JP2007320406A - Vehicle cargo deck vibration judging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cargo deck vibration judging device considering not only vibrations on the cargo deck floor of a vehicle, but also the vibration condition of a cargo on the deck. <P>SOLUTION: The frequency transfer function between the vertical acceleration of the cargo deck (120) of the vehicle (100) detected by a sensor (11) and the vertical acceleration of the cargo (200) on the deck (120) detected by a sensor (12) is calculated. Moreover, the frequency distribution map of the peak value of the transfer function is generated, and a frequency band accounting for a prescribed percentage is specified. When a value obtained by subjecting either one of the output signals to band-pass filter processing by using the frequency band exceeds a threshold, an alarm signal is output. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle bed vibration determination device, and more particularly to a device for determining vehicle bed vibration for preventing damage to a load.

  Conventionally, as a problem of damage to transported goods before the balance of the vehicle has been lost due to driving operation or loading status of the vehicle, it has become a sensitive issue with the recent commercialization, small-lot delivery, or specialized transportation of transporters. In order to handle loads that meet the needs of the times when you want to transport the load, you know how to share the driving methods and information that only experienced drivers can have so far, and that the driver can monitor and predict objectively. (For example, see Patent Document 1).

  This system has a vibration detection unit, a vibration analysis unit, a monitoring unit, and a recording unit in the loading platform. The vibration detection unit detects vibrations occurring in the loading platform, and the vibration analysis unit detects each time interval specified. A time average is compared with the previous value, and the monitoring unit always presents the result to the driver, and a device is provided that issues an alarm when the change in the average vibration value exceeds a predetermined range. Such information is recorded in a recording unit together with a digital tachograph or the like that records operation information such as vehicle speed, shift operation, travel time, travel distance, and the like, and a vibration database of the loading platform based on the operation information can be constructed. In addition, it is recorded in the recording unit together with GPS position information, etc., so that it can be notified in advance that the vehicle has approached the runway part where there is a high possibility of loading platform vibration based on past operation information related to loading platform vibration. I have to.

In this way, there is a system that presents feedback information for controlling the driving operation by notifying the driver of vehicle loading platform information that causes vibrations in the loading platform, while the specific frequency component of the loading platform itself is There is also a vibration isolator for transportation that reduces the vibration transmissibility (see, for example, Patent Document 2) and a device that reduces vibration transmitted to the carrier such as an air suspension.
JP 2006-001292 A JP-A-2-26438

  Since the input vibration of the loading platform is transmitted from the road surface to the loading platform through the tires, suspension, and vehicle frame, the vibration level and frequency characteristics of the vibration phenomenon generated in the loading platform are greatly influenced by the traveling road surface and the traveling speed. The vibration level captured at time intervals varies from moment to moment and varies. Therefore, even if the vehicle is traveling, the vibration level generated by the traveling road surface, the traveling speed, and the combination thereof may be greatly different. In addition, it is already known that such vibration of the loading platform varies depending on the weight of the loading loaded on the loading platform.

  Today's anti-loading problem is demanding that the entire load being carried can be prevented by the desire to carry sensitive loads and to reduce the loss of the loaded load as much as possible.

  However, for the above-mentioned Patent Document 1 that detects the vibration of the cargo bed and feeds it back to the driver, since the vibration of the cargo bed is fed back, it is impossible to grasp the original vibration status of the cargo caused by the type, weight and state of the cargo. . For this reason, the setting and driving operation that urges warnings at a level that does not cause damage must depend on the driver's learning experience. Even if the driver has learned and learned about the road surface and traveling speed according to the type of load, the driver cannot easily take preventive measures considering the condition of the loaded load itself because it refers to the vibration level of the loading platform. It was.

  In addition, when an air suspension or a vibration isolator for transportation that reduces the vibration transmissibility of a specific frequency component is provided on the platform itself as in Patent Document 2 above, the effect of reducing the level of the platform vibration on average Can only be obtained. Therefore, the vibration level that is caused by various factors and changes greatly in time series, that is, the vibration level that may cause fatal damage even if it is not frequent, is described in Patent Document 2. It cannot be prevented in general.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a platform vibration determination device that takes into consideration not only the vibration of the platform floor of the vehicle but also the vibration state of the load on the platform.

  The vibration generated in the loading of the platform such as a truck is generated by a combination of these various factors, but the vibration generated on the loading platform floor of the truck is shown in FIG. 8 (1) as a time series every Δt time, It is known that the level at the rear of the loading platform is higher than that at the front of the loading platform.

  On the other hand, the vibration generated by the load stacked on the loading platform is transmitted from the loading platform floor to the lower stage → middle stage → upper stage. In the resonance frequency band specific to the load, as shown in FIG. 8 (2), the vibration of the resonance frequency is greatly amplified toward the upper stage of the load, and is attenuated in a region other than the resonance frequency. As shown in the figure, the lower load rarely exceeds the vibration level of the loading platform floor, and the upper loading is different from the vibration level of the loading platform floor or the lower loading load. It can be seen that it is greater than the vibration level of the lower load.

  As shown in FIG. 8 (2), the inventor has shown that vibration generated on the cargo bed floor is transmitted from the lower part of the cargo bed to the upper part, and that the lowermost stage of the load is larger than the vibration of the cargo bed floor, as shown in FIG. We found that it is rare, and the upper stage of the load is more likely to generate larger vibration than the lower stage and the loading platform floor.

  Therefore, in order to achieve the above object, a vehicle bed vibration determination device according to the present invention detects a vertical acceleration of a load loaded on the bed and a first acceleration sensor that detects the vertical acceleration of the vehicle bed. Calculate a frequency transfer function between the second acceleration sensor and the acceleration detected by the first and second acceleration sensors and generate a frequency distribution map of the peak value of the transfer function to occupy a predetermined ratio A control unit that specifies a frequency band and outputs an alarm signal when a value obtained by performing band-pass filtering on one of the two accelerations using the frequency band exceeds a threshold value.

  That is, in the present invention, the frequency transfer function between the vertical acceleration of the vehicle carrier detected by the first acceleration sensor and the vertical acceleration of the cargo loaded on the cargo platform detected by the second acceleration sensor is calculated. calculate. Then, the control unit records the peak value of the calculated transfer function and generates a frequency distribution map thereof. The control unit identifies a frequency band that occupies a predetermined ratio in the peak value frequency distribution map, and is detected by the first acceleration sensor or the second acceleration sensor using the identified frequency band as a bandpass band. The vertical acceleration is filtered, and an alarm signal is output when the value obtained thereby exceeds a threshold value.

  The first and second acceleration sensors are preferably installed at the rear part of the loading platform. That is, since it is known that the vibration level is high at the rear part of the vehicle, it is possible to accurately detect vibrations in the entire load by using the transmission rate of vibration between the lower stage and the upper stage of the load at the rear part of the vehicle as frequency distribution information. Can do.

  Depending on the road surface shape, vehicle speed, driver's driving skill, cargo content, its condition, how it is loaded, etc., the magnitude of the cargo bed vibration and its frequency characteristics will change, but in the present invention, the frequency band to be extracted as vibration Can be appropriately changed to one corresponding to the vibration of the loading platform, so that appropriate vibration determination can be performed. In particular, it is possible to detect vibrations with high accuracy not only for collapse of cargo but also for minute vibrations that have an effect when transporting fresh foods and the like.

  In addition, in the present invention, in consideration of the needs of the times, in consideration of preventing damage to the entire cargo loaded on the truck bed, vibrations generated in the cargo bed depending on the loading situation, running environment / running situation / driving situation of the driving driver In addition to means for notifying the object objectively, vibrations that cause damage to the load can be accurately detected with a minimum number of detection points, and the prediction accuracy of the damage to the load can be improved.

  In addition, the present invention can provide a compact, low-cost, highly reliable system by sensing the vibration state of a load using a minimum acceleration sensor.

  Further, according to the present invention, the driver who transports the load can take preventive measures by accurately capturing the original vibration of the load as well as the vibration of the loading platform that changes every moment during operation. Even if it is an inexperienced person, it is always possible to feed back and learn only the vibration status related to the damage of the load according to the load status, and to refer to the indicators, monitors and warnings showing the results. Since it can be transported without damaging delicate loads, operations such as unnecessary deceleration and care can be omitted, and more accurate driving operations can be performed.

  FIG. 1 schematically shows a vehicle to which a vehicle bed vibration determination device according to the present invention is applied. That is, the control unit 2 and the monitor unit 3 connected to the cab 110 of the vehicle 100 are provided. The loading platform 120 is provided with the rear acceleration sensor 11 that tends to statistically have the largest acceleration, and the acceleration sensor 12 is provided at the uppermost stage of the last load 200 on the loading platform 120 correspondingly. The sensors 11 and 12 are connected to the control unit 2. These acceleration sensors 11 and 12 detect vertical acceleration (vibration acceleration) within a predetermined time.

  The sensor 12 at the last and uppermost part of the load is attached to the uppermost part of the last part after the work is loaded on the loading platform 120, and is removed when the load is lowered after transportation, so it can be easily removed from the load. A different form is required. Therefore, any means may be used as long as it can detect the movement of the last part of the load with a form that can be easily removed from the load, for example, a laser, ultrasonic waves, image processing, etc. in addition to the G sensor.

  Further, the sensor 11 on the loading platform 120 may be not only a G sensor but also a rate gyro (three-axis gyro), a speedometer, a displacement meter, or the like, as long as it can grasp the vibration state in the vertical direction of the loading platform. Anything that can be detected by, for example, the acceleration / deceleration status, angular velocity, etc. used in this system.

  FIG. 2 shows a control system diagram of the vehicle bed vibration determination apparatus shown in FIG. 1, and the acceleration sensor 11 provided on the load bed 120 and the acceleration sensor 12 provided on the uppermost stage of the load are the control unit 2 Is connected to the bed vibration determination unit 23, and the bed vibration determination unit 23 is connected to the monitor unit 3. Note that the cargo bed vibration determination unit 23 is connected to the power supply circuit 22 by the switch 21.

A functional block diagram of the platform vibration determination unit 23 in the control unit 2 shown in FIG. 2 is shown in FIG. 3, and the platform vibration determination unit 23 includes an FFT analysis unit 23a, a transfer function calculation unit 23b, and a frequency distribution analysis unit 23c. The vibration calculation unit 23d, the vibration determination unit 23e, and the output unit f are connected in series. FIG. 4 shows an outline of the processing of the platform vibration determination unit 23. First, the frequency band F1 used for vibration determination is specified (subroutine step S1), and then vibration determination / alarm is performed using this frequency band F1. (Subroutine step S2), and the determination is completed (step S3). Among these, step S1 is executed by the FFT analysis unit 23a, transfer function calculation unit 23b, and frequency distribution analysis unit 23c of FIG. 3, and step S2 is executed by the vibration calculation unit 23d and the vibration determination unit 23e. Note that the determination can be completed by, for example, confirming the following matters.
-When the engine is stopped-When the switch is turned off or the frequency band F1 is reset by the user-When the acceleration sensor 12 placed on the load is rearranged-After a predetermined time from the start, the above steps S1 and S2 are 5 and 6 respectively, the operation of the platform vibration determination device according to the present invention shown in FIGS. 1 and 2 will be described below with reference to FIGS.

Identification of frequency band F1: Fig. 5
First, the vertical acceleration α is input from the acceleration sensor 11 on the loading platform 120, and the vertical acceleration β is input from the acceleration sensor 12 provided on the load 200 (step S11).

  Thereafter, the accelerations α and β are sent to the FFT analysis unit 23a to perform FFT (Fast Fourier Transform), and further sent to the transfer function calculation unit 23b to calculate a transfer function Zn between them ( Step S12).

  That is, the FFT analysis unit 23a performs an FFT analysis on the vertical acceleration α within a predetermined time from the acceleration sensor 11 to obtain an analysis result Xn, and similarly performs an FFT analysis on the acceleration β within a predetermined time from the acceleration sensor 12 for analysis. Obtain the result Yn. This FFT analysis is performed, for example, with respect to a frequency band of 25 Hz or less, which is a main vibration level during truck running. Then, the transfer function (transfer rate) Zn between the two is obtained from the FFT analysis results Xn and Yn obtained in this way.

  Thereafter, the frequency distribution analyzing unit 23c obtains the peak value of the transfer function Zn calculated by the transfer function calculating unit 23b (step S13), and records the peak value (step S14). This is executed N times (steps S15 and S16).

  FIG. 7 (1) shows N transfer functions Zn [gain] obtained in this way.

  The frequency distribution analysis unit 23c further generates a frequency distribution map (histogram) based on the N peak values obtained as described above (step S17). This frequency distribution map is shown in FIG. 7 (2), and has a distribution in which the frequency decreases to the left and right around a certain frequency.

  Thereafter, the frequency distribution analysis unit 23c further specifies a frequency band F1 that falls within a predetermined ratio based on the frequency distribution shown in FIG. 2B (step S18). Here, as shown in the figure, the predetermined frequency band F1 is determined based on the tile section to which 90% of the transfer function peak value generation frequency band belongs.

  In other words, in order to establish a high frequency band with a high transmission factor that causes damage to the load, the frequency band F1 corresponding to, for example, 90% of the frequency distribution of the peak transmission rate is set as a high frequency band that causes the damage to the load. Determine. The tile width of this frequency distribution represents the frequency bandwidth. If the frequency bandwidth is widened, it is possible to set a frequency band that prevents damage to the safe zone, and if it is narrowed, it is possible to detect the frequency band caused by the damage more accurately. Used for band-pass filter to prevent.

Vibration detection / alarm: Fig. 6
After the frequency band F1 having a high transmission rate is determined, the vibration calculation unit 23d is always steady under any driving condition, for example, only the vibration acceleration α of the cargo bed floor 120 or only the vibration acceleration β of the load 200. The acceleration that can detect vibrations is inputted at certain time intervals (step S21). The vibration calculation unit 23d further performs frequency analysis such as FFT analysis on the acceleration data α or β obtained by sampling for a predetermined time (step S22), and then uses the predetermined frequency band F1 as a bandpass filter for acceleration α or A loading platform vibration determination value X of β is calculated (step S23).

  The calculated platform vibration determination value X is compared with the specified value A in the vibration determination unit 23e (step S24), and if it is found that X> A, the driver monitors the visual or voice alarm. 3 is given (step S25).

  As a result, among the vibration phenomena of the entire loaded load, the input part with the highest vibration level and the output part with the highest vibration level receiving it are detected with the minimum number of detections, causing damage to the load. By detecting the worst vibration level among the phenomena, it is possible to detect the maximum value of the safe region from the viewpoint of preventing damage to the entire cargo.

  The signal obtained from the G sensor, etc., can be visually determined by numerical values, graphs, diagrams, etc. that can be easily judged so as not to hinder the driving operation of the driving driver in the control unit section, or by a warning sound, etc. It is calculated in a form that can be presented easily and auditorily. The calculated result is like an indicator that can constantly monitor the fluctuation status in the monitor part, or like a color-coded graph, for example, when a change occurs or depending on the stage It is a means of notifying with sound or the like, and presenting in a method that does not hinder the driving operation of the driver and safety confirmation to the surroundings.

  In this way, the driver is always fed back with the results that change in time series by the presentation method that does not interfere with driving. Further, by having a certain time learning function and setting a bandpass filter, the detection portion can be simplified, and the cost can be reduced.

  Further, the loading platform vibration information is recorded together with a digital tachograph that records operation information such as vehicle speed, shift operation, traveling time, and traveling distance, and a loading platform vibration database based on the operation information can be constructed. In addition, it is recorded together with GPS location information, etc., and it is possible to notify in advance that the vehicle has approached the runway part where there is a high possibility of loading platform vibration based on past operation information related to loading platform vibration. It is. For this reason, when an alarm is issued, it is possible to prevent damage by considering the entire load in order to reduce the loss of the load more, such as reducing the speed or changing the traveling route based on the previously learned records. Become.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that various modifications can be made by those skilled in the art based on the description of the scope of claims.

It is the figure which showed the example of schematic structure of the loading platform vibration determination apparatus of the vehicle which concerns on this invention. It is the block diagram which showed the control system of the loading platform vibration determination apparatus of the vehicle which concerns on this invention. FIG. 3 is a functional block diagram of a platform vibration determination unit shown in FIG. It is the flowchart figure which showed the process outline | summary of the loading platform vibration determination part. FIG. 5 is a flowchart of a subroutine (S1) of the platform vibration determination unit shown in FIG. FIG. 5 is a flowchart of a subroutine (S2) of the platform vibration determination unit shown in FIG. It is the graph which showed the process of calculating | requiring the transfer function from two acceleration sensors by this invention, and calculating | requiring the predetermined frequency band which occupies a predetermined ratio. It is the graph which showed the relationship between the position of a loading platform, and a vibration level.

Explanation of symbols

100 vehicles
110 cab
120 cargo bed
200 cargo
2 Control unit
3 Monitor section
11, 12 Accelerometer
21 switch
22 Power supply circuit
23 Cargo body vibration judgment section
23a FFT analyzer
23b Transfer function calculator
23c Frequency distribution analyzer
23d Vibration calculator
23e Vibration detector
23f Output part In the figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

A first acceleration sensor for detecting the vertical acceleration of the loading platform of the vehicle;
A second acceleration sensor for detecting the vertical acceleration of the load loaded on the loading platform;
Calculate a frequency transfer function between the accelerations detected by the first and second acceleration sensors and generate a frequency distribution map of the peak value of the transfer function to identify a frequency band occupying a predetermined ratio, the frequency A control unit that outputs an alarm signal when a value obtained by performing bandpass filtering on either one of the two accelerations using a belt exceeds a threshold value;
A vehicle bed vibration determination device comprising: In claim 1,
The vehicle bed vibration determination device according to claim 1, wherein the first and second acceleration sensors are installed at a rear portion of the bed.

Images