GB2203262A

GB2203262A - Door control system

Info

Publication number: GB2203262A
Application number: GB8719431A
Authority: GB
Inventors: Michael John Wilkins; John Durrant
Original assignee: Westinghouse Brake and Signal Co Ltd
Current assignee: Siemens Mobility Ltd
Priority date: 1987-02-16
Filing date: 1987-08-17
Publication date: 1988-10-12
Also published as: GB2202967A; GB8718672D0; GB2201192A; GB8716940D0; GB2202967B; GB8703559D0; GB8719431D0

Abstract

The system includes an electric motor (29) and control means (30) for controlling the motor and thereby the door in dependence on control inputs, the control means including a microcomputer (42) which is provided with a memory (41) which stores a representation of a desired motion profile for the door, the microcomputer providing control outputs for controlling the motor in dependence on control inputs from the memory. The door may be for a vehicle or a building. Other features described are :- (a) door obstruction causes the door to stop and optionally retract. (b) users are detected at 50,51 for automatic opening and closing of the door. (c) a switch 52 selects the operational mode viz. fully automatic, exit only, hold open, lock close. (d) a link 53 operates associated doors. <IMAGE>

Description

0 2 2 0 3 91 '63 2 1 DOOR OPERATION The present invention relates to door

operation.

According to the present invention, there is provided a system including a door and a circuit arrangement for operating the door. the arranement comprising:- a) drive means; and b) control means f or controlling the drive means and thereby the door in dependence on control inputs, wherein the said control means includes a microcomputer which is provided with memory means which stores a representation of a desired motion profile for the door and the microcomputer provides control outputs for controlling the said drive means in dependence on control inputs from the said memory means.

For a better understanding of the invention and to show how the same may be carried into effect, reference-will now be made, by way of example, to the accompanying drawings, in which:20 Figure 1 is a perspective view of major parts of a first form of door assembly; Figure 2 is a side view of part of a second form of door assembly; Figure 3 is a sectional view of the part of the door assembly shown in Figure 2; Figure 4 is a side view of part of a third form of door assembly; Figure 5 is a sectional view of the part of the door assembly shown in Figure 4; and Figure 6 is a block diagram of a circuit arrangement for controlling the motor of such door assemblies.

Referring first to Figure 1, in the door assembly illustrated there are two doors 1, 2 movable transversely of a doorway from relatively spaced apart open positions to adjacent closed positions. Each door 0 2 is 1, 2 is coupled to a respective overhead carriage 3, 4, wheels 5 of which run on an overhead track 6, the doors being made f ast to the carriages by bolts 7 passed through keyhole slots 8 in the carriages and into threaded bushes in the doors. A.E one end of the carriage is a lock mechanism 9 (which will not be described in detail) that co-operates with a lock bar 10 at one end of the carriage 4 and which can be manually released by a lever 11.

Each carriage 3, 4 is clamped to either the upper (carriage 3) or the lower (carriage 4) run of an endless band which in the assembly illustrated is an endless toothed belt 12. This clamping is effected by a clamp assembly 13 which, for each door, includes a toothed block 14 against which the belt 12 is clamped by a U-clamp 15 having one of its walls terminating in lugs 16 that engage in slots 17 in the block 14. The other wall of each U-clamp 15 terminates in a flange 18 that is bolted to the block 14. Each block 14 is supported on a rod carried by a bracket 19 that is fast with the respective carriage 3 or 4, the block 14 being capable of limited sliding motion on its support rod against the ijesistance of a spring 20.

At each end of its runs, the belt 12 runs around idler sprocket wheels 21, 22 that are supported by the track 6. In addition to passing around the idler sprocket wheel 21 at one end of the runs, the belt 12 at this end of the runs also passes around a drive sprocket wheel 23 and a further idler wheel 24, the wheels 21, 23 and 24 being mounted on a face plate 25 of a bearing block 26 that is bolted to the track 6. A bearing in the block 26 supports a common shaft 27 of the drive sprocket wheel 23 and a single sprocket wheel 28 that is intermediate the drive sprocket wheel 23 and a prime mover that is an electric motor 29. The motor 29 is controlled by a control unit 30, the motor 29 and 0 3 its control unit 30 both being mounted on the track 6.

The motor drives the intermediate sprocket wheel 28 via a toothed drive belt 31. The intermediate sprocket wheel 28 is of larger effective diameter than the drive sprocket wheel 23 to provide a desired gearing ef fect in the drive assembly that is constituted by the wheels 21, 23, 24 and 28 and the bearing block 26.

In open positions, the doors 1, 2 are disposed remote from one another at opposite end portions of the two runs of the belt 12. To close the doors the motor 29 is run to drive the drive wheel 23 clockwise as viewed in Figure 1. The lower run of the belt 12 moves from right to left as viewed in Figure 1 and the upper run moves from left to right. The carriages 3, 4 are drawn along the track 6 by the belt 12, moving with the doors 1, 2 towards one another until the doors reach central closed positions.

The f orms of Figures 2 to 5 are in many respects similar to the form of Figure 1 and like parts are identified by like references.

In Figures 2 and 3 the sprocket wheel 21 of Figure 1 at one end of the runs of the belt 12 is replaced by a double sprocket wheel 21A/21B. The belt 12 passes around one wheel 21A of this double wheel and a secondary drive belt 32 passes around the other wheel 21B. The secondary drive belt 32 also passes around a sprocket wheel 33 that is fast on the shaft 27 of the intermediate sprocket wheel 28 of this form. In this f orm, the drive belt 31 between the motor 29 and the intermediate sprocket wheel 28 is a primary drive belt.

Drive passes from the motor 29 via the primary drive belt 31, the intermediate sprocket wheel 28, the sprocket wheel 33 and the secondary drive belt 32 to the double sprocket wheel 21A/21B to drive the endless belt 12, the sprocket wheel 21A serving as the driving wheel for the belt 12 in this form.

0 4 In the form of Figures 4 and- 5 the sprocket wheel 21 at one end of the runs of the belt 12 is mounted on the shaf t 27 of the intermediate sprocket wheel 28 which is driven, as in the other forms, by the motor 29 via the drive belt 31. Thus in this form the sprocket wheel 21 serves as the drive wheel for the belt 12.

It will be appreciated that door opening and closing is effected, in each of the forms of Figure 2 to 5, by driving the belt 12 as described with reference to Figure 1.

In all the forms described, 'the transmission of power from the motor 29 to the drive wheel 23 (Figure 1), 21A (Figures 2 and 3) or 21 (Figures 4 and 5) to drive the endless belt 12 to move the doors 1, 2 is achieved by a band and sprocket wheel drive arrangement that is of a simple nature.

Although the bands described throughout are toothed belts it will be appreciated that chain belts could be utilised.

There will now be described some particular forms of circuitry for the control unit 30 for controlling the motor 29.

The door assembly could be in a "carried system" (i.e. a system in a vehicle) or a "non-carried systemal (i.e. a system in a building or other non-vehicle application of the invention). In the following, two expressions are used to describe different modes of operation in response to an obstruction between the doors, namely:

"Pushback": This is used to define a mode of operation of the doors when an obstruction is encountered in which the action of the doors on obstruction is to stop immediately, the doors then being permitted to be pushed back a short distance in order to release the Y.

1 0 obstruction, after which normal door closing is resumed.

"Withdrawal an. d re-try":

In this mode of obstruction handling. in the event of obstruction while the doors are closing. the doors are powered back immediately on detection to a preset open position. The doors will then re-try a closing operation.

In the event of an object or person obstructing the doors from opening or closing, the operation of the doors may be as follows. The opening cycle has "Pushback" protection and the closing cycle has "Pushback" or "Withdrawal and re-try" according to selection.

In the "Pushback" mode, an obstruction will cause motor current to be reduced to a so-called "foldback" level and a stored movement profile to be no longer followed. Pushing back against the direction of rotation of the motor will reduce the current further. Releasing the obstruction will cause an increase in current up to crawl speed. The doors will continue to move at this low speed until the point where the, obstruction was originally detected is passed, whereupon full current will be applied and the doors resume following the normal profile.

In the "Withdrawal and re-try" mode, an obstruction will cause the doors to move back to a pre-set point and then re-close. If the obstruction is behind the pre-set point, the '1Pushback" mode should be operative. If the obstruction is not cleared after the third withdrawal cycle, the "Pushback" mode comes back into operation.

In the control unit 30 for "carried" and "non- carried" systems, there is a microcomputer for control purposes. In a "carried" system,. typically the inputs 0 6 to the microcomputer are such that in order to open the doors, f irst a door control relay is energised, thus putting power to the unit 30. A "Door open enable" signal. is then given. and together with an "Open signal" the opening cycle commences. The doors remain open until the "Open signal" is removed.

To close the doors, a "Close signal" is sent to the unit 30 and the closing profile commences. When the profile finishes, the doors are shut and mechanically locked. A proximity switch operated via the locking feeds a signal back into the control unit to check that the doors are locked. A door interlock is also connected in series with the rest of the doors in the system so that all the doors are locked before the is vehicle can run.

With reference to Figure 6, there will now be described in more detail an example of the control unit 30 of a "non-carried" system. The circuitry of unit 30 is within the broken outline and includes a microcomputer based printed circuit card 40 via which the motor 29 is controlled. The motor 29 is a threephase permanent magnet brushless electronically commutated D.C. motor and the microcQmpAter based printed circuit card 40 controls position according to a program contained in a plug-in erasable programmable read-only memory (EPROM) 41. The microcomputer 42 of the circuit card 40 is position locked to this information so that there is no reduction in speed as the load on the motor increases and therefore speed holding is exact. The microcomputer 42 of the circuit card 40 is an 8051 computer which incorporates an internal read-only memory (ROM) 43, the EPROM 41 used to store the motion profile being a 2764 EPROM. For providing a + 5 volts operating supply for the microcomputer 42 and + 5 volts and + 15 volts operating supplies for other circuitry in the control unit 30, 3 0 1 7 the latter includes a flyback switch-mode power supply 44 which itself is fed from bridge and smoothing circuitry 45 supplied by an A.C. or D.C. input. The bridge and smoothing circuitry 45 also provides a D.C.

bus voltage Vb for the motor 29. Reference numeral 46 denotes an emergency battery back-up power supply.

For commutating motor current, there is provided a power bridge 47. The power switches in bridge 47 for commutating current through the windings of motor 29 are HEXFETs and are controlled directly from the microcomputer 42 by way of level shifting logic and driver circuitry 48. Hardware protection circuitry 49 is provided for overcurrent, and under- and overvoltage. Currents above the tripping level will disable all switches, which will re-enable only when power is removed and re-applied. Underand overvoltages will disable the switches but only while the fault condition applies.

Entry and exit microwave sensors 50 and 51 mounted above opposite sides of the doorway detect a user approaching. When movement is detected, an "Open signal" is received by the microcomputer and the opening cycle commences. The doors are then held fully open for a predetermined time, after which the "Open signal" is removed and the closing profile commences.

In the event of the doors starting to close immediately after a user has walked through, the doors will not reopen in response to the user's movement, i.e. an "Open signal" only occurs with a user walking towards the doorway.

A mode switch 52 is a multi-way switch which enables various door functions to be set up by an operator. These modes are:

AUTOMATIC - Automatic entry and exit operation.

EXIT - Doors operate as an exit only, outer controls.automatically being switched 0 11 8 OPEN CLOSED position.

off. Doors are held in the open position. Doors are locked in the closed A serial data link 53 allows operation of all the doors in a system comprising a plurality of door assemblies as described to be controlled by a central computer. This enables each pair of doors to be individually identified and assigned a mode of operation and open commands to be transmitted when required. Reference numeral 54 denotes a door interlock, in accordance with that mentioned above for a "carried system". 5 The operation of the control unit 30 by virtue of the software of the microcomputer 42 will now be described. The microcomputer 42 takes signals comprising step- and- direction information to control motion. Additional software generates these signals internally according to a look-up table in the preprogrammed ROM 43. According to these signals, an internal register is incremented or decremented and the contents of this register are used to generate a pulse width modulated (PWM) value which controls the markspace ratio for control signals for the six power switches in the power bridge 47. As the motor 29 rotates, feedback signals from a Hall-effect commutation encoder associated with the motor 29 are decoded to change the switch outputs according to which winding should be energised, so that commutation occurs in the same way as with a conventional trapezoidal brushless D.C. system. In addition to controlling commutation, the encoder is used to generate "up" or "down" signals at every transition which are used to decrement or increment the register value which controls the PWM value. Thus, as the incoming control 9.

G 9 pulses increment the register, power is applied to the motor 29 which will rotate in such a way as to decrement the register. This register therefore -contains a value which is the position error expressed as a number of commutation segments.

Commutation occurs every 30 degrees with a fourpole motor, so performance is similar to a twelve-step stepping motor except that the position is closed loop and no cumulative error is possible. The speed holding is thus guaranteed, as application of a step change in load will merely increase the position error. In other words, the motor shaft will lag its previous position by perhaps three or four commutation segments as the power increases but will then maintain the position error by running at the same speed as bef ore the load was applied. For a given input pulse rate r the speed will be (F x 60)/(P x 3) rpm. where F = the input frequency and p = the number of motor poles. Since there are no analogue control loops for control of current, current limiting is achieved by calculation by using the formula:

V - E = I x R where V is the applied voltage, E is the generated back-emf and R is the motor resistance. V is calculated from the PWM value multiplied by the D.C.

bus voltage Vb, and E is calculated from the speed N of the motor and its voltage constant (KE). The speed is monitored by counting the commutations using a system clock in the control unit 30. 30 Substituting in the above formula: Vb x PWM - (N x KE) = I x R Therefore: PWM - N x (KEIVb) = I x RIVb The ratio KE/Vb used to calculate IR/Vb and this is the primary parameter of the system which is required in setting up.

c Also:

I = (PWM - N x (KE/Vb)) x Vb/R The second important parameter is the ratio of Vb/R which is used for current limiting although it is more of a speed regulation limit. As R increases with motor temperature, the current will reduce pro-rata and variation in Vb will cause the current limit level to vary with speed.

The switches of the power bridge 47 are controlled from the microcomputer 42 via the level shifting logic and driver circuitry 48, using an internal interrupt timer running at a repetition rate of 62 microseconds. This timer also provides the system clock by dividing the interrupt frequency by 256 to give a sample time of nominally 16 milliseconds for current/speed control.

This is used to measure the velocity of the motor using the commutation signals, and is also used to generate a commanded velocity value from the input pulses. The value is used to improve dynamic performance.

Software protection is provided for commutation errors and excessive position errors. If an invalid commutation state occurs due to loss of one or more signals or encoder supply, a trip will occur which requires powering down to reset. A similar trip will occur if the encoder registers an invalid code sequence, which guards against excessive noise, loss of position count or even short circuits between encoder channels.

The motion profile control uses a look-up table of position against time in the ROM 43 to run the preprogrammed motion profile which is contained in the EPROM 41. The table is constructed in blocks of 3 bytes, the first byte being a control byte of which the least significant bit is set to indicate that the prof ile is running but is clear in the last block of bytes to indicate the end of the profile. In each 1 h c 1 11 -block of bytes, the next two bytes are a signed sixteen bit value indicating the position required at the end of that update. The blocks are called into the micro computer 42 in sequence to update the motion profile every 16 'milliseconds to create the overall motion profile.

c 12

Claims

1. A system including a-door and a circuit arrangement for operating the door, the arrangement comprising:- a) drive means; and b) control means for controlling the drive means -and thereby the door in dependence on control inputs, wherein the said control means includes a microcomputer which is provided with memory means which stores a representation of a desired motion profile for the door and the microcomputer provides control outputs for controlling the said drive means in dependence on control inputs from the said memory means.

2. A system according to Claim 1, wherein the said memory means comprises an EPROM coupled to the said microcomputer.

3. A system according to Claim 1 or 2, wherein the said drive means is provided with feed-back means for feeding back to the microcomputer position information for control purposes.

4. A system according o Claim 3, wherein, if the said position information is such that it indicates that the door is not following the said motion profile whose representation is stored in the said memory means due to an obstruction during an opening or closing cycle, the cycle is terminated at least temporarily.

5. A system according to any preceding claim, wherein the drive means comprises an electric motor.

6. A system according to any preceding claim, wherein the said door is movable transversely of a doorway for opening and closing the doorway, there being a carriage coupled to the door and movable along a track extending c 13 transversely of the doorway, the drive means and the said control means being carried by the track.

7. A system according to Claim 6, wherein there are an endless band having two runs extending in the direction along the track. the carriage being coupled to one of these runs, and further drive means for driving the endless band, this drive means comprising a drive wheel engaged with the endless band to drive the endless band and the first drive means being connected to drive the drive wheel via a band and sprocket wheel drive arrangement.

r Published 1988 F_ The Patent Office, State House, 86M HoIborn, London WC11L 4TP. Purther copies may be obtained from The Patent Office. Sales Er-anch, St Mary Cray, OrpingtOr), Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary, Kent. Con' 1187'