NASA Tech Briefs, September 2012 45 Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets NASA’s Jet Propulsion Laboratory, Pasadena, California This software controls a rover plat- form to traverse rocky terrain auton- omously, plan paths, and avoid obsta- cles using its stereo hazard and navigation cameras. It does so while continuously tracking a target of inter- est selected from 10–20 m away. The rover drives and tracks the target until it reaches the vicinity of the target. The rover then positions itself to ap- proach the target, deploys its robotic arm, and places the end effector in- strument on the designated target to within 2–3-cm accuracy of the origi- nally selected target. This software features continuous navigation in a fairly rocky field in an outdoor environment and the ability to enable the rover to avoid large rocks and traverse over smaller ones. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover’s mast cameras. The navigation software uses stereo imaging, traversability analysis, path planning, trajectory generation, and trajectory execution. It also in- cludes visual target tracking of a desig- nated target selected from 10 m away while continuously navigating the rocky terrain. Improvements in this design include steering while driving, which uses con- tinuous curvature paths. There are also several improvements to the traversabil- ity analyzer, including improved data fu- Mission Analysis, Operations, and Navigation Toolkit Environment (Monte) Version 040 NASA’s Jet Propulsion Laboratory, Pasadena, California Monte is a software set designed for use in mission design and spacecraft naviga- tion operations. The system can process measurement data, design optimal trajec- tories and maneuvers, and do orbit deter- mination, all in one application. For the first time, a single software set can be used for mission design and navigation opera- tions. This eliminates problems due to dif- ferent models and fidelities used in legacy mission design and navigation software. The unique features of Monte 040 in- clude a blowdown thruster model for GRAIL (Gravity Recovery and Interior Laboratory) with associated pressure models, as well as an updated, optimal- search capability (COSMIC) that facili- tated mission design for ARTEMIS. Ex- isting legacy software lacked the capabilities necessary for these two mis- sions. There is also a mean orbital ele- ment propagator and an osculating to mean element converter that allows long-term orbital stability analysis for the first time in compiled code. The optimized trajectory search tool COSMIC allows users to place constraints and controls on their searches without any restrictions. Constraints may be user- defined and depend on trajectory infor- mation either forward or backwards in time. In addition, a long-term orbit stabil- ity analysis tool (morbiter) existed previ- ously as a set of scripts on top of Monte. Monte is becoming the primary tool for navigation operations, a core compe- tency at JPL. The mission design capabil- ities in Monte are becoming mature enough for use in project proposals as well as post-phase A mission design. Monte has three distinct advantages over existing software. First, it is being developed in a modern paradigm: ob- ject-oriented C++ and Python. Second, the software has been developed as a toolkit, which allows users to customize their own applications and allows the de- velopment team to implement require- ments quickly, efficiently, and with mini- mal bugs. Finally, the software is managed in accordance with the CMMI (Capability Maturity Model Integra- tion), where it has been appraised at ma- turity level 3. This work was done by Richard F. Sunseri, Hsi-Cheng Wu, Scott E. Evans, James R. Evans, Theodore R. Drain, and Michelle M. Guevara of Caltech for NASA’s Jet Propulsion Laboratory. This software is available for commercial li- censing. Please contact Daniel Broderick of the California Institute of Technology at danielb@caltech.edu. Refer to NPO-48184. structural loads in real time while the structure is in service. The amount of structural informa- tion can be maximized through the use of highly multiplexed fiber Bragg grat- ing technology using optical time do- main reflectometry and optical fre- quency domain reflectometry, which can provide a local strain measurement every 10 mm on a single hair-sized opti- cal fiber. Since local strain is used as input to the algorithms, this system serves multiple purposes of measuring strains and displacements, as well as de- termining structural bending moment, shear, and loads for assessing real-time structural health. The first step is to install a series of strain sensors on the structure’s surface in such a way as to measure bending strains at desired locations. The next step is to perform a simple ground test calibration. For a beam of length l (see example), discretized into n sections and subjected to a tip load of P that places the beam in bending, the flex- ural rigidity of the beam can be experi- mentally determined at each measure- ment location x. The bending moment at each station can then be determined for any general set of loads applied dur- ing operation. This work was done by W. Lance Richards and William L. Ko of Dryden Flight Research Center. Further information is contained in a TSP (see page 1). DRC-008-023 https://ntrs.nasa.gov/search.jsp?R=20120014097 2020-06-09T06:39:26+00:00Z