WO2001073393A1

WO2001073393A1 - A control system for and a method of controlling a test device

Info

Publication number: WO2001073393A1
Application number: PCT/SE2001/000662
Authority: WO
Inventors: Börje Johansson; Kjell Norberg; Johann Galic
Original assignee: Abb Ab
Priority date: 2000-03-27
Filing date: 2001-03-27
Publication date: 2001-10-04
Also published as: AU2001244946A1; SE0001093L; SE518791C2; AU2001242984A1; EP1279014A1; SE0001093D0; WO2001073392A1

Abstract

A control system for a collision test device in which at least a first and a second object (1, 2) are pulled towards each other by means of separate pulling devices. The control system comprises means (17, 28, 29) for determining the position and speed of the first object (1) continuously or repeatedly during the pulling of the first object (1) towards the second object (2), means (18, 28, 29) for determining the position and speed of the second object (2) continuously or repeatedly during the pulling of the second object (2) towards the first object (1), and a control unit (30) having means for controlling and synchronising the position and speeds of the first and second objects (1, 2) based on the positions and speeds determined for each object.

Description

A control system for and a method of controlling a test device

TECHNICAL FIELD

The invention relates to a control system for and a method of controlling a collision test device, in which at least a first and a second object are pulled towards each other by means of separate pulling devices. In particular, the system is applied to a collision test device for executing a collision between a first and a second object. The test device comprises a tow rope by which the first object is pulled and accelerated towards the second object.

The term tow rope, as used in this context, should be regarded in a wide sense, and is intended to include all kinds of wires, stranded wire ropes, webs or the like that could be used for the purpose of pulling a test object. However, such a rope should have a shape and a flexibility that permits it to be coiled on a drum.

The collision test could be of any kind for the purpose of testing specific collision properties of the object or objects in question. A typical application is the testing of cars that either are brought to collide with each other or with another object such as a wall, a post, a model of an animal or a human being or the like, for the purpose of testing what impact such a collision will have on the car itself, its passengers and/or the object with which it collides. Such a collision test is also known as a crash test.

Testing is performed for different speeds and for different collision angles. Different collision angles are normally referred to as differences in directions with which the objects are moved towards each other. For example, collision tests are conducted in order to test what effect a collision will have on a certain car part, such as a specific beam, when two cars collide with predetermined speeds and travel directions, for example defining an angle of 90 degrees between them. As the invention is particularly adapted, however not limited, to this kind of application, it will be described with regard to such an application. BACKGROUND OF THE INVENTION AND PRIOR ART

There is a plurality of different collision test devices or arrangements proposed by prior art.

One such device is disclosed in JP- 10-260106. The disclosed test device comprises a tow rope by means of which a tested vehicle is pulled to move in transit. The vehicle is detached from the tow rope when a predetermined velocity is reached in order for the tested vehicle to collide with a collision unit, for example a collision wall. The device comprises one multifunctional winding drum which is driven by means of a motor. The tow rope runs from the winding drum to and around a second non-driven drum and back to the winding drum. Hence, the tow rope is uncoiled from the winding drum at a sending end thereof and coiled onto the winding drum at a receiving end thereof. A rope tension adjusting unit is provided in the sending side of the tow rope and absorbs the slack of the tow rope near the winding drum. The rope tension adjusting unit contributes to the achievement of a precise control of the position and speed of the test vehicle. However, slack in the system in which the tow rope is linked may occur, having detrimental effect on the control of the position and speed of the test vehicle.

JP-9-257633 discloses a vehicle collision test device that includes a first tow rope and a second tow rope which are coupled to a first and a second vehicle individually and detachably. Each tow rope is connected to a respective winding drum. Each tow rope is uncoiled from its winding drum at a sending side thereof and coiled onto the drum at a receiving side thereof. A pair of guide pulleys are set up on a base which can be rotated and which is driven by an actuating cylinder. Hence, the moving direction of the vehicles, and the collision angle, can be adjusted. The tow ropes extend around at least one common, second drum. Thereby a purely mechanical synchronisation of the vehicle velocities is obtained. However, possible rope slack in the ropes around the common drum will have a detrimental effect on the synchronisation of the position and speeds of the vehicles and may result in an inexact test result. Moreover, collision tests where one vehicle has a substantially different speed than the other one or where such a speed difference is to be flexibly adjusted from test to test is not easily achieved by means of the device in question, due to the linking or winding of the ropes around the common drum.

OBJECT OF THE INVENTION

It is an object of the invention to suggest a control system for and a method for controlling a collision test device, particularly but not necessarily only adapted for the collision test device described in this application. The control system shall promote the execution of collision tests between two moving objects with equal or different individual speeds where a very precise control of the impact points on the respective object is required. In particular, the device shall permit precise control position and speed of the tested objects by collision tests between vehicles for the transportation of humans, preferably cars.

The system is and method should be adapted for controlling a collision test device by means of which a very precise control of the position and speed of at least one collision test object can be obtained thanks to the contribution of the features of the invention. The collision test device shall have a construction that promotes the execution of collision tests between two moving objects with equal or different individual speeds where a very precise control of the impact points on the respective object is required. In particular, the device shall permit precise control position and speed of the tested objects by collision tests between vehicles for the transportation of humans, preferably cars. However, a collision test may include such test objects as buses, trains, lorries, etc.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is also achieved by means of the initially defined control system, which is characterised in that it comprises: means for determining the position and speed of the first object continuously or repeatedly during the pulling of the first object towards the second object, means for determining the position and speed of the second object continuously or repeatedly during the pulling of the second object towards the first object, and a control unit having means for controlling and synchronising the speeds (and thereby the positions) of the first and second objects based on the positions and speeds determined for each object.

According to a preferred embodiment the means for determining the position and speed of the first object and/or the means for determining the position and speed of the second object comprises a laser device by means of which the position of the pulled object is continuously or repeatedly determined during the pulling thereof. The use of a laser device results in great precision advantages, in particular when the objects are moved at considerable speed and with a certain angle between the travel directions thereof, and hence even the smallest deviation from a predetermined position-speed profile would have a detrimental effect on the test result.

Preferably the means for controlling and synchronising the speeds of the first and second objects comprises a computer processor means for processing data comprising; means for comparing the data regarding position and speed of the first and second object with desired set values for position and speed of the first and second object, and to control the effect of separate pulling devices and hence the speed of the first and second object based on said comparison.

According to a further embodiment the control unit comprises a storage means for storing predetermined test parameters, and means for calculating said set values for the position and speed of the first and second object based on the given test parameters. The storage means may comprise a data storage disk or the like. The test parameters could, for instance, be the same as the ones mentioned above for the inventive test device.

Moreover, the control system is preferably adapted for the control of the inventive collision test device defined below. The invention also regards a method of controlling a collision test device in which at least a first and a second object are pulled towards each other by means of separate pulling devices, characterised in that:

-the position and speed of the first object is determined continuously or repeatedly during the pulling of the first object towards the second object.

-the position and speed of the second object is determined continuously or repeatedly during the pulling of the second object towards the first object - the speeds (and thereby the positions) of the first and second objects are controlled and synchronised by means of a control unit, based on the positions and speeds determined for each object.

Thereby, a very precise control of the collision test can be obtained, which is of a particular advantage when the objects in question are moved at considerable speed and with an angle towards each other.

According to the invention, the collision test device is preferably characterised in that it comprises a first driven coiling drum onto which the tow rope is coiled during the pulling of the first object, and a second, separate drum from which the rope is uncoiled during said pulling. The inventive solution results in a pulling device by means of which the position and speed of at least one of the test objects, here the first one, can be very precisely controlled during the pulling thereof. The occurrence of slack in the rope is largely eliminated and the risk of rope slip is also vastly reduced or even eliminated.

Preferably, the test device comprises a first motor for driving the first drum, and a second motor for driving the second drum. Thereby a very precise control of the tension is promoted during the whole pulling sequence, irrespective of the acceleration and deceleration conditions that might differ from test to test.

Preferably, the device comprises means for maintaining a predetermined tension of the tow rope between the first and second drums. According to one embodiment said means for maintaining a predetermined tension of the tow rope comprises a means for controlling the effect of the second motor based on the torque on the drum caused by the tow rope as the latter is uncoiled from the second drum.

The device should comprise means for determining the position and speed of the pulled object continuously or repeatedly during the pulling of the first object towards the second object. Information or data regarding the position and speed of the pulled object is preferably used for the purpose of controlling the torque of the motor driving the first drum, in order to enable adjustments of the speed and position during a pulling sequence, or even stopping the motor and braking the drum for the purpose of interrupting the pulling.

Preferably, the means for determining position and speed of the pulled object comprises a laser device by means of which the position of the pulled object is continuously or repeatedly determined during the pulling. Accordingly a very precise determination of the position and speed of the pulled object is permitted. Preferably, as a supplement or an alternative to the laser device, the test device comprises a transmitter connected to a shaft of the first or second drum, the transmitter being either an incremental pulse encoder or a position encoder. The signal from the transmitter is converted into speed and position values.

The inventive collision test device should comprise a control unit having means for comparing the position and speed values obtained by the means for determining position and speed with desired set values for position and speed of the first object, and to control the torque of the first motor and hence the speed of the pulled object based on said comparison. The set values define a position-speed profile that should be followed in order to obtain a desired speed and position at the collision moment. The position speed profile is based on given collision parameters such as geometry and weight of the object, collision point of the object, desired speed at the collision moment, etc.

According to the invention, for the purpose of executing a collision test in which both the first and second objects are moving, the test device comprises a second tow rope by means of which the second object is pulled and accelerated towards the first object, a third driven coiling drum onto which the second tow rope is coiled during the pulling of the second object, and a fourth, separate drum from which the second tow rope is uncoiled during said pulling. Preferably, the tension of the second tow rope and the control of the position and the speed of the second object is achieved in the same principle way as has been described above for the first object.

As a further feature, for the purpose of synchronising the positions and speeds of the first and the second objects, the test device comprises a control unit having means for controlling and synchronising the positions and speeds of the first and second object based on a continuous or repeated determination of the individual positions and speeds of the first and second objects during the pulling thereof, and a comparison of those positions and speeds. If, for example, the position and speed of one of the objects deviates from the desired values according to the position-speed profile, consideration thereof is taken for the control of the speed, and position, of both objects. This is essential because no matter how well one of the objects follow its position-speed profile, that will be meaningless if the other does not follow its position-speed profile. By means of the inventive device correction adjustments with regard to such offsets are taken. For example a certain offset above a threshold value should induce an interruption of the whole test procedure at an early stage in order to reduce costs.

Preferably the collision test device comprises at least one track along which the first object is pulled towards the second object, and that the angle with which the track is directed towards the second object or a track along which the second object is pulled is adjustable. Thereby the application flexibility of the inventive device is improved and, with regard to the precise position and speed control provided through the invention, a plurality of collision conditions can achieved. Preferably, the first and or the second object is a vehicle. The test device is particularly adapted to the testing of cars and may be used for collision tests between cars or cars and other vehicles.

The invention also regards the use of a the control system for controlling a collision test device according to the invention for testing the collision properties of vehicles. The vehicles may be of a similar type such as two cars, or dissimilar types including buses, trucks, etc.

Further features and advantages of the present invention are presented in the following detailed description and in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described more in detail with reference to the drawing, on which:

Fig.l is a schematic view of a preferred embodiment of a collision test device according to the invention,

Fig. 2 is a diagram representing a preferred embodiment of a control system for a test collision device.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows a collision test device according to one embodiment of the invention. The device is arranged for the purpose of executing collision tests between a first and a second test object 1,2. Here, the objects 1,2 comprise a first and a second vehicle, or, more precisely, a first and a second car.

The device comprises a first and a second tow rope 3,4 respectively for the purpose of pulling and accelerating the first and the second objects 1,2 towards each other until they meet and collide at a predetermined spot. The tow ropes 3,4 form parts of a first and a second track 5,6 for pulling and guiding the objects 1,2 towards each other. Each track 5,6 comprises a trolley (not shown) via which the object 1,2 is pulled by the respective tow rope 3,4. The trolley is clamped to the rope 3,4 associated thereto and has a pin or the like via which it engages the object 1,2. It runs in a suitably shapes groove or recess arranged on or under a floor, said groove or recess permitting a guiding of the trolley in two directions, vertically and horisontally to the direction of movement of the object 1,2 pulled thereby.

The first and second track 5,6 extend in the horizontal plane and are arranged so as to permit adjustment of the angle between them, that is the angle between the moving directions of the first and second objects 1,2 is variable. As a further development of the invention it might be considered to arrange the tracks 5,6 such that at least one of them presents an optional inclination, preferably an adjustable inclination, for the purpose of permitting tests in which at least one of the objects 1,2 confronts the other object while moving in a sloping direction.

The device also comprises a first and a second drum 9,10 for the purpose of coiling and uncoiling the first tow rope 3 during the pulling of the first object 1. Each track 5,6 further comprises a pair of guiding rolls 7,8 via which the rope is guided to the respective drum. The device comprises a corresponding third and fourth drum 1 1,12 for the second tow rope 4. Motors 13,14,15,16 that are torque, speed and position controlled drive a respective one of the drums 9-12. At least one of the drums 9-12 is equipped with brakes, preferably disk brakes for the purpose of permitting a rapid speed reduction or stopping. As the first and second tracks 5.6 with their respective tow ropes 3,4, drums 9-12 and motors 13-16 are generally identical as to the arrangement, only the first track will be described in detail hereinafter.

The first drum 9 is arranged at an end region of the track 5 and driven by a first motor 13. The second drum 10 is arranged at the opposite start end region of the track and driven by a second motor 14. During pulling of the first object 1, the first tow rope 3 is coiled onto the first drum 9, while it is uncoiled from the second drum 10. However, it should be emphasised that the drums can be driven in the opposite directions if necessary, for example in order to carry out a collision test at the other end of the test track. A control system that will be described more in detail below controls the motors 13,14 such that a predetermined rope tension is obtained throughout the test course, from initial acceleration to final stopping of the tow rope movement during a collision test. The same principles applies for the second track 6. The tracks 5,6 are independent in the sense that the tow ropes 3,4 are individually guided (not via any common roll or the like), and so, consequently, the speeds of the first and second object 1,2 can follow very different position-speed profiles during one and the same test collision course.

The test collision device also comprises a control system for the control thereof. The control system is schematically shown in Fig. 2. It comprises means 17,18 for determining the position and speed of the first and second objects 1,2, as shown in fig. 1. The means 17,18 comprise a laser device for each of the tracks 5,6 respectively by means of which the position of the pulled object 1 ,2 is continuously or repeatedly determined during the pulling. Position and speed measurements by means of such equipment permit a very exact and direct determination of the speed and position of the pulled objects 1,2.

Fig. 2 shows a block diagram in which the principles of the inventive control system is applied to a test device like the one described above.

Motors, corresponding to the motors 13-16, are indicated. The upper half of Fig. 2 is associated to the control of the first track 5, while the lower part is associated to the control of the second track 6. The means 17,18 for determining the position of the test objects are indicated and form part of the control system.

The control system comprises a means, i.e. a control unit 30, for controlling and synchronising the speeds and positions of the first and second objects 1,2, said means comprising a computer processor means or co-ordination control unit 19 for processing data comprising means, preferably an arithmetic logic circuit, for comparing the data regarding position and speed of the first and second object 1,2 with desired set values for position and speed of the first and second object 1,2, and to generate signals for controlling the effect of separate pulling devices, here the motors 13-16, and hence the speed of the first and second object 1,2 based on said comparison. The computer processor means comprises a personal computer or server including a CPU, or other type of digital controller. The set values define position- speed profiles that will ensure that the objects hit each other at predetermined impact points at the collision spot, that is the track intersection. Preferably, the co-ordination control unit 19 comprises a storage means, preferably a data disk, for storage of such position-speed profiles or a software routine for calculating such profiles based on given test parameters, such as weight and geometry of the object or objects, desired final speed of the objects, etc.

Each track 5,6 can be operated in single mode, for example when one of the objects is a vehicle and the other object is a stationary object, for example a test collision wall, also known as an impact block. Alternatively, the two tracks are operated in coordinated movements to make two moving objects collide with the requested precision.

The control unit 30 is arranged to control the operation of the test device according to the following principles:

The objects 1,2 are accelerated through the action of the motors 13-16 and are released from the trolleys shortly prior to collision in order to avoid interference from the respective propulsion system (pulling devices). Accordingly, the objects 1,2 are freewheeling from the release points to the collision spot. The control unit, or more precisely the software routine thereof, is configured to compensate for any loss of speed during freewheeling. The compensation is based on the test parameters already mentioned.

From the test parameters the control unit calculates the instantaneous speed value and position that each object 1,2 shall have along their respective track 5,6 at each moment and that will result in a collision with the specified speeds and impact points. For the control of the respective motors 13-16, the control unit 30 of the control system comprises position controllers 20, ramp generators 21, first and second summation units 22,23, a speed controller 24, differentiators 25, third summation units 26, and motor torque controllers 27. It also comprises position calculators 29. These means 20-29,29 are preferably arranged as logic circuits in current converters connected to the respective motors 13-16. They may however, as an alternative, be included in the co-ordination unit 19.

The co-ordination control unit 19 controls each track with a speed reference and acceleration rate setting (v-ref 1, v-ref. 2, ace. -set 1, and ace. -set 2). The control unit 19 also sets the rope tensioning force to the uncoiling motors 14,16 via a signal denoted FBAS in fig. 2. This dynamically controlled tension largely eliminates slack in the rope system.

The control unit 30 is preferably configured to record the relative distance of each vehicle from the point of impact, as measured, and to control the speeds, and hence the positions, of the first and second object based upon those relative distances. In a case where, for example, one vehicle is specified to impact the other one with twice the speed of the first vehicle, the control system is adapted to first check and control that the distance of the first vehicle from the impact point is always exactly twice the distance between the second vehicle and the impact point.

The speed reference from the co-ordination control unit 19 passes the ramp generator 21 and the first and second summation units 22,23 that are connected to the speed controller 24. The third summation unit 26 adds the output from the speed controller 24 and the differentiator 25. For the uncoiling motors 14,16 the FBAS signal is also added in the third summation unit 26. The output from the differentiator is a feedforward signal from the the ramp generator 21. The task of the ramp generator provide smooth operation by avoiding compensations that are too fast, that is excessive compensations for deviations from the given position- speed profile.

Claims

Deviations from the calculated position-speed profile result in a correction signal Δpos to the position controller 20, which adjusts the speeds of each track 5,6 so that the speeds and position of the test objects 1,2 are synchronised. In the normal situation the position measured by the laser device 17,18 (including a Δpos calculator as shown in fig 2 for calculating the position deviation with regard to set values) is used to generate the Δpos signal but in the case of loss of laser signal the position value derived from a shaft encoder 28 (arranged at the at least one drum motor shaft at each track 5,6 and part of the inventive device) is substituted for the laser based signal. In such a case the position is calculated by the position calculator 29 and forwarded as an input signal to the co-ordination control unit 19. The laser device may, however, be substituted by other means such as, for example, radar devices.The output from the third summation unit 26 is delivered to the motor torque controller 27, which controls the torque of the motor 13-16 based on that signal.It should be emphasised that the above description of a preferred embodiment only is presented by way of example and that, of course, a number of alternative embodiments will be obvious for a man skilled in the art without thereby going beyond the scope of protection conferred by the appended claims supported by the description and the drawings.In particular it should be emphasised that the control system of the invention preferably comprises a software means for calculating of position and speed of the objects (1,2), and that, when the software means is run on a computer or a processor it makes said computer or processor carry out the steps of- calculating set values for the position and speed of the first and second objects (1 ,2) based on given test parameters,- calculating a speed and position profile for the first and second objects (1,2), and- calculating an adjustment for the speed and position dependent on freewheeling following release by a pulling device of one or more of the first and second object. Further to what has been stated above it should also be mentioned that the invention contributes to smooth operation and a controlled acceleration so as not to disturb sophisticated and sensitive sensors that might be attached to crash test dummies placed in the vehicles under test. PATENT CLAIMS

1. A control system for a collision test device in which at least a first and a second object (1 ,2) are pulled towards each other by means of separate pulling devices, characterised in that it comprises:

-means (17,28,29) for determining the position and speed of the first object (1) continuously or repeatedly during the pulling of the first object (1) towards the second object (2). -means (18,28,29) for determining the position and speed of the second object (2) continuously or repeatedly during the pulling of the second object (2) towards the first object (1), and

-a control unit (30) having means for controlling and synchronising the position and speeds of the first and second objects (1,2) based on the positions and speeds determined for each object.

2. A control system according to claim 1, characterised in that the means (17,28,29) for determining the position and speed of the first object (1) and/or the means (18,28,29) for determining the position and speed of the second object (2) comprises a laser device (17,18) by means of which the position of the pulled object is continuously or repeatedly determined during the pulling thereof.

3. A control system according to claim 1 or 2, characterised in that the means for controlling and synchronising the position and speeds of the first and second objects comprises

-a computer processor means for processing data comprising; -means for comparing the data regarding position and speed of the first and second object with desired set values for position and speed of the first and second object (1,2), and to control the torque of separate pulling devices (13-16) and hence the speed of the first and second object (1,2) based on said comparison.

4. A control system according to claim 3, characterised in that the control unit (30) comprises:

-a storage means for storing predetermined test parameters, and -means (19) for calculating said set values for the position and speed of the first and second object (1 ,2) based on the given test parameters.

5. A control system according to any one of claims 1-4, characterised in that it comprises a software means for calculating of position and speed of the objects (1,2), and that, when the software means is run on a computer or a processor it makes said computer or processor carry out the steps of

- calculating set values for the position and speed of the first and second objects (1,2) based on given test parameters,

- calculating a speed and position profile for the first and second objects (1 ,2), and

- calculating an adjustment for the speed and position dependent on freewheeling following release by a pulling device of one or more of the first and second object

(1,2).

6. A method of controlling a collision test device in which at least a first and a second object (1,2) are pulled towards each other by means of separate pulling devices, characterised in that:

-the position and speed of the first object (1) is determined continuously or repeatedly during the pulling of the first object (1) towards the second object (2). -the position and speed of the second object (2) is determined continuously or repeatedly during the pulling of the second object towards the first object (1), and - the speeds and positions of the first and second objects (1,2) are controlled and synchronised by means of a control unit (30), based on the positions and speeds determined for each object (1,2).

7. A method according to claim 6, characterised in that the position of the first and/or the second object is executed by means of a laser device (17,18).

8. A method according to claim 6 or 7, characterised in that data regarding position and speed of the first and second object (1,2) are compared to desired set values for position and speed of the first and second object (1,2), and that the torque of the pulling devices (13-16), and hence the position and speed of the first and second objects (1,2) are controlled based on said comparison.

9. A method according to claim 8, characterised in that the set values for the position and speed of the first and second objects (1,2) are calculated based on predetermined test parameter values.

10. A method according to any one of claims 6-9, characterised in that the speeds and positions of the first and second objects (1,2) are controlled and synchronised by means of maintaining a constant relative distance between each of the objects (1 ,2) and the point of impact.

11. A method according to any one of claims 6-10, characterised in that it is performed on a collision test device for executing a collision between a first and a second object (1,2) comprising a tow rope (3) by which the first object (1) is pulled and accelerated towards the second object (2) and a first driven coiling drum (9) onto which the tow rope (3) is coiled during the pulling of the first object (1), and a second, separate drum (10) from which the rope (3) is uncoiled during said pulling.

12. Use of the system according to any one of claims 1-5 for controlling a collision test device for executing a collision between a first and a second object (1,2) comprising a tow rope (3) by which the first object (1) is pulled and accelerated towards the second object (2) and a first driven coiling drum (9) onto which the tow rope (3) is coiled during the pulling of the first object (1), and a second, separate drum (10) from which the rope

(3) is uncoiled during said pulling