JP2001215234A - Vehicle speed computing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the accuracy of computation when a vehicle speed for cruise control is computed from rotational frequency data produced from an output of a resolver. SOLUTION: Vehicle speed data is successively calculated based on rotational frequency data successively transmitted by means of serial communication in predetermined periods from the resolver provided on a motor, and an average vehicle speed is computed based on the speed data calculated in the predetermined periods. If an abnormality is detected in the serial communication, vehicle speed data calculated based on rotational frequency data serially communicated when the abnormality is detected is complemented by averaging vehicle speed data calculated before and after the detection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed calculating device for calculating a vehicle speed using rotational speed data calculated from a resolver output, and is particularly suitable for a cruise control which automatically holds the vehicle speed at a set value. The present invention relates to a vehicle speed calculation device used for a vehicle.

[0002]

2. Description of the Related Art In cruise control in which a vehicle speed is automatically maintained at a set value, for example, 48 ms
Since the vehicle speed is controlled in the cycle, it is necessary to detect an accurate vehicle speed in each cycle. Conventionally, a vehicle speed sensor using a pulse is frequently used for detecting such a vehicle speed.

A method of detecting a vehicle speed for cruise control using a vehicle speed sensor will be described with reference to FIG. In the vehicle speed detection method, a pulse output from a vehicle speed sensor 1 is input to a cruise control CPU 2 with the rotation of a signal rotor attached to an axle or the like of the vehicle. The CPU 2 has a control cycle of, for example, 4
The width of the pulse input during 8 ms is averaged to calculate the vehicle speed during the control cycle.

[0004] Recently, in an automobile using a motor or a combination of an engine and a motor as a power source, it has been considered to detect the vehicle speed from the output of a resolver provided in the motor. The resolver is originally used for detecting a rotation angle of a rotating machine such as a motor, and can also be used as a rotation speed sensor by calculating the amount of change in the rotation angle within a certain time. Therefore, a resolver indispensable for the motor control is used as a rotation speed sensor, and the vehicle speed of the automobile is calculated from the rotation speed.

In a cruise control vehicle speed detecting device using a resolver output, as shown in FIG. 6, a motor control CPU 3 calculates a rotational speed from a resolver output, and the rotational speed data is used for a cruise control control. It is transmitted to the CPU 2 by a very short cycle of, for example, 4 ms by serial communication. As shown in FIG. 7, the CPU 2 for cruise control sequentially calculates the vehicle speed data Vn from the transmitted rotation speed data and accumulates it in the buffer. Then, using the accumulated vehicle speed data,
An average vehicle speed is calculated for each control cycle.

That is, the transmission period of the rotation speed data is 4 ms.
The cruise control cycle is 48
ms, vehicle speed data Vn calculated at a cycle of 4 ms
Are sequentially stored in the buffer, and vehicle speed data Vn, Vn-1, Vn-2, Vn-3, Vn-4... V for 12 times every 48 ms
The moving average of n-11 is calculated by the following equation (1), and the average vehicle speed V is calculated.

V = (Vn + Vn-1 + Vn-2 + Vn-3 + Vn-4... Vn-11) / 12 (1)

[0008]

SUMMARY OF THE INVENTION CPU for motor control
In serial communication for transmitting rotation speed data from the CPU to the cruise control CPU, if a communication error occurs, the speed data is not transmitted to the cruise control CPU when the communication error occurs. For this reason, when the communication is abnormal, the vehicle speed data is lost. In this case, the update of the vehicle speed data is stopped in the buffer, and the vehicle speed data communicated last time is held. As a result, the vehicle speed data in the buffer when calculating the average vehicle speed V is as shown in FIG. 8, for example.

That is, as shown in FIG. 8, when a communication error occurs during transmission of the rotation speed data for calculating the tenth vehicle speed data Vn-2, the tenth vehicle speed Vn-2 is set as the tenth vehicle speed Vn-2. Ninth calculated vehicle speed data V
n-3 is retained. As a result, the calculated average vehicle speed V
Is expressed by the following equation (2). Since the accuracy of the average vehicle speed V decreases, the controllability in cruise control deteriorates.

V = (Vn + Vn−1 + Vn−3 + Vn−3 + Vn−4... Vn−11) / 12 (2) The underlined expression in the equation (2) means that data is updated due to a communication error. Is the tenth vehicle speed data not performed, and the previous (ninth) vehicle speed data Vn-3 is held. As a result, the accuracy of the calculated average vehicle speed V decreases, and controllability in cruise control deteriorates.

As a method for compensating for data loss due to a communication error, image data is separated and transmitted for each of R, G, and B image components, and image data for image components that have not been received is transmitted. Japanese Patent Application Laid-Open No. 8-317383 discloses a method of communicating image data that is complemented by estimating from other different normal image components transmitted separately.
However, the rotational speed data detected by the resolver is
Unlike image data, it is not easy to separate and transmit the effective components, and to separate and transmit the effective components, it is necessary to increase the number of communication lines. Is not preferred.

An object of the present invention is to solve the above-mentioned conventional problem, and an object of the present invention is to provide a vehicle speed calculating device capable of calculating a vehicle speed accurately even when an abnormality occurs in serial communication for transmitting rotation speed data. Is to do.

[0013]

A vehicle speed calculating device according to the present invention uses a motor control CP from a resolver provided in a motor.
U is a vehicle speed calculating device that sequentially calculates vehicle speed data based on rotation speed data sequentially transmitted at a predetermined cycle by serial communication and calculates an average vehicle speed based on the calculated vehicle speed data at a predetermined period. When an abnormality is detected in the serial communication, the vehicle speed data calculated based on the rotational speed data serially transmitted at the time of detecting the abnormality is complemented by averaging the vehicle speed data calculated before and after the abnormality. It is characterized by doing.

Further, the vehicle speed calculation device of the present invention sequentially calculates vehicle speed data based on rotation speed data sequentially transmitted at a predetermined cycle by a serial communication from a resolver provided in the motor, and calculates the calculated predetermined speed data. A vehicle speed calculating device that calculates an average vehicle speed based on vehicle speed data of a cycle, wherein when an abnormality is detected in the serial communication, the vehicle speed is calculated based on rotation speed data serially communicated when the abnormality is detected. The vehicle speed data is complemented based on a deviation of the vehicle speed data continuously calculated before or after the vehicle speed data.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of an embodiment of a vehicle speed calculating device according to the present invention. This vehicle speed calculation device is used as a control system for cruise control.

The control system of the cruise control is shown in FIG.
As shown in FIG. 1, the cruise control CPU 10 is provided.
Using the motor control CPU 20 and the resolver 30,
Car speed control is performed.

The resolver 30 is built in a motor (not shown) and outputs data corresponding to the rotation angle of the motor. The output of this resolver is the motor control CPU
20 and is converted into data corresponding to the number of rotations of the motor.

The rotational speed data generated by the motor control CPU 20 is transmitted to the cruise control CPU 10 at a predetermined cycle by serial communication. The transmission cycle of the rotation speed data is 4 ms in the present embodiment.

The CPU 10 for the cruise control and the CPU 20 for the motor control are implemented by software stored in a ROM (not shown) by a RAM (not shown).
A predetermined data processing is performed while transmitting and receiving signals to and from the same.

The cruise control CPU 10
In order to calculate an accurate vehicle speed for each control cycle, a first calculation unit 11, an abnormality detection unit 12, a data complement unit 13, a data storage unit 14, and a second calculation unit 15 are provided. These are configured by the above software.

The first arithmetic unit 11 is provided with a motor control CPU 2
From 0, the vehicle speed data Vn is sequentially calculated at a predetermined cycle from the rotational speed data sequentially transmitted at a cycle of 4 ms by serial communication. The calculation cycle of the vehicle speed data corresponds to the transmission cycle of the rotation speed data, and is 4 ms in the present embodiment.

The vehicle speed data calculated by the first calculation unit 11 is input to the abnormality detection unit 12 and the data complement unit 13.

The abnormality detecting unit 12 includes a motor control CPU 2
By monitoring the reception status of the rotation speed data transmitted from 0, it is determined whether the serial communication is normal or abnormal. For this determination, the rotation speed data is input to each of the first calculation unit 11 and the abnormality detection unit 12.

The data complementing unit 13 complements the vehicle speed data calculated by the first arithmetic unit 11 when a communication abnormality occurs based on the result of the determination by the abnormality detecting unit 12 from the vehicle speed data before and after the communication abnormality. It is output to the data storage unit 14 together with other vehicle speed data that does not need to be complemented and that is sometimes input.

The data storage section 14 is a buffer for temporarily storing vehicle speed data Vn calculated at a period of 4 ms in order to obtain vehicle speed data at a period matching the control period of the cruise control. The data storage unit 14 configured by a buffer sequentially stores a predetermined number of vehicle speed data including the complemented vehicle speed data output from the data complementing unit 13.

The control cycle of the cruise control is as follows:
In the present embodiment, it is set to 48 ms. Therefore, the number of data stored in the data storage unit 14 is 12 in this embodiment (4 ms × 12 = 48 ms).

The second arithmetic unit 15 calculates an average vehicle speed V from the twelve vehicle speed data stored in the data storage unit 14. As a result, an average vehicle speed of a 48 ms cycle corresponding to the control cycle of the cruise control is obtained.

The obtained average vehicle speed of the 48 ms cycle is used for a predetermined control process in the cruise control.

The motor control CPU 20 controls not only the resolver output but also other various data to control the motor as a whole. In the present embodiment, the motor is, for example, a motor used as a drive source of a hybrid vehicle.

FIG. 2 is a flowchart for explaining the operation of the vehicle speed calculation device according to this embodiment. Hereinafter, the operation of the vehicle speed calculation device will be described with reference to FIG.

The rotational speed data to be transmitted is sequentially read from the motor control CPU 20 at a cycle of 4 ms by serial communication (see step S1 in FIG. 2, the same applies hereinafter). Thereafter, vehicle speed data Vn is calculated at a predetermined cycle from the read rotation speed data (step S2), and the presence or absence of a communication abnormality is determined from the reception status of the rotation speed data (step S3). Specifically, data reading from the motor control CPU 20 is performed for one rotation speed data by two times.
It is determined that there is no abnormality in the serial communication and the read rotation speed data is normal if the two data substantially coincide. On the other hand, when the rotational speed data read continuously does not substantially match, it is determined that the serial communication is abnormal.

In place of such a method, two consecutive rotation speed data are compared. If the difference is smaller than the reference value, it is determined that the serial communication is normal. If the difference exceeds the reference value, It may be determined that the serial communication is abnormal.

When an abnormality occurs in the serial communication for transmitting the rotation speed data, the transmission data greatly changes, and by detecting this change, the abnormality in the serial communication is detected.

If it is determined in step S3 that the serial communication is normal, the vehicle speed data Vn calculated in step S2 is sequentially stored in a buffer serving as the data storage unit 14 (step S4). It is determined whether the number of data stored in the buffer is 12 or less (step S5).

If the number of data stored in the buffer is 12 or less, the process returns to step S1, and vehicle speed data is calculated in the same manner. In this manner, the vehicle speed data is sequentially calculated, and the calculated vehicle speed data is stored in the buffer serving as the data storage unit 14.

Thus, the twelve vehicle speed data are
The calculated vehicle speed data is sequentially stored in the buffer. When the number of data stored in the buffer reaches twelve, the twelve vehicle speed data stored in the buffer are read (step S6), and the read twelve vehicle speed data are subjected to a moving average. The average vehicle speed V is calculated (Step S7).

Thus, the vehicle speed data Vn is sequentially calculated at a period of 4 ms from the rotation speed data transmitted at a period of 4 ms from the motor control CPU 20 by serial communication, and the serial communication of the rotation speed data is not abnormal. For example, twelve vehicle speed data (Vn, Vn-
, Vn-2, Vn-3, Vn-4... Vn-11) are stored in the buffer of the data storage unit 14 as they are, as shown in FIG. Average vehicle speed V
Is calculated.

On the other hand, if it is determined in step S3 that the serious communication of the rotational speed data is abnormal, the vehicle speed data calculated from the motor rotational speed data at the time when the serious communication is determined to be abnormal is determined. Complementation is performed based on the vehicle speed data calculated before and after that (step S8). For example, in 12 vehicle speed data,
If the second vehicle speed data is affected by a communication error,
The vehicle speed data is complemented by calculating from the average of the ninth vehicle speed data and the eleventh vehicle speed data. as a result,
As shown in FIG. 3, the twelve vehicle speed data stored in the buffer are complemented with the tenth vehicle speed data corresponding to the serial communication abnormality and stored in the data storage unit 14 (step S4). And the twelve vehicle speed data
When the vehicle speed data is stored in the data storage unit 14 (step S8), the stored vehicle speed data is read (step S6).
The average vehicle speed V is calculated (Step S7).

In this case, as described above, the average vehicle speed V is calculated based on the twelve vehicle speed data stored in the data storage unit 14, but the first example vehicle speed data is supplemented. Then, an average vehicle speed is calculated based on the following equation (3).

V = (Vn + Vn-1 + Vn-2 '+ Vn-3 + Vn-4 ... Vn-11) / 12 (3) where Vn-2' is the tenth complemented vehicle speed data. , Vn-2 '= (Vn-1 + Vn-3) / 2.

When the vehicle speed data is complemented in this manner, the second to the second data other than the first and last calculated vehicle speed data are used.
The eleventh vehicle speed data has no problem because the vehicle speed data is continuously calculated before and after, but the first (first) vehicle speed data for which no vehicle speed data exists before the calculation,
For the last (twelfth) vehicle speed data for which there is no vehicle speed data after the calculation, the average vehicle speed cannot be calculated using the vehicle speed data before and after the calculation.

For this reason, for the last (twelfth) vehicle speed data, the deviation ΔV of two vehicle speed data continuously calculated before or after the calculation of the vehicle speed data is added to the vehicle speed data. By doing so, the vehicle speed data may be supplemented.

For example, when the twelfth vehicle speed data at the end of the calculation is affected by an abnormality in serial communication, the vehicle speed data is complemented by the following (4).

Vn '= Vn-1 + .DELTA.V (4) where .DELTA.V = Vn-1-Vn-2, and Vn' is the last (twelfth) vehicle speed data which has been complemented.

As a result, as shown in FIG. 4, the twelfth vehicle speed data is effectively complemented by the twelve vehicle speed data stored in the buffer serving as the data storage unit 14, and Vn + 1 is obtained. By calculating Vn 'again by the above-described complementing method at the time when is calculated, it is possible to calculate the vehicle speed with high accuracy even when the calculation cycle shifts or the control delay occurs when the CPU is overloaded. Can be.

As described above, in the vehicle speed calculating device according to the present embodiment, even when an abnormality occurs in the serial communication for transmitting the rotation speed data, there is no possibility of being directly affected by the data loss due to the abnormality. As compared with the case where the updating of data is stopped and the previous data is held, more accurate vehicle speed data can be obtained. As a result, the average vehicle speed V in a predetermined cycle can be calculated with high accuracy.

Further, since it is not necessary to transmit the rotation speed data separately, there is no possibility that the communication system of serial communication becomes complicated.

[0049]

As described above, according to the vehicle speed calculating device of the present invention, the rotational speed data sequentially transmitted at a predetermined cycle by the serial communication from the resolver provided in the motor is obtained.
Even when it is not possible to accurately obtain the average vehicle speed due to a communication abnormality, it is possible to calculate an accurate average vehicle speed. Therefore, when the calculated vehicle speed is used for cruise control, the controllability is significantly improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an embodiment of a vehicle speed calculation device according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the vehicle speed calculation device.

FIG. 3 is a conceptual diagram showing an example of data stored in a buffer serving as a vehicle speed storage unit in the vehicle speed calculation device.

FIG. 4 is a conceptual diagram showing another example of data stored in a buffer serving as a vehicle speed storage unit in the vehicle speed calculation device.

FIG. 5 is a schematic diagram for explaining the operation of a conventional vehicle speed detection device.

FIG. 6 is a schematic configuration diagram illustrating an example of a vehicle speed detection device using a resolver output.

FIG. 7 is a conceptual diagram showing a data storage state in a buffer of the vehicle speed detection device.

FIG. 8 is a conceptual diagram showing another example of a data storage state in the buffer.

[Explanation of symbols]

 Reference Signs List 10 CPU for cruise control 11 First operation unit 12 Abnormality detection unit 13 Data complement unit 14 Data storage unit 15 Second operation unit 20 Motor control CPU 30 Resolver

Claims (2)

[Claims] 1. A vehicle speed data is sequentially calculated from a resolver provided in a motor via a motor control CPU based on rotation speed data sequentially transmitted at a predetermined period by serial communication, and the calculated predetermined period is calculated. A vehicle speed calculation device that calculates an average vehicle speed based on the vehicle speed data of the vehicle, wherein when an abnormality is detected in the serial communication, the vehicle speed calculated based on the rotational speed data serially communicated when the abnormality is detected. A vehicle speed calculation device for averaging vehicle speed data calculated before and after the data to complement the data. 2. A vehicle speed data is sequentially calculated based on rotation speed data sequentially transmitted in a predetermined cycle by a serial communication from a resolver provided in a motor, and an average is calculated based on the calculated vehicle speed data in a predetermined cycle. A vehicle speed calculating device for calculating a vehicle speed, wherein when an abnormality is detected in the serial communication, the vehicle speed data calculated based on the rotational speed data serially communicated at the time of the abnormality detection is compared with any one of the data before and after the abnormality. A vehicle speed calculation device that complements the vehicle speed data based on the deviation of the vehicle speed data calculated continuously.