Abstract:
An acceleration gauge using solid-state accelerometers positioned along the major axes of a motor vehicle record and display values representing the acceleration forces on the vehicle. The acceleration gauges, of which there are at least two positioned along the major x-y axes, develop signals to a housing having a microprocessor-based system. The housing is connected to either an analog or digital read out system wherein the various accelerations are displayed. The system can be an analog or digital system using discrete wiring or fiber optics to convey light signals. In the preferred embodiment there are three accelerometers positioned a various locations on the motor vehicle and their signals generate relative forward and reverse speed signals and vehicle tilt angles with respect to the horizontal.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to co-pending Provisional Patent Application claiming the benefit of Ser. No. 60/362,042 entitled “Accelerometer Gage Using Solid State Accelerometers” filed on Mar. 6, 2002 by Chadwick Ray Traylor. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to accelerometers in general and more particularly to an accelerometer module as may be used in the brake light system of a motor vehicle or a braking/deceleration/acceleration warning system for any moving body. 
     SUMMARY OF THE INVENTION 
     This is an acceleration gauge using solid-state accelerometers for use in automotive, aircraft, marine or any application requiring acceleration measurements. The use of accelerometers along all of the major axes of the motor vehicle will generate data to a read-out about the status of the vehicle such as forward, reverse and vertical acceleration, and tilt with respect to the travel surface. 
     It is therefore a major advantage to have solid-state accelerometers positioned at the c.g. of the vehicle with secured signal lines routed to a gauge located in the cockpit of the vehicle. 
     It is yet another advantage to provide a system wherein the total acceleration vectors are summed and available to the reader of the gauge upon the actuation of a selector switch. 
     These and other advantages are found in the acceleration gauge typically used in a vehicle. The gauge uses solid-state accelerometers wherein a first accelerometer is mounted along one axis of the vehicle. The first gauge is responsive to the vehicle movement along one axis and generates a first acceleration signal. 
     A second accelerometer is mounted along a second axis of the vehicle and responds to the vehicle movement along a second axis. The second accelerometer generates a second acceleration signal; A third accelerometer is mounted along a third axis of the vehicle and responds to the vehicle movement in the vertical direction and generates a third acceleration signal. The accelerometers have signal transmission lines connected to a housing with a microcomputer-based system located therein. The system has input for receiving the acceleration signals and processes the signals by an algorithm stored in a memory. The system has a calculation means that responds to the several steps of the algorithm and the acceleration signals for generating control signals. 
     Located in the system are power drivers that respond to the control signals and generate driver signals. The driver signals control one or more displays for generating both analog and numeric displays to give acceleration values of the vehicle movement in human readable form. 
     These and other advantages will become apparent in the following drawings and specification wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a schematic of the accelerometer gauge system of the preferred embodiment; 
         FIG. 2A  is a block diagram of one of the solid state accelerometers; 
         FIG. 2B  is a block diagram of another of the solid state accelerometers; 
         FIG. 3  is an enlarged block diagrammatic schematics of the solid-state accelerometer gauge of  FIG. 1 ; 
         FIG. 4  is an enlarged view of the accelerometer module of  FIG. 3 ; 
         FIG. 4A  is a diagram of a motor vehicle illustrating the several axes when the vehicle is at rest; 
         FIG. 4B  is a diagram of the motor vehicle of  FIG. 4A  when the motor vehicle at a tilt angle; 
         FIG. 5  is an enlarged view of the microprocessor module of  FIG. 3 ; 
         FIG. 6  is an enlarged view of the power supply module of  FIG. 3 ; 
         FIG. 7  is an enlarged view of the servo motor control module of  FIG. 3 ; 
         FIG. 8  is an enlarged view of the light source control module of  FIG. 3 ; 
         FIG. 9  is an enlarged view of the digital display control module of  FIG. 3 ; 
         FIG. 10  is an enlarged view of the combined analog and light source modules of  FIG. 3 ; 
         FIG. 11  is an enlarged view of the digital display module of  FIG. 3 ; 
         FIG. 12  is a face view of an accelerometer gauge of the present invention; 
         FIG. 13  is a face view of an alternate embodiment of an acceleration gauge of the present invention; 
         FIG. 13A  is an enlarged view of the measuring points and the light source on each dial; and 
         FIG. 14  is a view of a two accelerometer mounting as may be used in the alternate embodiment of FIG.  13 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Executive Description of the Invention 
     The preferred embodiment of the present accelerometer is typically found in a motor vehicle application, but the application is not so limited. Airplanes, marine vehicles, on-road and off-road vehicles are also potential users of the accelerometer. 
     The accelerometer gauge of the present invention measures positive and negative accelerations along each axis and has the capability in the algorithm to store the highest acceleration value in each axis. This will allow the driver of the vehicle to know the highest acceleration forces in each axis direction that the driver&#39;s vehicle has experienced. Thus, a racecar driver, as an example, can drove the vehicle any distance or number of laps at any speed, and even repeat the same laps at different speeds to determine when both the driver and vehicle are experiencing the largest acceleration forces on each axis. This information will give the driver valuable information on how the vehicle should be driven for maximum race efficiency. As will hereinafter be shown, the acceleration gauge provides special switches that allow the various independent gauges to be reset to allow new information to be inputted to the gauges. 
     The “x” accelerometer provides both positive and negative acceleration values in the longitudinal or horizontal direction. The “y” accelerometer provides both positive and negative acceleration values in the orthogonal direction to the “x” axis and the “z” accelerometer provides both positive and negative acceleration values in the vertical direction as the vehicle become air-born or is following a course that change altitude. 
     As will be shown, the algorithm using the values from each of the three accelerometers will calculate the “tilt” acceleration forces as the vehicle leans in one of the directions such as when the vehicle is turning. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a schematic of one embodiment of the acceleration gauge  18  of the present invention. There is shown the first  20 , second  22  and third  23  accelerometers, a forward and reverse or backward gauge  24 , a left and right gauge  26 , an up and down gauge  27 , a microprocessor  28 , forward and backward gauge electronics  30 , left and right gauge electronics  32  and up and down gauge electronics  33 . The microprocessor system is housed in a housing and is a Parallax basic stamp II-SX. A connector output terminal  34  emanates from the microprocessor housing. The electrical output connector is also available for receiving input signals to the gauge. Such signals, which are generated from the circuitry and applied, to the read-out locations are also outputted from the electrical output connector. The above components are all interconnected in a manner similar to that shown in FIG.  1 . 
     Referring to  FIGS. 2A and 2B  are illustrations of two dual axis accelerometers  20 ,  22  such as the analog devices ADXL202AE. One of the analog devices  20 ,  FIG. 2A , would measure forward acceleration and left acceleration. The second analog device  FIG. 2B , would measure reverse deceleration or breaking deceleration and right acceleration. In  FIG. 2A , the first accelerometer, ACC 1 , operates according to the vector chart on the accelerometer illustrating forward acceleration on the “+y” axis  36  and left to right acceleration on the “+x” axis  38 .  FIG. 2B  is the second accelerometer, ACC 2 , illustrating backward acceleration on the “−y” axis  40  and right to left acceleration on the “−x” axis  42 . 
     Referring to  FIG. 3 , the block diagrammatic schematic of  FIG. 1  is enlarged showing more of the details of the several modules of the gauge  18 . These modules are the microprocessor module  44  receiving power from the power supply  46  via the power supply module  48 . Other inputs to the microprocessor are the accelerometer module  50 , the electrical switches  52  and the external electrical signal interface  34 . 
     Several of the outputs of the microprocessor  44  are the servo motor control module  54  that controls the analog displays  56  such as dial gauges, the light source control module  58  which is also usable on the dial gauges, and the digital display module  60 . The light source control module  58  controls the lights in the analog displays to indicate the values supplied to the gauge, as will be illustrated in  FIG. 13  in the same manner as does a pointer dial and the light sources  62 . The digital display module  60  controls the digital displays  64  in the gauge  18 . 
     Referring to  FIG. 4 , there is illustrated the accelerometer module  50  in detail. Previously in  FIG. 1  there was illustrated only three accelerometers  20 ,  22 ,  23 ; as this a complete gauge  18 , more accelerometers can be added. In  FIG. 4 , there is shown another accelerometer  66  for the z-axis  68 . The z-axis  68  is defined as the axis that is orthogonal to the x-y plane or vertical axis and in a direction that would be a direction of lift. Referring to  FIGS. 4A and 4B  illustrates the three axes as applied to a motor vehicle  70 . The vehicle  70  in  FIG. 4A  is at rest with the −y axis  40  horizontal or longitudinal to the ground. In  FIG. 4B  the −y axis  40  is raised at an angle Ø relative to the ground. Such an occurrence will take place during hard vehicle braking or as the vehicle travels up and down hills. The z-axis accelerometer  66  is used as the vertical sensor with basic trigonometry calculations in the algorithm  67  and the calculation means  69  of the microprocessor  28 , the tilt angle Ø is calculated and then the y-axis acceleration is calculated. 
     Referring to  FIG. 4 , additional accelerometers that may be provided are the x-y tilt axis  70 , the x-z tilt axis  72 , the y-z tilt axis  74  plus other accelerometers  76  as selected by the design engineer. In particular the x-y tilt axis acceleration  70  is measured by an accelerometer that is positioned at an angle to the x and y axis, typically a 45° angle. Likewise the x-z axis and the y-z tilt axes accelerations  72 ,  74  have accelerometers positioned at an angle to the axes. One of the main purposes of the tilt calculation is to recalibrate the gauge  18  due to the vehicle being on a non-level surface. 
     The acceleration signals  78  generated from the accelerometers are typically very low. The electrical wiring transmitting the acceleration signals should be shielded from EMI and appropriate amplifiers should be positioned as close to the accelerometers as possible to amplify the signal. These amplifiers and shielding are found in the I/O control and signal processing section  80 . If desired, the electrical design engineer may add power supply regulation  82  in the module  50 . The output of the module  50  is an I/O bus  84 . 
     Referring to  FIG. 5 , microprocessor module  44  is illustrated in more detail. The algorithm  67  is stored in the memory  86 . The calculation means  69  is coupled to the algorithm  67  and the memory  86  to perform the necessary calculations from the acceleration signals  78 . The calculation means  69  generates control signals that are applied to power drivers  90  for generating driver control signals  92 . These driver control signals  92  are emanated from the I/O bus  84  to the several modules  54 ,  58 , and  60 . Other sections of the microprocessor module  44  are a power distribution center  94  and support electronics including phase lock loop control  96 . 
     Referring to  FIG. 6 , the power supply module  44  illustrates the types of controls normally found in such a module. These are a voltage regulation section  98  that controls the level of the voltage to the several control circuits. A current regulation section  100  may be also used and placed in the power supply module. The several power level signals that are controlled by the power supply module  48  are conditioned by noise reduction circuitry  102  and then are outputted from the I/O bus  104  in the module  48 . 
       FIG. 7  represents the servomotor control module  54 . Located therein are the servo motor position drivers  106 , servo motor control feedback systems  108  and servo motor control power supply systems  110 . These several functions are within the control of the system designer and how such subsystems are implemented. All signals to and from this module are connected through its I/O bus  112 . 
       FIG. 8  illustrates the content of a light source module  58  if the gauge  18  has illumination. The gauge  18  may have its readout to be a light actuated system wherein the several read-out markers are identified by LEDs. If the gauge  18  is a light actuated gauge, the several functions such as the light source display power management systems  114 , matrix control system  116 , intensity control  118 , color control  120  and display speed  122  are contain herein. All electrical signals to and from the module  58  are through the I/O bus  124 . 
       FIG. 9  is similar to  FIG. 8  in that it is the digital display control  60 . Typically, the digital display and the light display have similar control functions. If the gauge  18  is a digital display gauge in completely or in part, the several functions are similar. These functions are the digital display power management systems  126 , pixel and matrix control system  128 , intensity control  130 , color control  132  and display speed  134  are contained herein. All electrical signals to and from the module  60  are through the I/O bus  136 . 
     Referring to  FIG. 10 , the analog display module  56  and the light source display module  62  are combined. The Fig. is shown with the use of three servomotors and/or light sources control  138 ,  140 ,  142  for controlling the displays in the gauge  18 . When the dials in the gauge are analog, typically servomotors are used to move or rotate the needles on the dials. Other drive control systems for the analog-gauge indicator needles may be accomplished by servomotors crystal watch movement, typical magnet needle movement devices/gauges and by stepper motors. Other drive control systems include DC motors, synchronous motors, three-phase motors (AC), and other similar type of electromagnetic motor system. As will hereinafter be shown with  FIG. 13 , light sources can be located on the dials to indicate the dial readings. 
       FIG. 11  is a detail of the digital display module  64  illustrating three or more digital displays are capable of being controlled by the system. 
     Referring to  FIG. 12  the gauge  18  has four quadrants  144 - 147 . Reading clockwise, the first quadrant  144 , “F”, is a forward acceleration indicator. It is divided into measuring points  148  in a clockwise direction beginning from the twelve o&#39;clock position. The needle  150  is shown in a normal position at twelve o&#39;clock. The first accelerometer  20  operates to show forward and/or reverse acceleration. This occurs when the forward acceleration causes the needle  150  to move from center “0” position to the right toward the gauge marked “F”. Reverse acceleration causes the needle  150  to move from the zero position to the left moving toward the gauge marked “B” or braking. 
     The fourth quadrant  145 , “R”, is a right acceleration indicator. It is divided into measuring points  148  in a counterclockwise direction beginning from the six o&#39;clock position. This portion of the gauge indicates acceleration from left to right as when making a right turn. The needle  152  is shown in a normal position at six o&#39;clock. This second accelerometer  22  operates to show the needle  152  going from the center or six o&#39;clock position to the right moving toward the gauge marked “R”. 
     The third quadrant  146 , “L”, is a left acceleration indicator. It is divided into measuring points  148  in a clockwise direction beginning from the six o&#39;clock position. This portion of the gauge  18  indicates acceleration from right to left as when making a left turn. 
     The second quadrant  147 , “B”, is a braking or deceleration indicator. It is divided into measuring points  148  in a counterclockwise direction beginning at the twelve o&#39;clock position and moves toward the gauge marked “B”. This portion of the gauge indicates deceleration when the vehicle  69  is braking. 
     On the left side of the gauge  18 , is a vertical Up-Down acceleration gauge  154  with the measuring points or indices  156  increasing from the center point  158  of the gauge  154 . “U” being the up position and “D” being the down position and this gauge responds to the “z” axis accelerometer  66  as previously explained. 
     Along the central horizontal axis of the gauge  18  is a band having a plurality of digital or numerical read-out locations  160 . This portion of the gauge  18  indicates total acceleration or any other parameter calculated by the microprocessor from the accelerometer inputs. This shows the summed acceleration vectors and shows the maximum summed acceleration when the “max button”  162  is depressed. In the alternative, this digital read-out can be programmed to show the maximum acceleration on any axis as hereinbefore explained. 
     The max button  162  is shown located to the left of the Up-Down acceleration read-out gauge  154 . If the Up-Down acceleration read-cut gauge is not used, then the max button  162  could be typically located to the right of the read-out locations and is approximately located at the three o&#39;clock position of the gauge  18 . The actual position of the max button  162  is a design choice. The max button  162  activates the digital read-out locations  160  and when depressed will drive all of the servo-motors driving the needles to the maximum number indicated. 
     Located near the max button  162  is a reset button  164 . The reset button  164  will likewise cause the gauge  18  to read-out the maximum-recorded acceleration to the memory unit  86  and then when released will reset the read-out locations  160 . 
     The location of the several read-out locations  160  on the face of the acceleration gauge  18  is a matter of design. 
     Positioned along the circumference of the gauge  18  is an electrical output connector  34 . In  FIG. 12 , it is shown at approximately two o&#39;clock. From this output connector  34 , the acceleration values may be outputted which are any forms of signal consistent with the mode of the output desired. Such modes are analog, digital, mechanical, or any other characteristic signal that is capable of generating the acceleration signal values for input to a computer or other device. 
     The accelerometer gauge  18  is illuminated by any number of various light emitting devices such as LED&#39;s, LCD&#39;s, or any type of infrared device. Recording devices may be added to the accelerometer gauge  18 . 
     With only three needle read-outs as shown in  FIG. 12 , the upper needle  150  gauge is connected to the ACC 1   20  y-axis  36 . The lower needle read-out is connected to ACC 1   20  x-axis  38  and the ACC 2   22  x-axis  42  and the Up-Down gauge is connected to the z-axis accelerometer. Accelerometers are capable of indicating or measuring negative axis accelerations. 
     Referring to  FIG. 13  is an example of an alternate embodiment of a complete acceleration gauge  164 . This is an example where each of the gauges  166 ,  168 ,  170  that are of interest to the driver is an individual gauge. As an example, the first gauge  166  is a vertical acceleration gauge, the second gauge  168  is a longitudinal acceleration gauge and the third gauge  170  is a lateral acceleration gauge. The order and type of readout from the various gauges is a matter of design. In  FIG. 13  each gauge  166 - 168 - 170  is an analog gauge with the needles  172 ,  174 ,  176  pivoting from the center of the gauge. The needles can pivot both left and right from the center or twelve o&#39;clock position. As illustrated, each gauge has measuring points or indices  148 , which in  FIG. 13  extend from approximately the nine o&#39;clock to the three o&#39;clock position. As an alternative, or in addition to the needle, a small light emitting read-out bulb  178  can identify each measuring point. 
     Positioned within the field of the gauge faceplates  180  and shown in line with the twelve o&#39;clock position are larger lights  182  that indicate a warning to the driver. These warning lights  182  may be used to indicate when the actual value being calculated by the microprocessor-based system is beyond that which the driver wants to be. This may be a maximum acceleration value, a maximum “g” value or whatever. The value is a design option and is loaded into the algorithm  67  so that when the value is reached, the lights  182  are illuminated. 
     The first gauge  166  reads vertical acceleration and the dial markings  148  are from +1000 mg through 0 to −1000 mgs. Zero mg is at the twelve o&#39;clock position. If a vehicle is climbing a hill, the acceleration could reach a number of Gs. A 1.0 G measurement is 1000 mgs or gravity. Note that if the vehicle becomes air-borne and is a free-falling body, the acceleration of 0 mgs would be encountered. Thus, the center warning light  182  could be lighted at 1500 mgs or less than 500 mgs. This gage  166  displays both real-time and maximum acceleration measurements. 
     The second gauge  168  indicates the forward and backward acceleration placed on vehicle or body when vehicle is stopped and level. This gage centers on 0 mgs. If the vehicle or body decelerates, acceleration could reach −1000 mgs or 1000 mgs in reverse direction. If vehicle accelerates rapidly by speeding up, acceleration could reach +1000 mg or 1000 mg in forward direction. The warning light  182  will light at accelerations of greater than 500 mgs in reverse direction (greater than 500 mgs of deceleration) and at acceleration greater than 500 mg in forward direction (greater than 500 mg of acceleration). This gage  168  displays both real-time and maximum acceleration measurements. 
     The third gauge  170  indicates the lateral acceleration placed on the vehicle or body. When vehicle as stopped and level, this gage centers on 0 mg. If the vehicle or body makes a hard left turn (or any degree of left turn) the acceleration could reach 1001 mgs in the left direction. If the vehicle or body makes a hard right turn, the acceleration could reach 1000 mg in the right direction. The warning light  182  will light at accelerations greater than 500 mg in the left direction and at accelerations greater than 500 mg in the right direction. This gauge  182  displays both real-time and maximum acceleration measurements. 
     The digital display  184  displays both real-time and maximum acceleration measurements for the vertical, longitudinal and lateral accelerations. If the display  184  is divided into at least three sections, all of the accelerations can be read simultaneously. This allows the user to see analog and digital, real-time and maximum displays, simultaneously. The digital display  184  is a two line sixteen characters per line display although any size can be used. The display  184  can also be backlit. 
     When the max button  162  is depressed and held depressed this causes the maximum acceleration vectors/values experienced by accelerometers since the last reset to be displayed on the analog gages  166 ,  168 ,  170  and digital display simultaneously  184 . All three axes of acceleration and both direction and magnitude of maximum accelerations are displayed. Also works for the tilt mode. 
     When the accelerometer node/tilt mode switch  186  is in the accelerometer mode the accelerometer gauge system operates as desired above. When this switch  186  is in the tilt mode both the analog gages and the digital display displays the levels of tilt for each of the three tilt axes in units of degrees. The three axes of tilt are the X-Y, the X-Z, and the Y-Z. 
     When the max button  188  is depressed and held depressed this causes the maximum tilt calculations expressed by accelerometers since the last reset to be displayed on the analog gages  166 ,  168 ,  170  and digital display  184  simultaneously. All three axes of tilt and both magnitude and directions of tilt are displayed. Tilt is calculated using basic trigonometry and differences in accelerometer values by the operation of the algorithm  67 . The tilt values or all three above described axes are both real-time and static for maximum tilt display when using the max button  162 . 
     In the tilt mode the warning lights  182  will light at angle of tilt greater than 15° for any axis. The analog gage faceplates  180  have both mg and degree of tilt, i.e. tilt degree markings  148 . The digital display  184  shows both inputs of mg for acceleration mode and units of degrees for tilt mode. The tilt angle range of the prototype is from zero to ninety degrees for all three-tilt axes. The tilt mode can use up to all six accelerometers shown in the accelerometer module FIG.  4 . More than six accelerometers may be used as well. 
     When the reset button and switch  188  is depressed and released the maximum display value held in the memory of the microprocessor memory  86  is cleared or zeroed for all three acceleration axes and all three-tilt axes. 
     The on-off power switch  190  is used to remove power from all the electronics and accelerometers causing a complete system shutdown. 
     The two-way electrical and optical signal interface  192  provides a means for all electrical and optical signals to be sent/received from an external source. Any electrical and/or optical signal may be sent or received via this port. All functionality described this far is valid. 
       FIG. 14  illustrates the mounting of two accelerometers  194 ,  195  namely an x-z axis and x-y accelerometer on a bracket  197  in a housing  198  that is shielded from EMI signals. By this means all three axis, x, y, z, can be calculated and the result displayed on the gauge. 
     It is understood that many different technologies may be use without departing from the spirit of the invention. Some of such technologies may be wireless, optical, light transmission, etc. to name but a few. 
     While the present invention has been described in an illustrative manner, it should be understood that the terminology used is intended to be in a nature of words of description rather than of limitation. 
     Accordingly, various changes and modifications may be made to the illustrative embodiment without departing from the spirit or scope of the invention. It is to be appreciated that those skilled in the art will readily apply these teachings to other possible variations of the inventions. However, it is intended that the scope of the invention not be limited in any way to the illustrative embodiment shown and described but that the invention be limited only by claims appended hereto.