A computational approach for time-optimal planning of high-rise elevators

An important issue in elevatoring is to transport passengers in near-minimum time while satisfying the elevator's intrinsic dynamic constraints, such as allowable hoist torque/power, and extrinsically imposed comfort constraints, such as allowable acceleration and deceleration. Furthermore, a solution is sought in near-real-time using concurrently sensed data of passenger load and destination. In this paper, a new approach for minimum-time trajectory generation for high-rise elevators is presented. It is shown that, for systems characterized by linear differential equations, subject to linear or nonlinear inequality constraints, the time-optimal trajectory possesses the special property that at least one constraint is always active. This property is exploited to build an efficient algorithm to compute minimum-time solutions.