Sliding door control based on jerk-limited door speed reference curve

Abstract

ASSA ABLOY Entrance Systems AB has developed an automatic door operator (30) for an entrance system (1) that has at least one sliding door (D1…Dm). The automatic door operator (30) has a drive unit (34) being configured, when energized, for causing movement of the sliding door (D1…Dm). A control arrangement (20) is configured for controlling energization of the drive unit (34) to cause the sliding door (D1…Dm) to move at variable door speed between first and second positions of sliding door travel. Controlling energization of the drive unit (34) comprises controlling the actual door speed to track a door speed reference curve (65) which defines respective desired door speeds for different door positions between the first and second positions. The door speed reference curve (65) comprises at least one portion that imposes a limitation on door acceleration change.

Description

[0001] SLIDING DOOR CONTROL BASED ON JERK-LIMITED DOOR SPEED

[0002] REFERENCE CURVE

[0003] TECHNICAL FIELD

[0004] The present invention relates to the technical field of sliding door entrance systems, and more specifically entrance systems of the kind having an automatic door operator for controlling movement of at least one sliding door. In particular, the present invention relates to an automatic door operator for an entrance system of such a kind, an entrance system comprising the automatic door operator, and a related method of operating the automatic door operator.

[0005] BACKGROUND

[0006] Sliding door entrance systems having automatic door operators are frequently used for providing automatic opening and closing of one or more sliding doors in order to facilitate entrance and exit to shops, buildings and other venues, typically in public areas.

[0007] Controlling the movement of sliding doors is subject to various conditions, as identified by the present inventors.

[0008] First of all, there are regulatory requirements that must be followed, for instance regarding the maximum door speed or the maximum driving force applied to a sliding door. The regulatory requirements are both detailed and different between geographical regions.

[0009] Secondly, for reasons of sustainability, it is desired to open and close the sliding door as fast as possible to reduce the heat exchange between the inside and the outside of the entrance system (for instance, between the inside climate in a shop and the outdoor environment).

[0010] Thirdly, there are financial concerns. Operating a sliding door at a higher speed of movement may require a stronger electrical motor in the automatic door operator, which may be more costly component-wise, in addition to a higher expense due to increased consumption of electrical energy for driving the motor.

[0011] A fourth perspective is that of the people around the entrance system (e.g. shop personnel, customers, pedestrians passing by on the street outside, and the general public. The door movement should stay smooth to avoid startling people nearby because of a sudden movement of the sliding door, and also to limit the noise caused by the operation of the sliding door.

[0012] At the same time, a smooth door movement may help to reduce long-time wear and tear of the mechanical components of the drive unit, automatic door operator or other parts of the entrance system, which in turn has benefits both financially and in terms of sustainability (less wear and tear means less malfunction and need for repair or replacements of the mechanical components).

[0013] SUMMARY

[0014] An object of the present invention is therefore to provide one or more improvements in the field of entrance systems having an automatic door operator for controlling movement of at least one sliding door.

[0015] Accordingly, a first aspect of the present invention is an automatic door operator for an entrance system that comprises at least one sliding door. The automatic door operator comprises a drive unit which is configured, when energized, for causing movement of the sliding door. The automatic door operator moreover comprises a control arrangement configured for controlling energization of the drive unit to cause the sliding door to move at variable door speed between first and second positions of sliding door travel. More specifically, controlling energization of the drive unit comprises controlling the actual door speed to track a door speed reference curve which defines respective desired door speeds at respective door positions between the first and second positions, wherein at least one portion of the door speed reference curve imposes a limitation on door acceleration change..

[0016] The first and second positions of sliding door travel are typically at or near the respective end positions of the sliding door when being moved from a fully closed to a fully opened position, and vice versa.

[0017] The present inventors have realized that controlling the energization of the drive unit by controlling the actual door speed to track a door speed reference curve which defines respective desired door speeds for different door positions between the first and second positions of sliding door travel, with at least one portion of the door speed reference curve imposing a limitation on door acceleration change, will allow optimizing the sliding door movement with respect to the various conditions presented in the Background section above.

[0018] Notably, the door speed reference is not a function of time during door actuation, but of actual door position during door actuation. This allows for tracking of the door speed reference very closely and will therefore contribute to meeting the various conditions as required. Also, not building the door movement control upon a door speed reference as a function of time during door actuation will avoid a problem that could otherwise occur should the sliding door be blocked by an object or person. Had the door speed reference been a function of time, the door speed reference would rise even though the door still remains at the same position, leading to inaccurate and even dangerous door movement control.

[0019] Defining the door speed reference curve such that at least one portion of it imposes a limitation on door acceleration change will contribute to smoothing the door speed reference curve itself, and therefore also the resulting control of the door movement. This may be particularly beneficial for reducing the long-time wear and tear of the mechanical components of the drive unit, automatic door operator or other parts of the entrance system.

[0020] In a nutshell, the present invention presents a sophisticated approach to sliding door movement control by iteratively calculating a door speed reference value based on the current door position. An optimized door speed reference curve may be obtained which in turn enables an optimized sliding door movement control, thus facilitating meeting of the various conditions presented in the Background section.

[0021] In one or more embodiments of the present invention, the control arrangement comprises a plurality of modules as follows:

[0022] • A door position module configured for repeatedly determining positions of the sliding door.

[0023] • A door speed control module coupled to the door position module and configured for repeatedly determining: o from the determined positions of the sliding door, a present door speed, o from a determined present position of the sliding door and the door speed reference curve, a desired door speed, and o from the present door speed and the desired door speed, a drive unit energization reference value.

[0024] • A drive unit control module coupled to the door speed control module and to the drive unit and configured for controlling energization of the drive unit based on present energization of the drive unit and the determined drive unit energization reference value as repeatedly determined by the door speed control module.

[0025] The door position module, door speed control module and drive unit control module may be implemented, in one or more embodiments of the present invention, as functional modules of software or firmware executable by a hardware processing device of the automatic door operator.

[0026] In one or more embodiments of the present invention, the drive unit comprises a motor, and the drive unit control module is configured for controlling the energization of the drive unit by controlling a motor current of the motor. Such embodiments may further comprise a rotary encoder positioned for detecting rotation of a motor shaft of the motor, wherein the door position module may be configured for determining the positions of the sliding door from an output of the rotary encoder.

[0027] In one or more embodiments of the present invention, the door speed reference curve is divided into different parts from the first position to the second position:

[0028] • An acceleration part that defines accelerating movement of the sliding door from a position at or close to the first position of sliding door travel.

[0029] • A constant speed part for positions of the sliding door following after an end of the acceleration part.

[0030] • A deceleration part for positions of the sliding door following after the constant speed part and ending at or close to the second position of sliding door travel, the deceleration part defining decelerating movement of the sliding door.

[0031] In some embodiments, there may be no constant speed part. In such cases, the deceleration part will follow directly after the acceleration part.

[0032] In one or more embodiments of the present invention, the acceleration part of the door speed reference curve may follow, or be approximated with, an elliptic curve, while the deceleration part of the door speed reference curve may follow, or be approximated with, a linear curve. This may represent a convenient implementation.

[0033] In one or more refined embodiments of the present invention, particularly beneficial for reducing the risk of wear and tear of mechanical components, the deceleration part of the door speed reference curve may follow a linear curve except for an initial part that follows an elliptic curve.

[0034] In one or more embodiments of the present invention, the door speed reference curve further comprises a creep part for positions of the sliding door following after the deceleration part and the second position of sliding door travel, the creep part defining a second constant speed movement of the sliding door at a lower constant speed than the constant speed part. The provision of a creep part at the end of the door speed reference curve may facilitate a smooth and accurate conclusion of the sliding door movement to bring the sliding door to a complete stop at a final position slightly beyond the second position of sliding door travel.

[0035] Advantageously, the door speed reference curve may impose the limitation on door acceleration change by limiting to zero door acceleration change at least according to one or more of the following: at the beginning of accelerating movement of the sliding door, at the end of accelerating movement of the sliding door, at the beginning of decelerating movement of the sliding door, and at the end of decelerating movement of the sliding door. Further features and advantages of embodiments of the first aspect of the present invention will appear from the following detailed description as well as the drawings and the appended claims.

[0036] A second aspect of the present invention is an entrance system comprising one or more sliding doors and an automatic door operator according to the first aspect of the present invention, connected to the one or more sliding doors for causing movement thereof. The entrance system according to the second aspect of the present invention may have any or all features and advantages as provided by the automatic door operator according to the first aspect of the present invention, including any of its embodiments.

[0037] A third aspect of the present invention is a method of operating an automatic door operator for an entrance system that comprises at least one sliding door. According to the method, energization of a drive unit of the automatic door operator is controlled to cause the sliding door to move at variable door speed between first and second positions of sliding door travel, wherein controlling energization of the drive unit comprises controlling the actual door speed to track a door speed reference curve which defines respective desired door speeds for different door positions between the first and second positions. At least one portion of the door speed reference curve imposes a limitation on door acceleration change.

[0038] The method according to the third aspect of the present invention may have any or all advantages and functional features corresponding to those that are provided by the automatic door operator according to the first aspect of the present invention, including any of its embodiments.

[0039] It should be emphasized that the term “comprises / comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the [element, device, component, means, step, etc.]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Objects, features and advantages of embodiments of the invention will appear from the following detailed description, reference being made to the accompanying drawings. Figure l is a schematic block diagram of an entrance system generally according to the present invention or embodiments thereof, the entrance system having an automatic door operator for causing movement of at least one sliding door.

[0042] Figure 2 is a schematic block diagram of an automatic door operator which may be included in the entrance system shown in Figure 1.

[0043] Figure 3 is a schematic block diagram of a control arrangement of an automatic door operator in embodiments of the present invention.

[0044] Figure 4 serves to illustrate the concept of jerk-limited driving, by way of position, speed, acceleration and jerk graphs.

[0045] Figure 5 is a schematic illustration of a door speed reference curve for use in a first embodiment of the present invention, the door speed reference curve defining respective desired door speeds at respective door positions between first and second positions of sliding door travel.

[0046] Figure 6 presents position, speed, acceleration and jerk graphs for an exemplifying use of the door speed reference curve in Figure 5.

[0047] Figure 7 serves to illustrate a problem that may occur with a door speed reference curve having a solely linear deceleration part.

[0048] Figure 8 serve to illustrate a solution to the problem identified in Figure 7, the solution including a modification of the door speed reference curve.

[0049] Figure 9 is a schematic illustration of a door speed reference curve for use in a second embodiment of the present invention, the door speed reference curve being modified in accordance with the solution illustrated in Figure 8.

[0050] Figure 10 presents position, speed, acceleration and jerk graphs for an exemplifying use of the door speed reference curve in Figure 9.

[0051] Figure 11 is a schematic top view of an entrance system with two sliding doors.

[0052] DETAILED DESCRIPTION OF EMBODIMENTS

[0053] Embodiments of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.

[0054] By way of introduction, Figure 1 is a schematic block diagram illustrating an entrance system 1 in which the inventive aspects of the present invention may be applied. The entrance system 1 comprises one or more movable sliding doors DI . . .Dm, and an automatic door operator 30 for causing movements of the sliding door(s) DI . . .Dm, typically between closed and open positions (first and second positions of sliding door travel). In Figure 1, a transmission mechanism 40 conveys mechanical power from the automatic door operator 30 to the sliding door(s) DI . . .Dm. As is customary, the transmission mechanism 40 may comprise elements such as rails, belts, cables, gears, wheels and wagons, without limitation. Figure 2 illustrates an embodiment of the automatic door operator 30 in some more detail. An example of a sliding door entrance system will also be described later with reference to Figure 11.

[0055] As can be seen in Figure 2, the automatic door operator 30 comprises a controller 32. Moreover, a plurality of sensor units SI ... Sn is provided. Each sensor unit may generally be connected to the controller 32 by wired connections, wireless connections, or any combination thereof. As will be exemplified in the subsequent description of the sliding door entrance system in Figure 11, each sensor unit is arranged to monitor a respective zone Z1 . . .Zn at the entrance system 1 for presence or activity of a person or object. The person may be an individual who is present at the entrance system 1, is approaching it or is departing from it. The object may, for instance, be an animal or an article in the vicinity of the entrance system 1, for instance brought by the aforementioned individual. Alternatively, the object may be a vehicle or a robot. In alternative embodiments, there may be just a single sensor unit (i.e., n=l).

[0056] The automatic door operator 30 may typically be arranged in conjunction with a frame or other structure which supports the door members DI . . .Dm for the sliding movements between closed and open positions and vice versa, often as a concealed overhead installation in or at the frame or support structure.

[0057] In addition to the aforementioned controller 32, the automatic door operator 30 comprises a drive unit 34 which is configured, upon energization, for conveying mechanical power via the transmission mechanism 40 to the sliding door(s) DI . . .Dm, so make them move in opening and closing directions. In alternative embodiments, there may be more than one drive unit.

[0058] The automatic door operator 30 has a power unit 38b that supplies power to the drive unit 34, controller 32 and other components of the automatic door operator 30 as appropriate. The power unit 38b typically comprises an AC / DC converter, such as a switch mode power supply (SMPS), having an input end coupled to AC mains 38a and an output end for supplying internal DC power to the drive unit 34, controller 32, etc.

[0059] In addition to the power unit 38b, the disclosed embodiment of the automatic door operator 30 furthermore comprises a battery 39 that may supply power to the drive unit 34, etc., for instance in an evacuation operating mode of the automatic door operator 30, or in times of AC mains power shortage. The battery 39 may be coupled for charging by the power unit 38b, or alternatively by other means, such as external battery charging equipment. Preferably, therefore, the battery 39 is a rechargeable battery made from, for instance, lithium-ion (Li-ion), lithium-ion polymer (Li-ion polymer), nickel-metal hydride (NiMH), nickel-cadmium (NiCd) or lead-acid technology. In alternative embodiments, there may be no battery.

[0060] The controller 32 may be implemented in any known controller technology, including but not limited to a microcontroller, processor (e.g. PLC, CPU, DSP), FPGA, ASIC or any other suitable digital and / or analog circuitry capable of performing the intended functionality. The controller 32 in the disclosed embodiment is therefore a hardware processing device.

[0061] The controller 32 also has an associated memory 33. The memory 33 may be implemented in any known memory technology, including but not limited to E(E)PROM, S(D)RAM or flash memory, or any combination thereof. In some embodiments, the memory 33 may be wholly or partly integrated with or internal to the controller 32. The memory 33 may store program (software) instructions 33a for loading into the controller 32. Once loaded into the controller 32, the program (software) instructions 33a are executable by the controller 32. Alternatively or additionally, the controller 32 may comprise executable firmware instructions 33a. The memory 33 may furthermore store temporary and permanent data used by the controller 32, as seen at 33b and 32b.

[0062] The automatic door operator 30 may be operable in different operating modes. The controller 32 is arranged for performing various functions of the automatic door operator 30 in these operating modes, using inter alia sensor input data from the plurality of sensor units SI . . . Sn. Hence, the controller 32 is operatively connected with the plurality of sensor units SI ... Sn. At least some of the functions performable in the different operating modes by the controller 32 serve to cause desired movements of the door members DI . . .Dm. To this end, the controller 32 has at least one control output connected to the drive unit 34 for controlling the actuation thereof.

[0063] In the embodiment shown in Figure 2, the entrance system 1 has a communication bus 37. Some or all of the plurality of sensor units SI ... Sn are connected to the communication bus 37, and so is the automatic door operator 30. In the disclosed embodiment, the controller 32 and the memory 33 of the automatic door operator 30 are connected to the communication bus 37; in other embodiments this may be the case for other devices or components of the automatic door operator 30. In still other embodiments, the outputs of the plurality of sensor units SI . . . Sn may be directly connected to respective data inputs of the controller 32. The automatic door operator 30 in Figure 2 is enabled for external data communication by means of a data communication interface 36 which is furthermore connected to the communication bus 37 at 36a. The external data communication is typically made with another communication device or system over a data communication network 36b, such as a wide area network (WAN) or local area network (LAN). Accordingly, the data communication network 36b may comply with any commercially available mobile telecommunications standard, including but not limited to GSM, UMTS, LTE, 5G, D-AMPS, CDMA2000, FOMA and TD-SCDMA. Alternatively or additionally, the data communication network 36b may comply with one or more short- range wireless data communication standards such as Bluetooth®, BLE, WiFi (e.g. IEEE 802.11, wireless LAN), Near Field Communication (NFC), RFID (Radio Frequency Identification) or Infrared Data Association (IrDA). In some embodiments, the communication may be wired, such as USB or TCP / IP over Ethernet. An operator panel 10 may be operatively connected to the automatic door operator 30 by data communication 1 lb via the data communication interface 36, by being connected to the bus 37, as is seen at I la, or by being connected directly to I / O terminals of the controller 32.

[0064] Figure 3 illustrates a control arrangement 20 of the automatic door operator 30 in embodiments of the present invention. The control arrangement 20 is configured for controlling energization of the drive unit 34 to cause the sliding door (or each sliding door) DI . . .Dm to move at variable door speed between first and second positions of sliding door travel. The first and second positions of sliding door travel are typically at or near the respective end positions of the sliding door when being moved from a fully closed to a fully opened position, and vice versa. Examples of the first and second positions of sliding door travel are seen at 81 and 82 in Figures 5 and 10, to be described in more detail later.

[0065] More specifically, controlling energization of the drive unit 34 comprises controlling the actual door speed to track a door speed reference curve 65 which defines respective desired door speeds for different door positions between the first and second positions 81, 82. At least one portion of the door speed reference curve 65 imposes a limitation on door acceleration change. Here, “door acceleration change” is to be understood as jerk (also known as jolt). As is well-known as such, jerk j(t) is the rate of change of an object's (in this case the sliding door’s) acceleration over time t. The jerk j(t) can be expressed as the first time derivative of acceleration a(t), second time derivative of velocity v(t), and third time derivative of position p(t).

[0066] An underlying idea here is to obtain a smooth driving of the sliding door DI . . .Dm by limiting the jerk. Limiting the jerk leads to a continuous, trapezoidal acceleration signal which in turn leads to an S-curve in the velocity signal which is perceived as a smooth door movement. Figure 4 illustrates the concept of jerk-limited drive by four graphs representing, from top to bottom, the position p(l), the velocity (speed) v(t), the acceleration a(t) and the jerk j(t) for a sliding door during a 4,5 s period of time t. Note that the graphs in Figure 4 do not illustrate the door speed reference curve 65 as such (recalling that the door speed reference curve defines respective desired door speeds at respective door positions as opposed to time, for reasons that will be explained in more detail later).

[0067] Referring back to Figure 3, the control arrangement 20 of the automatic door operator 30 generally comprises three functional modules: a door position module 50, a door speed control module 60 and a drive unit control module 70. These three functional modules 50, 60 and 70 may be implemented by software or firmware 33a, 32a executable by the aforementioned hardware processing device (controller) 32 of the automatic door operator 30.

[0068] The door position module 50 is configured for repeatedly determining positions 55 of the sliding door DI . . .Dm by functionality 52.

[0069] The door speed control module 60 is coupled to the door position module 50 and is configured for repeatedly receiving the determined positions 55 of the sliding door DI . . .Dm and determining a present door speed 63 by functionality 62. The functionality 62 may operate on the received positions 55 to determine the present speed essentially as a first time derivative of the positions 55 as they vary over a time period. Depending on implementation and as needed for this operation, the functionality 62 may buffer the received positions 55 as seen at 61.

[0070] The door speed control module 60 further has functionality 64 configured for repeatedly determining a desired door speed 67 from a determined present position 55 of the sliding door DI . . .Dm and using the aforementioned door speed reference curve 65, as seen at 66.

[0071] Moreover, the door speed control module 60 has functionality 68 configured for repeatedly determining, from the present door speed 63 and the desired door speed 67, a drive unit energization reference value 69.

[0072] The drive unit control module 70 is coupled to the door speed control module 60 and to the drive unit 34. The drive unit control module 70 has functionality 72 configured for controlling energization 75 of the drive unit 34 based on present energization 73 of the drive unit 34 and the determined drive unit energization reference value 69, as repeatedly determined by the door speed control module 60.

[0073] Notably, the door speed reference curve 65 is not a function of time during door actuation, but of actual door position during door actuation. This allows for tracking the door speed reference very closely and will therefore contribute to meeting the various conditions as required. Also, not building the door movement control upon a door speed reference as a function of time during door actuation will avoid a problem that could otherwise occur should the sliding door be blocked by an object or person. In such a situation, a door speed reference being a function of time would rise even though the door still remains at the same position, leading to inaccurate and even dangerous door movement control.

[0074] In the disclosed embodiment, the drive unit 34 comprises an electric motor 35 having an output shaft 35c coupled with an internal gear box 35d, as is customary per se. In turn, the internal gear box 35d is coupled with the transmission mechanism 40 and ultimately the sliding door(s) DI . . .Dm. In this embodiment, the drive unit control module 70 is thus configured for controlling 75 the energization of the drive unit 34 by controlling a motor current 73 of the motor 35. This may be done by customary control, such as PWM (pulse width modulation) to drive the motor 35 with a varying duty cycle of DC voltage to cause variations of the rotational speed of the motor 35. In alternative embodiments, there may be no internal gear box.

[0075] The disclosed embodiment further comprises a rotary encoder 35a positioned for detecting rotation of an input shaft 35b (or alternatively the output shaft 35c) of the motor 35. As is commonplace, the encoder 35a is an electromechanical device that converts the angular position or motion of the motor shaft 35b or 35c to electric output signals.

[0076] Accordingly, the functionality 52 of the door position module 50 is configured for determining the positions of the sliding door DI . . .Dm from an output 51 of the rotary encoder 35a. To this end, the functionality 52 may keep track of a count 53 of a present number of revolutions of the shaft 35b or 35c and convert it to a door position 55, as is customary per se. Alternative embodiments may use other means for determining the positions of the sliding door DI . . .Dm, such as a Hall sensor arrangement or a sensorless door position estimation arrangement,

[0077] The door speed reference curve 65 will now be discussed in more detail. In a first embodiment, the door speed reference curve 65 may generally take the form as illustrated in Figure 5. As can be seen, the door speed reference curve 65 maps different positions (55 in Figure 3) of the sliding door DI . . .Dm, as represented by the x-axis of the diagram, to desired door speeds (67 in Figure 3), as represented by the y-axis of the diagram. The door speed reference curve 65 is divided into different parts from the first position 81 (e.g. the start position of the sliding door member, such as a fully opened position or a fully closed position) to the second position 82 (e.g. the end position of the sliding door member, such as the other one of the fully closed or fully opened position) of sliding door travel.

[0078] The acceleration part 91 defines accelerating movement of the sliding door DI . . .Dm from a position at or close to the first position 81 of sliding door travel.

[0079] The constant speed part 92 is for positions of the sliding door DI . . .Dm following after an end of the acceleration part 91. The constant speed part 92 defines constant speed movement of the sliding door DI . . .Dm.

[0080] The deceleration part 93 is for positions of the sliding door DI . . .Dm following after the constant speed part 92 and ending at or close to the second position 82 of sliding door travel. The deceleration part 93 defines decelerating movement of the sliding door DI . . .Dm.

[0081] One way to limit door acceleration change is to approximate the acceleration part 91 of the door speed reference curve 65 with an elliptic curve, as can be seen in the encircled portion 91a of the door speed reference curve 65 in Figure 5. Some mathematic explanations on how to derive the door speed reference curve 65 with the elliptic acceleration part 91 will now follow. Starting with nomenclature:

[0082] Then, for the acceleration part 91 where p P start and p < Pstart + ace, an ellipsoid is used:

[0083] With reference to Figure 5, the speed reference values vref(p) (cf. desired door speed 67, Figure 3) pertain to the y-axis of the curve, whereas the position values p (cf. door position 55, Figure 3) pertain to the x-axis of the curve.

[0084] For the constant speed part 92, where p > P start + dace and p < perid - d acc-> i.e. between acceleration and deceleration, the door travels at maximum speed, vmax. If the distance is not long enough to reach the maximum speed vmax, the door directly switches from acceleration to deceleration, and there is in effect no constant speed phase in such a case. In other words, alternative embodiments are possible for which the door speed reference curve does not have a constant speed part. In such cases, the deceleration part will follow directly after the acceleration part. The inventors have identified a drawback if using a (fully) elliptic curve also for the deceleration part 93, like for the acceleration part 91. The door would crash into its end stops because a) there is always a delay between the velocity reference and the actual reference, and b) the velocity reference is still quite high close to the end position. To mitigate this problem, the disclosed embodiment of Figure 5 instead uses a linear curve for the deceleration part 93, which applies for positions p > pend - dace'.

[0085] For the boundary conditions p = poid and p = poid + ace, respectively:

[0086] As can be seen for the disclosed embodiment in Figure 5, the door speed reference curve 65 further comprises a creep part 94 for positions of the sliding door DI . . .Dm following after the deceleration part 93 and the second position 82 of sliding door travel. The creep part 94 defines a second constant speed movement of the sliding door DI . . .Dm at a lower constant speed than the constant speed part 92. The creep part 94 may be beneficial for bringing the sliding door DI . . .Dm safely all the way to its final end position (being slightly beyond the second position 82 of sliding door travel).

[0087] Figure 6 presents position, speed, acceleration and jerk graphs for an exemplifying use of the door speed reference curve in Figure 5.

[0088] A refined embodiment of the door speed reference curve 65 will now be described with reference to Figures 7 to 10. The present inventors have identified a potential for further improvement as follows.

[0089] When using a linear deceleration curve, like the aforementioned linear deceleration curve 93 described above with reference to Figure 5, instead of a (fully) elliptic deceleration curve (corresponding to the elliptic acceleration curve 91 described above with reference to Figure 5), an unpleasant edge may occur between constant speed and linear deceleration. Such an edge is seen at 100 in a schematic speed vs time graph in Figure 7. This may lead to a rather aggressive gear backlash between teeth of interacting gears in the gear box 35d of the drive unit 34 or in the transmission mechanism 40, causing audible noise and increasing component wear and tear. Softening the torque direction change may beneficially reduce noise and wear.

[0090] As is illustrated in Figure 8, the solution according to the refined embodiment is to use a part of the elliptic deceleration curve to create a smooth transition 130 between the constant speed phase and the linear deceleration phase, i.e. between points a and b of the door speed reference curve 65. In effect, this means that the deceleration part 93 of the door speed reference curve 65 is divided into two sections, which are seen at 93a and 93b in Figure 9.

[0091] The door speed reference curve 65 in the refined embodiment of Figure 9 comprises an acceleration part 91 and a creep part 94 which can be the same as in the embodiment of Figure 5. The constant speed part 92 is modified to the extent that it applies for p > Pstart + b acc and p Pend ~ dl-d acc i.e. it ends a bit sooner than in Figure 5 but the door speed is the same maximum speed, vmax. Again, if the distance is not long enough to reach the maximum speed vmax, the door directly switches from acceleration to deceleration, and there is in effect no constant speed phase in such a case.

[0092] As can be seen in Figure 9, an initial section 93a of the deceleration part 93 of the door speed reference curve 65 follows an elliptic curve. It applies for positions p > Pend ~ dl-d acc and p Pend (l / 2)-<5 acc, and can be expressed mathematically as follows:

[0093] As can be further seen in Figure 9, a second section 93b of the deceleration part 93 of the door speed reference curve 65 makes up the rest of the deceleration part 93, applies for positions p Pend / (1 / 2)-<5 acc and p < pend, and follows a linear curve. It can be derived mathematically as follows: For the boundary conditions p = poid and p = poid + ace, respectively:

[0094] Figure 10 presents position, speed, acceleration and jerk graphs for an exemplifying use of the door speed reference curve in Figure 9.

[0095] An exemplifying embodiment of the entrance system 1 will now be described with reference to Figure 11, in the form of a sliding door system 410 which is shown in a schematic top view. The sliding door system 410 comprises first and second sliding doors (a.k.a. door wings, door panels or door members) DI and D2, being supported for sliding movements 450i and 4502 in parallel with first and second wall portions 460 and 464. The first and second wall portions 460 and 464 are spaced apart; in between them there is formed an opening which the sliding doors DI and D2 either blocks (when the sliding doors are in closed positions), or makes accessible for passage (when the sliding doors are in open positions). An automatic door operator (not seen in Figure 11 but referred to as 30 in Figures 1 and 2) causes the sliding movements 450i and 4502 of the sliding doors DI and D2.

[0096] The sliding door system 410 comprises a plurality of sensor units, each monitoring a respective zone Z1-Z6. The sensor units themselves are not shown in Figure 11, but they are generally mounted at or near ceiling level and / or at positions which allow them to monitor their respective zones Z1-Z6. To facilitate the reading, each sensor unit will be referred to as Sx in the following, where x is the same number as in the zone Zx it monitors (Sx being selected from {SI . . . S6}, Zx being selected from {Z1...Z6}.

[0097] A first sensor unit SI is mounted at a lateral positon to the far left in Figure 11 to monitor zone Zl. The first sensor unit SI is a side presence sensor, and the purpose is to detect when a person or object occupies a space between the outer lateral edge of the sliding door DI and an inner surface of a wall or other structure 462 when the sliding door DI is moved towards the left in Figure 11 during an opening state of the sliding door system 410. The provision of the side presence sensor SI will help avoiding a risk that the person or object will be hit by the outer lateral edge of the sliding door DI, and / or jammed between the outer lateral edge of the sliding door DI and the inner surface of the wall 462, by triggering abort and preferably reversal of the ongoing opening movement of the sliding door DI. A second sensor unit S2 is mounted at a lateral positon to the far right in Figure 11 to monitor zone Z2. The second sensor unit S2 is a side presence sensor, just like the first sensor unit SI, and has the corresponding purpose - i.e. to detect when a person or object occupies a space between the outer lateral edge of the sliding door D2 and an inner surface of a wall 466 when the sliding door D2 is moved towards the right in Figure 11 during the opening state of the sliding door system 410.

[0098] A third sensor unit S3 is mounted at a first central positon in Figure 11 to monitor zone Z3. The third sensor unit S3 is a door presence sensor, and the purpose is to detect when a person or object occupies a space between or near the inner lateral edges of the sliding doors DI and D2 when the sliding doors DI are moved towards each other in Figure 11 during a closing state of the sliding door system 410. The provision of the door presence sensor S3 will help avoiding a risk that the person or object will be hit by the inner lateral edge of the sliding door DI or D2, and / or be jammed between the inner lateral edges of the sliding doors DI and D2, by aborting and preferably reversing the ongoing closing movements of the sliding doors DI and D2.

[0099] A fourth sensor unit S4 is mounted at a second central positon in Figure 11 to monitor zone Z4. The fourth sensor unit S4 is a door presence sensor, just like the third sensor unit S3, and has the corresponding purpose - i.e. to detect when a person or object occupies a space between or near the inner lateral edges of the sliding doors DI and D2 when the sliding doors DI are moved towards each other in Figure 11 during a closing state of the sliding door system 410.

[0100] The side presence sensors SI and S2 and door presence sensors S3 and S4 may be image-based sensor units, active IR (infrared) sensor unit, etc.

[0101] A fifth sensor unit S5 is mounted at an inner central positon in Figure 11 to monitor zone Z5. The fifth sensor unit S5 is an inner activity sensor, and the purpose is to detect when a person or object approaches the sliding door system 410 from the inside of the premises. The provision of the inner activity sensor S5 will trigger the sliding door system 410, when being in a closed state or a closing state, to automatically switch to an opening state for opening the sliding doors DI and D2, and then make another switch to an open state when the sliding doors DI and D2 have reached their fully open positions.

[0102] A sixth sensor unit S6 is mounted at an outer central positon in Figure 11 to monitor zone Z6. The sixth sensor unit S6 is an outer activity sensor, and the purpose is to detect when a person or object approaches the sliding door system 410 from the outside of the premises. Similar to the inner activity sensor S5, the provision of the outer activity sensor S6 will trigger the sliding door system 410, when being in its closed state or its closing state, to automatically switch to the opening state for opening the sliding doors DI and D2, and then make another switch to an open state when the sliding doors DI and D2 have reached their fully open positions.

[0103] The inner activity sensor S5 and the outer activity sensor S6 may, for instance, be radar (microwave) sensor units or image-based sensor units.

[0104] As the skilled reader will readily understand, the invention disclosed in this document additionally pertains to a method of operating an automatic door operator 30 for an entrance system 1 that comprises at least one sliding door DI . . .Dm. The method comprising controlling energization of a drive unit 34 of the automatic door operator 30 to cause the sliding door DI . . .Dm to move at variable door speed between first and second positions of sliding door travel, wherein controlling energization of the drive unit 34 comprises controlling the actual door speed to track a door speed reference curve 65 which defines respective desired door speeds for different door positions between the first and second positions, and wherein at least one portion of the door speed reference curve 65 imposes a limitation on door acceleration change.

[0105] As will be understood particularly from Figure 3, the method may beneficially comprise the following:

[0106] • repeatedly determining positions of the sliding door DI . . .Dm;

[0107] • repeatedly determining: o from the determined positions 55, 61 of the sliding door DI . . .Dm, a present door speed 63, o from a determined present position 55 of the sliding door DI . . .Dm and the door speed reference curve 65, a desired door speed 67, o from the present door speed 63 and the desired door speed 67, a drive unit energization reference value 69; and

[0108] • controlling energization 75 of the drive unit 34 based on present energization 73 of the drive unit 34 and the repeatedly determined drive unit energization reference value 69.

[0109] As will be understood particularly from Figures 5 and 9, the door speed reference curve 65 may advantageously be divided into different parts from the first position 81 to the second position 82 of sliding door travel:

[0110] • an acceleration part 91 that defines accelerating movement of the sliding door DI . . .Dm from a position at or close to the first position 81;

[0111] • a constant speed part 92 for positions of the sliding door DI . . .Dm following after an end of the acceleration part 91, the constant speed part 92 defining constant speed movement of the sliding door DI . . .Dm; and

[0112] • a deceleration part 93 for positions of the sliding door DI . . .Dm following after the constant speed part 92 and ending at or close to the second position 82 of sliding door travel, the deceleration part 93 defining decelerating movement of the sliding door DI . . .Dm.

[0113] Advantageously, the method may operate on a door speed reference curve 65, the acceleration part 91 of which follows an elliptic curve. The deceleration part 93 of the door speed reference curve 65 may follow an entirely linear curve (as seen in Figure 5), or a linear curve except for an initial section that follows an elliptic curve (as seen at 93a and 93b in Figure 9).

[0114] The door speed reference curve 65 may further comprise a creep part 94 for positions of the sliding door DI . . .Dm following after the deceleration part 93 and the second position 82 of sliding door travel, the creep part 94 defining a second constant speed movement of the sliding door DI . . .Dm at a lower constant speed than the constant speed part 92.

[0115] It is recalled that alternative embodiments are possible for which the door speed reference curve does not have a constant speed part, wherein the deceleration part will follow directly after the acceleration part.

[0116] Finally, the invention has been described above in detail with reference to embodiments thereof. However, as is readily understood by those skilled in the art, other embodiments are equally possible within the scope of the present invention, as defined by the appended claims.

Claims

CLAIMS1. An automatic door operator (30) for an entrance system (1) that comprises at least one sliding door (DI . . .Dm), the automatic door operator (30) comprising: a drive unit (34) configured, when energized, for causing movement of the sliding door (DI . . .Dm); and a control arrangement (20) configured for controlling energization of the drive unit (34) to cause the sliding door (DI . . .Dm) to move at variable door speed between first and second positions (81, 82) of sliding door travel, wherein controlling energization of the drive unit (34) comprises controlling the actual door speed to track a door speed reference curve (65) which defines respective desired door speeds for different door positions between the first and second positions (81, 82), wherein at least one portion of the door speed reference curve (65) imposes a limitation on door acceleration change.

2. The automatic door operator (30) as defined in claim 1, wherein the control arrangement (20) comprises: a door position module (50) configured for repeatedly determining positions (55) of the sliding door (DI . . .Dm); a door speed control module (60) coupled to the door position module (50) and configured for repeatedly determining: from the determined positions (55, 61) of the sliding door (DI . . .Dm), a present door speed (63), from a determined present position (55) of the sliding door (DI . . .Dm) and the door speed reference curve (65), a desired door speed (67), from the present door speed (63) and the desired door speed (67), a drive unit energization reference value (69); and a drive unit control module (70) coupled to the door speed control module (60) and to the drive unit (34) and configured for controlling energization (75) of the drive unit (34) based on present energization (73) of the drive unit (34) and the determined drive unit energization reference value (69) as repeatedly determined by the door speed control module (60).

3. The automatic door operator (30) as defined in claim 2, wherein the door position module (50), door speed control module (60) and drive unit control module (70) are functional modules of software or firmware executable by a hardware processing device (32) of the automatic door operator (30).

4. The automatic door operator (30) as defined in any preceding claim, wherein the drive unit (34) comprises a motor (35), and the drive unit control module (70) is configured for controlling (75) the energization of the drive unit (34) by controlling a motor current (73) of the motor (35).

5. The automatic door operator (30) as defined in claim 4, further comprising a rotary encoder (35a) positioned for detecting rotation of a motor shaft (35b) of said motor (35), wherein the door position module (50) is configured for determining the positions of the sliding door (DI . . .Dm) from an output (51) of the rotary encoder (35a).

6. The automatic door operator (30) as defined in any preceding claim, the door speed reference curve (65) being divided into different parts from the first position (81) to the second position (82): an acceleration part (91) that defines accelerating movement of the sliding door (DI . . .Dm) from a position at or close to the first position (81) of sliding door travel; a constant speed part (92) for positions of the sliding door (DI . . .Dm) following after an end of the acceleration part (91), the constant speed part (92) defining constant speed movement of the sliding door (DI . . .Dm); and a deceleration part (93) for positions of the sliding door (DI . . .Dm) following after the constant speed part (92) and ending at or close to the second position (82) of sliding door travel, the deceleration part (93) defining decelerating movement of the sliding door (DI . . .Dm).

7. The automatic door operator (30) as defined in claim 6, wherein the acceleration part (91) of the door speed reference curve (65) follows an elliptic curve (91a).

8. The automatic door operator (30) as defined in claim 6 or 7, wherein the deceleration part (93) of the door speed reference curve (65) follows a linear curve.

9. The automatic door operator (30) as defined in claim 6 or 7, wherein the deceleration part (93) of the door speed reference curve (65) follows a linear curve (93b) except for an initial section that follows an elliptic curve (93a).

10. The automatic door operator (30) as defined in any of claims 6 to 9, wherein the door speed reference curve (65) further comprises a creep part (94) for positions ofthe sliding door (DI . . .Dm) following after the deceleration part (93) and the second position (82) of sliding door travel, the creep part (94) defining a second constant speed movement of the sliding door (DI . . .Dm) at a lower constant speed than the constant speed part (92).

11. The automatic door operator (30) as defined in any preceding claim, wherein the door speed reference curve (65) imposes said limitation on door acceleration change by limiting to zero door acceleration change at least according to one or more of the following: at the beginning of accelerating movement of the sliding door (DI . . .Dm); at the end of accelerating movement of the sliding door (DI . . .Dm); at the beginning of decelerating movement of the sliding door (DI . . .Dm); at the end of decelerating movement of the sliding door (DI . . .Dm).

12. An entrance system (1) comprising: one or more sliding doors (DI . . .Dm); and an automatic door operator (30) according to any of claims 1-11, connected to the one or more sliding doors (DI . . .Dm) for causing movement thereof.

13. A method of operating an automatic door operator (30) for an entrance system (1) that comprises at least one sliding door (DI . . .Dm), the method comprising: controlling energization of a drive unit (34) of the automatic door operator (30) to cause the sliding door (DI . . .Dm) to move at variable door speed between first and second positions of sliding door travel, wherein controlling energization of the drive unit (34) comprises controlling the actual door speed to track a door speed reference curve (65) which defines respective desired door speeds for different door positions between the first and second positions, wherein at least one portion of the door speed reference curve (65) imposes a limitation on door acceleration change.

14. The method as defined in claim 13, comprising repeatedly determining positions of the sliding door (DI . . .Dm); repeatedly determining: from the determined positions (55, 61) of the sliding door (DI . . .Dm), a present door speed (63), from a determined present position (55) of the sliding door (DI . . .Dm) and the door speed reference curve (65), a desired door speed (65),from the present door speed (63) and the desired door speed (65), a drive unit energization reference value (69); and controlling energization (75) of the drive unit (34) based on present energization (73) of the drive unit (34) and the repeatedly determined drive unit energization reference value (69).

15. The method as defined in claim 13 or 14, wherein the door speed reference curve (65) is divided into different parts from the first position (81) to the second position (82): an acceleration part (91) that defines accelerating movement of the sliding door (DI . . .Dm) from a position at or close to the first position (81) of sliding door travel; a constant speed part (92) for positions of the sliding door (DI . . .Dm) following after an end of the acceleration part (91), the constant speed part (92) defining constant speed movement of the sliding door (DI . . .Dm); and a deceleration part (93) for positions of the sliding door (DI . . .Dm) following after the constant speed part (92) and ending at or close to the second position (82) of sliding door travel, the deceleration part (93) defining decelerating movement of the sliding door (DI . . .Dm).

16. The method as defined in claim 15, wherein the acceleration part (91) of the door speed reference curve (65) follows an elliptic curve (91a).

17. The method as defined in claim 15 or 16, wherein the deceleration part (93) of the door speed reference curve (65) follows a linear curve.

18. The method as defined in claim 15 or 16, wherein the deceleration part (93) of the door speed reference curve (65) follows a linear curve (93b) except for an initial section that follows an elliptic curve (93a).

19. The method as defined in any of claims 13 to 18, wherein the door speed reference curve (65) further comprises a creep part (94) for positions of the sliding door (DI . . .Dm) following after the deceleration part (93) and the second position (82) of sliding door travel, the creep part (94) defining a second constant speed movement of the sliding door (DI . . .Dm) at a lower constant speed than the constant speed part (92).

20. The method as defined in any of claims 13 to 19, wherein the door speed reference curve (65) imposes said limitation on door acceleration change zero bylimiting to zero door acceleration change at least according to one or more of the following: at the beginning of accelerating movement of the sliding door (DI . . .Dm); at the end of accelerating movement of the sliding door (DI . . .Dm); at the beginning of decelerating movement of the sliding door (DI . . .Dm); at the end of decelerating movement of the sliding door (DI . . .Dm).

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