Abstract:
Truck hunting determination involves taking samples of side to side acceleration in a vehicle, evaluating the samples by comparing the samples, and determining the degree of truck hunting on the basis of the comparison.

Description:
RELATED APPLICATIONS 
     This application is related to and a the regular application and continuation and/or continuation-in-part of Provisional Application Ser. No. 60/053,143 filed Jul. 18, 1997. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to methods and apparatus for determination of truck hunting. 
     BACKGROUND OF THE INVENTION 
     The various means for determination of truck hunting, that is lateral movement, in railroad cars and other cargo carriers have depended on cumbersome and inaccurate arrangements which are difficult to transmit to remote locations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic elevation of an embodiment of the invention in the form of a railroad car including equipment for truck hunting determination. 
     FIG. 2 is a schematic elevation of an embodiment of the invention showing a vehicle roof line with a solar panel 
     FIGS. 3 and 4 are graphs illustrating performance under various conditions. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     1. TRUCK HUNTING DETERMINATION 
     1.1. DEFINITION 
     Truck hunting is defined as a lateral movement from side to side of a railcar. The AAR has set parameters for defining problematic truck hunting as 10 or more events of greater than 0.75 g at a rate of 2-6 Hz. Lower levels of events are indicative of degradation of railcar components, and could further degrade. 
     1.2. DETERMINATION 
     The aforementioned shaking leaves a measurable lateral signature on the y-axis accelerometer. This signature will be captured and monitored for evaluation under two different scenarios. The first deals with routine car health evaluation and monitoring, the second with truck hunting “events” in which the hunting exceeds certain levels. 
     1.2.1. IDENTIFICATION OF TRUCK HUNTING EVENTS 
     Two methods are available to capture this problem. They are: 
     1.2.1.1. Routine Monitoring 
     During the course of operation, the unit will be taking samples and evaluating them (see below). The comparison of energy and peaks over time is one way to determine the level of truck hunting. 
     1.2.1.2. Event Monitoring 
     The second method involves evaluating specific events that exceed certain set parameters. In this case, should the peak g exceed this number, then further analysis is done to determine whether it is a hunting event, or the car has gone over a piece of bad track. 
     The unit will take the 3 seconds buffer and an additional continuous 7 seconds (for a total of ten) and analyze the number of peaks over a set g to determine if there has been a hunting event, or something else. 
     1.2.2. TRUCK HUNTING HEALTH EVALUATION AND MONITORING 
     10 second y-axis samples will be taken periodically (2-4 times per hour) throughout the day, and only when the car is moving. 
     1.2.2.1. Sample Analysis 
     Each sample will have a number of peaks during the sample period. These peak numbers will be captured and stored in a database for eventual use in the truck hunting histogram. The data itself will be stored in the following format: 
     
       
         Date/time, speed, mass, peak 1 , peak 2 , peak 3 , peak 4 , peak 5 , peak 6   
       
     
     Where: 
     Peak 1 =The number of peaks between 0.2-0.299 g 
     Peak 2 =The number of peaks between 0.3-0.399 g 
     Peak 3 =The number of peaks between 0.4-0.499 g 
     Peak 4 =The number of peaks between 0.5-0.599 g 
     Peak 5 =The number of peaks between 0.6-0.699 g 
     Peak 6 =The number of peaks at or above 0.7 g 
     These bins will be stored on-car until the car is queried (once or twice a month) and then compiled into two histograms: one for unloaded, one for when the car is loaded. 
     1.2.2.2. Truck Hunting Histogram 
     The histogram will have the number of peaks between these g levels within specific ranges of speed (see chart below). 
     
       
         
               
               
               
               
               
               
               
             
               
             
           
               
                   
                   
               
               
                   
                 0.2- 
                 0.3- 
                 0.4- 
                 0.5- 
                 0.6- 
                   
               
               
                   
                 0.299 g 
                 0.399 g 
                 0.499 g 
                 0.599 g 
                 0.699 g 
                 0.7+ g 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 10-19.9 mph 
               
               
                 20-29.9 mph 
               
               
                 30-39.9 mph 
               
               
                 40-49.9 mph 
               
               
                 50-59.9 mph 
               
               
                 60+ mph 
               
               
                   
               
             
          
         
       
     
     As the mass of the car may affect the hunting signature, at least two 36 bin histograms will be forwarded, one for when the car is unloaded, one for when the car is loaded. The addition of the two histograms together can all be done on the data server. 
     1.2.2.3. Trend Analysis 
     The forwarded histograms will then be compared to the historical histograms we have on file. And significant changes can be noted and forwarded to the customer. The specific changes that might signal a trend towards truck hunting include any move towards the right columns (i.e. higher peak g&#39;s). 
     1.2.3. ON-CAR PARAMETERS 
     One of the benefits to the RM7000 system is the two way communication and the fact that much of the analysis and parameters are dynamic. We can, therefore, remotely set the key parameters as we learn more about the functioning of the cars. The key remote-settable parameters are: 
     Sample frequency—The number of times per day (e.g. 2 times/hour) that a sample is taken 
     Sample duration—The length of time (e.g. 10 seconds) that a sample lasts 
     Alarm trigger—The peak g that must be exceeded (e.g. 0.5 g) for capture to start and for analysis to be done on the captured sample. 
     Bin parameters—Histogram parameters (speed and g ranges) 
     1.2.4. COMMANDS 
     Reset—Will reset/re-calibrate the data on-car. This is needed if a repair has recently been done, etc. 
     1.2.5. MESSAGES 
     1.2.6. ALARM—WAKE 
     The unit will automatically wake and capture data if y-axis peak g&#39;s exceed a certain level (i.e. 0.5 g). At this point the unit will save the buffer and capture for an additional period of time. 
     This analysis will evaluate whether there have been a number of peaks over certain levels within the sample period of time. These parameters will be set in a manner similar to the AAR definitions. For example: 
     If the number of peaks over 0.5 g is greater than some set number (5-10) then an alarm message is sent to the customer, alerting them to the potential problem. 
     1.2.7. ALARM—BAD SWITCH 
     If the peak exceeds some other number (e.g. 1 g) and seems to be a single event, then another alarm is sent, indicating that there was a bad switch, or perhaps a bad section of track or other anomaly. 
     Summary of Truck Hunting Health Determination Event Flow 
     
       
         
               
               
             
           
               
                   
               
               
                 During Standard Monitoring 
                 After Awakening from Trigger 
               
               
                   
               
             
             
               
                 Sample waveform (typically 10 
                 Sample waveform is taken (3 
               
               
                 seconds) is taken 
                 seconds from buffer, 7 additional 
               
               
                   
                 seconds, for total of 10) 
               
               
                 Peak Analysis is performed (i.e. 
                 Peak Analysis is performed (i.e. 
               
               
                 # peaks within each range of g 
                 # peaks within each range of g 
               
               
                 [0.2-0.3, etc.]) 
                 [0.2-0.3, etc.]) 
               
               
                 Results are saved in database 
               
               
                 Results are saved in histogram 
               
               
                 Waveform analyzed to determine 
                 Waveform analyzed to determine 
               
               
                 whether the frequency of 
                 whether the frequency of signifi- 
               
               
                 significant peaks (i.e. those over 
                 cant peaks (i.e. those over some set 
               
               
                 some set number [typically 0.5 g]) 
                 number [typically 0.5 g]) is 
               
               
                 is greater than some other set 
                 greater than some other set number 
               
               
                 number (typically 2-6 Hz) 
                 (typically 2-6 Hz) 
               
               
                 Histogram analyzed for trends to 
               
               
                 determine potential degradation of 
               
               
                 performance 
               
               
                 If trend alarm triggered, then alarm 
               
               
                 and histogram sent to base station 
               
               
                 If not, histogram forwarded at set 
               
               
                 period (e.g. month end) 
               
               
                 If any peak exceeds some set 
                 If any peak exceeds some set 
               
               
                 number (typically 0.5 g), and fre- 
                 number (typically 0.5 g), and 
               
               
                 quency is not greater than trigger, 
                 frequency is not greater than 
               
               
                 then alarm is sent to base station 
                 trigger, then alarm is sent to base 
               
               
                 regarding possible bad track 
                 station regarding possible bad track 
               
               
                 section 
                 section 
               
               
                 Periodic geographic analysis done 
                 Periodic geographic analysis done 
               
               
                 in central server to determine any 
                 in central server to determine any 
               
               
                 possible track anomalies. 
                 possible track anomalies.