Dynamic angle of attack measurement system and method therefor
First Claim
1. A method for measuring the angle of attack in a set of wheels on track, said method comprising the steps of:
- obtaining angle of attack time sampled data for each wheel in the set of wheels, taking a derivative of each time sampled data for each wheel, locating the peaks in the derivative of each time sampled data, determining an angle of attack value based on said located peaks.
1 Assignment
0 Petitions
Accused Products
Abstract
A method measures the angle of attack for the leading and trailing sets of wheels in trucks of rail vehicles traveling over track in a wayside system. At a first point on the outside rail of a track vertical force is measured with a first vertical strain gage, lateral force is measured with a first lateral strain gage and an outside angle of attack timing signal is measured with a first angle of attack strain gage. This process is repeated on the inside track so that a raw angle of attack for each set of wheels can be determined based upon speed and time difference. Ratios between the lateral force and the vertical force for the wheels of each are used to select raw angle of attack values for properly steering trucks that are averaged together to obtain an average angular offset value related to any misalignment of the strain gages. A dynamic angle of attack for each set of wheels is obtained by subtracting the average angular offset value from each raw angle of attack value to obtain a dynamic angle of attack value for each set of wheels. Greater accuracy in measuring angle of attack values occurs by taking a derivative of the data and using a polynomial fit to find the derivative'"'"'s peak.
11 Citations
19 Claims
-
1. A method for measuring the angle of attack in a set of wheels on track, said method comprising the steps of:
-
obtaining angle of attack time sampled data for each wheel in the set of wheels, taking a derivative of each time sampled data for each wheel, locating the peaks in the derivative of each time sampled data, determining an angle of attack value based on said located peaks. - View Dependent Claims (2, 3, 4)
sensing outside angle of attack forces at a predetermined time sample rate at a first point on an outside rail of the track, sensing inside angle of attack forces at the predetermined time sample rate at a second point on an inside rail of the track, the inside point and the outside point located on a line perpendicular to a line tangent to the outside rail.
-
-
3. The method of claim 1 wherein the step of locating a time of each of the peaks includes the step of selecting time sampled data within a predetermined window about each of the peaks.
-
4. The method of claim 3 wherein the step of locating the peaks uses a polynomial fit process on the time sampled data within each predetermined window.
-
5. A method for measuring the angle of attack in a set of wheels on track, said method comprising the steps of:
-
obtaining angle of attack time sampled data for each wheel in the set of wheels, taking a derivative of each time sampled data for each wheel, locating the peaks in the derivative of each time sampled data, selecting time sampled data within a predetermined window about each of said peaks calculating the time of each located peak in each predetermined window based on the selected time sampled data, determining an angle of attack value based on the determined times of the located peaks. - View Dependent Claims (6)
-
-
7. A method for measuring the dynamic angle of attack for the leading and trailing sets of wheels in trucks of rail vehicles on track, said method comprising the steps of:
-
determining raw angles of attack for all sets of wheels, selecting only those raw angles of attack from the aforesaid step that have trucks on the track within a predetermined range of lateral to vertical force ratios wherein the selected trucks are properly steering trucks, calculating a dynamic angular offset value based on the selected raw angles of attack of the properly steering trucks, subtracting the calculated dynamic angular offset value from the raw angles of attack determined for all sets of wheels to arrive at a dynamic angle of attack for each wheel set. - View Dependent Claims (8, 9, 10, 11, 12, 13)
at a first point on the outside rail of the track measuring an outside angle of attack value with a first angle of attack sensor for each outside wheel at the time when the outside wheel passes directly over a first point, at a second point on the inside rail of the track measuring an inside angle of attack value with a second angle of attack sensor for each inside wheel at the time each inside wheel passes directly over a second point, the second point located on a line perpendicular to a line tangent to the outside rail at the first point, measuring the speed of each set of wheels, determining a raw angle of attack for each set of wheels based on the speed and the outside and inside angle of attack values.
-
-
9. The method of claim 8 wherein the times when the outside wheel passes directly over the first point and when the inside wheel passes directly over the second point are determined by:
-
taking a derivative of time sampled data from the corresponding angle of attack sensor, locating a peak time of the derivative in a predetermined window of time sampled data to obtain an angle of attack value at said peak time.
-
-
10. The method of claim 9 wherein the step of locating a peak uses a polynomial fit process.
-
11. The method of claim 7 wherein the step of selecting includes the steps of:
-
at a point on the outside rail of the track measuring (1) vertical force with a first vertical strain gage, and (2) lateral force with a first lateral strain gage, determining a ratio between the measured lateral force and the measured vertical force at the point for the outside wheel of each leading set of wheels in each truck, determining whether the ratio is within a predetermined range and, if so, averaging the raw angles of attack for the trailing wheel connected to the leading wheel with all other trailing wheel raw angles of attack that have corresponding ratios within the predetermined range to obtain an average angular offset value.
-
-
12. The method of claim 11 wherein the predetermined range is less than 0.1.
-
13. The method of claim 12 wherein the predetermined range also includes when the ratio is between 0.1 and 0.17 and the ratio for trailing wheel divided by the ratio of the leading wheel is less than 0.5.
-
14. A method for measuring the angle of attack for a set of wheels traveling over track having outside and inside rails, the method comprising the steps of:
-
at a first point on the outside rail of the track measuring (1) vertical force with a first vertical sensor, (2) lateral force with a first lateral sensor and (3) an outside angle of attack value with a first angle of attack sensor for the outside wheel at the time when the outside wheel passes directly over the first point, at a second point on the inside rail of the track measuring (1) vertical force with a second vertical sensor, (2) the lateral force with a second lateral sensor and (3) an inside angle of attack value with a second angle of attack sensor for the inside wheel at the time the inside wheel passes directly over the second point, the second point located on a line perpendicular to a line tangent to the outside rail at the first point, measuring the speed of each set of wheels, determining a raw angle of attack for the set of wheels based on the speed and the outside and inside angle of attack values, determining a ratio between the measured lateral force and the measured vertical force at the first point for the outside wheel, determining whether the ratio is within a predetermined range and, if so, averaging the raw angle of attack with all other raw angles of attack that have corresponding ratios within the predetermined range for other sets of wheels to obtain an average angular offset value, calculating a dynamic angle of attack for the set of wheels by subtracting the average angular offset value from each raw angle of attack to obtain a dynamic angle of attack value for the set of wheels. - View Dependent Claims (15, 16)
taking a derivative of time sampled data from the corresponding angle of attack strain gage, locating a peak time of the derivative so as to obtain an angle of attack value at said peak time.
-
-
16. The method of claim 15 wherein the step of locating a peak time uses a polynomial fit process.
-
17. A method for measuring the angle of attack for the leading and trailing sets of wheels in trucks of rail vehicles traveling over track having outside and inside rails, the method comprising the steps of:
-
at a first point on the outside rail of the track measuring (1) vertical force with a first vertical sensor, (2) lateral force with a first lateral sensor and (3) an outside angle of attack value with a first angle of attack sensor for each outside wheel at the time when the outside wheel passes directly over the first point, at a second point on the inside rail of the track measuring (1) vertical force with a second vertical sensor, (2) the lateral force with a second lateral sensor and (3) an inside angle of attack value with a second angle of attack sensor for each inside wheel at the time each inside wheel passes directly over the second point, the second point located on a line perpendicular to a line tangent to the outside rail at the first point, measuring the speed of each set of wheels, determining a raw angle of attack for each set of wheels based on the speed and the outside and inside angle of attack values, determining a ratio between the measured lateral force and the measured vertical force at the first point for the outside wheel of each leading set of wheels in each truck, determining whether the ratio is within a predetermined range and, if so, averaging the raw angles of attack for the trailing wheel connected to the leading wheel with all other trailing wheel raw angles of attack that have corresponding ratios within the predetermined range to obtain an average angular offset value, calculating a dynamic angle of attack for each set of wheels by subtracting the average angular offset value from each raw angle of attack to obtain a dynamic angle of attack value for each set of wheels. - View Dependent Claims (18, 19)
-
Specification