Methods and systems for estimating the orientation of an object

Abstract

The system receives position information in both an internal coordinate frame and an external coordinate frame. The system uses a comparison of position information in these flames to determine orientation information. The system determines one or more orientation hypotheses, and analyzes the position information based on these hypotheses. The system may include on-board accelerometers, gyroscopes, or both that provide the measurements in the internal coordinate frame. These measurements may be integrated otherwise processed to determine position, velocity, or both. Measurements in the external frame are provided by GPS sensors or other positioning systems. Position information is transformed to a common coordinate frame, and an error metric is determined. Based on the error metric, the system estimates a likelihood metric for each hypothesis, and determines a resulting hypothesis based on the maximum likelihood or a combination of likelihoods.

1 .- 29 . (canceled) 
     
     
         30 . A system comprising:
 control circuitry configured to:
 receive first position information from a first sensor expressed in an internal coordinate frame; 
 receive second position information from a second sensor expressed in an external coordinate frame; 
 determine a state estimate for an object based on the first position information, the second position information, and an orientation hypothesis used to transform the first position information and the second position information to a common coordinate frame; and 
 determine whether the state estimate has converged. 
   
     
     
         31 . The system of  claim 30 , wherein the control circuitry is further configured to, in response to the state estimate not converging, abort updating the state estimate. 
     
     
         32 . The system of  claim 30 , wherein the control circuitry is further configured to, in response to the state estimate not converging, determine a fault has occurred. 
     
     
         33 . The system of  claim 32 , wherein the fault comprises one of a sensor fault, a transceiver fault, or a signal fault. 
     
     
         34 . The system of  claim 32 , wherein the fault comprise a magnetometer fault. 
     
     
         35 . The system of  claim 30 , wherein the control circuitry is configured to determine whether the state estimate has converged by comparing a convergence criterion to a threshold. 
     
     
         36 . The system of  claim 30 , wherein the control circuitry is further configured to determine a plurality of state estimates for the object based on the first position information, the second position information, and a plurality of orientation hypotheses. 
     
     
         37 . The system of  claim 36 , wherein the control circuitry is further configured to determine a plurality of hypothesis likelihoods for the plurality of state estimates. 
     
     
         38 . The system of  claim 37 , wherein the control circuitry is further configured to, in response to the state estimate not converging, update the state estimate having a maximum hypothesis likelihood and abort updating the state estimate for the remaining one or ones of the plurality of state estimates. 
     
     
         39 . The system of  claim 30 , wherein the second sensor comprises a localization system or a motion capturing system. 
     
     
         40 . A method comprising:
 receiving first position information from a first sensor expressed in an internal coordinate frame;   receiving second position information from a second sensor expressed in an external coordinate frame;   determining a state estimate for an object based on the first position information, the second position information, and an orientation hypothesis used to transform the first position information and the second position information to a common coordinate frame; and   determining whether the tate estimate has converged.   
     
     
         41 . The method of  claim 40 , further comprising, in response to the state estimate not converging, aborting updating the state estimate. 
     
     
         42 . The method of  claim 40 , further comprising, in response to the state estimate not converging, determining a fault has occurred. 
     
     
         43 . The method of  claim 42 , wherein the fault comprises one of a sensor fault, a transceiver fault, or a signal fault. 
     
     
         44 . The method of  claim 42 , wherein the fault comprise a magnetometer fault. 
     
     
         45 . The method of  claim 40 , wherein determining whether the state estimate has converged comprises comparing a convergence criterion to a threshold. 
     
     
         46 . The method of  claim 40 , further comprising determining a plurality of state estimates for the object based on the first position information, the second position information, and a plurality of orientation hypotheses. 
     
     
         47 . The method of  claim 46 , further comprising determining a plurality of hypothesis likelihoods for the plurality of state estimates. 
     
     
         48 . The method of  claim 47 , further comprising, in response to the state estimate not converging, updating the state estimate having a maximum hypothesis likelihood and aborting updating the state estimate for the remaining one or ones of the plurality of state estimates. 
     
     
         49 . The method of  claim 40 , wherein the second sensor comprises a localization system or a motion capturing system.