×

Digital signal processing method and system thereof for precision orientation measurements

  • US 6,725,173 B2
  • Filed: 09/04/2001
  • Issued: 04/20/2004
  • Est. Priority Date: 09/02/2000
  • Status: Expired due to Term
First Claim
Patent Images

1. A digital signal processing system for orientation measurements of a body frame, comprising:

  • an acceleration producer, measuring gravity acceleration analog signals in orthogonal three-axes expressed in said body frame;

    a conditioning and analog/digital converting circuitry, suppressing noises of said gravity acceleration analog signals and digitizing said gravity acceleration analog signals to form three-axes gravity acceleration digital signals;

    a Digital Signal Processor (DSP) chipset, which is interfaced with said conditioning and analog/digital converting circuitry, receiving said three-axes gravity acceleration digital signals and producing pitch and roll angle using DSP algorithms;

    a user interface, which is connected with said DSP chipset, for displaying, inputting and outputting measurement data;

    an Earth'"'"'s Magnetic Field (EMF) detector, detecting Earth'"'"'s magnetic field analog signals in three-axes expressed in said body frame; and

    an EMF conditioning and analog/digital converting circuitry, suppressing noise of said Earth'"'"'s magnetic field analog signals and digitizing said Earth'"'"'s magnetic field analog signals to form three-axes Earth'"'"'s magnetic field digital signals;

    wherein said DSP chipset is further interfaced with said EMF conditioning and analog/digital converting circuitry to receive a three-axes digital Earth'"'"'s magnetic field vector and produce attitude and heading measurements using said DSP algorithms;

    wherein said conditioning and analog/digital converting circuitry, which is connected between said acceleration producer and said DSP chipset, substantially acquires said gravity acceleration analog signals, which are proportional to an Earth'"'"'s gravity field, from said acceleration producer;

    amplifies said gravity acceleration analog signals to suppress said noises in said gravity acceleration analog signal to form amplified gravity acceleration signals, wherein said noises are signals of said gravity acceleration analog signals not proportional to said Earth'"'"'s gravity field;

    converts said amplified gravity acceleration signals to form said three-axes gravity acceleration digital signals which are input to said DSP chipset; and

    provides data/control/address bus connection with said DSP chipset so as to produce an address decode function to enable said DSP chipset to access said acceleration producer and pickup said three-axes gravity acceleration signals;

    wherein said DSP chipset comprises a first pre-processing module, an initial pitch and roll estimation module, a level-plane gravity acceleration computation module, a pitch and roll refinement loop closure module, a second pre-processing module, a magnetic field vector error compensation module, and a magnetic heading estimation module, said first pre-processing module smoothing said three-axes gravity acceleration digital signals expressed in said body frame at high sampling rate, and compensating errors in said three-axes gravity acceleration digital signals with calibration parameters, including scale factor, bias and misalignment, so as to achieve and output smoothed and compensated three-axes gravity acceleration digital signals to said initial pitch and roll estimation module and said level-plane gravity acceleration computation module;

    said initial pitch and roll estimation module receiving said smoothed and compensated three-axes gravity acceleration digital signals from said first pre-processing module and running one time initially to provide rough pitch and roll angle estimates;

    said level-plane gravity acceleration computation module receiving said smoothed three-axes gravity acceleration digital signals and a transform matrix from said body frame to a level-plane frame from said pitch and roll refinement loop closure module, and transforming said smoothed three-axes gravity acceleration digital signals into gravity acceleration data expressed in said level-plane frame;

    said pitch and roll refinement loop closure module receiving said rough pitch and roll angle from said initial pitch and roll estimation module, level-plane plane gravity acceleration components from said level-plane gravity acceleration computation module, and heading angle from said magnetic heading estimation module, so as to refine said rough pitch and roll angles;

    said second pre-processing module smoothing said three-axes digital Earths magnetic signals at high sampling rate, which are expressed in said body frame, wherein said smoothed three-axes Earth'"'"'s magnetic digital signals are output to said magnetic field vector error compensation module;

    said magnetic field vector error compensation module performing a compensation procedure using calibration parameters, including scale factors, misalignment parameters, and effects of nearby ferrous materials;

    said magnetic heading estimation module receiving said three-axes digital Earth'"'"'s magnetic field signals from said error compensation module of said magnetic field vector and said pitch and roll angle data from said pitch and roll refinement loop closure module to estimate an optimal heading angle, which is output to said pitch and roll refinement loop closure module.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×