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Optimal Trajectories by Implicit Simulation
NASA Glenn Research Center
Cleveland, OH


In the mid 1980's, the Boeing Company, under contract to the United States Air Force, wrote the original OTIS programs. A subsequent small contract in 1988 resulted in OTIS 2 which featured several improvements that various users suggested and the USAF required. Charles Hargraves (now retired) and Steve Paris wrote OTIS and conceived of the then novel approach of collocation (or implicit integration) as the principal method for optimizing a trajectory. They documented their approach in Direct Trajectory Optimization Using Nonlinear Programming and Collocation as found in the AIAA's Journal of Guidance, Control, and Dynamics, Volume 10, Number 4, pages 338 to 342. Hargraves and Paris made further modifications to OTIS under contract to NASA Glenn Research Center (then Lewis) to add easier input definition and add flexibility.

Since 1995, John Riehl and Waldy Sjauw of the NASA Glenn Research Center have maintained the program and controlled its distribution to U.S. governmental agencies and aerospace contractors. They have added a number of refinements to OTIS (and its supporting utility programs) and increased its speed by incorporating the SNOPT non-linear programming software that Phillip Gill and his associates have developed. Rob Falck of NASA Glenn Research Center has added or improved some features of the program, such as making the calculator more robust, and added some utilities to make the installation and running of OTIS on various platforms easier.

Responsible NASA Official: Maria Babula
Web Curator Rob Falck
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Date of Last Site Update: May 2008