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ABSTRACT ineteen months before the launch of the Mars Exploration Rovers (MER), it was discovered that sustained horizontal winds during descent could cause the lander to impact with enough force to tear the airbags and damage the rover payload. At this point, the MER Entry Descent and Landing (EDL) system had small transverse rockets that could point the large retro rockets to reduce the horizontal speed of the lander, but it did not have a sensor for measuring horizontal velocity. Because incorporating a traditional radar-based velocity sensor into the relatively mature EDL mechanical and electrical design was infeasible, the MER Project decided, against the advice of many, to pursue an unprecedented camera based approach to velocity estimation. Thus began the accelerated development of the Descent Image Motion Estimation System (DIMES), the first autonomous machine vision system used during planetary descent. DIMES is composed of sensors and software including a descent imager, a radar altimeter, an inertial measurement unit and an algorithm to estimate horizontal velocity. This algorithm combines radar, image and inertial data in novel way to create a low cost, robust and computationally efficient solution to the horizontal velocity estimation problem. This talk describes the DIMES hardware and software development, the DIMES field tests over Mars analogs in the Mojave Desert and the successful performance of DIMES during the Spirit and Opportunity landings in January 2004. SPEAKER BIO Dr. Andrew E. Johnson graduated with Highest Distinction from the University of Kansas in 1991 with a BS in Engineering Physics and a BS in Mathematics. In 1997, he received his Ph.D. from the Robotics Institute at Carnegie Mellon University where he developed the spin-image surface signature for object recognition and surface matching. Currently, he is a Senior Member of Technical Staff at NASA’s Jet Propulsion Laboratory where he is developing image-based techniques for autonomous navigation and mapping during descent to planets moons, comets and asteroids. At JPL, Dr. Johnson has worked on technology development tasks as well as flight projects. For the Mars Exploration Rover Project, Dr. Johnson was the lead algorithm developer for the Descent Image Motion Estimation Subsystem (DIMES), the first autonomous machine vision system used during planetary landing. Following the successful development and execution of DIMES, he is now moving back to the development of machine vision systems for landing hazard avoidance and pin-point landing. Part of this work includes a collaboration with USC in the area of vision guided safe and precise landing for autonomous helicopters. In 2003, Dr Johnson was awarded the JPL Lew Allen Award for Excellence for “his groundbreaking contributions in the area of machine vision algorithms for safe and precise landing.” Andrew E. Johnson Senior Member of Technical Staff Jet Propulsion Laboratory California Institute of Technology URL: http://robotics.jpl.nasa.gov/people/johnson/homepage.html |
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