Robust Ground Vehicle Constraints for Aiding Stand Alone INS and Determining Inertial Sensor Errors

J. Ryan, D. Bevly

Abstract:	Ground vehicle velocity constraints are commonly used to aid inertial navigation systems (INS) in land vehicle applications, especially in the absence of other external aiding sensors such as GPS. It is common to make the assumption that the lateral velocity of the vehicle in the frame of the road surface is zero, and that the vertical velocity in this frame is also zero. The latter assumption practically means that the vehicle does not leave the ground, which is reasonable for the vast majority of applications. However the former assumption means that the vehicle is not sliding, or that that there is no sideslip. While there are many operating conditions for which this assumption is valid, there are also many scenarios for which this assumption is violated. Such violations introduce error into the navigation solution and can be especially problematic when no external aiding to the inertial measurement unit (IMU) is available. This paper examines the errors in an unaided INS navigation solution caused by violating the lateral assumption and introduces a method of detecting when the constraint is violated. This allows for a best of both worlds solution in which the benefits of the aiding constraint can be taken advantage of when the constraint is valid without introducing errors when it is not valid. First, experiments are conducted using Carsim, a high fidelity commercial vehicle simulation package. The relative positioning performance when using different approaches for the lateral constraint is analyzed. Additionally, data collected from an electric all terrain vehicle (ATV) which instrumented with various sensors, is used to validate the conclusions. Finally, the velocity constraints are used to estimate biases in the lateral and vertical accelerometers. Results based on both the real world and simulated experiments are discussed.
Published in:	Proceedings of the 2012 International Technical Meeting of The Institute of Navigation January 30 - 1, 2012 Marriott Newport Beach Hotel & Spa Newport Beach, CA
Pages:	374 - 401
Cite this article:	Ryan, J., Bevly, D., "Robust Ground Vehicle Constraints for Aiding Stand Alone INS and Determining Inertial Sensor Errors," Proceedings of the 2012 International Technical Meeting of The Institute of Navigation, Newport Beach, CA, January 2012, pp. 374-401.
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