Group collective

Group Collective is a conventional control system (with up and down landing call buttons) that allocates hall calls by:

• Estimating the expected travel distance between hall calls and each elevator.
• Allocating the call to the “nearest” elevator.

Allocations are regularly reviewed in case a delay to one elevator means that another could answer the call sooner. A load bypass feature (80% by mass) is included to avoid the elevator stopping to pick up passengers when it is already full.

For a more detailed discussion of group control, refer to The Elevator Traffic Handbook: Theory & Practice.

Group control algorithms normally have a range of modes, as discussed in the following sections.

Uppeak 1 Mode

In Uppeak 1 mode, “idle” cars are returned to the Home Floor with a parking call that does not open the elevator doors on arrival. This strategy normally improves uppeak traffic handling. Using this algorithm, elevators are loaded one at a time to encourage full loading of one elevator rather than partial loading of multiple elevators.

Uppeak 2 Mode

In Uppeak 2 mode, “idle” cars are returned to the Home Floor with a parking call that opens the elevator doors on arrival. This strategy is more effective during particularly heavy traffic situations when loading multiple elevators simultaneously is advantageous. Otherwise, it is generally less efficient than Uppeak 1.

Down Peak Mode

In Down Peak mode, the served floors above the Home Floor are divided into sectors, equal to the number of elevators. Elevators are dispatched to the sectors in turn. After serving the down calls in its allocated sector, an elevator may also stop for additional hall calls on the way back to the Home Floor. This improves performance during high down traffic flow periods.

Auto Mode

In most design scenarios, it is preferable to manually select the appropriate mode (uppeak, down peak, etc.) rather than use Auto mode. Auto mode is best suited to real systems or all-day simulations, where modes need to change throughout the day.

Detection parameters are available via the Advanced settings button.

Uppeak Detection Logic

• When a car leaves the Home Floor, the system checks if the load exceeds the Load Switch Detection Level (%).
• If above the threshold, the Uppeak Detection Counter increments by 1; if below, it decrements.
• When the counter reaches the On level, the Uppeak program starts.
• The Clock Inhibit Timer reduces the counter by 1 at regular intervals, as defined by the Clock Rate.
• When the counter drops to the Clock Inhibit Level, the timer turns off.
• Once the counter hits the Off level (always set at 1), the Uppeak program is disabled.

Down Peak Detection

Down Peak detection mirrors Uppeak detection but measures load as cars arrive at the Home Floor rather than when they depart. This triggers the down peak mode accordingly.

There are default values for Auto Mode detection parameters, but no universally recommended settings. Optimal values depend on trial and error. Lower switch detection levels result in quicker peak mode activation and more responsive performance adaptation.