State/interval redundant controller system for traffic signals

• US 4,463,339 A
• Filed: 07/01/1981
• Issued: 07/31/1984
• Est. Priority Date: 01/02/1979
• Status: Expired due to Fees

• Current Assignee: Ralph E. Frick
• Original Assignee: Ralph E. Frick
• Inventors: Frick, Ralph E., McNulty, Nelson E.
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/279,334
• Time in Patent Office: 1,126 Days
• Field of Search: 340/32-34, 340/41 R, 340/41 A, 340/35, 340/46, 340/641, 340/642, 340/663, 340/664, 340/40, 364/424, 364/436, 364/200 MS File, 364/900 MS File, 455/95, 455/99
• US Class Current: 340/906
• CPC Class Codes: G08G 1/07 Controlling traffic signals
• CPC Class Codes: G08G 1/087 Override of traffic control, e.g. by signal transmitted by an emergency vehicle
• CPC Class Codes: G08G 1/097 Supervising of traffic control systems, e.g. by giving an alarm if two crossing streets have green light simultaneously

Abstract

Traffic signals at an intersection are controlled by one or more controllers of the state/interval type, located in the vicinity of the intersection. One or more remote units that are portable or mobile communicate with the controller via a coded signal to command specific light operations, instruct a secondary controller to take-over light control at the intersection from a primary controller, and to reprogram the operation of the controller on a temporary or permanent basis. The remote units generate a code that must be received accurately by the controller before commands are followed. In order to economically provide such a code, the code generator employs a diode matrix that orders data words and address words and is easily reprogrammed. The traffic signal indicator operation is monitored by the controller both to detect controller error, as by a voltage error resulting from an incorrect controller action, and to detect a non-controller error, as by a current error resulting from a burned out indicator. The controller may take different corrective action depending upon the nature of the error, including switching to another controller. An anti-coincidence logic circuit is connected between a state/interval controller and the light driver and disconnect.

Claims

1. A traffic signal control system for operating an associated at least one traffic signal of the type having a plurality of indicators, comprising in combination:

(a) a first state/interval controller generating commands for the operation of a plurality of traffic signal indicators of an associated traffic signal through definition of individually selected states and definition of an individual time interval to be associated with each individual state for each indicator;

said controller including a clock means supplying time pulses for use by the controller in determining the end of a defined time interval associated with a defined indicator state, and a storage means for containing said individually selected current signal indicator state data and current interval definition data, wherein the controller determines the termination of the stored current interval in said storage means in response to time pulses received from said clock means, in response to said determined termination of the current interval generates an operating command for terminating said stored current state, individually selectes a next state and next interval, and loads said next state and next interval into said storage means; and

(b) signal light driver means operatively connected to said first controller for receipt of operating commands from the controller and operation of traffic signal indicators in response thereto wherein said storage means comprises;

a current interval register containing time data relating to an immediate state of a traffic signal indicator, having operative communication with said clock means and said signal light driver means; and

a current state register containing the identity of the immediate light state and in operative connection to the signal light driver means; and

further comprising;

a next interval register containing time data relating to the state following the current state of the traffic signal indicator, having operative connection to said current interval register for loading the next interval time data after conclusion of the immediate light state, and having operative connection to said first controller for receiving subsequent interval time data; and

a next state register containing state identity data for the signal indicator in the interval following the immediate interval, having operative connection to said current state register for loading the next state data after conclusion of the current state, and having operative connection to said first controller for receiving subsequent state data.

2. The traffic signal control system of claim 1, wherein said first controller further comprises a remote unit communication receiver means, wherein the control system further comprises at least one remote control unit having signal generating means and communication transmitter means for communicating a generated signal to said receiver means, said remote control unit comprising means for programming said first controller.

3. The traffic signal control system of claim 2, wherein said programming means comprises data word and access word sequencing means.

4. The traffic signal control system of claim 3, wherein said sequencing means comprises:

(a) a plurality of data gates connected to said signal generating means for supplying a variable bit data word in response to generating signals;

(b) a diode matrix having connected to said data gates at least one data line, a plurality of bit lines, and a stop line, and having a plurality of decoder output lines crossing the stop, data, and bit lines with diodes at selected intersections;

(c) a decoder connected to the decoder output lines for selected individual activation of the output lines; and

(d) a pull-up resistor attached to each of said stop, data, and bit lines.

5. A traffic signal control system for operating at least one traffic signal of the type having a plurality of signal indicators, comprising in combination:

first and second redundant controllers, each comprising a central processing means, a memory means, and a light driver interface means; and

a signal light driver means having associated therewith a means for sensing voltage and means for sensing current to the individual signal indicators;

wherein

(a) said central processing means is adapted to interpret and execute instructions for the operation of the signal indicators, is connected to said light driver interface means for receiption of present voltage and current indicating data from the signal light driver means and for communication of signal indicator operating instructions to the signal light driver means, is connected to said memory means for receipt of reference voltage and current indicative data corresponding to a present operational routine for the signal indicators and for receipt of selected instructions for further operation of signal indicators;

(b) said memory means is adapted to store instructions and data and is connected to said central processing means for communication of said instructions and data, wherein said memory means contains at least

(1) first instructions designating initial priority of the first controller as between said first and second controllers,

(2) second instructions designating a first operational routine for the signal indicators,

(3) reference data of current and voltage indicative information corresponding to said first operational routine,

(4) third instructions designating at least one alternate operational routine for use in response to a variation between reference and present current indicative data,

(5) fourth instructions designating at least in the memory means of said second controller a switch of controller priority to the second controller, for use in response to a variation between reference and present voltage indicative data; and

(c) said signal light driver means is operatively connected to said light driver interface means for receipt of commands for operation of signal indicators from the central processing means and return communication of present voltage and current indicating data to the central processing means; and

(d) said central processing means being further adapted to compare present voltage and current indicative data to reference voltage and current indicative data and to select operational instructions from said memory means in response to the comparison results.

6. The traffic signal control system of claim 5, further comprising communications interface means for communicating priority information between said first and second controllers.

7. The traffic signal control system of claim 5, further comprising at least one remote control unit having means for generating a signal and means for transmitting the generated signal to at least one of said controllers, wherein said one controller further comprises a communications receiver means for receiving the generated signal from said remote control unit and communicating the signal to the central processing means, and wherein said memory means further contains instructions designating an alternate operational routine for use in response to receipt of the generated signal at said central processing means.

8. The traffic signal control system of claim 7, wherein said remote control unit further comprises a code generator and a parallel-to-serial encoder, said code generator receiving input from said signal generating means and sending output in parallel to said parallel-to-serial encoder, which, in turn, communicates the signal to said transmitting means;

and said communications receiver means further comprising a series-to-parallel decoder in communication with said central processing means.

9. The traffic signal control system of claim 5, wherein said signal light driver means further comprises:

(a) a signal light disconnect and driver means operatively connected to the signal indicators for the operation thereof through said voltage sensing means and current sending means;

(b) a sensor register operatively connected to the voltage sensing means and current sensing means for receiving voltage and current indicative data therefrom and monitoring actual present signal indicator operation, said sensor register being in communication with at least one central processing means for transmittal of indicator operation data; and

(c) an anti-coincidence logic means operatively connected between said at least one central processing means and said disconnect and driver means next preceding said last mentioned means for preventing undesired simultaneous states in the traffic signal indicators.

10. The traffic signal control system of claim 5, wherein each of said controllers comprises a real time calendar/clock means in intercommunication with said central processing means for providing time data;

and wherein said memory means further contains instructions designating an alternate operational routine for use in response to receipt of specified real time data at said central processing means.