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A fast and Robust Algorithm for general inequality/equality constrained minimum time problems

Technical Report ·
DOI:https://doi.org/10.2172/225042· OSTI ID:225042
 [1];  [2]
  1. Sandia National Labs., Albuquerque, NM (United States)
  2. Georgia Inst. of Tech., Atlanta, GA (United States). School of Mechanical Engineering

This paper presents a new algorithm for solving general inequality/equality constrained minimum time problems. The algorithm`s solution time is linear in the number of Runge-Kutta steps and the number of parameters used to discretize the control input history. The method is being applied to a three link redundant robotic arm with torque bounds, joint angle bounds, and a specified tip path. It solves case after case within a graphical user interface in which the user chooses the initial joint angles and the tip path with a mouse. Solve times are from 30 to 120 seconds on a Hewlett Packard workstation. A zero torque history is always used in the initial guess, and the algorithm has never crashed, indicating its robustness. The algorithm solves for a feasible solution for large trajectory execution time t{sub f} and then reduces t{sub f} and then reduces t{sub f} by a small amount and re-solves. The fixed time re- solve uses a new method of finding a near-minimum-2-norm solution to a set of linear equations and inequalities that achieves quadratic convegence to a feasible solution of the full nonlinear problem.

Research Organization:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC04-94AL85000
OSTI ID:
225042
Report Number(s):
SAND--95-2433C; CONF-960662--1; ON: TI96002783
Country of Publication:
United States
Language:
English

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