UCR EE Department

1
Flexible Integer Ambiguity Resolution for
Magnetometer and GPS aided INS

• Jay Farrell, Jenna Cheng,
• Haitao Qiu, Elmer Thomas, Yu Lu
• University of California, Riverside
• Han-Shue Tan
• University of California, Berkeley
• Liu Huaixun
• Luoyang Institute of Technology

2
Project Objectives

• Objective To design and build a reliable,
  accurate, high sample rate navigation system
• cm accuracy
• graceful degradation to failures
• Applications
• Driver Warning
• Driver Guidance
• Vehicle Position Control

3
Driver Warning

• Lane Departure Warning
• Requirement
• Accurate determination position relative to lane
• Collision Warning
• Requirements
• Accurate determination of position relative to
  nearby vehicles
• Accurate position determination
• Communication between vehicles

4
Snowplow Snowblower Guidance

• Problem Limit visibility due to fog and snow
• roadway relative position may be difficult or
  impossible to perceive visually
• driver fatigue
• guardrail collisions
• snowplow down time
• driver safety

5
Automated Driving
6
Project Subgoals

• Absolute Position Determination
• Determines earth relative position,
  velocity, acceleration, attitude, angular rates
• Relative Position Determination
• Lane relative
• Neighboring vehicle relative
• Vehicle Control (PATH)
• Determine the steering commands to force the
  relative states to the desired values

7
Complementary Filter
8
INS Attitiude Equations
9
INS Translational Equations
10
Inertial Navigation System
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Inertial Navigation System

• Advantages
• minimal infrastructure cost
• high output rate
• full vehicle state vector
• integrative process reduces high frequency noise
• Disadvantage
• slow, but unbounded, error growth
• unless aided by other sensors

12
INS Integration with other Sensors

• Motivations
• Fault Tolerance through sensor redundancy
• Magnetometer
• Integrated navigation and control demonstrated in
  2001
• GPS
• Integrated navigation control demos starting in
  1997
• Current research on aided signal tracking, fast
  reacquisition, integer ambiguity
• Pseudolites
• current research
• Roadway altitude
• current research

13
Carrier Phase Differential GPS

• Advantages cm accuracy independent of speed, all
  weather, worldwide, minimal infrastructure cost,
  trajectory independent
• Disadvantages
• Integers must be estimated
• Signals can be blocked

14
Signal Blockage Data
15
GPS Measurements
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Initially all satellites are unlocked
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Finally all satellites are locked
18
Intermediate
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Aiding Integer Search
20
Status Ongoing Research

• Rapid Integer Ambiguity Resolution
• GPS only algorithm implemented and tested in
  Matlab
• GPS only algorithm implemented in C (tested in
  lab)
• Magnetometer aided Ambuity Resolution not
  started
• INS aiding of GPS Receiver
• Theory is nearly in place
• Hardware interface prototype is working
• Requires replication and test
• Theory implementation and test not started

21
Signal Blockage Data