MCMANIS@Usc-Eclc@sri-unix (12/01/82)
From: Chuck McManis <MCMANIS@Usc-Eclc>
Hello, for the past year we (the Image Processing Institue) have been
developing a mobile base in conjunction with the engineering department
here. Here are some of the things that we have discovered.
1.) Power in a robot is critical. There is always a need for more of it,
for the motors and for the CPU. This means that when we build our
new base unit it will use CMOS logic components @12V so that we can
use similar supplies for the smarts and the brawn.
2.) In the category of motors, the appropriate ones are extremely difficult
to come by. The best place to find them has been C&H Surplus in
Pasadena. It appears that a high speed motor with a 250:1 reduction will
give reasonable control and speed. (we are shooting for 3 MPH at
emergency Warp 8)
3.) 3 wizards are needed. A) a Mechanical wizard to design a sturdy base for
all of this, and the 250:1 reduction, and the steering mechinism. (Six
wheels with center drive wheels doesn't work) B) An electronics wizard
to design an interface that can talk to a computer AND switch 30 Amps
when those motors decide they want to move. C) A software wizard to
allow those motors to switch on in a reasonable and controlled fashion
as well as figure out that they are against a wall, and to figure out
what the "Host" computer is telling it to do.
The processor you use is of course your choice, however, I recommend that
instead of putting all of your intelligence "on-board" (remember that 2
car batteries weigh about 70 pounds and will drive this thing for about
3 hours) Use 8 bit micros (RCA 1802 (CMOS) or even some single chip
system ala Intel 8245) for "local" intelligence, these should consist of
a motion processor to do absolute moving about, an environment processor
to provide information about bumper sensors etc, and a supervisor processor
to provide communication facilities to the "host" and indicate errors or
take corrective action whenever the environment dictates it (low battery,
bumper contact, loss of target, etc)
To get this thing up and rolling about quickly, you can save a little on
the mechanics wizard by investing in an electric car for kids of roughly
100 lbs and using that as your starting point. I also recommend that the
motor and logic power be seperate as the voltage on the motor battery
will fluctuate significantly with the load.
Any other questions feel free to zip me a line,
--Chuck
-------