September 2-3, 2004
Salar Grande, Atacama Desert, Chile
• Test rover motion control
• Test sun tracking camera (in a sunny place, not Pittsburgh)
• Boot and test position estimation computer
• Boot and test power management and distribution computer
• Set up environmental monitoring station
• Finalize science site
Status and Progress
Tuned rover motion control. Zoë is now set up for wireless communication and is off its pendant. We conducted a series of tests to calibrate the feed forward control for Zoe’s double-axle passive-steering configuration. Zoë has four wheel drive but control of the orientation of the front and rear axle steering angle is achieved through control of wheel velocities. The makes Zoë lighter and more reliable since it has only four motors which drive the wheel though high efficiency 80:1 harmonic drives. But it also means that drive control is somewhat more complicated since vehicle speed and steering are controlled simultaneously and factors like axle roll angles and wheel slip must be considered.
Booted up position estimation and power management computers. These computers are Pentium-processor PC104 stacks have been running in our lab for months but their installation in Zoë happened shortly before shipping out. The position estimation computer and sensors including a fiber-optic gyro and six-axis inertial measurement unit are packaged as a single unit which we have been testing in Hyperion. The entire unit moved over to Zoë for field experimentation. Next steps are to confirm Zoë’s kinematic model and orientation estimation from the sun tracker.
Assembled environmental monitoring station. The environment station we configured during our 2003 field season to characterize the insolation and compare silicon and gallium-arsenide horizontal and tracked panels will serve us again this year. The station has been set up initially in the region of our science investigation site well in advance of the remote investigation so that we can get trend information on fogs which we suspect to be a regular afternoon occurance. The environmental staion has temperature, humidity, wind speed and direction, insolation and a “leaf sensor”. The leaf sensor measures the amount moisture of condensing on a surface.
Visited remote investigation science site. We made a preliminary visit to the area in which we plan to conduct the remote science investigation. The area, bordered by mountains, is approximately 7 kilometers by 3 kilometers in extent. Zoë will be able to traverse much of it, but there are small and large features that are two steep to ascent/descend making for interesting challenges to navigation. We have made some preliminary ground-truth observations of some of the insolation, moisture, and soil content factors that relate to the presence and absence of photosynthetic micro-organisms.
Repairing Zoë main power relay. One of Zoë’s two main power relays failed today. This is an item with a 100,000 cycle lifetime that failed after only a few hundred cycles suggesting it was defective in some way. As a research project we do not have the resources to rigorously test every system component and since we don’t have a spare for what was expected to be a low-risk element, we’re fashioning a field replacement to get locomotion power back online until a replacement arrives with field team members arriving next week.
• Test sun tracking and orientation estimation
• Replace locomotion power enable switch
• Power up environmental monitoring station
• Calibrate navigation cameras and system
• Test visible-near-infrared and thermal infrared spectrometers
Morning: Clear, calm, 12-14C, humidity 40%
Afternoon: Clear, light breeze 10-15kph, hot 28, humidity 25%
Evening: Clear, no wind, cool 10-15C, humidity 70%, heavy dew overnight
Quote of the Day
"Enrique has arrived."