaping section lowering flag F1 is set, and if it is negative, the reaping section ascending flag F0 is set (n43, n44). Next, based on the deviation found in n41,
The on-time period of the electromagnetic valve drive pulse, that is, the duty ratio, is determined from the table shown in FIG. 3 (n45). For n46, the deviation is the dead band width, that is, 0 to
Determine whether it is within 20.4 mm.
If it is within the dead band width, move to n56, turn off the solenoid valve, and end the process. If the deviation exceeds the dead zone width, it is determined in n47 whether the deviation is larger or smaller than the reference height data H1 stored in area A14. This reference height data H1 is set to 261 mm. As shown in the table of FIG. 3, when the deviation is 261 mm or more, the on-time is continuous, and when it is smaller, the driving pulse of the solenoid valve is an intermittent pulse.
Therefore, if the deviation is larger than the reference height data H1 at n44, flags R0, N48 and n49 are set.
Check F1, and if the flag F0 is set, the reaping section is continuously raised, and when the flag F1 is set, the reaping section is continuously lowered. Also, if the deviation is smaller than the reference height data H1,
The states of the flags F0 and F1 are checked at n52 and n53, and if the flag F0 is set, the reaping section is intermittently raised (n54), and when the flag F1 is set, the reaping section is intermittently lowered (n55). In this case, the duty ratio of the drive pulse for the intermittent drive of the reaping section is determined by the length of the on-time corresponding to the deviation, as shown in the table of FIG. In this way, the deviation is the reference height data
If it is larger than H1, raise the cutting part continuously,
Alternatively, the height can be lowered continuously, and if the height becomes smaller than the standard height data H1 at the next sampling time, the height can be lowered or raised intermittently depending on the size of the deviation, and the appropriate duty cycle can then be set depending on the size of the deviation obtained for each sample. The ratio of drive pulses allows the cutting section to approach the target height. In addition, n24
If flag F2 is set in or
When the internal timer stops at n18, if the timer has overflowed, the height data update subroutine is not executed, so there is no vertical movement of the reaping section.

Through the above operations, if the size of the measured height data exceeds 1044 mm, that is, if the internal timer overflows, that data is invalidated and the sensing error counter, which is an invalid data counter, is counted up. Furthermore, when the data is less than 1044 mm, the data is considered valid and the sensing error counter is counted down, and a sensor error is detected only when the count value reaches 16, that is, when abnormal data occurs 16 times in a row. It is possible to inform.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a cutting height control device embodying the present invention. FIG. 2 is a configuration diagram of the RAM included in the microcomputer of the control device. FIG. 3 is a diagram showing the contents of a table stored in the RAM. 4A to 4D are flowcharts showing the operation of the control device. 1... Ultrasonic sensor control circuit, 2... Transmitter,
3...Receiver, 7...Microcomputer.

Claims (1)

[Scope of Claims] 1. A fixed number of measured height data based on the output of a non-contact distance sensor driven at a constant cycle is stored in the measurement order each time the non-contact distance sensor is driven, and the measured average height is determined. A cutting height control method that compares a measured average height with preset target height data to determine a deviation, and controls the cutting height according to the magnitude of the deviation, the method comprising: is above a certain value,
The data is discarded as invalid data, and the content of an invalid data counter that counts the number of consecutive occurrences of invalid data is counted up, and when the counted content of the invalid data counter reaches a predetermined value, an error occurs in the non-contact distance sensor. A mowing height control method using a non-contact distance sensor, which is characterized by providing notification.