HK1159588A - Elevator motion profile control - Google Patents

Description

Elevator motion profile control

Background

Elevator systems are useful, for example, for carrying passengers, cargo, or both between different floors (levels) within a building. There are various considerations associated with operating an elevator system. For example, it is desirable to provide efficient service to passengers. One way to achieve this desire is by controlling the travel time (flight time) of the elevator car as it moves between different floors in the building. There are practical constraints on elevator travel time as dictated by the machine used to move the elevator and the desire to provide a certain level of ride quality. For example, if the elevator car accelerates or decelerates at a certain rate, passengers will feel discomfort. Thus, the ride comfort constraint is achieved to ensure that the passenger has a comfortable ride.

There are competing considerations when attempting to maximize the traffic-bearing capacity of an elevator system (i.e., minimize travel time) and maximize ride comfort for passengers. Adjusting the control parameters in one direction to reduce the travel time typically results in a degraded ride quality. Conversely, adjusting control parameters to increase ride quality typically results in an efficiency sacrifice in terms of travel time.

For example, elevator control settings typically specify a motion profile of the elevator car, which sets limits on speed, acceleration, and jerk (jerk). When the vibration level of the elevator car is too high, a typical approach is to reduce the value of jerk, acceleration, speed, or a combination of these. However, attempting to minimize vibration and improve ride quality typically increases the associated travel time. In order to maintain a comfortable ride, conventional measures are, for example, to reduce acceleration to provide improved ride quality. Unfortunately, however, reduced acceleration increases the travel time of a particular elevator run, which may prove inconvenient or inefficient in terms of performance. If the goal is to reduce acceleration while avoiding an increase in travel time in an attempt to improve passenger comfort, there will typically be an associated increase in jerk (jerk rate). However, introducing a higher amount of jerk results in a higher amount of vibration of the elevator car, which above all does not achieve a reduction in acceleration (e.g. to improve ride quality or passenger comfort).

Fig. 1 shows a typical elevator motion profile 20. The first graph 22 represents the position of the elevator car during a single run from the initial position to a selected landing (landing) at a predetermined stop. The speed of the elevator car is shown at 24. The associated acceleration curve is shown at 26. The example of fig. 1 includes a graph 28 showing jerk values during elevator operation. In this example, the jerk value starts at 30 and changes to a maximum value shown at 34 at instant 32. At the same time (e.g., at 32) elevator car acceleration begins in this example. Once the acceleration reaches a constant level, the jerk value momentarily changes at 36 back to the zero value shown at 38. The remaining distance to the planned landing ensures the start of the stopping sequence when the elevator car continues to move in this example. This causes jerk to momentarily change at 40 to a level at 42, which in turn causes the acceleration to begin to decrease. As the elevator car approaches the planned landing, the jerk at 42 is maintained until the acceleration rate (acceleration rate) crosses a zero value and becomes the negative of the value taken at 36. This causes a transient change in jerk at 44. As the elevator car moves closer to the landing, there is a transient change in jerk value at 46 back to the maximum shown at 48 and eventually a transient change at 50 back to zero.

As can be appreciated from fig. 1, a typical elevator motion profile includes a generally square waveform jerk profile. Setting appropriate limits on acceleration, velocity and jerk allows controlling the ride comfort of passengers on such elevator runs.

It would be useful to be able to control elevator motion profiles in a manner that provides a desired level of ride quality without sacrificing performance, for example, by increasing travel time.

Disclosure of Invention

An exemplary apparatus for controlling an elevator car motion profile includes a controller programmed to cause an associated elevator car to move with a motion profile that includes a plurality of jerk values. The controller is programmed to cause at least one transition between two of the jerk values to have a non-instantaneous transition rate.

In one example, the controller is programmed to cause a transition between two of the jerk values to have a first transition rate that is different from a second transition rate between two of the jerk values at another time in the motion profile.

An exemplary method of controlling an elevator car motion profile includes moving an elevator car with a motion profile that includes a plurality of jerk values. At least one transition between two of the jerk values is controlled to have a non-instantaneous transition rate.

In one example, the transition between two of the jerk values has a first transition rate for one portion of the motion profile and a second transition rate between two of the jerk values for another portion of the motion profile.

The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

Drawings

Fig. 1 schematically illustrates an elevator motion profile according to the prior art.

Fig. 2 schematically illustrates selected portions of an example elevator system.

Fig. 3 schematically illustrates an example elevator motion profile designed according to an embodiment of this invention.

Fig. 4 schematically illustrates another example elevator motion profile.

Detailed Description

Figure 2 schematically illustrates selected portions of an elevator system 60. For example, an elevator car 62 is supported for movement within the hoistway. The controller 64 is programmed to control operation of the machine 66 to achieve a desired movement of the elevator car 62. The controller 64 is programmed to cause the elevator car 62 to move with a motion profile that includes a plurality of jerk values. Controller 64 is programmed to cause at least one transition between two of the jerk values to have a non-instantaneous transition rate. Controlling the transition between different jerk values in this example provides a reduced amount of vibration in the elevator car 62 to improve ride quality. At the same time, the non-instantaneous rate of change between different jerk values is used so that the travel time of the elevator run is not extended.

Fig. 3 schematically shows an elevator motion profile 70. The motion profile is implemented by a controller 64 that generates commands for controlling, for example, a machine 66. Graph 72 shows the change in position of elevator car 62 during a single run, for example, between an initial position and a scheduled stop. Curve 74 shows the speed of the elevator car during the same run. Another curve 76 shows the associated acceleration.

The jerk value of the example motion profile 70 begins at 78, which corresponds to the time before the elevator car 62 begins to move. At 80, there is a transient transition to the maximum jerk value shown at 82. In this example, the transient transition at 80 corresponds to the beginning of elevator car movement. The jerk value remains at the maximum value shown at 82 while the change in acceleration rate 76 (i.e., slope) remains relatively constant.

When the jerk at 82 continues to reach a point where the acceleration will exceed its imposed limit. The jerk transition at 84 is applied by the controller 64 to vary the jerk from a jerk (jerk rate) at 82 to a lower value at 86. In this example, the value at 86 corresponds to a zero jerk value. The transition rate at 84 is non-transient. As can be appreciated from fig. 3, the slope at 84 is inclined from the perfect vertical and the transition between the jerk values shown at 82 and 86 occurs over time. Using the non-transient transition rate at 84 reduces the amount of vibration associated with the change in jerk value.

In the example of FIG. 3, the zero jerk value at 86 is for a period of time and then there is another transition shown at 88 that drops to a negative jerk value shown at 90. The transition at 88 occurs at a non-transient transition rate. In some examples, the transition rate at 84 is the same as the transition rate at 88. In other examples, the regions indicated at 84 and 88 in the example of fig. 3 use different transition rates. Both transition rates shown at 84 and 88 are different from the transition rate shown at 80. The transition rates at 84 and 88 are both less than the instantaneous transition rate shown at 80.

The midpoint 92 of the motion profile 70 is schematically shown in fig. 3. Midpoint 92 occurs when car 62 is moving at, for example, a maximum or contract speed during a run. The motion profile 70 shown in fig. 3 contains a mirror image on each side of the midpoint 92. For example, the rate of change shown at 94 between the jerk values shown at 90 and 96 corresponds to the rate of change 88. A transition rate 98 between the jerk values shown at 96 and 100 corresponds to the transition rate 84. Mirror symmetry is not required because the slope of jerk may change naturally. The maximum jerk value shown at 100 is associated with the elevator car 62 stopping at the planned destination. In this example, jerk value 100 corresponds to the one shown at 82. When the elevator car 62 reaches a full stop, a transient transition from jerk value 100 occurs at 102 back to zero.

In the example of fig. 3, the transition rates at 80 and 102 are instantaneous. The non-instantaneous transition rates 84, 88, 94, and 98 are used when the elevator car 62 is moving during a scheduled run.

One feature of the illustrated example of fig. 3 is that certain portions of the motion profile may be considered asymmetric, in that different rates of rotation are used on different sides of a particular jerk value. For example, the transition rate at 80 is different from the transition rate at 84, both of which occur on opposite sides of the time when the jerk value is at 82. This is significantly different from a square wave or the like, such as shown in fig. 1, where the transition rates on opposite ends of different jerk values are the same, i.e., the instantaneous transition rates, symmetrical setup. It is to be understood that the rate of transition at opposite ends of a particular jerk value in other portions of the motion profile may be symmetric, for example, where the rate of transition at each end (e.g., 88 and 94 in FIG. 3) is non-instantaneous.

Fig. 4 illustrates an example in which non-instantaneous transition rates are used at all transitions in jerk values of an example elevator motion profile 70'. In the example of fig. 3, the motion profile 70 includes a jerk profile having vertical transitions at the illustrated single run start and end of the elevator car 62. Oblique (i.e. non-transient) transitions occur between different jerk values between the beginning and the end of the elevator car run. In FIG. 4, each transition between different jerk values occurs at a non-instantaneous rate of transition (e.g., none of the transition portions of the jerk profile have a true vertical line).

In the example of FIG. 4, the jerk value starts at 110 and there is a non-instantaneous rate of change up to the maximum jerk value shown at 114. This corresponds to the beginning of movement of the elevator car 62, for example. The example of fig. 4 differs from the example of fig. 3 in that the transition rate at 112 is non-transient and the transition rate at 80 in the example of fig. 3 is transient (i.e., as represented by the vertical line).

Another transition at 116 occurs between the maximum jerk value and the zero jerk value at 114. Then during elevator operation, another transition rate is used at 118 to drop to the minimum jerk value shown at 120. The transition rate at 116 may be the same as the transition rate at 118. The non-transient transition occurs at 122 to ramp back up to a value of zero jerk. In this example, the midpoint 123 of the motion profile 70' occurs when there is a zero acceleration value and a zero jerk value. The transition rate at 124 occurs until the jerk value reaches a minimum amount at 126. Another non-transient transition rate occurs at 128 and 130. Toward the end of an elevator run, the maximum jerk value occurs at 132 and there is a non-transient rate of transition at 134 back to a zero jerk value.

In the example of fig. 4, like the example of fig. 3, the motion profile 70' is symmetrical about its midpoint 123. In some examples, the motion profile need not be symmetrical in terms of transition rate and in terms of the time at which such transition rate changes as they travel along the car.

In some examples, the non-instantaneous transition rate is constant. In some examples, the rate of change varies during a transition between two of the jerk values (e.g., at least partially curved lines represent jerk during such a transition).

One feature of the illustrated example is that controlling the rate of change of jerk allows for selection of a particular level of ride quality. The non-transient transition rate for varying between different jerk values does not excite elevator hoistway dynamics during acceleration and deceleration times, which may provide improved ride quality. In one example, a reduction of approximately 20% in vibration level may be obtained using a non-instantaneous rate of transition between different jerk values.

By controlling jerk and acceleration as shown in the examples above, the rate of application of force on the elevator system may be controlled. Controlling jerk to achieve smoother acceleration provides improved ride quality by "pushing" the system rather than "jerking" it around. In other words, the non-instantaneous transition between jerk values provides smoother acceleration and lower resulting vibration. With the example discussed, higher ride comfort and quality is achievable without increasing the amount of time it takes to complete the run.

Meanwhile, the illustrated example does not require that the travel time be extended by decreasing, for example, the maximum acceleration or jerk value. With the illustrated example, it is possible to achieve a desired ride quality within a desired travel time. It is possible to maintain a desired level of ride quality and improve travel time.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims (18)

1. An apparatus for controlling an elevator car motion profile, comprising:

a controller programmed to cause an associated elevator car to move with a motion profile comprising a plurality of jerk values, the controller programmed to cause at least one transition between two of the jerk values to have a non-instantaneous rate of transition.

2. The apparatus of claim 1, wherein the controller is programmed to cause a first transition between two of the jerk values to have a first transition rate that is different from a second transition rate during a second transition between two of the jerk values.

3. The apparatus of claim 2, wherein the controller is programmed to generate the first and second transition rates during a single run of an associated elevator car between a starting position and a scheduled stop.

4. The apparatus of claim 2, wherein the first transition rate is faster than the second transition rate.

5. The apparatus of claim 4, wherein the first transition rate is instantaneous.

6. The apparatus of claim 2, wherein at least one of the first or second transition rates is constant.

7. The apparatus of claim 1, wherein the motion profile comprises a jerk profile having vertical transitions at a start and an end of a single run of the associated elevator car and having oblique transitions between different jerk values occurring between the start and end of the run.

8. The apparatus of claim 1, wherein a portion of the motion profile between the start of a single run and the midpoint of the run is asymmetric.

9. The apparatus of claim 8, wherein another portion of the motion profile between the midpoint of the run and an end of the run is a mirror image of a portion of the motion profile between the start and the midpoint of the run.

10. A method of controlling an elevator car motion profile, comprising the steps of:

moving the elevator car with a motion profile comprising a plurality of jerk values; and

transitioning between two of the jerk values at a non-instantaneous transition rate.

11. The method of claim 10, comprising transitioning between two of the jerk values at a first transition rate that is different from a second transition rate between two of the jerk values.

12. The method of claim 11, comprising using the first and second transition rates during a single run of an elevator car between a starting location and a scheduled stop.

13. The method of claim 11, wherein the first transition rate is faster than the second transition rate.

14. The method of claim 13, wherein the first transition rate is transient.

15. The method of claim 11, wherein at least one of the first or second transition rates is constant.

16. The method of claim 10, wherein the motion profile comprises a jerk profile having vertical transitions at a beginning and an end of a single run of an elevator car, the jerk profile comprising oblique transitions between different jerk values occurring between the beginning and the end of the run.

17. The method of claim 10, comprising

Controlling the motion profile to be asymmetric between a start of a single run of the elevator car and a midpoint of the run.

18. The method of claim 17, comprising

Controlling a motion profile between the midpoint of the run and an end of the run to be a mirror image of a portion of the motion profile between the start and the midpoint of the run.