Real-time wireless dynamic tire pressure sensor and energy harvesting system

Abstract

An instantaneous/real-time wireless dynamic tire pressure sensor (DTPS) for characterizing pavement qualities and for detecting surface and subsurface pavement defects under normal driving conditions. Signal processing provides quantitative assessment of surface conditions. DTPS includes a vehicle tire valve stem-mounted pressure sensor and wheel hub-mounted signal conditioning, amplification, and transmitting circuitry. A signal processing computer within the vehicle is wirelessly coupled to the hub-mounted circuitry. Tire pressure changes caused by ground vibration excitation from the interaction between the tire and pavement at normal driving speeds are detected. When acoustic radiation from a surface wave is significantly stronger than acoustic noise, subsurface information can be extracted. An energy harvester based on strong magnetostatic coupling between a high permeability core solenoid, fixed proximate a vehicle wheel, and a bias magnet array, fixedly mounted in conjunction with a dust shield, can provide power the DIPS.

1 - 24 . (canceled) 
     
     
         25 . An energy harvester for vehicular applications, comprising:
 an arcuate array of magnets, disposed within a fixture mounted on the vehicle adjacent a first wheel thereof;   at least one solenoid disposed in conjunction with the first wheel for rotation therewith and proximate the array of magnets; and   a rectifier for receiving power from the at least one solenoid and for providing a direct current power output.   
     
     
         26 . The energy harvester of  claim 25 , wherein the magnetization of the magnets of the array is arranged antiparallel. 
     
     
         27 . The energy harvester of  claim 26 , wherein a spatially heterogeneous magnetic field exists above each pair of magnets of the array. 
     
     
         28 . The energy harvester of  claim 25 , wherein the magnets of the array are Neodymium cylindrical hard magnets. 
     
     
         29 . The energy harvester of  claim 25 , wherein the fixture is disposed in conjunction with a brake dust shield associated with the first wheel. 
     
     
         30 . The energy harvester of  claim 25 , wherein the rectifier is disposed in a hub cover mounted on the first wheel. 
     
     
         31 . The energy harvester of  claim 25 , wherein the fixture is formed of a semicircular aluminum block. 
     
     
         32 . The energy harvester of  claim 25 , wherein the at least one solenoid comprises a soft magnetic core. 
     
     
         33 . The energy harvester of  claim 25 , further comprising a charging circuit, in communication with the rectifier, and a battery, for charging by the charging circuit. 
     
     
         34 . The energy harvester of  claim 25 , whereby the rectifier is in electrical communication with a dynamic tire pressure sensor connected to a valve stem of a tire mounted on the respective wheel for providing power thereto. 
     
     
         35 . A method for isolating and amplifying roadway surface vibration in the presence of external noise, comprising:
 dynamically detecting the internal pressure of a first vehicle tire while the vehicle is traveling on a portion of a roadway using a dynamic tire pressure sensor disposed in conjunction therewith;   sampling the tire pressure data;   transmitting the sampled tire pressure data to a processing device disposed within the vehicle;   generating pressure profile data by the processing device;   performing a frequency analysis of the pressure profile data, by the processing device, for identifying roadway surface vibrations.   
     
     
         36 . The method of  claim 35 , further comprising the step of comparing, by the processing device, the results of the frequency analysis results to threshold data stored in conjunction with the processing device for identifying roadway subsurface or surface defects. 
     
     
         37 . The method of  claim 36 , further comprising the step of issuing an alert to an operator within the vehicle or remote thereto when one or more thresholds are attained. 
     
     
         38 . The method of  claim 35 , further comprising the step of low-pass filtering, by the processing device, the frequency analysis results to remove roadway geometry features therefrom. 
     
     
         39 . The method of  claim 35 , wherein the frequency analysis is performed in the range of 0 to 400 hz. 
     
     
         40 . The method of  claim 35 , further comprising the steps of, prior to the step of dynamically detecting:
 impacting a roadway with a point impacts of varying intensity proximate the stationary vehicle;   measuring the ground acceleration due to the point impacts using a ground-mounted accelerometer proximate the first vehicle tire;   measuring the first vehicle tire pressure changes due to the point impacts using the dynamic tire pressure sensor;   calculating, using the processing device, a transfer function between the ground accelerations and the respective tire pressure changes; and   using the transfer function in the step of performing a frequency analysis.   
     
     
         41 - 44 . (canceled) 
     
     
         45 . A method of energy harvesting on a vehicle, comprising:
 disposing an arcuate array of magnets, disposed within a fixture, on the vehicle adjacent a first wheel thereof;   disposing at least one solenoid in conjunction with the first wheel for rotation therewith and proximate the array of magnets; and   a rectifier for receiving power from the at least one solenoid and for providing a direct current power output.   
     
     
         46 . The method of  claim 45 , wherein the magnetization of the magnets of the array is arranged antiparallel. 
     
     
         47 . The method of  claim 46 , wherein a spatially heterogeneous magnetic field exists above each pair of magnets of the array. 
     
     
         48 . The method of  claim 45 , wherein the fixture is disposed in conjunction with a brake dust shield associated with the first wheel. 
     
     
         49 . The method of  claim 45 , wherein the rectifier is disposed in a hub cover mounted on the first wheel.