Collison prevention in hoistway with two elevator cars

A method of operating an elevator system having a plurality of cars within a single hoistway, each having a controller, and in which calls for elevator service designate the desired destination floor, said method comprising:

• assigning each call for service to one of said elevator cars in a manner which will assure that the elevator cars will not collide;
• continuously determining whether there is a likelihood of collision between the elevator cars to determine whether an assigned call should be reassigned to a different one of said elevator cars;
• and
• mitigating the likelihood of collision by at least one of
• (a) reducing a maximum speed of at least one of said cars,
• (b) reducing an acceleration of at least one of said cars;
• (c) reducing a deceleration of at least one of said cars;
• (d) causing an unscheduled stop of at least one of said cars;
• (e) causing at least one of said cars to wait at a stop;
• and
• (f) reversing a direction of motion of one of said cars.

A method of operating an elevator system having a plurality of cars within a single hoistway, each having a controller, and in which calls for elevator service designate the desired destination floor, said method comprising:

• assigning each call for service to one of said elevator cars in a manner which will assure that the elevator cars will not collide;
• determining whether an assigned call should be reassigned to a different one of the elevator cars based on a likelihood of collision between the elevator cars determined after the assigning;
• continuously determining whether one of said cars is within a first distance of another one of said cars and responsively causing a brake of at least one of said cars to operate;
• and
• continuously determining whether one of said cars is within a second distance, smaller than said first distance, of another one of said cars and responsively causing a safety of at least one of said cars to be engaged.