A stress free service is achieved by complete elimination of the most critical issue, long waiting times during congestion periods.
Hitachi has evolved its elevator operation control to reduce waiting times, particularly long
wait times, which comprises the heart of group control performance.
The future reference-trajectory control is a group control system aiming to minimize the long waiting period by operating elevator cars at equal time intervals while forecasting future trajectory.
Generally speaking, a group of elevator cars must be operated at
equal time intervals to minimize passenger waiting times, but in
heavy traffic conditions, cars are frequently operated in a bunch,
or all cars would end up clustering around the same level on their
way and moving in the same direction in unison. In the conventional
method, the most available cars at that moment are
allocated to hall calls to eliminate local bunching, but when heavy
traffic conditions are prolonged, this state cannot be completely
eliminated, resulting in long waiting times.
In contrast, with future reference-trajectory control, elevator cars are controlled by taking into account their forecasted trajectories, allowing shorter passenger waiting times and reducing the probability of a long wait.
