Claims:We claim,
1. A method (100) for controlling a door drive of an elevator, said door drive having a motor (102) provided in communication with an elevator controller (104) and adapted to open and close said elevator door (110), said method (100) comprising:
storing an algorithm, in a micro-controller (106) associated with said motor (102), for computing a predetermined travel curve defining values of door velocity as a function of door position for said elevator door (110), said travel curve being formed of a plurality of adjacent segments (S1 and S2), said algorithm includes a mathematical function for computing each of said segment;
inputting position variables corresponding to a start position, a deceleration position and a target position of said first and second segments (S1 and S2) of said predetermined travel curve into said algorithm;
sensing at least one door operation command signal (108) generated by an elevator control (104) associated with the elevator door (110);
providing a plurality of sensors (112) for generating travel position signals representative of position of said door travel;
acquiring feedback from said sensors (112) representing a difference between actual values of door velocity and target values of door velocity according to said travel curve; and
generating at least one velocity command signal (114) by said micro-controller (106) based on a velocity deviation obtained from said feedback to control movement of said elevator door (110),
wherein,
said plurality of segments include a first segment S1 and a second segment S2; and
said mathematical function for said first segment S1 and said second segment S2defines a sine curve and a cosine curve, respectively.

2. The method (100) for controlling said door drive as claimed in claim 1, wherein said method includes providing a predetermined current flow to said motor (102) based on said velocity command signal (114).

3. The method (100) for controlling said door drive as claimed in claim 1, wherein said mathematical function for said first segment S1 includes said sine curve defining values of door velocity as a function of door position between said start position and said deceleration position.

4. The method (100) for controlling said door drive as claimed in claim 1, wherein said mathematical function for said second segment S2 includes said cosine curve defining values of door velocity as a function of door position between said deceleration position and said target position.

5. The method (100) for controlling said door drive as claimed in claim 1, wherein said predetermined travel curve is an accumulation of said first segment S1 and said second segment S2, each having a beginning point, an end point and an associated predetermined mathematical function defining a portion of the travel curve between the beginning and end points, the end point of said first segment S1 after said sine curve segment forms said corresponding start point of said second segment which immediately continues after said first curve segment to define said cosine curve.

6. The method (100) for controlling said door drive as claimed in claim 1, wherein said method (1000 includes providing a door position indicating means (116) representative of door open limit (DOL) and door closed limit (DCL) in communication with said micro-controller (106).

7. The method (100) for controlling said door drive as claimed in claim 1, wherein said method (100) includes identifying an obstruction by an obstruction detecting means (118), said obstruction detecting means (118) configured to stop and/or reverse said motor (106) rotation direction upon identifying the obstruction.

8. The method (100) for controlling said door drive as claimed in claim 1, wherein said micro-controller(106) includes:
an input terminal adapted to receive at least one of obstruction detecting signal, said door drive control signal, and said DOL and DCL signals;
an output terminal for communicating at least one velocity command signal and initiating door open and door closed cycles; and
a means for communicating with said elevator controller.

9. The method (100) for controlling said door drive as claimed in claim 1, wherein said micro-controller (106) and said elevator controller (104) each includes on-board, programmable memory for storing an operating program, said micro-controller(106) is adapted for storing said predetermined travel curve values between open and closed positions of said door (110).

10. The method (100) for controlling said door drive as claimed in claim 1, wherein said method (100) includes a step of ascertaining values for a door width, a door mass, a friction force, a maximum acceleration and a maximum speed of the elevator door.
, Description:TECHNICAL FIELD
[001] The embodiments herein generally relate to elevator doors, and more particularly to a method for controlling a door drive of elevator(s).
BACKGROUND
[002] Conventionally elevator door control systems are electro-mechanical in nature. Typically, elevator doors require different motor speeds during the opening and closing thereof i.e. the elevator door, because of its mass and in order to ensure passenger safety, requires a relatively slow motor rotation but high torque motor force at the beginning of its run. Once in motion, however, the motor force requires less torque but higher speed to accelerate the door until the elevator door has travelled about three quarters of its full distance. Thereafter, the elevator door needs to be slowed prior to reaching the end of its run.
[003] A variety of methods are available to achieve the change in velocity or speed of the elevator doors operations. A conventional approach to changing the velocity of elevator doors is to use resistors. The resistors are placed in series with a voltage source and a DC motor, and adjusted to provide smaller or greater values of resistance. The greater resistance value corresponds to slower DC motor operation and to smaller generated velocity output. The converse is true for the smaller resistance values. However, this approach has a number of limitations. The resistors cannot compensate for changes in friction or other loading on the doors. Further, when resistors heat up, the resistance value changes and results in changes in the velocity of the elevator doors. Such changes in velocity are highly undesirable because this does not provide a consistently smooth profile.
[004] It is highly desirable to have smooth transitions from one velocity value to another, to achieve smooth operation of the elevator doors. The transition from one velocity level to another is currently achieved by building in constant jerk (rate of change in acceleration divided by rate of change in time) segments and constant acceleration segments fora profile. The constant jerk segments, used for smoothening the corners of the transition from constant velocity phase to constant acceleration phase of the doors, must match values of velocity and acceleration where the constant jerk segments join the constant acceleration phase and the constant velocity phase. A great deal of processor time is required for matching the constant jerk segment with the constant acceleration phase and the constant velocity phase at numerous transition points.
[005] Therefore, there exists a need for a method for controlling door drive of elevator(s), which obviates the aforementioned drawbacks.
OBJECTS
[006] The principal object of the embodiments herein is to provide a method for controlling door drive of an elevator.
[007] Another object of the embodiments herein is to provide a method for controlling door drive of the elevator which is configured to control speed and position of elevator door.
[008] Another object of the embodiments herein is to provide a method for controlling door drive of the elevator wherein the elevator door is moved between an open position to a closed position, and vice-versa in a smooth and controlled manner.
[009] Yet another object of the embodiments herein is to provide a method for controlling door drive of the elevator which includes a motor microcontroller which is adapted to store an algorithm for computing a predetermined travel curve defining values of door velocity as a function of door position for the elevator door.
[0010] Still another object of the embodiments herein is to provide a method for controlling door drive of the elevator wherein the algorithm includes a mathematical function for computing each segment of the travel curve.
[0011] Another object of the embodiments herein is to provide a method for controlling door drive of the elevator wherein the mathematical function defining a sine curve for first segment and a cosine curve for a second segment.
[0012] Another object of the embodiments herein is to provide a method for controlling door drive of the elevator wherein a door operation command signal is generated by an elevator control associated with the elevator door.
[0013] Yet another object of the embodiments herein is to provide a method for controlling door drive of the elevator which includes a jerk-free travel curve during the operations of opening, closing and reversal.
[0014] Still another object of the embodiments herein is to provide a method for controlling door drive of the elevator wherein movement of the door is adaptable to changing load conditions.
[0015] Another object of the embodiments herein is to provide a method for controlling door drive of the elevator which provides shorter opening and closing times of the elevator door.
[0016] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0017] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0018] FIG. 1 depicts a block diagram of an elevator door control, according to an embodiment as disclosed herein;
[0019] FIG. 2 depicts a door travel curve plotted as velocity versus position for an elevator door, according to an embodiment as disclosed herein.
[0020] FIG. 3 depicts a flowchart of a method for controlling door drive of an elevator, according to an embodiment as disclosed herein; and
[0021] FIG. 4 depicts an image of an elevator door with a door drive operating the door, according to an embodiment as disclosed herein.

DETAILED DESCRIPTION
[0022] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0023] The embodiments herein achieve a method for controlling door drive of an elevator. Further, the embodiments herein achieve the method for controlling door drive of the elevator which is configured to control speed and position of elevator door. Furthermore, the embodiments herein achieve the method for controlling door drive of the elevator which includes a motor microcontroller which is adapted to store an algorithm for computing a predetermined travel curve defining values of door velocity as a function of door position for the elevator door. Additionally, the embodiments herein achieve the method for controlling door drive of the elevator wherein the algorithm includes a mathematical function for computing each segment of the travel curve. Moreover, the embodiments herein achieve the method for controlling door drive of the elevator wherein the mathematical function for computing each segment of the travel curve includes a sine curve and a cosine curve. Referring now to the drawings, and more particularly to Figs. 1through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0024] FIG. 1 depicts a block diagram of an elevator door control, according to an embodiment as disclosed herein. The present invention relates to a method for controlling door drive of elevator doors (110), in which the doors are moved linearly and at variable speed in accordance with positioning along a travel path. In an embodiment, an elevator system typically includes an elevator car (not shown) and elevator car doors (110) (hereafter described as elevator door or door in this description) which are driven into open and closed positions by an electric motor (102) (hereafter described as motor in this description) and a first toothed belt (102a) (as shown in FIG. 4) which rotates a drive roller (not shown). The elevator doors (110) typically are coupled to hoistway doors (not shown) by means of a coupling device (not shown) and pull the hoistway doors into open and closed positions. Further, the motor (102) is supplied with electrical energy by connection to a power supply unit (not shown). A motor micro-controller (106) is provided in communication with the motor (102). The micro-controller (106) is adapted to receive input from a door position indicating system (116) and commands to move the elevator doors (110) by generating velocity command signal (114). The micro-controller (106) includes an input terminal (not shown) adapted to receive at least one of obstruction detecting signal, a door drive control signal, and a door open limit DOL and a door close limit DCL signals. Further, the micro-controller (106) includes an output terminal for communicating at least one velocity command signal and initiating door open and door closed cycles. Furthermore, the micro-controller (106) is provided with a means (not shown) for communicating with the elevator controller (104).
[0025] The door movement is based upon a travel curve which is computed in dependence on the door position by utilizing predetermined parameters. The door position information is, for example, generated by a position magnetic sensor (116) which is provided in communication with a drive shaft (not shown) of the motor (102). The door movement is represented in a co-ordinate system, as shown in the FIG. 2, which is plotted as velocity vs position of the door (110) along a predetermined travel curve. The travel curve is formed of a plurality of segments, in which each curve segments correspond to predetermined mathematical function. The entire travel curve is defined by a few position variables which are identified as start position, target position and deceleration position. Only the co-ordinates of these points must be defined in order to generate any desired travel curve from the predetermined curve segments.
[0026] As shown in the FIG. 2, each curve segment is bounded by two points with adjacent segments sharing a common point. The transition from one curve segment into another is continuously differentiatable so that the mathematical functions meeting at the common points have the same slope. In an embodiment, the number of the segments and associated points can be variable and unlimited.
[0027] As shown in the FIG. 2, each travel curve (also referred to as velocity profile in this description) is formed of plurality of curve segments. In an embodiment, the plurality of segments include a first segment S1 and a second segment S2. The functions of the adjacent segments must have the same slopes at the common points so that the function of the one segment flows smoothly into the function of the next segment. For example, the first segment S1 begins at a first point P1(X0, Y0) and ends at a second point P2(X1, Y1). The second segment S2 begins at a third point P3(x0, y0), which also is the end point for the first segment S1, and ends at a fourth point P4(x1, y1). A standard travel curve is generated by computation a mathematic function for the individual curve segments. The first curve segment is obtained from the co-ordinates of P1(X0, Y0) and P2(X1, Y1) between which the mathematical function is computed. Similarly, the second curve segment is obtained from the co-ordinates of P3(x0, y0)and P4(x1, y1) between which the mathematical function is computed.
[0028] In an embodiment, a mathematical equation for velocity profile generation is provided below.
vel_demand_sin=0.85*vel_dcc_pos*sinf(PI/2*(Position -start_pos)/ (dcc_position-start_pos));
vel_demand_cos=0.85*vel_dcc_pos*cosf(PI/2*(Position-dcc_position)/ (target_position-dcc_position));
Wherein,
Position_mm – actual position of door,
sinfandcosf – sine and cosine functions,
vel_dcc_pos- velocity at deacceleration position,
dcc_position – deacceleration position,
vel_reference – desired/ ideal velocity,
vel_demand_sin- desired sine function velocity,
vel_demand_cos- desired cosine function velocity.
[0029] After these computations are performed for all of the curve segments, a continuous travel curve TC1(also referred to as predetermined travel curve in this description) is obtained as shown in the FIG. 2. In an embodiment, the predetermined travel curve TC1 is an accumulation of the first segment S1 and the second segment S2, each having a beginning point, an end point and an associated predetermined mathematical function defining a portion of the travel curve between the beginning and end points. In an embodiment, the mathematical function for the first segment S1 includes a sine curve defining values of door velocity as a function of door position between the start position i.e. P1 (X0, Y0) and the deceleration position P2 (X1, Y1). Similarly, the mathematical function for the second segment S2 includes the cosine curve defining values of door velocity as a function of door position between the deceleration position i.e. P3(x0, y0) and the target positionP4(x1, y1). The end point of the first segment S1 after the sine curve segment forms the corresponding start point of the second segment S2 which immediately continues after the first sine curve segment to define the cosine curve. In an embodiment, the micro-controller (106) is adapted to follow a predetermined condition defined by the mathematical function for opening and closing of the door (110) as mentioned herein. The predetermined condition applied includes velocity_reference=vel_demand_sin, if the Position_mm=dcc_position, and vel_reference = vel_demand_cos, if the Position_mm>dcc_position, i.e. if current position of the door (110) is less than or equal to the deacceleration position, then sine profile is generated, and if the current position of the door (110) is greater than dcc_position, cosine profile is generated. In an embodiment, the dcc_position indicates a position to initiate the deacceleration of the door (110).
[0030] FIG. 3 depicts a flowchart of a method for controlling door drive of an elevator, according to an embodiment as disclosed herein. In an embodiment, the method (100) for controlling a door drive of an elevator, includes steps of storing an algorithm, in a micro-controller (106) associated with said motor (102), for computing a predetermined travel curve defining values of door velocity as a function of door position for said elevator door (110), said travel curve being formed of a plurality of adjacent segments (S1 and S2), said algorithm includes a mathematical function for computing each of said segment (At step 102). Further, the method includes inputting position variables corresponding to a start position, a deceleration position and a target position of said first and second segments(S1 and S2) of said predetermined travel curve into said algorithm (At step 104). Furthermore, the method includes sensing at least one door operation command signal (108) generated by an elevator control (104) associated with the elevator door (110) (At step 106). Moreover, the method includes providing a plurality of sensors (112) for generating travel position signals representative of position of said door travel (At step 108). Additionally, the method includes acquiring feedback representing a difference between actual values of door velocity and target values of door velocity according to said travel curve (At step 110). Also, the method includes generating at least one velocity command signal (114) by said micro-controller (106) based on a speed/velocity deviation obtained from said feedback to control movement of said elevator door (110) (At step 112). In an embodiment, the plurality of segments include a first segment S1 and a second segment S2. The mathematical function for the first segment S1 and the second segment S2 defines a sine curve and a cosine curve, respectively.
[0031] The method for controlling door drive of an elevator is described herein. The method includes storing an algorithm, in a micro-controller (106) associated with said motor (102). The micro-controller (106) is adapted to store the algorithm which includes the mathematical function for computing each of said segments of the predetermined travel curve. A standard travel curve TC1 is generated by computation of the mathematic function for the individual curve segments. The generated travel curve defines values of door velocity as a function of door position for the elevator door (110). Further, the method includes inputting position variables corresponding to the start position, the deceleration position and the target position of the first and second segments(S1 and S2) i.e. the first curve segment is obtained from the co-ordinates of P1(X0, Y0) and P2(X1, Y1)between which the mathematical function is computed. Similarly, the second curve segment is obtained from the co-ordinates of P3(x0, y0) and P4(x1, y1)between which the mathematical function is computed. The mathematical function for the first segment S1 includes a sine curve defining values of door velocity as a function of door position. The mathematical function for the second segment S2 includes the cosine curve defining values of door velocity as a function of door position. Furthermore, the method includes sensing at least one door operation command signal (108) generated by the elevator control (104) associated with the elevator door (110). In an embodiment, the door operation command signal (108) is at least one of opening the elevator door (110), closing the elevator door (110), landing the elevator in a particular floor. The elevator controller (104) is adapted to generate the door operation command signal (108). Moreover, the method includes providing a plurality of sensors (112) for generating travel position signals representative of position of said door travel. In an embodiment, the plurality of sensors (112) are provided in communication with the micro-controller (106) to sense the movement of the door (110) along the generated travel curve. Further, the plurality of sensors (112) are adapted to provide a feedback representing a difference between actual values of door velocity and target values of door velocity according to the standard travel curve TC1. The feedback representing the deviation is communicated to the micro-controller. Additionally, the method includes generating at least one velocity command signal (114) by said micro-controller (106) based on a speed/velocity deviation obtained from said feedback to control movement of said elevator door (110). The micro-controller (106) upon receiving the feedback from the sensors generates an output which is communicated through the output terminal to cancel-out the difference between actual values of door velocity and target values of door velocity according to the standard travel curve. The micro-controller (106) generates the velocity command signal (114) which cancels the deviation between the actual values of door velocity and the target values of door velocity.
[0032] In an embodiment, the method further includes providing a predetermined current flow to the motor (102) based on the velocity command signal (114). In an embodiment, the motor (102) is supplied with an AC current or power thereby to control the movement of the elevator door (110). The current or the AC power is supplied to the motor (102) based on the velocity command signal (114) so that the deviation between the actual values of door velocity and the target values of door velocity is cancelled.
[0033] In an embodiment, method (100) for controlling said door drive includes identifying an obstruction by an obstruction detecting means (118). For example, in case a person tries to enter the elevator when the door is closing, the door (110) needs to be stopped and travel backwards (reverse) to open the door for entry of the person. The elevator (not shown) includes at least one sensor (not shown) mounted on the elevator door (110) along its height, so that when the person tries to enter the elevator, the sensor senses the obstruction (the person is considered as the obstruction in this description) and gives at least one input signal to the elevator controller (104) to stop the movement of the door in forward direction and initiate reverse movement of the door (110) to open the door (110). The obstruction sensor is adapted to detect an obstruction in a pathway of the door (110). The elevator controller (104) upon receiving the input signal from the sensor transmits a command to the motor microcontroller (106) to stop and reverse the door movement for opening the door (110). Further, when the elevator controller (104) receives the door close command or the destination floor command (108) due manual actuation of pressing button, the elevator controller (104) senses the corresponding command and provides a command to the motor microcontroller (106) based on which the micro-controller (106) takes respective action to rotate a rotor of the electric motor (102) in at least one of clockwise or anticlockwise direction to close the elevator door (110).
[0034] In an embodiment, the micro-controller (106) and the elevator controller (104) each includes an on-board, programmable memory for storing an operating program. The micro-controller (106) includes a printed circuit board (PCB) which is adapted for storing the predetermined travel curve values between open and closed positions of the door (110).In an embodiment, the standard travel curve TC1 values are generated and calculated in the micro-controller (106) for each present door position by ascertaining values for a door width, a door mass, a friction force, a maximum acceleration and a maximum speed of the elevator door.
[0035] The advantages provided by the embodiments herein include better control of elevator door operation, improved smoothness in opening and closing of elevator door, inexpensive and accurate control on speed and position of elevator door.
[0036] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.