Adaptive traffic signal with adaptive countdown timers
View Patent ↗Traffic signals that adapt to traffic conditions are provided with countdown timers. These countdown timers count down from some number towards zero, and indicate the approximate duration remaining before a traffic signal changes state. Since the traffic signal is continuously adapting to traffic conditions, the exact time before a state change occurs is not known in advance. Using a countdown algorithm, the countdown timers imperceptibly modify the countdown sequence in real time so that the traffic signal state change coincides approximately with the moment the countdown reaches its minimum count.
1. A system of controlling vehicular and pedestrian traffic at an intersection comprising:
a plurality of lights configured to signal vehicles and pedestrians to stop and go in various directions,
sensors for detecting the presence of vehicles and pedestrians, computation mechanism present close to the intersection, and one or more countdown timers, each countdown timer configured to display a count that counts downwards, wherein the computation mechanism is configured to use information gathered from the sensors for detecting the presence of vehicles and pedestrians to change the lights to signal vehicles and pedestrians in a signaling pattern that is not predetermined,
each countdown timer is associated with a group of lights in such a way that when the count displayed by the countdown timer reaches a first count that is a number among zero, one, two or three, the state of the group of lights changes, and
at least one countdown timer adjusts the speed of the countdown in a manner that is hard to perceive in such a way that the moment of change of state of the associated group of lights occurs when the count displayed by the countdown timer is among zero, one, two or three.
2. The system of claim 1 wherein the countdown timer that adjusts the speed of the countdown is part of a single hardware unit also configured to run a countdown algorithm, the countdown algorithm configured to adjust the speed of the countdown displayed by the countdown timer.
3. The method of claim 1 , wherein the first count is zero.
4. The method of claim 1 , wherein the first count is a count expected by at least one of drivers, pedestrians, and autonomous vehicles.
5. A method of controlling vehicular and pedestrian traffic at an intersection comprising:
detecting the presence of vehicles and pedestrians,
using the information of the presence of vehicles and pedestrians to signal vehicles and pedestrians to stop and go in various directions,
displaying one or more counts that are counting down to vehicles or pedestrians, and
adjusting the speed of counting down in a manner that is hard to perceive in such a way that the moment of changing from stop to go or go to stop in a particular direction occurs while the displayed count is zero, one, two or three.
6. The method of claim 5 , wherein the step of adjusting the speed of counting down in a manner that is hard to perceive comprises minimizing a metric.
7. The method of claim 6 , wherein the metric is calculated based upon differences between successive countdown time intervals.
8. The method of claim 7 , wherein the metric is calculated also based upon the differences between the successive differences between successive countdown time intervals.
9. The method of claim 6 , further comprising minimizing the expected value of the minimum metric calculated as a function of the random variable state change time.