CN108190712B

CN108190712B - Monitoring device for manned transport means

Info

Publication number: CN108190712B
Application number: CN201611236827.8A
Authority: CN
Inventors: S.梅基马蒂拉
Original assignee: Kone Elevators Co Ltd; Kone Corp
Current assignee: Kone Elevators Co Ltd; Kone Corp
Priority date: 2016-12-08
Filing date: 2016-12-28
Publication date: 2020-09-04
Anticipated expiration: 2036-12-28
Also published as: CN206569890U; FI127157B; FI20165935A; CN108190712A

Abstract

The invention relates to a monitoring device for a people mover, comprising transport elements, each transport element comprising a guide roller and a tread member having a tread surface on which a person can stand; and a plurality of elongate guide rails for guiding and supporting the guide rollers of the conveying elements; the plurality of elongated rails includes first and second side rails for guiding and supporting guide rollers of the conveying element on the first and second sides of the conveying element, respectively; the sensing device includes first and second sensing devices disposed on rail segments of the first and second side rails, respectively, and arranged to sense forces exerted on the rail segments of the first and second side rails by guide rollers of the conveying element.

Description

Monitoring device for manned transport means

Technical Field

The invention relates to the monitoring of people carriers, such as escalators, moving walkways or moving ramps.

Background

Escalators, travelators and moving ramps are people carriers, each of which typically includes an endless belt of conveying elements, such as steps or pallets for supporting a load (i.e., a person) to be transported. The conveying elements typically include guide rollers and a tread member having a tread surface on which a person may stand. Conventional people carriers also comprise elongated guide rails for guiding and supporting the guide rollers of the transport element. The elongated guide rails typically comprise two first side guide rails for guiding and supporting the guide rollers of the conveying elements on a first side of the conveying elements and two second side guide rails for guiding and supporting the guide rollers of the conveying elements on a second side of the conveying elements. The relative positioning of the guide rails can be used to control the inclination angle of the transport element, whereby the people carrier can comprise sections of different inclination. The conveying elements are typically connected to each other by a drive chain on one or both sides of each step. Typically, one guide roller of each step is coupled to the drive link on one or both sides of the step. Thus, the drive chain is also guided by the guide rollers.

People carriers are usually equipped with monitoring devices for monitoring and ensuring their safe operation. The monitoring device may comprise a monitoring unit comprising electronic processing means, such as a microprocessor. Monitoring is usually achieved with the aid of a sensing device connected to the monitoring unit. People carriers usually comprise a number of different functions and components which are monitored by sensing means. Monitoring is required to ensure the safety of people and the system is working as intended. Monitoring may also be used to obtain various information that may be used for other purposes, such as information to estimate maintenance needs and/or information to make operations more efficient or economical. The sensing means typically comprise a sensor which serves as a means for the monitoring unit to obtain first hand information of the people mover.

A disadvantage of the prior art monitoring devices is that they do not efficiently obtain information about the flow of people. In particular, efficient detection of the position of the passenger has not been provided. Camera devices have been able to collect some relevant information, but are not particularly accurate during rush hour traffic when the information is already particularly relevant. Another drawback of the monitoring devices of the prior art is that the known systems are always complex, since there are many separate means for monitoring the flow of people, the status of the different components and the occurrence of different phenomena.

Disclosure of Invention

The object of the present invention is to introduce a new people carrier which is improved in its monitoring capabilities. The object is to introduce a solution by means of which one or more of the above defined problems of the prior art and/or problems discussed or suggested elsewhere in the specification can be solved. It is an object to introduce an improved solution that provides information about the flow of people, in particular about the position of passengers. Furthermore, it is an object to introduce a versatile solution that can be used for sensing the occurrence of additionally more than one phenomenon related to the safety of the operation of a people carrier, for the control and analysis of the flow of people, or for estimating the need for maintenance.

In particular, embodiments are presented which may be used to obtain information about the position of a passenger, but additionally include one or more of the following: the detection of a misalignment of a transport element, the detection of an asymmetric wear of a drive chain connecting the transport element of a people mover, the detection of a misaligned or misaligned guide roller, and the detection of a passenger movement.

A new monitoring device for a people mover is proposed, which comprises an endless belt of conveying elements, such as steps or pallets, each conveying element comprising a guide roller and a stepping member having a stepping surface on which a person can stand; and a plurality of elongate guide rails for guiding and supporting the guide rollers of the conveying elements; the plurality of elongated rails comprises a first side rail for guiding and supporting the guide rollers of the conveying elements on a first side of the conveying elements and a second side rail for guiding and supporting the guide rollers of the conveying elements on a second side of the conveying elements, the first and second sides being opposite sides of the conveying elements in a width direction of the people mover, the width direction being orthogonal to the longitudinal direction of the rails; and a monitoring unit comprising electronic processing means, such as one or more microprocessors; and a sensing device connected with the monitoring unit. The sensing means comprises first sensing means provided on a guide rail section of the first side guide rail and arranged to sense a force exerted on the guide rail section of the first side guide rail by a guide roller of a conveying element; and second sensing means provided on a guide rail section of the second side guide rail and arranged to sense a force exerted on the guide rail section of the second side guide rail by a guide roller of a conveying element; and the first and second sensing devices are connected to a monitoring unit; and the monitoring unit is configured to determine a position of a load in a width direction of the people mover, the load being placed on top of the tread surface of the transportation element, based on the forces sensed by the first and second sensing means.

With this solution one or more of the above mentioned objects can be achieved. An intelligent guideway solution is provided that obtains first-hand information about the flow of people, in particular information about where passengers are located in the width direction of a people mover. However, the proposed solution can also be used for one or more additional purposes, if desired. The use for additional purposes may be omitted in some individual people carriers and used in some individual people carriers. In the following, preferred further details of the people mover are presented, which may be combined with the method alone or in any combination.

In a preferred embodiment, strain gauges are utilized in particular. By utilizing embodiments of strain gauges, a number of advantages can be achieved, which relate in particular to simplicity, accuracy and suitability for sensing the occurrence of additionally more than one phenomenon.

Drawings

The invention will be described in more detail hereinafter, by way of example, with reference to the accompanying drawings, in which:

fig. 1 shows a monitoring device of a people carrier comprising a transport element and a guide for guide rollers of the transport element.

Fig. 2 shows a block diagram of a monitoring device.

Fig. 3 shows the monitoring device of fig. 1, wherein a passenger is located on top of the tread surface of the conveying element.

Fig. 4 shows a detail of the monitoring device seen in the longitudinal direction of the rail.

Fig. 5 shows a detail of the monitoring device seen from below in the direction of the normal of the guide rail.

Fig. 6 shows details of a preferred embodiment of a strain gauge for use in the monitoring device.

Fig. 7 shows an alternative configuration of the slot of the guide rail.

The foregoing aspects, features and advantages of the invention will be apparent from the accompanying drawings and from the detailed description that follows in connection therewith.

Detailed Description

Fig. 1 shows a monitoring device of a people conveyor, comprising an endless belt of conveying elements 1, such as steps or pallets, each conveying element 1 comprising guide rollers 2a-2d and a tread member 3a having a tread surface 3a on which a person can stand. The people mover comprises a number of elongated guide rails 4a-4d for guiding and supporting the guide rollers 2a-2d of the transportation element 1. For the sake of clarity, in fig. 1, only guide rails 4a-4d of smaller length and only one conveying element 1 are shown, as seen in the normal direction N along the guide rails 4a-4 d. The dashed lines show the direction in which the conveying elements 1 are positioned consecutively. The arrows show the direction of movement of the conveying element 1. The successive conveying elements 1 can be connected to each other by at least one drive chain, as is common in conventional people carriers, for example. For example, the people mover may be arranged to apply a force to move the transport element 1 by means of a motor connected to the above-mentioned drive chain.

The plurality of elongated guides 4a-4d comprises two

first side guides

4a, 4b for guiding and supporting

guide rollers

2a, 2b of the transport element 1 on a first side of the transport element 1 in the width direction W, and two

second side guides

4a, 4b for guiding and supporting

guide rollers

2c, 2d of the transport element 1 on a second side of the transport element 1 in the width direction W, said first and second sides of the transport element 1 being opposite sides of the transport element 1 in the width direction W of the people mover, which width direction W is orthogonal to the longitudinal direction L of the guides 4a-4d and thus also to the direction L in which the transport element 1 is movable.

The monitoring device comprises a monitoring unit 5, which monitoring unit 5 comprises electronic processing means 5 a. The monitoring device further comprises sensing means 6a-6d connected to the monitoring unit 5, as shown in fig. 2. The connection may be a wire connection or a wireless connection. The processing means 5a are preferably in the form of one or more microprocessors.

The sensing means 6a-6d comprise first sensing means 6a arranged on a guide rail section 7 of the first side guide 4a and arranged to sense a force exerted on said guide rail section 7 of said first side guide 4a by the guide roller 2a of the conveying element 1, and second sensing means 6c arranged on a guide rail section 7 of the second side guide 4c and arranged to sense a force exerted on said guide rail section 7 of said second side guide 4c by the guide roller 2c of the conveying element 1. The first and second sensing means 6a,6c are connected to the monitoring unit 5. The first side rail 4a and the second side rail 4c are preferably arranged to guide

coaxial guide rollers

2a, 2 c. Preferably, the first and second sensing means 6a,6c are positioned such that the forces exerted by the

guide rollers

2a, 2c are sensed simultaneously. This is simplest when the guide rolls 2a, 2c are coaxial and the sensing means 6a,6c are positioned beside each other. However, simultaneous sensing is not necessary, as the monitoring unit 5 may be configured to take into account differences in the positioning of the components and delays caused by these differences.

Said first side guide 4a and said second side guide 4c are preferably arranged to guide the

guide rollers

2a, 2c, the

guide rollers

2a, 2c not being coupled with a drive chain via which a force for moving the conveying element 1 is applied to the conveying element 1. Thus, the

guide rollers

2a, 2c are not directly affected by the driving force, and the sensing applied by them is reliable for determining said position P of the load L.

The monitoring unit 5 is configured to determine the position P of a load L in the width direction W of the people mover, which load is located on top of the tread surface 3a of the conveying element 1, based on the forces sensed by the first and second sensing means 6a,6 c. The load referred to herein is preferably a passenger.

The above-mentioned monitoring unit 5, which comprises electronic processing means 5a, such as one or more microprocessors, may for example be in the form of a computer.

By providing the sensing means 6a on only one first side rail 4a and the sensing means 6c on only one second side rail 4a, the position P of the load L in the width direction W of the people mover can be determined with sufficient accuracy. However, if more than two rails, preferably each rail 4a-4d is provided with sensing means 6a, 6b, 6c, 6d, the accuracy of the determination and the usability of the system for additional purposes is facilitated. Fig. 1 also shows these additional sensing means 6b, 6d, which additional sensing means 6b, 6d are optional and not necessary. If their presence is required, the sensing means 6a-6d additionally comprise a further first sensing means 6a arranged on the guide track section 7 of the further first side guide 4b and arranged to sense the force exerted on said guide track section 7 of said further first side guide 4b by the guide roller 2b of the conveying element 1, and a further second sensing means 6d arranged on the guide track section 7 of the further second side guide 4d and arranged to sense the force exerted on the guide track section 7 of said further second side guide 4d by the guide roller 2d of the conveying element 1. Then, the first and second sensing means 6b, 6d are connected to the monitoring unit 5.

Fig. 3 shows the monitoring device of fig. 1, wherein the load L, i.e. the passenger, is located on top of the tread surface 3a of the conveying element 3. The position of the load L is marked by reference sign P. Here, the position P is the center of gravity of the load L.

The determination of the widthwise position P of the load L placed on top of the tread surface 3a of the conveying element 1 preferably comprises a comparison of the forces sensed by the first and second sensing means 6a,6 c.

Preferably, the monitoring unit 5 is configured to determine that the load L is on a first side of the tread surface 3a of the conveying element 1 in the width direction W of the people mover when the force sensed by the first sensing means 6a is larger than the force sensed by the second sensing means 6c, and to determine that the load L is on a second side of the tread surface 3a of the conveying element 1 in the width direction W of the people mover when the force sensed by the first sensing means 6a is smaller than the force sensed by the second sensing means 6 c.

Preferably, the monitoring unit 5 is configured to determine that the load L is in the center in the width direction W of the people mover 1 when the force sensed by the first sensing means 6a is the same as the force sensed by the second sensing means 6 c.

In addition or as an alternative to the above comparison, the determination may comprise calculating the position P of the load L in the width direction W of the people carrier based on the forces sensed by the first and second sensing means 6a,6 c. The calculation may be performed by basic mathematics.

The information about the determined position P may be utilized in various ways. Preferably, the monitoring unit 5 is configured to trigger one or more predetermined actions if the force sensed by one of the first sensing means 6a is larger than the force sensed by the second sensing means 6c, and to refrain from triggering said one or more predetermined actions if the force sensed by one of the first sensing means 6a is smaller than the force sensed by the second sensing means 6c, and vice versa. Thus, the position of the load L can be reacted to. The action may comprise sending a signal to the passenger, wherein the signal may be a signal using a signaling device, such as a display or a speaker. The signal may then be a command to move in the width direction W of the people mover. Thus, the people mover can control the position of the passengers and specifically cause them to move to be positioned in an optimal way with respect to the current traffic situation. In some traffic situations, it may be advantageous for the passengers to fill the entire tread surface area of the people mover as completely as possible side by side. In some other traffic situations, it may be advantageous for the passengers to be on the same side to allow for overrunning by walking along the people carrier on only one side.

The sensing of the force exerted on the guide rail section 7 is preferably achieved with strain gauges. Preferred details of the implementation by strain gauge 10 are shown in fig. 4-7. As shown, in a preferred embodiment, the first sensing means 6a comprises at least one strain gauge 10 fixed on the rail section 7 of the first side rail 4a, and correspondingly the second sensing means 6c comprises at least one strain gauge 10 fixed on the rail section 7 of the second side rail 4 c. The proposed solution with strain gauge 10 makes sensing simple and relatively accurate. An additional advantage is that sensing can also be used for additional purposes if needed, which makes it a versatile solution.

Preferably, each guide rail segment 7 to which at least one strain gauge 10 is fixed comprises a slot 8. The guide track section 7 of the first side guide 4a has an upper side 7a on top of which the guide rollers 2a are arranged to run when the endless belt of the conveyor element 1 moves. The guide rail section 7 comprises adjacent slots 8 and strips 9 between each pair of adjacent slots 8, and a strain gauge 10 is fixed on the underside 7b of at least one strip 9 and arranged to sense dimensional changes of the strips 9, in particular caused by guide rollers running on the guide rail section 7. The guide track section 7 of the second side guide track 4c has an upper side 7a on top of which the guide rollers 2c are arranged to run when the endless belt of the conveyor element 1 moves. The guide rail section 7 comprises adjacent slots 8 and strips 9 between each pair of adjacent slots 8, and a strain gauge 10 is fixed on the underside 7b of at least one strip 9 and arranged to sense dimensional changes of the strips 9, in particular caused by guide rollers 2c running on the guide rail section 7. As shown, said slots 8 are preferably elongated in the longitudinal direction L of the rails 4a-4d and at a distance from each other in the width direction W of the rails 4a-4d, and a strip 9 is provided between each pair of adjacent slots 8 in the width direction W of the rails 4a-4d, and the strip 9 is elongated in the longitudinal direction L of the rails 4a-4d, and each of said strain gauges 10 is fixed on the underside 7b of one of said strips 9 and arranged to sense a change in the dimension of the strip 7 in the longitudinal direction L of the rails 4a-4 d.

The slot 8 increases the flexibility of the rail structure where the strain gauge 10 is fixed. This effect is most significantly promoted, especially when the slot 8 is elongated. The strip 9 formed between each pair of adjacent slots 8 forms a bridge structure between the parts of the

guide rails

4a, 4b, 4c, 4d that are on opposite sides of the slot 8 in the longitudinal direction L of the

guide rails

4a, 4b, 4c, 4d, thus between the parts of the

guide rails

4a, 4b, 4c, 4d that are free of the slot 8. Sensing may be implemented for only one strip 9 per

sensing device

6a,6 c. However, it is preferred that each

sensing device

6a,6c has a plurality of strips 9, as this makes it possible to compare the bending of adjacent strips 9. Based on the difference in bending sensed by the strain gauges 10, problems such as worn guide rollers, guide roller surface peeling, misalignment, or inclined guide rollers can be identified. The strips 9 and the slots 8 are elongated in the longitudinal direction L of the guide rails 4a-4d, so that the bending of a relatively long part of the path of the guide roller can be sensed simply with a small number of strain gauges 10. The slots 8 are preferably oriented parallel to each other and to the longitudinal direction L of the guide rails 4a-4 d. The slot 8 is preferably straight.

The slot 8 is preferably made by cutting the slot 8 in the material of the elongated guide rail 4a-4d with a laser. The elongated guide rails 4a-4d for guiding and supporting the guide rollers 2a-2d of the conveying element 1 are preferably made of metal. Laser cutting provides an accurate and efficient way of manufacturing the slot.

As mentioned above, the slot 8 is preferably elongated in the longitudinal direction L of the guide rails 4a-4 d. In particular, they preferably each have a length which is greater than the width, the length/width ratio being greater than 10, wherein the length is measured in the longitudinal direction L of the guide rails 4a-4d and the width is measured in the width direction W of the guide rails 4a-4d, respectively. The slots 8 are preferably narrow as they do not excessively weaken the rail structure. The slots 8 are particularly preferably each less than 2mm wide and more than 2cm long. The length of the slot 8 is preferably 2-20 cm. These dimensions are preferred because they fit well with the typical dimensions of the guide rollers of people carriers in the form of escalators, moving walkways or moving ramps.

The dimensions of the strip 9 are preferably as follows: the width of each of said strips 9 is 2-10mm and the width of the strain gauge 10 fixed to the underside 7b of the strip 9, measured in the width direction W of the guide rails 4a-4d, is 2-5 mm. The length of each strain gauge 10 is preferably greater than 1 cm. Here, when referring to the length of the strain gauge 10, it means the length measured in the longitudinal direction of the guide rails 4a-4 d.

The slot 8 preferably extends through the material of the elongated rails 4a-4d, as shown in fig. 4. Thereby contributing to their ability to increase the bendability of the guide rail section 7.

These figures show the wires protruding from each strain gauge 10, which may be electrically connected to the monitoring unit 5.

Strain gauges are commercially available components. Fig. 6 shows a preferred embodiment of strain gauge 10. In this case, the strain gauge 10 is an ohmic resistance strain gauge. The ohmic resistance strain gauge 10 includes a conductor c extending in the longitudinal direction of the strain gauge 10. In particular, it is preferable that the conductor c extends back and forth in the longitudinal direction of the strain gauge 10. In case the strain gauge 10 is of this type, the monitoring unit 5 is arranged to monitor an electrical characteristic of the conductor c, most preferably to detect its ohmic resistance. Even a slight dimensional change of the strip 9 due to bending of the strip 9 will still result in a detectable change in the ohmic resistance of the conductor. Thus, the solution can be very accurate.

As described with reference to fig. 4, the slot 8 preferably extends through the material of the elongated rails 4a-4d, whereby the bendability of the strip 9 may be assisted. However, this is not essential. Figure 7 shows an alternative configuration of the slot 8. In this case each of said slots 8 is a blind slot extending into the material of the elongate rails 4a-4d and not extending through it. The fact that the slot 8 is a blind groove helps the structure of the guide rails 4a-4d not to be excessively weakened. It is furthermore preferred, although not necessary, that the blind groove 8 extends in particular from below into the material of the elongated guide rails 4a-4d, without extending through it. Thus, the top surfaces of the guide rails 4a-4d do not become uneven due to the slots 8 and even contribute to the rolling of the guide rollers 2a-2 d. Furthermore, strain gauge 10 may also be positioned relative to slot 8 in the case where strain gauge 10 and slot 8 are on the same side of rails 4a-4 d.

The monitoring device may further comprise a position sensor 11 for sensing the position of the guide rollers 2a-2d on top of the guide rail section 7 at the point of the strain gauge 10, which position sensor 11 is also connected to the monitoring unit 5. However, this is optional. The position sensor 11 is preferably also arranged to sense the position of the guide rollers 2a-2d in the width direction W of the guide rails 4a-4 d. Therefore, the influence of the guide roller position in the width direction W can be considered in the derivation performed based on sensing. This is advantageous because the guide roller position affects the way in which its weight is distributed over the strip 9, and possibly also over the part of the guide rail that is not covered by the sensing. Preferably, the position sensor 11 is mounted more specifically such that it is located beside the path of the guide rollers 2a-2 d. Preferably, it involves sensing the position of the central axis of the guide roll 2a-2d in question. As for the form of the position sensor 11, it is preferably a non-contact sensor, such as a magnetic, capacitive or optical sensor.

The monitoring means may optionally be arranged to stop the movement of the transport element 1 if the dimensional change sensed by one or more strain gauges 10 exceeds a predetermined limit. This provides an additional security feature of the system. Thereby, an overload condition can be detected and reacted to. This may prevent dangerous situations from developing, for example when an object is wedged between moving parts of the people mover. This is particularly relevant in the vicinity of the comb plate of a people mover. When implementing a solution to prevent this, the sensing means 6a-6d should be arranged on a guide rail section located near the comb plate of the people mover.

Likewise, in case the dimensional change sensed by one or more strain gauges 10 is below a predetermined limit and further signals and/or further data received by the monitoring device indicate that the guide rollers 2a-2d are located on top of the guide rail section 7 at the point of the strain gauge 10, additional optional features of the system may be provided if the monitoring device is arranged to stop the movement of the transport element 1, or at least to send a signal to a remote monitoring center. This will enable the device to detect and react to, for example, a misalignment of the conveying elements, an asymmetric wear of the chain connecting the conveying elements of the people mover, a worn guide roller or a misaligned or misaligned guide roller.

Generally, to facilitate comparison and/or calculation, the monitoring unit 5 is preferably configured to receive a sensing signal from each of said strain gauges 10 and to generate a numerical force value thereof.

Generally, the people mover may be an escalator, a travelator or a moving ramp. If the people mover is an escalator, the above-mentioned transport element 3a is a step, and if the people mover is a travelator or moving ramp, the above-mentioned transport element 3a is a pallet.

As described above, the width direction W is a horizontal direction and is orthogonal to the longitudinal direction L of the guide rails 4a to 4d, and thus also orthogonal to the direction L in which the conveying element 1 is movable. In the figure, a direction N is also shown, which is a normal direction and is orthogonal to both the width direction W and the longitudinal direction L of the guide rails 4a-4 d. The longitudinal direction L of the guide rails 4a-4d may be horizontal, but this is not essential, as the guide rails may be inclined with respect to the horizontal plane such that their longitudinal axes are at an angle with respect to the horizontal plane. This may be the case if the people mover is a moving ramp or escalator comprising an inclined portion.

In the preferred embodiment described above, strain gauges are used. In addition to the determination of the load position, strain gauges may be used to sense the occurrence of additionally more than one phenomenon related to the safety of the operation of the people mover, for the control and analysis of the flow of people, or for estimating the need for maintenance. For example, dimensional changes caused by guide rollers or their absence may indicate a variety of conditions. The lack of dimensional change when a guide roller is or at least should be placed on top of the sensed guide rail section indicates a problem such as the presence of a staggered guide roller, a staggered step or excessive roller wear or some other problem. On the other hand, excessive dimensional changes may indicate an overload condition, such as an object being wedged between moving parts of a people mover. Typically, sensing may be made to trigger an emergency stop, an alarm signal, or as an input for analysis, for example, to determine an optimal time for maintenance.

It should be understood that the above description and accompanying drawings are only intended to teach the best way known to the inventors for making and using the invention. It is obvious to a person skilled in the art that the inventive concept can be implemented in various ways. Thus, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the above-described embodiments of the present invention may be modified or varied without departing from the invention. It is therefore to be understood that the invention and its embodiments are not limited to the examples described above, but may vary within the scope of the claims.

Claims

1. A monitoring device for a manned vehicle comprises

Conveying elements (1), each conveying element (1) comprising a guide roller (2a-2d) and a tread member (3) having a tread surface (3a) on which a person can stand; and

-a plurality of elongated guides (4a-4d) for guiding and supporting the guide rollers (2a-2d) of the transport element (1);

the plurality of elongated guides (4a-4d) comprises a first side guide (4a) for guiding and supporting guide rollers (2a) of the conveying element (1) on a first side of the conveying element (1) and a second side guide (4a) for guiding and supporting guide rollers (2c) of the conveying element (1) on a second side of the conveying element (1), the first and second sides being opposite sides of the conveying element (1) in a width direction (W) of the people mover; and

a monitoring unit (5) comprising electronic processing means (5 a); and

sensing means (6a-6d) connected to the monitoring unit (5),

characterized in that the sensing means (6a-6d) comprise first sensing means (6a) provided on a guide rail section (7) of the first side guide rail (4a) and arranged to sense a force exerted by a guide roller (2a) of a conveying element (1) on the guide rail section (7) of the first side guide rail (4 a); and second sensing means (6c) provided on a guide rail section (7) of the second side guide rail (4c) and arranged to sense a force exerted by a guide roller (2c) of a conveying element (1) on the guide rail section (7) of the second side guide rail (4 c);

and in that the first and second sensing means (6a, 6c) are connected to the monitoring unit (5);

and in that the monitoring unit (5) is configured to determine a position (P) of a load (L) in a width direction (W) of the people mover, which load is placed on top of the tread surface (3a) of the transportation element (1), on the basis of the forces sensed by the first and second sensing means (6 a; 6c),

the first sensing means (6a) comprises at least one strain gauge (10) fixed on a rail section (7) of the first side rail (4a) and the second sensing means (6c) comprises at least one strain gauge (10) fixed on a rail section (7) of the second side rail (4c), the rail section (7) of the first side rail (4a) to which at least one strain gauge (10) is fixed comprises a slot (8) and the rail section (7) of the second side rail (4b) to which at least one strain gauge (10) is fixed comprises a slot (8),

the guide rail section (7) of the first side guide rail (4a) having an upper side (7a), guide rollers (2a) being arranged to run on top of them, and the guide rail section (7) comprising adjacent slots (8) and strips (9) between each pair of adjacent slots (8), and the strain gauge (10) being fixed on the lower side (7b) of at least one strip (9) and being arranged to sense a change in the dimension of a strip (9),

the first and second sensing devices are directed to the plurality of strips to compare the bending of adjacent strips.

2. A monitoring device of a people mover according to claim 1, characterized in that the determination comprises a comparison of forces sensed by the first sensing means (6a) and the second sensing means (6 c).

3. Monitoring device of a people mover according to any of the preceding claims, characterized in that the monitoring unit (5) is configured to determine that the load (L) is on a first side of the landing surface (3a) of a conveying element (1) in the width direction (W) of the people mover when the force sensed by the first sensing means (6a) is larger than the force sensed by the second sensing means (6c), and to determine that the load (L) is on a second side of the landing surface (3a) of a conveying element (1) in the width direction (W) of the people mover when the force sensed by the first sensing means (6a) is smaller than the force sensed by the second sensing means (6 c).

4. Monitoring device of a people mover according to claim 1 or 2, characterized in that the monitoring unit (5) is configured to determine that the load (L) is central in the width direction (W) of the people mover (1) when the force sensed by the first sensing means (6a) is the same as the force sensed by the second sensing means (6 c).

5. Monitoring device of a people mover according to claim 1 or 2, characterized in that the monitoring unit 5 is configured to trigger one or more predetermined actions if the force sensed by the first sensing means (6a) is larger than the force sensed by the second sensing means (6c) and to refrain from triggering said one or more predetermined actions if the force sensed by the first sensing means (6a) is smaller than the force sensed by the second sensing means (6c) and vice versa.

6. A people mover monitoring apparatus according to claim 1 or 2, characterized in that the determining is configured to comprise calculating a position of a load (L) in a width direction (W) of the people mover (1) based on forces sensed by the first sensing means (6a) and the second sensing means (6 c).

7. A monitoring device of a people mover according to claim 1, characterized in that the guide rail section (7) of the second side guide (4c) has an upper side (7a), that a guide roller (2c) is arranged to run on top of it, and that the guide rail section (7) comprises adjacent slots (8) and a strip (9) between each pair of adjacent slots (8), and that the strain gauge (10) is fixed on the lower side (7b) of at least one strip (9) and arranged to sense a change in the dimension of the strip (9).

8. Monitoring device of a people mover according to the preceding claim 1, the slots (8) being elongated in the longitudinal direction (L) of the guide rails (4a-4d) and being at a distance from each other in the width direction (W) of the guide rails (4a-4d), and the strip (9) is arranged between each pair of adjacent slots (8) in the width direction (W) of the guide rails (4a-4d), and the strip (9) is elongated in the longitudinal direction (L) of the guide rail (4a-4d), and each strain gauge (10) is fixed on the underside (7b) of one of the strips (9), and arranged to sense a change in dimension of the strip (9) in a longitudinal direction (L) of the guide rail (4a-4 d).

9. A people mover monitoring device according to claim 1, characterized in that each of the strain gauges (10) is an ohmic resistance strain gauge.

10. A monitoring arrangement of a people mover according to claim 1, characterized in that each strain gauge (10) comprises a conductor (c) extending in the longitudinal direction of the strain gauge (10), and that the monitoring unit (5) is arranged to monitor an electrical characteristic of the conductor (c).

11. A monitoring device of a people mover according to claim 10, characterized in that the monitoring unit is arranged to monitor the ohmic resistance of the conductor (c).

12. A monitoring device of a people mover according to claim 1, characterized in that the monitoring device is arranged to stop the movement of the transportation element (1) if the change in size sensed by one or more strain gauges (10) exceeds a predetermined limit.

13. A device for monitoring a people mover according to claim 1, characterized in that each of the slots (8) has a length greater than its width, with a length/width ratio greater than 10.

14. A monitoring device of a people mover according to claim 1, characterized in that the slots (8) are straight and parallel to each other.

15. Monitoring device of a people mover according to claim 1 or 2, characterized in that the monitoring device further comprises a position sensor (11) for sensing the position of the guide rollers (2a, 2c) on top of the guide rail section (7) at the point of the strain gauge (10), which position sensor (11) is connected to the monitoring unit (5), wherein the position sensor (11) is arranged to sense the position of the guide rollers (2a, 2c) in the width direction (W) of the guide rail (4a-4 d).

16. Monitoring device of a people mover according to claim 1 or 2, characterized in that the people mover is an escalator, a travelator or a moving ramp.