Re: Mars Rover Controlled By Java
From: Jan Panteltje (pNaonStpealmtje_at_yahoo.com)
Date: 01/18/04
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Date: Sun, 18 Jan 2004 01:11:35 GMT
On a sunny day (Sat, 17 Jan 2004 21:28:13 GMT) it happened Tony Hill
<hilla_nospam_20@yahoo.ca> wrote in
<670f421519c840a1d534f4a79b43fdcc@news.1usenet.com>:
>
>You know, believe it or not, Java isn't all that slow. Here are a
>couple of tests comparing different languages for very simple
>algorithms:
OK, but my latest test on THAT java mars rover soft ran 1.3 frames / second
on a 1 GHz PC.
Before it crashed mind you.
This was posted to sci.astro a week or 2 ago:
>from the rovers will be provided and can be loaded into the program.
>
>http://mars.telascience.org/home/
>
>"The Jet Propulsion Laboratory has released Maestro, a public version
>of the primary software tool used by NASA scientists to operate the
>Mars Exploration Rovers. Anyone can download Maestro for free from
>http://mars.telascience.org/ and use it to follow along with the
>rovers' progress during the mission. You can use Maestro to view
>pictures from Mars in 2D and 3D and create simplified rover activity
>plans. During the mission, updates will be released for Maestro
>containing the latest images from Mars."
Me replying:
OK I downloaded the Linux version last night (I am in Europe),
realizing after it turned out to be a 2 1/2 hour download on a V90 modem,
that I really must be confident that lander worked this time....
Anyways it is based on java rle, the install script has some errors,
so you can not run it as the indicated executable,
but I had to run it as (I untarred it in /video/compile/maestro/ )
/video/compile/maestro/R2004_01-Public-Linux/JPL/SAP/bin/WITS
while 'SAP', that should start it (in /usr/local/bin), points to
SAP -> /video/compile/maestro/R2004_01-Public-Linux/WITS
So directory JPL/bin is missing from the softlink in /usr/local/bin
Also the install script 'forgets' to do
tar -xvf mer.tar
in
/video/compile/maestro/R2004_01-Public-Linux/JPL/SAP/WITS-db
so that you actually see some data.
Because of java (likely) the thing is slower then a dead snail glued with
superglue to a scrapped Apollo.
I followed the intro to the point where it had to move to a target, then it
froze with this message in the console:
An unexpected exception has been detected in native code outside the VM.
Unexpected Signal : 11 occurred at PC=0x400C32F7
Function=memcpy+0x27
Library=/lib/libc.so.6
Current Java thread:
****************
Another exception has been detected while we were handling last error.
Dumping information about last error:
ERROR REPORT FILE = (N/A)
PC = 0x0x400c32f7
SIGNAL = 11
FUNCTION NAME = memcpy
OFFSET = 0x27
LIBRARY NAME = /lib/libc.so.6
Please check ERROR REPORT FILE for further information, if there is any.
Good bye.
So, 1.3 frames / second before it crashed, and this system plays live video
at normal speed no problem.
But THAT code is written in asm and C.
I remember the old vrml browsers (was there al the way from the beginning).
After some of these got ported to Java it was a factor 10 slower (at least).
And NO reason in the world to do that, portability of good C code is excellent.
Java is a mistake.
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