Modelling Lifts

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As there are no lift/elevator actors currently in MassMotion, you need to simulate them using Paths

To create a Path, first draw a three-element line that starts on one floor and goes to the next. Create it using the Model > Create Curve > Draw Linear command. You will probably then need to edit its points to get them to the correct locations as the linear curve is drawn on the plane of the view. Ensure that you have 0.4m legs on each floor to allow the Agents on and off the Path. Select the line and use the Content > Import From Scene command and then assign the resulting unclassified actors as Paths.

Note that as Paths are unidirectional you will need both up and down Paths, so duplicate them and adjust the directions in their properties. Although the Agents on the Paths will ignore other Agents, it can be worth offsetting the Paths a little so as to make them easier to see and select.

There are three basic ways to simulate lifts; which is best is up to you.

Gated Links This method is good for lifts that go between just two floors

Model the lift doors as Links and ensure that they are gated. On the Events tab of the workbench create an Open Gate event for each lift door. Uncheck Fixed Duration and check Cycling On/Off Is Enabled. Set the duration On to how long the lift door is open for and the Duration Off for the time that it takes the lift to complete its journey away from and back to that floor. Ensure that you specify the relevant Links in the event properties.

For extra accuracy set the flow limits on the door Links so that the number of agents who access or leave the lift are not more than the lift capacity. As you want to limit the Agents exiting the lifts as well as entering you will need coincident in and out Links. Note that the flow rate is per minute, so if the capacity is eight and it is open for 10 seconds then the max rate will be 48 (8*60/10).

One problem with this method is that the lift shaft can contain more Agents than the lift capacity, though the flow limits on the links will ensure that no more than is appropriate can exit, the internal congestion can interfere with the Agents access to the Paths.

Flow-limited Paths Working on the principle of average travel times, rather than modelling the actual location of the lift assuming that it works to a time table rather than in response to passenger requests, dispense with the lift door Links and instead set a flow limit to the paths so that they carry and average number of agents between the floors. For example if a lift can carry eight people from the ground to top floor in one minute and then eight back, the capacity and hence the flow rate is four per minute. As the paths will carry two-way traffic while the real lifts only one, you should halve the lift speed and apply that as a Limit Speed.

You also need to take the waiting time into account: divide the average wait for a lift by the average number of floors that the agents will travel and apply that as a wait task whenever an agent enters the path. Of course, if you have more accurate data then make use of that.

This is possible the simplest method but will produce a steady if slow flow of agents in a steady stream rather than the groups that are produced by real lifts.

Gated Paths This is similar to the gated Links method except that you are gating the Path instead. You shouldn't need Links to the lift areas for this method.

Ensure that you limit the flows entering the Paths to match the lift capacity in the time that the gate is open. Note that the flow rate is per minute, so if the capacity is eight and it is open for 10 seconds then the max rate will be 48 (8*60/10). Set the spacing between the Agents to a constant zero to ensure that this does not interfere with the flows.

Set the Path speed limit to match the lift speed to ensure that the Agents do not reach the next floor too soon.

Visualisation To complete the lift, enclose in a stretched cube assigned as a visualisation-only actor to hide the inner workings.

Example Click here for an example model with the three lift options.

LINK:	http://www.oasys-software.com/blog/2012/11/modelling-lifts/...
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