No movement for over 50 sols now.I'm a bit bored of seeing the same images.
You are aware there has been technical problems recently, right?
According to http://www.jpl.nasa.gov/news/fact_sheets/mars-science-laboratory.pdf Curiousity can go about 200 meters per day. What limits its average speed to such a low value?
I initially thought energy might be the limiting factor but a quite calculation shows its ~100 Watts is enough to go ~3 kilometers straight up each day!
The driving is more-or-less automatic since there's no actual driver ( just a set of commands from the ground). The rover proceeds a bit, uses the hazcams to examine the terrain for problems, makes its way a little further, checks for obstacles, etc.
Maybe the slow CPU has something to do with the rover's slow (physical) speed.
Autonav and visodom are slower due to processing. However, the top speed for directed drives is only 4 cm/s. IIRC that autonav comes out to about half that, but I may be mistaken. Curiosity is geared for torque, not speed.
Quote from: hop on 03/27/2013 01:30 amAutonav and visodom are slower due to processing. However, the top speed for directed drives is only 4 cm/s. IIRC that autonav comes out to about half that, but I may be mistaken. Curiosity is geared for torque, not speed.That comes to 1728 m per 12 hour day under ideal conditions. Clearly navigation and surface conditions play a massive role in keeping actual triving distance below what is theroetically possible from the maximum speed.
There are lots of reasons why the rover is slower that terrestrial autonomous vehicles.Power for the wheels is one. Limited number of CPUs because of power issues is another. Curosity has a few hundred watts available, a terrestrial vehicle can have a kilowatt or more of electrical power available.CPU performance inherent in having a Mars-capable unit. In particular there is radation resistance to consider. Then there is the navigation question. Primary route finding for terrestrial autonomous vehicles is GPS, which of course is not available for Mars. Then there are issues of the terrain roughless and potential hazards, which would slow the rover down.
Two cents here. Power is only a problem for calculation because radiation is a problem. They're using decade old (or older) computer electronics because of the radiation protection which makes them lose out a lot on Moore's law. They also redesign the radiation proofed CPUs to use extra computation checking for radiation effects. All in all, if several modern cpus non-radiation hardened CPUs were used in a voting scheme, you'd have much faster performance at lower power, while maintaining the radiation resistance.
Two cents here. Power is only a problem for calculation because radiation is a problem. They're using decade old (or older) computer electronics because of the radiation protection which makes them lose out a lot on Moore's law. They also redesign the radiation proofed CPUs to use extra computation checking for radiation effects. All in all, if several modern non-radiation hardened CPUs were used in a voting scheme, you'd have much faster performance at lower power, while maintaining the radiation resistance.
Quote from: mlindner on 03/27/2013 02:11 amTwo cents here. Power is only a problem for calculation because radiation is a problem. They're using decade old (or older) computer electronics because of the radiation protection which makes them lose out a lot on Moore's law. They also redesign the radiation proofed CPUs to use extra computation checking for radiation effects. All in all, if several modern non-radiation hardened CPUs were used in a voting scheme, you'd have much faster performance at lower power, while maintaining the radiation resistance.How is the power saving achieved with several CPUs rather than one?
Quote from: deltaV on 03/26/2013 11:39 pmI initially thought energy might be the limiting factor but a quite calculation shows its ~100 Watts is enough to go ~3 kilometers straight up each day! Your calculation is almost certainly wrong. AFAIK energy is the main limit. Note that just rolling the wheels is not the only energy draw!
Table 18 MSL rover drive modes, their usage and estimated drive rates (including slip checks)Drive ModeUsageRateBlindNo obstacles, low-slope terrain114 m/hrAutoNavObstacles, rugged terrain, scarps45 m/hrVisodomHigh-slope terrain, cohesionless terrain29 m/hrAutoNav+VisodomRugged, sloped terrain20 m/hr