WO1989001604A1

WO1989001604A1 - Method and apparatus for the determination of the weight of an elongate body

Info

Publication number: WO1989001604A1
Application number: PCT/DK1988/000132
Authority: WO
Inventors: Svend Aage Jensen; Jensen Ole Krarup
Original assignee: Svend Aage Jensen; Jensen Ole Krarup
Priority date: 1987-08-14
Filing date: 1988-08-11
Publication date: 1989-02-23

Abstract

A method for the determination of the weight of an elongate body, in which method a registration of the dimensions of the body is made at intervals by means of a number of photodetectors arranged approximately in line on a carrier means, said detectors performing during a scanning a relative movement in relation to the body, the registrations in the signal computing means being summed up into one signal forming the basis for the determination of the weight. To be able to determine also the weight of bodies, which cannot be moved or placed on a weighing device, or who are alive and may become restless during a normal weighing procedure, the relative movement is registered by means of a wheel placed on the carrier means and which wheel rolls along the surface of the body in the longitudinal direction thereof, thereby determining the intervals of the registrations, the line, on which the detectors are placed, being parallel with and approximately coinciding with the axis of the wheel.

Description

METHOD AND APPARATUS FOR THE DETERMINATION OF THE WEIGHT OF AN ELONGATE BODY

The present invention relates to a method for the de¬ termination of the weight of an elongate body, in which method a registration of one of the dimensions of the body is made at intervals by means of a number of detectors arranged approximately in line on a carrier means, said detectors performing during a scanning a relative movement in relation to the body, the registrations in signal compu- ting means being summed up into one signal forming the basis for the determination of the weight. The invention also relates to an apparatus for carrying out the method.

From British patent specification no. 2,147,996 A a similar method is known, in which the object is conveyed at regular speed through a measuring frame on a roller con¬ veyor. The measuring frame comprises a number of photodetec¬ tors, which, when the object passes through the measuring frame, scan the dimension of the body at short intervals. The signals from the detectors are then transferred to sig- nal computing means carrying out the necessary calculation of the dimension of the object. On basis of this calculation also other characteristics of the object may be determin- able, for instance its weight. A similar arrangement is known from German Offenlegungsschrift no. 3,120,193. Not all bodies are suited for being conveyed through a measuring frame by means of a roller conveyor or a con¬ veyor of a similar kind. The bodies may for instance be very voluminous and heavy and consequently difficult^' to handle, or the bodies may be live animals becoming disturbed and trying to resist being placed on the conveyor roller and conveyed through the measuring frame.

The object of the present invention is to provide a method, which can be used no matter where the body is, the

Fig. 1 shows a first embodiment of the apparatus according to the invention partially intersected and seen from the front, fig. 2 shows the apparatus according to fig. 1 seen from below, fig. 3 shows another embodiment of the apparatus according to the invention for the determination of the weight of pigs for slaughtering, fig. 4 shows the apparatus according to fig. 3 seen from below, and fig. 5 is a modification of the apparatus according to figs. 3 and 4, seen from below.

The apparatus according to the invention comprises a housing 1, in which a number of photodetectors 2 is placed in a straight line. The photodetectors 2 are placed at the back end of each of a number of parallel tubes 3. If the length of the tubes is approx. 100 mm and the diameter 2 mm, the photodetector will, in a distance corresponding approx. to half the bodily height of a pig, get a field of vision with a diameter of only 5-6 mm. At the underside of the apparatus the openings of the tubes form diaphragms with a diameter of 2 mm. On the apparatus a wheel 5 is placed, said wheel beeing provided with a number of magnets, for instance one for each circumferential length of 1 cm. The magnets activate, when the wheels rotate a Reed-switch 6, which emits an impulse each time the wheel 5 has run 1 cm. From the photodetectors the signals received are transferred to signal computing means, which may for instance be a 40- channel parallel-to series-converter for a computer. If the apparatus is rolling along the back of a pig from its ears to its tail head, a kind of picture of its back will have been taken, the picture consisting of a number of signals indicating the width of the pig at the place in question as well as a value stating the length of the body of the pig. If these signals are summed up, an approximate expression for the vertical projection of the pig on the underlayer is obtained. Measuring and weighing of a large number of pigs of different breed and differing growth conditions have shown that by placing the result from the summing up in a simple algorithm it is possible to determine the weight of the pig with a certainty of 2.5 kg, which is sufficiently exact for most breeding purposes. The apparatus and the method are also applicable for the determination of the volume of big, bulky objects, such as logs. Using the same procedure as with the pigs, it is possible, by letting the apparatus roll along the part of the log, which is interesting, to get a number of diameter measurements on the way. By means of a suitable, empirically determined algorithm, the volume and thus also the weight of the log can be deduced.

To encrease the security that the measurements received are reliable, when for instance disturbed animals are to be measured, the apparatus may be improved by the ad¬ dition of various details. It is for instance possible to provide the roller 5 with a sensor registering the contact pressure of the roller against the back of the animal. The sensor is connected to signal computing means in such a way that if the contact pressure drops below a predetermined value, the summing up is discontinued, and if subsequently more impulses are received from the Reed-contact, a signal of error is emitted. The operator can thus be certain that the apparatus has rolled over the whole back of the animal, and, therefore, a greater certainty that the measurement is correct will be achieved also in the cases, where the animal is restless during the measuring.

The apparatus is provided with suitable (not shown) handles, as it is normally adapted to being conveyed manual- ly along the object.

In a similar way as with the control of the contact pressure, the roller may be provided with means registering whether it changes its rotational direction, and emitting, if that is the case, a signal of error to the signal computing means.

For use in connection with bodies, which can be provided with an optically readable marking, the apparatus can be provided with reading means for reading these mark-

operating means for resetting of the summing up means as well as a display for showing the results of the measuring. Another embodiment of the apparatus according to the invention comprises as shown in fig. 3 an elongate housing 10, which is essentially symmetrical around a centre line 12. The housing 10 is provided with a handle 13, with which it is possible manually to convey the apparatus along the body, the weight of which is to be determined. In the centre line 12 of the apparatus a scanning wheel 14 is arranged, the axis of which runs perpendicularly to the centre line 12. The scanning wheel is provided with an impulse emitter, which at the turning of the wheel emits impulses at pre¬ determined angle intervals to a summing up means placed in the housing. Furthermore, the apparatus comprises two rol- lers 15 and 16, each placed symmetrically in relation to the centre line on a swing arm 17, respectively 18. The swing arms are pivotally connected to the housing at the end opposite to the scanning wheel 14, the arms becoming thereby comparatively long without making the apparatus unmanage- able. The object of the arms 17,18 is namely to make it pos¬ sible to move the rollers away from each other from the centre line of the apparatus in a direction running approx¬ imately in parallel with the axis of the scanning wheel. In a simple embodiment of the apparatus the arms^' are pivotally connected to two shafts stationary with respect to the housing 10 close to the handle 13, and the arms are at the shafts provided with angle emitters emitting impulses to summing up means dependent on the distance of the rollers from the centre line. In such an arrangement the rollers are conveyed along a curved path, which, in particular when it is a question of bigger distances from the centre line, deviates to some extent from a line parallel to the axis of the scanning wheel. This deviation causes a certain dis¬ placement of the width measurements obtained in relation to the scanned length, but with bodies of a uniform shape but of different size it is possible to adjust such a measuring error in the algorithm, on the basis of which the sum obtained in the summing up means is converted to a weight

Claims

1. A method for the determination of the weight of an elongate body, in which method a registration of the dimen- sions of the body is made at intervals by means of a number of photodetectors arranged approximately in line on a carrier means, said detectors performing during a scanning a relative movement in relation to the body, the registrations in the signal computing means being summed up into one sig- nal forming the basis for the determination of the weight, c h a r a c t e r i z e d in that the relative movement is being registered by means of a wheel placed on the carrier means aHd-which wheel rolls m the surface of the body in the longitudinal direction of the body, which wheel then determines the intervals of the registrations, the line, on which the detectors are placed, being parallel and approximately coincident with the axis of the wheel.

2. A method as claimed in claim 1, c h a r a c t e r¬ i z e d - in that the contact pressure of the wheel during the relative movement is being registered, and in which, provided that after the contact pressure has dropped below a predetermined value further registrations of the dimensions of the body are received by the signal computing means, a signal of error is released. 3. A method as claimed in claim 1, c h a r a c t e r¬ i z e d in that the relative movement of the photodetectors in relation to the body is made manually.

4. Apparatus for the determination of the weight of an elongate body in performing the method according to claim 1, said apparatus comprising a carrier means with a number of detectors arranged approximately in line, which detectors are adapted to make, during a scanning, a relative movement in relation to the body, said apparatus comprising signal computing means adapted to sum up a number of signals re- ceived at intervals from the photodetectors into one signal forming the basis for the determination of the weight, c h a r a c t e r i z e d in that the carrier means comprises a scanning wheel adapted to roll over the surface

rollers and with the impulses from the scanning wheel.

11. Apparatus as claimed in claims 9 or 10, c h a r a c t e r i z e d in that the handle comprises a lever, by means of which the two rollers may be moved away from one another against the force of an elastic return biasing and released towards the elongate body.

12. Apparatus as claimed in claims 9, 10, or 11, c h a r a c t e r i z e d in that the swing arms are resting in the housing in such a way that besides the swing movement they can also be displaced in relation thereto, the arms being at their middle connected with the housing in the area, where the scanning wheel is placed, by means of a pair of extra "arms.

13. Apparatus as claimed in any of the claims 4-8, c h a r a c t e r i z e d in that the detectors are a row of direction-sensitive light detectors placed in the carrier means.