Alt-BEAM Archive
Message #01226
To: beam@corp.sgi.com
From: Justin jaf60@student.canterbury.ac.nz
Date: Thu, 04 Mar 1999 05:02:50 +1300
Subject: [alt-beam] Re: Question on sensors..:)
> Ok, here goes...Lets say that the robot(walker) front sensor
> is triggered...then the bot reverse...fine..then just imagine that as it
> reverse, the back sensor touches another object and triggers the back
> sensor...my question is..since the reversing circuit is still active,
> how do I make sure that it stop reversing after triggering the back
> sensor and move forward again??Any ideas/comments/info is
> appreciated.Thanks in advance.
Depends on the circuit and design of your robot.
Assuming that your reverse sensor (at the front) is based on a capacitor
and resistor in parallel, forming a "timer" (when the sensor closes it
charges the cap, which will graduly leak through the resistor until the
cap is finally discharged and the time is up), then:
Assuming also that the sole purpose of the sensor at the back is to
change the direction of the bot when it is reversing back to forward,
then:
The solution is simple; the back sensor is wired in parallel with the
resistor and capacitor timing circuit, thus when it is triggered, it
shorts the cap, instantly discharging it and the bot returns to moving
forward, just like when the timer normally runs its course.
If you have some other sort of reverse system in mind, then for the sake
of clarity, I should note that the capacitor to which I'm refering to
above is _not_ the cap that drives your robot, but an extra one used to
add a timing function to a sensor :-)
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