EP0263829A1 - Vehicular speedometer having acceleration and deceleration indicating means - Google Patents

Abstract

An electronic speed / acceleration indicator (40) for large vehicles such as railroad locomotives, trams, and other types of unauthorized vehicles on highways includes a rear reflective display (30, 40). Signs (42) prominently displayed and easily viewed on the rate of change of any indicated speed provide the operator with useful information when applying power to the vehicle or braking it. The screen includes an analog configuration device (32, 39) for displaying digitally processed speed information. The speed, acceleration and / or deceleration of the vehicle are continuously calculated by a microprocessor (10) which samples and averages the speeds for a fixed duration long enough to avoid floating or `` instability '' of the vehicle. 'display. An innovative test (Fig. 3-1) triggered by the user subjects the microprocessor and the digital components associated with a cycle of predetermined operational sequences, clearly visible indications of the device failure being given on the display device.

Description

VEHICULAR SPEEDOMETER HAVING ACCELERATION AND DECELERATION INDICATING MEANS

CROSS-REFERENCE TO RELATED APPLICATIONS

Digital speed indicators and recorders disclosed and claimed in U.S. Patents 3,525,044, 3,699,563, and 3,864,731 assigned to the same assignee as this application, feature techniques and methods for recording, measuring, and indi¬ cating speed of large vehicles. The specifications and claims of these patents are incorporated by reference herein.

BACKGROUND OF THE INVENTION

This invention relates to measurement of the speed and acceleration of locomotives, earth moving tractors, and other large vehicles. More particularly, the invention pertains to a novel measurement, determination and display of vehicle speed and acceleration, wherein digital tech¬ niques are utilized to produce an analog representation.

The equipment disclosed and claimed in this applica¬ tion provides analog/digital indication of vehicular speed and acceleration utilizing both internal and ambient light sources.

Prior art digital speedometers (reference U.S. Patents 3,525,044 and 3,699,563 incorporated by reference above,) incorporated displays of an early type which, in operation, were found to have certain and sometimes substan¬ tial shortcomings. Among others, these shortcomings include small numeric figures, low intensity displays, and inability to incorporate any ambient light to improve display intensi¬ ty. Numeric displays of currently used units present perhaps the most difficult to overcome shortcoming, i.e. absence of pattern recognition. Analog displays are known to require less attention of the vehicle operator for the amount of information transmitted. However, digital tech¬ niques do not easily lend themselves to analog displays. Further, digital techniques, while presenting convenient means for determining higher order functions such as accel¬ eration are in use, a single device combining an analog speed and acceleration display with digital signal process¬ ing has been hitherto unknown. This type of display pro- vides invaluable assistance to vehicle operators in perfor¬ mance of braking and applying tractive power.

Accordingly, it is an object of this invention to provide a speed indicating and measuring device for large vehicles wherein the display has an essentially analog character.

It is a further object of this invention to provide a speed indicating and measuring device having prominent indication of speed, enhanced by increased ambient illumina¬ tion. It is an additional object of this invention to provide a speed indicating device which includes an essen¬ tially analog indication of vehicular acceleration.

It is yet an additional object of this invention to provide a speed indicating and measuring device for large vehicles utilizing digital techniques to produce analog displays.

It is a further object of the invention to provide a vehicular speed indicating device incorporating an operator initiated test providing visual indication of equipment malfunction.

It is yet an additional object of the invention to provide a vehicular speed indicating device providing controlled access means for entering and adjusting speed determining vehicular parameters.

It is an additional object of the invention to provide restricted and secure access to speed indicator 5 adjustments, thereby greatly increasing unit reliability.

SUMMARY OF THE INVENTION

A vehicular speedometer, operating from a wheel driven pulse generator which includes an essentially analog indication of speed, and acceleration/deceleration of the

10 vehicle. The display further incorporates a precise auxil¬ iary digital readout of the analog speed display and incor¬ porates a transflective liquid crystal display for all indications. The transflective characteristic provides enhanced viewing of the display in the presence of increased

15 ambient light.

Digital techniques enabled by a microprocessor are utilized to measure speed through counting pulses from an end of axle, i.e axle driven pulse generator for accurate predetermined time intervals. Subsequent values of measured ,20 speed are stored during predetermined sampling periods for use in determining vehicular acceleration.

A novel technique for speed -and acceleration mea¬ surement and display utilize at least two subsequent speed measurements averaged over a sample time somewhat larger

25 than that required to determine two specific speeds. The acceleration is then averaged by determining the difference in speed over the given overall time interval. The acceler¬ ation display utilizes a logical ergonometrically correct configuration, wherein rates of change of acceleration and

30 deceleration are presented as vertical bars in increasing and/or decreasing sizes. Typically, in the. left-hand portion of the speedome¬ ter display, deceleration is signified by vertical bars of decreasing size, while on the right-hand portion of the display, acceleration is signified by vertical bars of increasing size.

The analog nature of the combined presentation, including speed, acceleration, and/or deceleration, provides the vehicular operator with a maximum of information in a short period of time. It is well known that "patterns" of values represented by analog displays are quickly recognized so that any abnormal representations can be identified, and corrective action taken.

A visual test, initiated at any time by the vehicu¬ lar operator, provides a predetermined display of indica- tions of normal unit operation, and in the alternative, identifies malfunctions and establishes shutdown, providing the operator with beforehand knowledge that unit repair or alternate methods of speed measurement must be utilized. Calibration and adjustment of factors used in speed and acceleration measurement such as wheel diameter can also be user initiated. Access to adjustment and calibration is limited through the use of concealed switches actuated by an external permanent magnet.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows^• a functional block diagram of the invention, particularly showing the signal/power flow paths for major system components.

Figures 2 and 2a are plan views of the display portion of the invention,^' particularly showing the analog scale and pointer, with digital indication of the speed represented by the analog pointer, for operation wherein acceleration and/or deceleration is indicated by designated bars.

Figure 3 (pages 1 through 14) is an operating flow chart of the speed indicator and display system of the invention, particularly showing the microprocessor function and including operation of the speed indicator measuring system, user initiated test/calibrate function and operator initiated diagnostic feature of the system.

Figure 4 is a graphic and algebraic description of determining acceleration using concepts of the invention.

Figure 5 is a perspective view of the speedometer indicator and electronic housing. A partial tear-away shows location of magnetically actuated test/adjust switches.

Appendix "A" is a detailed instruction set, partiσu- larly keyed to acronyms of Figure 3, describing microproces¬ sor operation.

While the speed indicator described herein is depicted as a preferred embodiment, it will be understood that applicant does not intend to limit the invention disclosed to that particular embodiment. On the contrary, applicant's disclosure is intended to cover all alterna¬ tives, modifications, and equivalents of the speed indicator as may be included within the spirit and scope of appli¬ cant's invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

With reference to Figure 1, the system diagram 2 of the invention, a rotating input shaft or vehicular shaft 7 drives an end-of-axle pulse generator 6, of the type dis¬ closed and claimed in U.S. Patent 3,566,169. Electrical pulses at a repetition frequency proportional to the rota¬ tional speed of the input shaft 7 are processed in a filter 8, and transmitted to an appropriate input of a microprocessor 10 such as the Intel 80351. Power for the microprocessor is supplied by supply 4. The power supply 4, also supplies operating electrical power for the display driver 16, operating an electroluminescent portion 18 of the display 14. After performing appropriate operations accord¬ ing to the invention on the pulsed input, the microprocessor 10 supplies display information in a digital form to the liquid crystal display driver 12. Operation of the micro¬ processor 10 in providing correct display information will be further described below. The liquid crystal display driver further conditions the microprocessor output in order to provide indication (reference Figures 2 and 2a) of speed and acceleration on the display 14 in both analog and digital forms. It should be noted that the display combina- tion of the liquid crystal display 14 and electroluminescent panel 18 incorporate a transflective background. The transflective feature enhances viewing images on the display screen 14 using both ambient light and electroluminescent emissions. With further reference to Figures 2, 2a, and 5, the display portion of display 14 is a configuration 30 (or 40) incorporating an analog-like indicator or pointer 32, which in operation traverses a circular path in radial alignment with the speed indicating circular scale 34. The electroluminescent display is contained in a housing 3, containing concealed magnetic control switches 20 and 22 (ref. Figure 5). These switches initiate micropro¬ cessor operation to adjust vehicle operating parameters and speedometer operational checks respectively (ref. "TEST ALL", "INITIAL EDGE", and "TEST EDGE" of Figure 3, page 3). Major speed divisions of the circular scale are arithmetically indicated in miles per hour, although kilome¬ ters per hour can be displayed as well. Typically, the circular scale contains 100 divisions. At the lower central portion of the display 30, an additional, centrally located digital indication of the speed shown by the combination of the pointer 32 and scale 34 is shown at 44. The digital speed indication 44 incorporates speeds from zero to 99.99 miles per hour or, if desired, the kilometer per hour equivalent.

At the upper left hand corner of the display 30, there is shown an essentially trapezoidal pattern of essen- tially vertical segments or bars 36. The individual bars 38 have the same width but vary in height from left to right. In keeping with the concept of the invention, the display 36 is an indication of negative acceleration, sometimes termed deceleration, in miles per hour per second (MPH/SEC) . As shown, ten vertical bars indicate deceleration in decreasin magnitudes from left to right. As depicted, the extrem left hand bar indicates six miles per hour per second, whil the extreme right hand bar indicates deceleration of .2 miles per hour per second. Intermediate bars indicat decelerations of 4, 3, 2.5, 2.0, 1.5, 1.0, .75, and .5. Those skilled in the art will readily understand that othe combinations of deceleration, i.e. values and/or bar sizes, could be incorporated as well. The visual indicatio provided by Figure 2 is therefore an instantaneous speed o 30.00 miles per hour, at a deceleration rate of .75 mile per hour per second. It should be noted that the approxi mate variation between the indicated .75 miles per hour pe second and .75 or 1.0 miles per hour per second, provides stable, non-varying or "jittering" acceleration display. The display pattern 40 shown in Figure 2a depict the opposite of that of Figure 2, i.e. vehicular accelera tion at a speed of 30 miles per hour. As in the decelera tion pattern, an acceleration pattern 41, having a indication of acceleration by bars 42. The phantom or dashed indication of the location of acceleration bars 45 are typically 1.0 miles per hour per second, with a maximum acceleration bar at the extreme right hand portion of the pattern, typically 5.5 miles per hour per second. Those skilled in the art will readily understand that acceleration and deceleration values will need to be adjusted in order to accommodate vehicles of varying size and power. The embodi¬ ment disclosed reflects values found appropriate for diesel electric locomotives hauling "typical" freight trains of 100 cars.

With reference to Figures 3 and 4, the method of determining acceleration as described in detail, involves utilization of two successive values of speed. As shown, after initialization of the display to zero, and other microprocessor functions described in some detail in the compound Figure 3, a timer incorporated in the microproces¬ sor 10 measures two complete cycles 52 and 53 (ref. "CALC SPEED" of Figure 3, page 3) . The time of each measured cycle is recorded within the microprocessor for use in determining a first speed as indicated at 52. It should be noted that a complete cycle is determined by the zero of crossing the voltage 50 having a frequency as generated by the end-of-axle generator 6. Similarly, a second speed 53 is determined through measuring the time required for two complete cycles of the pulse generated voltage 50, as shown at 56.

Acceleration of the vehicle in the time required to go from the first speed 52 to the second speed 53 is deter- mined as shown at 57 (ref. "AD" of Figure 3, page 3). It should be noted that the overall determination of accel¬ eration includes a variable or incremental speed delta t, in this case delta t2 (55). A similar incremental time, delta tl (54), was utilized in determining speed 1 (52). Measure¬ ment or determination of vehicular acceleration proceeds within the microprocessor as shown at 57, wherein the acceleration computation is symbolically depicted. Measure- ment of acceleration in the manner disclosed herein provides essentially jitter free or stable values for acceleration, due to the inclusion of the interim time, i.e. delta t, between successive vehicular speed measurements (ref. Figure 3C). With further reference to Figure 3, continued internal microprocessor handling of the information provided by pulses generated within the end-of-axle generator 6 and processed in signal filter 8 proceed as shown, with addi¬ tional reference to appropriate locations indicated in the attached Figure 3, describing in some detail internal operation of the microprocessor 10. It should be noted that the program disclosed utilizes ASM51 assembly language in programming the Intel 80351 microprocessor/controller, and further incorporating peripheral input/output devices. A detailed instruction set coordinated with ,the flow chart of Figure 3 is attached as Appendix "A".

In further keeping with the invention disclosed, the analog/digital speedometer provides ^' an operating feature comprising advances in the digital speedometer art in order assist operating personnel in handling and maintaining the particular vehicle containing the speedometer. These features include; a) operational checks of the speedometer system providing operators with clear indication of an failure (ref. "TEST ALL" of Figure 3); b) convenient calibration of the speedometer including restricted access means of changing speedometer constants such as overspee trip point and wheel size ; and vehicular overspeed detec¬ tion and alarm (ref. "TEST EDGE" of Figure 3). In keeping with the concepts of the invention disclosed, the above features are operator initiated through use of novel a system incorporating concealed magnetically actuable switches 20 and 22, located in the housing below the liquid crystal display, along with an enabling switch located on the rear side of the unit's housing (not shown). It should be noted that this switch is rendered a security switch in that a seal or safety wire is incorporated in order to prevent unauthorized recalibration of the speedome- ter internal constants which would alter speed and accelera¬ tion measurements, possibly defeating safety related infor¬ mation provided by speedometer readouts.

Turning now to the user initiated operational check and more particularly to Figure 3, page 1, at "TEST-ALL", actuation of the left-hand switch 20 by placing a magnetic probe in its proximity at position 24, establishes the TEST- LL procedure. As shown on Figure 3, the entire microprocessor is subjected to a predetermined series of tests, followed by an indication on the display face (refer- ence Figure 2), of each displayed indication, i.e. as shown, the deceleration bars 36, the acceleration bars 40, the rotating pointer 32, the rotary scale markings 39, and the digital speed indication 44.

Continuing on Figure 3, if the security switch has been closed and the right-hand switch 22, actuated as previously described (not shown) , wheel size and dimension are next displayed in the speed indication location 44 (ref. Figure 3, page 3, at "TEST EDGE") .

Operation then proceeds as best shown on Figure 3, page 3, beginning with "AT-A", to initialize all micropro¬ cessor registers and begin programmed functions, i.e. speed measurement and display. These operations proceed as shown on Figure 3 at "CALC-SPD", "A-D", and as shown on Figure 3, all speed and acceleration values are transmitted to the liquid crystal display 30.

Those skilled in the microprocessor programming arts will readily recognize the transition from functional operations indicated above to the specific microprocessor language indicated in Appendix "A".

In the event that it is decided or necessary to alter or reset previously stored constants utilized in determining speed, acceleration, or overspeed, the security switch (not shown) located at the right rear portion of the indicator cabinet is enabled, essentially bringing the microprocessor program to the "INITIAL-EDGE" portion as shown on Figure 3. Magnetic actuation of the right-hand concealed hall effect switch 22 moves the program to Figure 3, page 6, at "SIZE", where at "WAIT 1", it is necessary to actuate the concealed mode switch 20 within a 30 second period. Upon actuation, indication of the previously stored wheel diameter is obtained, having its left-most digit in a flashing mode indicating that subsequent actuation with the adjust or left-hand concealed switch 20_, will change the flashing digit. Proceeding in this manner, all displayed digits of the wheel diameter can be adjusted. If no opera¬ tion of the adjust switch 20 is present within a predeter¬ mined time interval, typically 30 seconds, the program proceeds to "RANGE" (Figure 3, page 8), display "SCAL CHNG". As in the case of adjusting the wheel size, subse¬ quent operation of the adjust switch within the 30 second interval results in display of the previously stored scale, i.e. "DUAL", or "SINGLE". The designation of "DUAL" or "SINGLE" indicates the choice of either continuous indica¬ tion of speeds from 0 to 99.9 miles per hour for the single mode, or initial indication from 0 to 9.99 miles per hour with automatic scale change to the 0 to 99.9 miles per hour scale.

Continuing on in the program sequence of Figure 3, page 8, at "SCL CHNG", the choice of dual/single is initiat- ed through operation of the concealed left-hand magnetic "ADJUST-TEST" switch 20 on the assumption that a change has been made, at "right-hand switch-mode". Further scale changing is precluded and if no further actuation of the left- or right-hand switches has occurred within 30 seconds, at "OVR SPD" the value of maximum vehicular speed beyond which the overspeed alarm or indication will be actuated is displayed.

Proceeding to Figure 3, page 9, on the assumption that the adjust test switch 20 has been actuated in the last 30 seconds, at "OVR SPD-CHNG" the previous overspeed value is displayed. As in the case of the wheel diameter, the left-most digit is now in condition for adjusting as indi¬ cated by a flashing digit.

Continuing on in Figure 3, all digits in the over- speed can be adjusted through subsequent, operation of the left-hand adjust test switch 20. After adjustment of the overspeed indication, operation proceeds to Figure 3, page 10, whereat "SAVE OVSP" the new value of overspeed is stored. As with the wheel diameter and overspeed quantities, absence of operation of the right-hand or mode switch 22 for 30 seconds results in display of the previously stored end of axle (EOA) signal rate, a number from 0 to 199, with the left-most digit in a flashing mode. Proceeding on Figure 3, page 10, subsequent opera¬ tion of the left-hand test adjust switch 20 allows changes in the end of axle signal rate, signifying the allowable number of pulses per wheel revolution which will be 13

incorporated in determining both acceleration and speed. It should be noted that the versatility of the disclosed speedometer system allows adjustment to a relatively high rate of input signal pulses, thereby accommodating outputs of certain radio frequency doppler radar speed detectors.

As in the above wheel size, overspeed, and range adjustments, after no actuations of the test adjust switc 20 for three 30 second intervals, the program proceeds to "ACCEL-BARS" where all display indications are simultaneous- ly displayed. At this point, the speedometer is in condi¬ tion for operation, utilizing a newly entered or change quantity of wheel size overspeed and end of axle picku pulse rate in measuring and indicating vehicle speed and/o acceleration. Thus, it is apparent that there has been provided i accordance with the invention, a vehicular speedomete having acceleration and deceleration indicating means, tha fully satisfies the objects, aims, and advantages as se forth above. While the invention has been described i conjunction with a specific embodiment thereof, it will b evident to those skilled in the art that many alternatives, modifications, and variations are possible given the con cepts and details disclosed in the foregoing description. Accordingly, it is intended to embrace all such alterna tives, modifications, and variations as fall within th spirit and broad scope of the appended claims. Therefore, what is claimed is:

Claims

1. In a speed measuring and indicating device for large, wheeled vehicles, of the type utilizing pulse voltage inputs from a rotating generator driven by the vehicle's axle, the improvement comprising; a composite liquid crystal display further compris¬ ing; a plurality of scale indicators disposed in an essentially circular arc, having predetermined groups indicated by highlighted ones of said indications, said indications essentially radial of a common center; an essentially radial indicator rotating around said scale center, said indicator occupying a unique predeter¬ mined and singular location adjacent any one of said scale indicators for a predetermined vehicular speed; and a plurality of essentially vertically disposed bars adjacent said arc, said bars arranged in a trapezoidal pattern parallel to one another, of increasing length and traversing said trapezoidal pattern from base,to base; means responsive to said determining means for generating a display of said bars in an increasing and/or decreasing group in accordance with acceleration or deceler¬ ation of said vehicle; means displaying said radial indicator and scale, said indicator corresponding to vehicular speed; and means determining said acceleration/deceleration corresponding to vehicular speeds immediately adjacent said vehicular speed indication; means correlating said acceleration and deceleration displays; wherein said pointer end radial scale indications and acceleration bars provide indication of vehicular motion.

2. The speed indicating means of claim 1, wherein said acceleration determination means comprises; means generating a repetitive alternating voltage signal having a frequency indicative of the rotation of said vehicular axle; means generating first and second groups of sai alternating signals during corresponding first and secon time intervals, over a continuous third time interval; means determining first and second speeds from said first and second signals and intervals; means determining a speed difference from said first and second speeds; means determining vehicular acceleration over sai third time interval; means matching said acceleration with appropriat ones of said acceleration bars, thereby displaying vehicula acceleration and the last determined speed.

3. The speed indicating means of claim 2 wherei the acceleration and speed determining means includes microprocessor.

4. The speed indicating means of claim 3 wherei the generating means includes an axle driven pulse genera tor.

5. The speed indicating means of claim 4 furthe comprising concealed switch means for directing sai microprocessor from speed and acceleration determination to system testing.

6. Apparatus for displaying speed and acceleration of a wheeled vehicle comprising; a liquid crystal display; an axle on said vehicle; a generator driven by said axle for generating a pulse train corresponding to vehicular wheel speed; a microprocessor responsive to said pulse train for generating signals indicative of vehicular speed and accel¬ eration; means in said display responsive to said speed and acceleration signals for producing a display pattern com¬ prising; a plurality of scale indicators of limited length radially disposed about a common center; a single radial indicator rotating about said scale center, said indicator having predetermined radial locations aligned with and abutting said scale indicators, said locations in one-to-one correspondence with predetermined vehicular speed; a plurality of essentially vertically disposed parallel bars arranged in a trapezoidal pattern, said bars of increasing length and traversing said trapezoidal pattern from base to base and responsive to said acceleration signals; wherein said pointer and acceleration bars provide indication of vehicular movement.

7. The apparatus of claim 6 wherein said micro- processor acceleration signals further comprise; means generating first and second groups of alter¬ nating signals during corresponding first and second time intervals over a continuous third time interval; means determining first and second speeds from said first and second signals and intervals; means determining a speed difference from said first and second speeds; means determining vehicular acceleration over said third interval; means correlating said acceleration in predetermined ranges with appropriate predetermined acceleration bars, thereby displaying vehicular acceleration and speed over a related time interval.

8. The apparatus of claim 7 wherein said accel- eration determining means further comprises; counting a predetermined integral number of pulses over a predetermined time interval, said interval including a fixed and variable portion; counting a second predetermined , number of pulses over a second predetermined time interval, said second time interval including a fixed and variable portion; determining a value of speed corresponding to a ratio of each said counted cycle and measured time interval; determining the difference of said speeds; determining the ratio between said speed difference and the sum of said time intervals.