Strapdown Associates, Inc.

4727 South Lake Sarah Drive

 Maple Plain, Minnesota 55359

 Phone:  (763) 479-1981     Ground Line Fax:  (763) 479-1476


Paul G. Savage - President  - Resume Professional ActivitiesPublications Through May 2020

Strapdown Associates, Inc. (SAI) is an independent Minnesota corporation founded in 1980.  SAI provides engineering consulting and educational services to aerospace companies and government agencies for design and test of aided and unaided strapdown inertial navigation systems

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Paul G. Savage Books In Stock

Paul G. Savage Free-Access Articles

Strapdown Humor

Note: Some of the files linked from this web are in .pdf format.  Translating the files requires Adobe Acrobat Reader which can be downloaded for free from the following website:

Strapdown Analytics II  &  Intro-To-Strapdown-Nav Course Books

    We Are Sorry But SAI Book Sales Had To Be Temporarily Suspended During  

                  The Covit 19 crisis.  Please Inquire Later For Status.

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Paul G. Savage Free-Access Technical Articles Available At This Website

Selected Previously Published Articles Formatted For Web Access

"Improved Strapdown Inertial Measurement Unit Calibration Procedures", SAI WBN-14028, June 2, 2020

"Performance Analysis Of Strapdown Systems", SAI WBN-14011, June 2, 2015

"Computational Elements For Strapdown Systems", SAI WBN-14010, May 31, 2015

"Blazing Gyros - The Evolution Of Strapdown Inertial Navigation Technology For Aircraft", SAI WBN-14009, May 29, 2015

 Free Access Articles Prepared For This Website - Although every effort has been made to eliminate errors in the following Free Access articles, it is inevitable that some errors will pass undetected.  If readers plan to use the technical material for engineering projects, they are encouraged to re-verify the material by analytical means and simulation.

"Simplified Description of Optical Gyros - A Rigorous Analytical Development Without Vector Calculus", SAI WBN-14027, May 23, 2020

"Generating Strapdown Specific-Force/Angular-Rate For Specified Attitude/Position Variation From A Reference Trajectory", SAI WBN-14026, April 21, 2020

"Appendices F, G, And H to Generating Strapdown Specific-Force/Angular-Rate For Specified Attitude/Position Variation From A Reference Trajectory", SAI WBN-14026a, April 21, 2020

"Modern Strapdown Attitude Algorithms And Their Accuracy, Versus Accuracy Requirements For Unaided Strapdown Inertial Navigation", SAI WBN-14025, February 9, 2020

"Analytical Description Of Optical Gyros", SAI WBN-14024, April 3, 2019 (Updated May 23, 2020)

"Analytically Deriving How Ring Laser And Fiber Optic Gyros Measure Angular Rotation", SAI WBN-14023, November 1, 2018 (Updated March 31, 2019)

"Differential Point-To-Point Relativity Under Rotation", SAI WBN-14022, May 28, 2018 (Updated November 5, 2018)

"Differential Kinematics Of Point-To-Point Relativity", SAI WBN-14021, March 11, 2018

"Improved Strapdown Inertial System Calibration Procedures - Part 1 - Procedures And Accuracy Analysis", SAI WBN-14020-1, October 20, 2017 (Updated January 11, 2018)

"Improved Strapdown Inertial System Calibration Procedures - Part 2 - Analytical Derivations", SAI WBN-14020-2, October 20, 2017  (Updated January 11, 2018)

"Improved Strapdown Inertial System Calibration Procedures - Part 3 - Numerical Examples", SAI WBN-14020-3, November 10, 2017 (Updated January 11, 2018)

"Down-Summing Rotation Vectors For Strapdown Attitude Updating", SAI WBN-14019, July 16, 2017

"Digital Integration Algorithm Error For Band - Limited Random Process Inputs", SAI WBN-14018, June 26, 2017

"Skewed Sensor Failure Detection Using Parallel Navigation Solutions", SAI WBN-14017, June 16, 2016

"Introduction To The Kinematics Of Point-To-Point Relativity", SAI WBN-14015, April 17, 2016 (Updated May 3, 2018)

"Designing An Extended Kalman Filter For A Stellar Aided Strapdown Inertial Attitude Reference", SAI WBN-14012, January 16, 2016

"Lever Arm Corrections During INS Transfer Alignment With Wide Angle Initial Heading Error", SAI WBN-14008, April 17, 2015 (Updated 09/05/16)

"Coarse Leveling Of INS Attitude Under Dynamic Trajectory Conditions", SAI WBN-14007, January 29, 2015

 "Moving Base INS Alignment With Large Initial Heading Error", SAI WBN-14006, October 3, 2014

"Modifying The Kalman Filter Measurement To Mitigate Second Order Amplification In INS Velocity Matching Alignment Applications", SAI WBN-14005, July 15, 2014

"Fixed Gain Digital Filter Design For Specified Phase Versus Frequency Response", SAI WBN-14004, June 29, 2014

"Schuler Oscillations", SAI WBN-14003, June 27, 2014

"Redefining Gravity And Newtonian Natural Motion", SAI WBN-14002, May 21, 2014

"Mitigating Second Order Error Effects In Linear Kalman Filters Using Adaptive Process And Measurement Noise", SAI WBN-14001, May 16, 2014

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Strapdown Humor

"Blazing Gyros - The Movie (Early Preview)", SAI WBN-14016, May 25, 2016

"Geordie's Quaternion Decision", SAI WBN-14014, February 17, 2016

"Program Management", SAI WBN-14013, January 18, 2016

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