JPH079437B2 - Digital speed recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention detects the speed of an automobile and catches the change in the increase / decrease ratio thereof. The present invention relates to a digital speed recording method in which a speed immediately before a change is stored in a storage unit.

[Prior Art] [Problems to be Solved by the Invention] Conventionally, in order to manage the daily operating conditions of buses, trucks, taxis, etc., the speed at the time of traveling is detected and recorded as a digital value. Various devices have been developed. In comparison with the existing analog operation recording device, this type of recording device is required to record the speed every 0.5 seconds while running, and it is said that the recording time is too long for one day. If the speed detected every 0.5 seconds is recorded as a digital value as it is, an extremely large storage capacity is required, which causes a drawback such as an increase in the cost of the apparatus. In order to eliminate this defect, JP-A-60-2
The device described in 43567 is invented. This device
The sampling period is selected so that the maximum speed change at the time of sudden acceleration / deceleration of the car becomes the maximum allowable error value, the speed of the car is detected, and the sampling value rises, falls compared to the previous sampling value, It is configured to determine whether there is no change, and when there is no change, measure the time between them and store this. With this device,
Since there is no sudden acceleration / deceleration during normal operation, it is determined that the speed has not changed several times in succession. Therefore, while there is no change in speed, it is not necessary to display the speed for each sampling cycle, and the transition of the speed can be recorded only by recording the time during that time. However, this device determines whether or not the change in speed is constant. Therefore, if the vehicle is traveling at a constant speed, it is not necessary to record the speed change flag during that time. Even when the vehicle is traveling in a constant acceleration / deceleration state, the speed change flag has to be recorded each time because of the speed change, and there is a drawback that the storage amount cannot be significantly reduced. Moreover, since the speed fluctuation of the vehicle is small during normal driving with this device, the amount of memory for recording the speed transition during that time is small, but the maximum speed change during rapid acceleration / deceleration of the vehicle is kept within the maximum allowable error value. In order to achieve this, the maximum allowable error is generally set to ± 2.5 km / h, and considering the state in which a car is operating at a high speed of 100 km / h or more and then suddenly stops, the sampling cycle is extremely small. It must be shortened, and as a result, the amount of memory is increased, and there are drawbacks such as a device that ignores such recording at the time of sudden stop.

[Means for solving problems]

The present invention is intended to eliminate the above-mentioned drawbacks, and detects the speed of an automobile by a speed detection unit, samples the detected value at predetermined intervals, temporarily stores this, and measures the sampling duration time. Is configured.
In addition, the increase / decrease ratio of the sampling value is calculated from the twice sampled values, and it is determined whether or not the increase / decrease ratio of the next sampling value is changed. At this time,
While calculating the first slope showing the change in the increase / decrease ratio,
A first permissible range within a predetermined error in which it is determined that the increase / decrease ratio does not change is calculated, and a second slope indicating a change in the increase / decrease ratio is calculated from the next sampled value, which is within the first allowable range. Determine whether or not.

When the increase / decrease ratio of the sampling value does not change, the next sampling value is read, the increase / decrease ratio is calculated in the same manner, and the above judgment is repeated, while when the increase / decrease ratio changes from the previous increase / decrease ratio, the previous sampling The value and the sampling duration are stored in the storage unit, the sampling duration is reset, and the sampling value at this time and the sampling value immediately before are temporarily stored.

[Action]

In this digital speed recording method, the speed of an automobile is measured at a predetermined sampling cycle, temporarily stored, and the sampling duration is measured. The increase / decrease ratio is calculated from the two sampled values, and the allowable range that does not change in the increase / decrease ratio of the next sampled value is calculated, and the next sampled value is read to determine whether the increase / decrease ratio has changed. To be done.

When there is no change in the increase / decrease ratio of the sampling value, the next sampling value is read, the increase / decrease ratio is calculated, and the determination is repeated.

On the other hand, when the increase / decrease ratio of the sampling value changes, the previous sampling value and the sampling duration time are stored in the storage unit. At the same time, the measurement of the sampling duration is once reset and then restarted, the next sampling value is read, the increase / decrease ratio is calculated, and the previous determination is repeated. Therefore, not only when the vehicle travels at a constant speed, but also when the vehicle is accelerated and decelerated in a constant state and travels, it is not necessary to record the speed during that time, and only the time information can be used.

〔Example〕

Embodiments will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 is a digital velocity recording device.
This digital type speed recording apparatus 1 has a speed detection unit 2 mounted on an automobile, an interface circuit 3 to which the detection value of the speed detection unit 2 is supplied, and a sampling value read from the interface circuit 3 at a predetermined sampling cycle. 4, a RAM 5 for temporarily storing various information such as sampling values, a ROM 6 for storing an operation program of the microcomputer 4 and an operation program for performing a predetermined operation, an IC card for data recording connected to the microcomputer 4. It consists of 7. The microcomputer 4 operates according to the next operation program stored in the ROM 6.

1) When the power is turned on, each data is initialized (first sampling value v1, second sampling value v2, third sampling value v2,
After sampling value v3 etc. → 0), the detection value detected by the speed detecting unit 2 is sampled at a predetermined sampling period (0.5 s) through the interface circuit 3 to obtain the first sampling value. Is recorded on the IC card. The second sampling value is read and this is the second sampling value.
Temporarily store in RAM as v2. At this time, the sampling value is recorded by 7 bits following the parking flag indicating whether or not the vehicle is parked. The parking flag records "0" during traveling and "1" during parking. (Refer to the address map in FIG. 5) 2) The first slope indicating the increase / decrease ratio is calculated from the first sampling value v1 and the second sampling value, and the next allowable value is read as the third sampling value v3. A first permissible range in which it is determined that the increase / decrease ratio of the sampling value does not change is calculated. At the same time, a common correction range formed by the first allowable range and the previous first allowable range is calculated, and the corrected range is temporarily stored in the RAM 5 as the first allowable range.

3) Count up the time counter that measures the sampling duration.

4) Read the third sampling value as the third sampling value v3, temporarily store it in RAM, and
A second slope of the increase / decrease ratio is calculated from the sampling value v1 and the third sampling value v3, and the second slope is the first slope.
Determine whether it is within the allowable range.

5) When the second slope is not within the first allowable range, the second sampling value v2 and the count number of the time counter are stored in the IC card 7.

6) The second sampling value v2 and the third sampling value v3 are temporarily stored in the RAM 5 as the first sampling value v1 and the second sampling value v2, respectively, and the time counter is reset.

7) Determine whether the power is off.

8) When the power is on, return to 3).

9) Ends when the power is off.

10) When the second slope is within the first allowable range, the third sampling value v3 is temporarily stored in the RAM 5 as the second sampling value v2.

11) Return to 3).

Since the speed is recorded every 7 bits, if the speed exceeds 120 km / h, the speed overflow determination unit shown in FIG.
When all 7 bits for recording vt are "1", the following 8 bits may be used as a speed over flag to record the amount exceeding 120 km / h.

(See the address map in FIG. 5) Similarly, as shown in FIG. 4, a time over determination unit may be used to record the time during parking. (Refer to the address map in FIG. 5) In this case, the following subprogram may be operated.

1) It is determined whether or not the count number of the time counter is within a predetermined number, and when it is a predetermined number or more, it is determined whether or not the sampling value vt is 0, and the next reading is continued.

2) When the sampling value vt is 0, the parking flag "1" is recorded, and the count number of the time counter is stored in the following 15 bits.

3) It is determined whether the sampling value vt is 0, and if it is 0, the next sampling value is read.

4) When the sampling value vt is not 0, the count number of the time counter is stored in the IC card 7 at that time, and the time counter is reset to continuously perform the next sampling.

In the above speed recorder, when the power of the device is turned on, the microcomputer 4 is activated, the device is initialized, and the first sampling value v1,
The sampling value v2 and the third sampling value v3 are set to 0. The detection value supplied from the vehicle speed detection unit 2 to the interface circuit 3 is sampled at a predetermined cycle. As shown in FIG. 6, the first sampling value is read and stored in the IC card. The next sampled value is read as the second sampled value v2 and temporarily stored in the RAM 5, and the first slope indicating the increase / decrease ratio is calculated from the first sampled value v1 and the second sampled value v2. A first allowable range in which it is determined that there is no change in the increase / decrease ratio is calculated, a common correction range formed by the first allowable range and the first allowable range of the previous time is calculated, and this corrected range is set as the first allowable range. Stored in RAM. At the same time, the time counter that measures the sampling time counts up.

In this state, the third sampling value is read as the third sampling value v3, which is temporarily stored in the RAM5.
A second slope indicating the increase / decrease ratio of the third sampling value v3 is calculated from the first sampling value v1 and the third sampling value v3, and it is determined whether the second slope is within the first allowable range.

When the second slope is not within the first allowable range, the second sampling value v2 and the count number of the time counter are stored in the IC card 7. After that, the second sampling value v2 and the third sampling value v3 are respectively the first sampling value v
1, temporarily stored in RAM5 as the second sampling value v2,
The next sampling value is read as a new third sampling value v3 and the above determination is repeated.

On the other hand, when the second slope indicating the increase / decrease ratio of the third sampling value v3 is within the first allowable range, the third sampling value v3 is temporarily stored in the RAM 5 as the second sampling value v2, and the next sampling value is newly added. The third sampling value v3 is read and the above determination is repeated.

〔The invention's effect〕

As described above, the present invention captures the change in the increase / decrease ratio of the sampling value when recording the transition of the speed of the vehicle, and records the speed immediately before the change and the time between the changes when the increase / decrease ratio does not change, Since the speed is recorded only when there is a change in the increase / decrease ratio, there is no need to digitally record the speed detected for each sampling. Even when traveling in a decelerated state, it is only necessary to record the speed immediately before the traveling state changes and the time in between, and not only can the storage capacity for recording the transition of the speed be reduced,
There are advantages such that the sampling speed can be reliably set within a predetermined range from the actual speed, and extremely accurate recording can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the whole of the present invention, FIG. 2 is a flowchart showing a program for explaining the outline of the present invention, FIG. 3 is a flow chart showing a subroutine at the time of velocity overflow according to the present invention, and FIG. FIG. 5 is a flow chart showing a subroutine during parking according to the present invention, FIG. 5 is a main part address map of a storage section according to the present invention, and FIG. 6 is a main part explanatory view showing an operating state of the present invention. 1 ... Digital speed recorder, 2 ... Speed detector,
3 ... Interface circuit, 4 ... Microcomputer, 5 ... RAM, 6 ... ROM, 7 ... IC card, v1 ... First sampling value, v2 ... First sampling value, v3 ...
The first sampling value,

Claims (1)

[Claims] 1. A speed detector detects the speed of an automobile,
This detected value is sampled at every predetermined cycle and temporarily stored, and the sampling continuation time is measured to
The first sampling value v1 is temporarily stored as the first sampling value v1 and the second sampling value v2.
And the second sampling value v2 and the first slope indicating the increase / decrease ratio are calculated, and the first allowable range within the allowable error in which the increase / decrease ratio of the next sampling value is determined to be unchanged is calculated from the first slope. , This is temporarily stored, the next sampling value is read as the third sampling value v3, this is temporarily stored, and the second slope indicating the increase / decrease ratio is calculated from the first sampling value and the third sampling value, It is determined whether the second slope is within the first allowable range, and when the second slope is within the first allowable range, the third sampling value v3 is set as the second sampling value v2 to prepare for the next sampling value. When the second slope is not within the first allowable range, the second sampling value v2 and the sampling duration are stored in the storage unit, the sampling duration is reset, and the second sample The digital velocity recording method is characterized in that the sampling value v2 and the third sampling value v3 are respectively provided as the first sampling value v1 and the second sampling value v2 for the next sampling value.