Newsgroups: comp.robotics
Path: brunix!uunet!olivea!hal.com!decwrl!concert!sas!mozart.unx.sas.com!sasrer
From: sasrer@unx.sas.com (Rodney Radford)
Subject: Re: Robot based on 8052 microcontroller
Sender: news@unx.sas.com (Noter of Newsworthy Events)
Message-ID: <sasrer.745686997@cinnamon>
Date: Wed, 18 Aug 1993 15:16:37 GMT
References: <CByIyy.Gz7@watserv2.uwaterloo.ca>
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Organization: SAS Institute Inc.
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nowinski@sciborg.uwaterloo.ca (Andrew Nowinski) writes:

>I would really appreciate if someone helped me write a program
>that can do the things I want to do below.

> List starts here 

>When first turned on go forward.

>If a switch is pushed move back then turn 90 degrees to the left
>or right then go forward.

> List ends here 

If that is all you want, that can easily be solved with two motors, a
power source (battery), a microswitch, a 555 delay timer, and a relay - 
no MICROPROCESSOR required...!

Basically have the left motor on all the time running forward until the
contact switch in front detects an obstacle. This contact switch is wired
up to the TRIGGER line of the 555 (running in one shot mode). When the
TRIGGER input is activated (high/low - can't remember) the output of the
555 changes state energizing the relay for a specified amount of time.
The relay is actually a DPDT relay that reverses the voltage to the right
motor - since the left motor is still going forward, the robot spins in
one location (effecting a turn to the right).  Just adjust the time delay
on the 555 so that it approximately equals the time for the robot to 
turn to the required relative heading (90 degrees, for example).

This works better if the microswitch in front is attached to a 'boom' of
piano wire about 4-5" long so there is no hard THUMP when the robot runs
into the wall at full speed ahead. The extra few inches should give enough
time to allow the robot to turn gracefully.

Wow - a relay 'computer' to the rescue....

--
---
Rodney Radford          || Computer Graphics/Imaging
sasrer@unx.sas.com      || SAS Institute, Inc.
(919) 677-8000 x7703    || Cary, NC  27513

