Khaled S. Ali

Attitude and position estimation on the Mars exploration rovers

NASA/JPLs Mars exploration rovers acquire their attitude upon command and autonomously propagate their attitude and position. The rovers use accelerometers and images of the sun to acquire attitude, autonomously searching the sky for the sun with an articulated camera. To propagate the attitude and position the rovers use either accelerometer and gyro readings or gyro readings and wheel odometry, depending on the nature of the movement Earth-based operators have commanded. Where necessary, visual odometry is performed on images to fine tune the position updates, particularly in high slip environments. The capability also exists for visual odometry attitude updates. This paper describes the techniques used by the rovers to acquire and maintain attitude and position knowledge, the accuracy which is obtainable, and lessons learned after more than one year in operation.

Health care robotics: a progress report

This paper describes the approach followed in the design of a service robot for health care applications. Under the auspices of the NASA Technology Transfer Program, a partnership was established between JPL and RWI, a manufacturer of mobile robots, to design and evaluate a mobile robot for health care assistance to the elderly and the handicapped. The activities of the first phase of the project include the development of a multi-modal operator interface, and the design and fabrication of a manipulator arm for the mobile robot. This paper describes the architecture of the system, the features of the manipulator arm, and the operator interface.

Internet-based operations for the Mars Polar Lander mission

The Mars Polar Lander (MPL) mission was the first planetary mission to use Internet-based distributed ground operations where scientists and engineers collaborate in daily mission operations from multiple geographically distributed locations via the Internet. This paper describes the operations system, the Web interface for telescience (WITS), which was used by the MPL mission for Internet-based operations. WITS was used for generating command sequences for the landers robotic arm and robotic arm camera, and as a secondary tool for sequence generation for the stereo camera on the lander. WITS was also used as a public outreach tool. Results are shown from the January 2000 field test in Death Valley, California.

ADVANCED ROBOTICS TECHNOLOGY INFUSION TO THE NASA MARS EXPLORATION ROVER (MER) PROJECT

Abstract This paper presents four new technology developments and their infusion into the Mars Exploration Rover (MER) mission. These technologies were not ready for infusion prior to the launch of this mission. Three of these new capabilities are designed to increase the level of autonomy for the operations, i.e., fewer ground-in-the-loop steps for executing commands. One of the new capabilities is designed to intelligently filter rover obtained images and return only those that are very likely to contain useful information. These new capabilities will be used for this and future NASA planetary missions.

Lunar Surface Operation Testbed (LSOT)

This paper describes a high fidelity mission concept systems testbed at JPL, called Lunar Surface Operations Testbed (LSOT). LSOT provides a unique infrastructure that enables mission concept studies designers to configure and demonstrate end-to-end surface operations using existing JPL mission operations and ground support tools, Lander, robotic arm, stereo cameras, flight software, and soil simulant (regolith), in a high fidelity functional testbed. This paper will describe how LSOT was used to support the MoonRise mission concept study. MoonRise: Lunar South Pole-Aitken Basin Sample Return Mission would place a lander in a broad basin near the moons South Pole and return approximately two pounds of lunar materials to Earth for study. MoonRise was one of three candidate missions competing to be selected as the third mission for NASAs New Frontiers Program of Solar System Explorations. LSOT was used to demonstrate JPLs extensive experience and understanding of the MoonRise Lander capabilities, design maturity, surface operations systems engineering issues, risks and challenges.

The Effects of Clock Drift on the Mars Exploration Rovers

All clocks drift by some amount, and the mission clock on the Mars Exploration Rovers (MER) is no exception. The mission clock on both MER rovers drifted significantly since the rovers were launched, and it is still drifting on the Opportunity rover. The drift rate is temperature dependent. Clock drift causes problems for onboard behaviors and spacecraft operations, such as attitude estimation, driving, operation of the robotic arm, pointing for imaging, power analysis, and telecom analysis. The MER operations team has techniques to deal with some of these problems. There are a few techniques for reducing and eliminating the clock drift, but each has drawbacks. This paper presents an explanation of what is meant by clock drift on the rovers, its relationship to temperature, how we measure it, what problems it causes, how we deal with those problems, and techniques for reducing the drift.