COLLISION DETECTION SYSTEM FOR A CRASH GUARD

Abstract

A collision detection system (1) for detecting and assessing the state of a crash guard (2), comprising at least one crash guard (2), which is provided with a sensor for detecting a collision onto or against the said crash guard (2), wherein the said system comprises a processing unit, which is provided to assess, on the basis of the signals generated by the sensor, the effect of a collision on the crash guard (2) and, if necessary, to initiate an alarm signal.

Claims

1. A collision detection system for detecting and assessing the state of a fixedly erectable crash guard, comprising: at least one crash guard; wherein the crash guard is provided with at most one sensor for registering an acceleration of the crash guard in order thus to detect a collision onto or against the said crash guard; wherein the system further comprises a processing unit configured to assess, on the basis of signals generated by the sensor, an effect of a collision on the crash guard and, if necessary, to initiate an alarm signal.

2. Collision detection system according to claim 1, characterized in that the processing unit is configured to calculate an impact energy (Ei) of a collision onto or against the crash guard on the basis of the registered acceleration and a time of the acceleration.

3. Collision detection system according to claim 2, characterized in that an alarm signal is generated if the calculated impact energy is higher than a preset value (Et).

4. Collision detection system according to claim 1, characterized in that the processing unit is configured to register detected collisions.

5. Collision detection system according to claim 1, characterized in that the signal generated by the sensor contains information on the place of the collision and the magnitude of the collision.

6. Collision detection system according to claim 1, characterized in that the assessment of a collision takes place during an assessment phase, wherein the assessment is made on the basis of at least the signals generated by the sensor and properties of the material from which the crash guard is made.

7. Collision detection system according to claim 1, characterized in that the said sensor is an accelerometer, a mechanical strain gauge and/or an optical sensor.

8. Collision detection system according to claim 1, characterized in that the crash guard is a rack protector, a safety barrier, a wheel stopper, a protective screen, a bollard, or a column protector.

9. Method for detecting and assessing the state of a fixedly erectable crash guard, characterized in that a collision onto or against the crash guard is detected by means of at most one sensor for registering an acceleration of the crash guard, and wherein, by means of a processing unit, an effect of the collision on the crash guard is assessed and, if necessary, an alarm signal is initiated.

10. Method according to claim 9, characterized in that the assessment of a collision takes place during an assessment phase, wherein the assessment is made on the basis of at least the signals generated by the sensor and properties of the material from which the crash guard is made.

Description

[0017] In this description, reference is made by means of reference numerals to the accompanying drawings, wherein:

[0018] FIG. 1: is a representation of a general stress-strain diagram for polymers;

[0019] FIG. 2: is a schematic representation of a collision detection system according to the invention;

[0020] FIGS. 3 to 11: show a number of possible embodiments of a crash guard which can be used in the collision detection system according to the invention.

[0021] A solution for recognizing the impact event of a crash guard, and thus for making the invisible damage visible, is to place the collision (impact) detection system in accordance with this invention, which registers each crash and calculates the seriousness thereof.

[0022] In accordance with this invention, the collision detection system (1) for detecting and assessing the state of a crash guard (2) and as represented schematically in FIG. 2 comprises at least one crash guard (2), which is provided with a sensor for detecting an acceleration on or against the said crash guard (2), wherein the said system (1) comprises a processing unit, which is provided to assess, on the basis of the signals generated by the sensor, the effect of a collision on the protection device (2) and, if necessary, to initiate an alarm signal.

[0023] The processing unit will calculate the impact energy (Ei) of a collision onto or against the crash guard on the basis of the registered acceleration and the time of the acceleration. An alarm signal is generated if the registered impact energy is higher than a preset value (E).

[0024] Non-critical crashes (thus with values in the elastic deformation zone in the stress-strain diagram—see FIG. 1) and critical crashes (values in the plastic deformation zone in the stress-strain diagram—see FIG. 1) are registered and recorded. Rules (values) are set up for each type of crash guard. These rules stipulate the behaviour which the collision detection system must exhibit in the event of a crash. Thus the system, for example, can generate an (alarm) signal in the event of a serious crash.

[0025] The processing unit makes use of an algorithm. The algorithm can be provided both in the processing unit and in the crash guard. This algorithm identifies the type of crash from the profile of the impact data. For this, the pattern of the acceleration during the period of the impact is looked at. In this way, a distinction can be drawn between a slow, but powerful crash and a brief crash. Both can lead to a critical impact, but have a completely different impact profile. A few parameters which are important in this context: the moment at which the acceleration becomes negative, the number of times that the acceleration changes successively from positive to negative, the duration of the various phases in the acceleration-time graph.

[0026] The algorithm (the processing unit) afterwards, as a function of the type of crash, translates the acceleration values into an impact value in Joules. This value is then compared with the threshold values which are determined for each product. Thus an evaluation is made of the seriousness of the crash.

[0027] In this way, for example empirically, a number of threshold values were determined. Thus it was determined that the threshold value of the energy which the crash guard as shown in FIG. 5 can maximally absorb lies at 15,800 Joules. At higher values, the crash guard fails (breaks). If thus an impact occurs on this crash guard (2), in the case of the crash guard shown in FIG. 5 an alarm signal will thus be generated if the registered impact energy is higher than the set value of 15,800 Joules. In the case of the crash guard shown in FIG. 11, the maximum value before a break occurs lies at 3,200 Joules.

[0028] By keeping record of the history of the crashes, it is also possible to plan preventive maintenance, so that the risk of a failing system is lessened.

[0029] The impact energy of a crash can be measured and calculated with various sensors: an accelerometer, a mechanical strain gauge, an optical sensor, or similar sensor. Preference is given to an accelerometer.

[0030] In the case of an accelerometer, the measured acceleration values are dependent on the following parameters: [0031] the mechanical construction; [0032] the location of the sensor; [0033] the material, or combination of materials, of the construction; [0034] energy of the impact.

[0035] But these parameters are also crucial for the other sensors.

[0036] The measured values of acceleration (G-values) during (time t) the impact are used to calculate the energy (E.sub.i) of the impact.

[0037] By virtue of simulations and physical tests (with known vehicle speeds and masses), it is known what is the behaviour is of a specific protection device in the event of impact at various energy values (E.sub.t).

[0038] The comparison of (E.sub.i) and (E.sub.t) thus provides an evaluation of the seriousness of the crash, and thus also of the damage to the system.

[0039] An impact sensor is attached to a protection device (2). The fastening can be realized both on the inside or the inside. The data from the sensor are sent to a processing unit. The processing unit can be integrated or can be located at a distance from the protection device (2). The processed values are then sent to a read-out apparatus. This can be incorporated in the detection system, as well as be accommodated in the external processing unit, but can also be an external computer.

[0040] A sensor can be accommodated in various types of crash guards (2) (see FIGS. 3 to 11). Below, a non-limiting number of embodiments is briefly described: [0041] safety barriers (FIG. 3): consisting of base plate, plastics vertical pole and plastics horizontal bars. The bars are fixed in the vertical pole. The base plate is fixed in the floor. [0042] protective screens (FIG. 4): consisting of base plate, plastics vertical poles and plastics screens fixed to the vertical poles. The base plate is fixed in the floor. [0043] single and double crash protection (FIGS. 5 and 6): consists of ‘posts’ and ‘beams’. The posts consist of a base plate, on which is mounted a plastics tubular casing. Around this sits a second (outermost) tube. Between the two tubes sits an impact-absorbing element. The beams are mounted on the posts by means of a horizontal inner tube. The base plate is fixed in the floor. [0044] crash protection and safety barriers combination: FIG. 7; [0045] free-standing rack protection: (FIG. 8) [0046] rack protection (FIG. 9): plastics shell which is fastened around a metal rack. [0047] gates (FIG. 10): a hinged unit constructed from a combination of plastics and metal components. [0048] protective portals; [0049] free-standing protective poles (FIG. 11) analogous to a post. [0050] column protectors: consist of two hollow plastics shells, which are placed one against the other. [0051] wheel stoppers: solid rubber products.