Engineering topics

Matijevic, Jacob R.

Publications and source records attributed to Matijevic, Jacob R..

5 records

NASA NTRS2006

Anomaly Recovery and the Mars Exploration Rovers

The premise of the design of operations for the Mars Exploration Rovers (MER) is that the vehicles will drive each day. As a result, they will encounter some aspect of the terrain environment that cannot be anticipated or otherwise accommodated by the sequences linked onboard that day. The operations team then must correct the problem by planning then commanding the execution of a different drive the next day. Often other aspects of the operation on the surface of Mars: environmental changes, component degradation, errors in sequence design or execution, etc., lead to anomalies which must be addressed before normal operations can resume. The operational design that makes it possible to recover from a driving error each day also reduces the time needed to recover from anomalies. As an example of the efficiency achieved, less than 5% (about 30 sols out of 700 sols of operations) of the time on the surface has been devoted to recovery from anomalies for each vehicle. In this paper the major anomalies experienced by the MER rovers will be recounted and the streamlined approaches to addressing these problems described. The operational flexibility developed for these missions is also a function of the system design that anticipated a number of likely faults and conditions arising from uncertainty in sequence execution and environmental change. This design will be described as well as the considerations in operation that motivated this design. These considerations will likely be present in any future surface mission.

rovers↗

NASA NTRS2000

Summary of Results from the Risk Management Program for the Mars Microrover Flight Experiment

On 4 July 1997, the Mars Pathfinder landed on the surface of Mars carrying the first planetary rover, known as the Sojourner. Formally known as the Microrover Flight Experiment (MFEX), the Sojourner was a low cost, high-risk technology demonstration, in which new risk management techniques were tried. This paper summarizes the activities and results of the effort to conduct a low-cost, yet meaningful risk management program for the MFEX. The specific activities focused on cost, performance, schedule, and operations risks. Just as the systems engineering process was iterative and produced successive refinements of requirements, designs, etc., so was the risk management process. Qualitative risk assessments were performed first to gain some insights for refining the microrover design and operations concept. These then evolved into more quantitative analyses. Risk management lessons from the manager's perspective is presented for other low-cost, high-risk space missions.

Shishko, Robert↗

NASA NTRS1992

Directions for lunar construction - A derivation of requirements from a construction scenario analysis

This paper provides an initial trade-off study among several lunar construction options available to the Space Exploration Initiative. The relative time effectiveness of Extra-Vehicular Activity (EVA), Intra-Vehicular Activity (IVA), and Earth-based remote control assembly and construction methods are studied. Also considered is whether there is any construction time savings to building roads in advance, or surveying the construction sites with orbiters or rovers in advance. The study was conducted by adding detail to a potentially real scenario - a nuclear power plant - and applying time multipliers for the various control options and terrain alternatives, provided by roboticists among the authors. The authors conclude that IVA is a faster construction method than either EVA or construction conducted remotely from Earth. Surveying proposed sites in advance, with orbiters and rovers, provides a significant time savings through adding to certainty, and therefore may be cost effective. Developing a heavy-lift launch capability and minimizing assembly and construction processes by landing large payloads is probably worthwhile to the degree possible, as construction activities would use a large amount of surface operations time.

Dias, William S.↗

NASA NTRS1991

Testbed For Telerobotic Servicing

Telerobot testbed used to evaluate technologies for remote servicing, including assembly, maintenance, and repair. Enables study of advantages and disadvantages of modes and problems encountered in implementing them. Best technologies for implementing modes chosen. Provides delays simulating transmission delays between control stations on ground and orbiting spacecraft. Includes five major equipment subsystems, each consisting of such commercially available equipment as video cameras, computers, and robot arms. Used on Space Station and on Space Shuttle and satellites in orbit. Also used in hazardous and underwater environments on Earth.

Matijevic, Jacob R.↗

NASA NTRS1990

Test Bed For Telerobots

Assembly of electromechanical and electronic equipment (including computers) constitutes test bed for development of advanced robotic systems for remote manipulation. Combines features not found in commercial systems. Its architecture allows easy growth in complexity and level of automation. System national resource for validation of new telerobotic technology. Intended primarily for robots used in outer space, test bed adapted to development of advanced terrestrial telerobotic systems for handling radioactive materials, dangerous chemicals, and explosives.

Matijevic, Jacob R.↗