US 3594572 A
Description (OCR text may contain errors)
United States Patent L1 614 SOLJQCE.
 References Cited UNITED STATES PATENTS 3,353,619 11/1967 Lambert 180/98 Primary ExaminerArthur L. La Point Assistant ExaminerGeorge l-l. Libman Attorney-Lindenbcrg and Freilich ABSTRACT: A system for automatically controlling a train employs a control means extending parallel to and along the length of the track wayside which represents information for controlling the train motion, for example. Means are provided on the train for scanning the control means and producing a velocity control signal based on the ratio of two different light radiations provided by the control means for example. This control signal is applied to the motor control system of the train to determine motor speed and thus, train velocity.
WAYSIDE CONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates to automatic train control systems and more particularly to an improvement therein.
There is a trend today toward the complete automation of trains. One of the problems which confronts the automation designer is thatof the control of the speed of the train. There are a number of difierent approaches to this. For example, when it is desired to automatically slow a train down for a curve, a switch-tripping device may be located adjacent the track to engage a reciprocal device on the train which results in slowing the train down. Another technique may be to use special colored lights for signalling road conditions. Yet, another may involve electrical signal-radiating devices.
These types of mechanisms however are subject to a .common problem, that is they must be maintained continuously to insure that no failure of the wayside mechanism occurs, otherwise the train may move into a curve at too great a speed, or may come down a hill at too great a speed with consequent disaster.
v OBJECTS AND SUMMARY OF- THE INVENTION light-radiating stripes which extend parallel to the. wayside.
There is provided on a train two photocells, one of which is made sensitive only to one color light or one radiation, and the other of which is made sensitive to only the other color light or the other radiation. The ratio of the two stripes is varied to provide a desired resultant control signal. The output signals of the two photocells are applied to a bridge network whereby the ratio of these two signals may be detected and used as a control signal for controlling the velocity of the train, for example.
Means are also provided for monitoring the control signal. Should it not fall within a predetermined range the controlled function is safely terminated. Means are also provided for monitoring the apparatus generating the control signal in order to abort the controlled function should the controlsignal-generating apparatus become defective.
The novel features of the invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the appearance of the wayside control stripe for different desired speed conditions.
FIG. 2 is illustrative of the placement of the wayside control stripe with respect to a train.
FIG. 3 is a block schematic diagram showing the arrangement of the control system on the train.
FIG. 4 is a circuit diagram illustrating the bridge arrangement employed for detecting the ratio of the photocell output voltages, to be used for a control signal.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. I, there is illustrated, by way of example, five difi'erent manners of striping 10, for the purpose of control, in accordance with this invention. It should be noted that the illustrations in FIG. I are to be considered as exemplary only and not as limiting. The first striping section, 10A illustrates the two different color stripings respectively I2 and half speed for example.
The next striping 10C, shows the two colors with approximately 60 percent of the color 14 and 40 percent of the color 12. This can represent slow speed.
The illustrative section, 10D, shows less than 25 percent of the color 12 with the remainder being the color I4. This can call for a stop condition. In order to start a train after it has stopped, an override control may be employed. This may be automatically operated, as by a timer at a station causing a train to start moving after a predetermined interval; or a human operated override control may be employed.
Striping section 10E illustrates a transition region 10F from a stop-signalling condition to a full-speed-signalling condition and another transition region 106 from a full-specd-signalling condition to a half-speed signalling condition. The ability to predetermine the distance over which a speed change takes place by means of these transition regions and to completely control the train speed during transition is a feature of this invention. It avoids over or under accelerating, as the case may be, and enables an optimal velocity program over a trackway which is rigidly followed. This results not only in a conservation of power and braking use, but also insures safety of operation since the train will invariably slow down in time before reaching regions such as curves, switch crossings etc. which require slowdown of a car to a certain safe speed, and
thereafter the train will be sped up at the right time and not prematurely.
which the, detecting equipment which includes a light source l9,and photocells 20, is positioned. As the train rolls along the track, the photocells scan the control stripe which is illuminated by the light source 19. The photocell outputs are applied to control equipment 22 which converts the signal outputs of the photocells into a control signal, which can be used for controlling motor speed. The illustrated location for the control stripe 10 is exemplary, of course. The control stripe may be placed at other locations adjacent the train, without departing from the spirit and scope of the invention.
FIG. 3 illustrates the control arrangement which may be employed in accordance with this invention. A first and a second photocell, respectively 30, 32, each has a respective filter 34, 35 positioned in front of it, so that photocell 30 is sensitive to only one color and photocell 32 is sensitive to only the other color of the two colors on the wayside stripe. The output of the two photocells is applied to a control signal sensor 34. This, as will be seen in FIG. 4, constitutes a circuit, which provides an output signal which represents the ratio of the two photocell outputs. Since this control signal is proportional to the ratio of the two photocell outputs, changes in visibility due to conditions such as dirt or fog or rain will not have any effect on this signal.
A third photocell 33, which has no filter in front of it scans the entire stripe and applies its output to safety circuits 40.
The output of the control signal sensor is applied to the control circuits 36, for the motor. These are well-known circuit arrangements which can control the speed as well as the stopping of a motor 38 in response to the level of the signal which isreceived.
In the event that there is an improper speed control signal provided out of the control signal sensor, either due to an absence of illumination or radiation from the control 10, or due to a failure of one of the components, there is a safety override device indicated as safety circuits, 40. These circuits function either in the absence of a control signal or in the presence of an improper control signal to instruct the motor controls to stop the motor and to apply brakes.
Once the motor has been stopped, in order to start it operating again, a manual override control 42 is provided. This serves the function of supplying a signal to the motor controls so that the motor is started. Once the motor is started then the train rolls out of the region D to one of the other regions. The train will then operate under the guidance of the control stripe and the manual override control may be terminated. The manual override control need by nothing more than a signal source which is connected to the motor controls 36 by operation of a switch.
Referring now to FIG. 4, the control signal sensor 34 comprises a bridge arrangement in which the two photocells 30, 32 are represented as variable resistors, and are connected as two arms of the bridge. A small resistor 43 is connected in series with the photocell 32 in one arm of the bridge. The other two arms of the bridge, respectively 44, 46, are variable resistors. These variable resistors are set at values such that a desired range of voltages is obtained for the control signal. A potential source 48 is connected across the two opposite ends of the bridge. The other two opposite ends of the bridge are connected to an amplifier 50 which serves to detect and amplify the bridge unbalance voltage and to apply it as a control signal to the motor controls 36. The output of the amplifier 50, which detects the bridge unbalance voltage, is also applied to another amplifier 52. These amplifiers together with associated relays 56 and 58, act as the no signal detector. Amplifier S2 is connected to the coil of a normally open relay 56 and to the coil of a normally closed relay 58. The contacts of the normally open and normally closed relays are connected in series and to the motor controls. They both must be closed for the motor controls to operate. ln the presence of a proper unbalance bridge signal, the normally open and normally closed relay contacts are closed thus enabling the motor controls 36 to function. Should the bridge unbalance voltage exceed a predetermined threshold, then it enables the relay coil of relay 58, to open the normally closed relay contacts thus rendering the motor controls and the motor inoperative. The normally closed contact may be biased in well-known manner, such as by a spring to require that a predetermined threshold must exceeded by the signal applied to the coil of the relay 58 in order to open its normally closed contact.
The third photocell 33, is energized by a potential received from a potentiometer 60 which has a potential source 62 connected across it. The voltage across the photocell 33 represents the average illumination reflected by the control stripe. This signal is applied to the input terminals of a differential amplifier 62. A second signal applied to the input terminals of the differential amplifier is derived from the resistor 43. The current flowing through this resistor is determined by the outputs of photocells 30 and 32 since they are all connected in series in the bridge.
The differential amplifier output is connected to a normally closed relay 64. The relay is spring biased to open in response to the differential amplifier output exceeding a predetermined threshold. The potential established across photocell 33, by
the setting of potentiometer 60 is such that so long as both photocells 30, 32 are operative and produce an output in response to viewing a control stripe than the differential amplifier output does not exceed the threshold signal required to operate relay 64. Should either photocell 30 or 32 become inoperative, relay 64 opens its normally closed contacts. These are connected to the motor controls and have the effect, when open, to cause the motor controls to instruct the motor to stop. The motor of the train remains stopped until either a repair has been effectuated or a manual override operation has occurred.
In the foregoing description, the control function is ascribed to two colors being applied to the rail alongside of the track, the respective percentages of the two colors determining the velocity of the train. These colors may be any suitable colors which are long wearing, readily visible, and with a finish which does not soon become dirty. However, this by way of illustration and not to be considered as limiting since, one can also use the presence and absence of color (including black and white where suitable) or infrared and ultraviolet radiations for enabling the photocells to provide different signal ratios for the purpose of controlling a train. The advantage of two 5 photocells over a single photocell, it will be appreciated, is
that one cannot obtain a signal ratio out of a single photocell which is unaffected by loss of visibility due to atmospheric conditions or due to dirt.
The control signal developed as a result of the photocells scanning a control stripe have been discussed as controlling the speed of the train. It will be understood that this is to be considered exemplary. Other functions may be controlled by wayside control stripes besides speed such as light level, fan or air-conditioning operation and announcements. This may also be done by using additional control stripes besides the one controlling train speed which are placed adjacent the speed control stripe. Brake application may also be controlled from the control signal developed from the control stripes, if desired.
There has accordingly been described and shown a novel, and useful control system for automatically controlling the functioning ofa train.
Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and consequently it is intended that the claims be interpreted to cover such modifications and equivalents.
What l claim is:
1. A train control system comprising wayside means extending along a train wayside for representing a desired train function at every location along said wayside,
means on said train for scanning said wayside means and generating signals representative thereof,
35 means on said train to which said signals are applied for performing the desired train function in response to said signals and means on said train responsive to said signals from said means for scanning not being within predetermined limits for aborting the performance of said desired train function.
2. A train control system as recited in claim 1 wherein there is included means on said train responsive to defective operation of said means for scanning said wayside means for aborting the performance of said desired function.
3. A train control system as recited in claim 1 wherein said means extending along a train wayside for representing a desired train function at every location along said wayside comprises two physical quantities which by their ratio 50 represent the desired train function.
4. A system for automatically controlling train operation comprising means extending along the train wayside for producing two different light radiations in relative quantities representative of a desired train operation,
means on said train for receiving said two different light radiations and producing an electrical signal representative of the ratio thereof,
means on said train for controlling the operation of said train responsive to said electrical signal, and
means on said train responsive to said electrical signal not being within a predetermined range for aborting said train operation.
5. A system for automatically controlling train operation comprising means extending along the wayside of said train for producing two different light radiations in relative quantities representative of a desired velocity for said train,
means on said train for receiving said two different light radiations and producing two different electrical signals representative thereof,
means on said train responsive to said two different electrical signals for producing a control signal which is representative of the ratio of said two different signals, and
means responsive to said control signal for controlling the operation of said train accordingly.
6. A control system as recited in claim 5 wherein said two different light radiations comprise two different colors, and said means on said train for detecting said two different light radiations and producing two different electrical signals representative thereof comprise:
a first photocell means responsive only to light of one of said two different colors and a second photocell means responsive only to light of the other of said two different colors.
7. Apparatus as recited in claim 6 wherein said means to which said two different electrical signals are applied for generating a control signal representative of the ratio of said two different signals comprises a bridge circuit wherein said first and second photocell means constitute two of the arms.
8. A system as recited in claim 5 wherein there is included means responsive to said control signal not being within a predetermined range for terminating said train operation.
9. Apparatus as recited in claim 7 wherein there is included a third photocell means for scanning said two different light radiations and producing an output signal representative thereof,
means for deriving a bridge signal from said bridge circuit, means for opposing said output and bridge signals to produce a resultant signal, and
means responsive to said resultant signal exceeding a predetermined threshold for terminating said train operation.
10. A system for controlling the velocity of a train comprising a support extending along the wayside of said train and having thereon a first and a second color, said first and second colors extending along said wayside on said support, the ratios of said first and second colors which are present at any location on said support being representative of a desired velocity for said train,
first and second photocell means on said train for scanning said wayside support,
said first photocell means being responsive only to light 0 said first color and said second photocell means being responsive only to light of said second color,
means responsive to the outputs of said first and second photocell means for producing a control signal representative of the ratio of said two outputs, and
motor control means to which said control signal is applied for controlling the speed of said train responsive to said control signal.
11. Apparatus as recited in claim 10 wherein there is included means responsive to said control signal being outside of a predetermined range for causing said motor control means to stop said train.
12. Apparatus as recited in claim 10 wherein there is included a third photocell means on said train for scanning the colors on said wayside support and producing an output signal representative thereof,
means for deriving an indicator signal from said means for producing a control signal indicative of ,the operation of said first and second photocell means, means for comparing said output and indicator signals for producing a resultant signal representative of said comparison, and
means responsive to said comparison exceeding a predetermined threshold for causing said motor control means to stop said train.