Nonlinear optimal control problems are challenging to solve due to the prevalence of local minima that prevent convergence and/or optimality. This paper describes nearest-neighbors optimal control (NNOC), a data-driven framework for nonlinear optimal control using indirect methods. It determines initial guesses for new problems with the help of precomputed solutions to similar problems, retrieved using k-nearest neighbors. A sensitivity analysis technique is introduced to linearly approximate the variation of solutions between new and precomputed problems based on their variation of parameters. Experiments show that NNOC can obtain the global optimal solution orders of magnitude faster than standard random restart methods, and sensitivity analysis can further reduce the solving time almost by half. Examples are shown on optimal control problems in vehicle control and agile satellite reorientation demonstrating that global optima can be determined with more than 99% reliability within time at the order of 10–100 milliseconds.
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This work was partially supported by NSF (Grant No. IIS-1816540).
Gao Tang is a Ph.D. student in the Department of Mechanical Engineering and Materials Science at Duke University. He received his B.S. and M.S. degrees in the Department of Aerospace Engineering at Tsinghua University. He is interested in trajectory optimization with an ambitious goal to achieve them in real time.
Kris Hauser is an associate professor at Duke University with joint appointments at the Departments of Electrical & Computer Engineering and Mechanical Engineering and Materials Science. He received his Ph.D. degree in computer science from Stanford University in 2008, B.S. degrees in computer science and mathematics from UC Berkeley in 2003, and was a postdoc at UC Berkeley. He joined the faculty of Indiana University from 2009 to 2014, where he started the Intelligent Motion Lab, and began his current position at Duke in 2014. He is a recipient of a Stanford Graduate Fellowship, Siebel Scholar Fellowship, Best Paper Award at IEEE Humanoids 2015, and an NSF CAREER Award.
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Tang, G., Hauser, K. A data-driven indirect method for nonlinear optimal control. Astrodyn 3, 345–359 (2019). https://doi.org/10.1007/s42064-019-0051-3
- data-driven approach
- indirect method
- optimal control
- sensitivity analysis