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What if you were to make a small platform for the light sensors in between
the legs that rest on the ground and has a slide somewhere so when the robot
moves up or down it stays touching the ground.
----- Original Message -----
From: "Elizabeth Mabrey" <emabrey@storming-robots.com>
To: <lugnet.robotics.rcx.legos@lugnet.com>;
<lugnet.robotics.rcx.robolab@lugnet.com>
Sent: Wednesday, May 19, 2004 9:16 AM
Subject: issues with 6-legs bot
> Hi,
>
> I built this 6-legs bug for a black line tracking test.
>
> The construction:
> It is a walker with 2 motors, one for 3-left-legs, another one for the
> right. Middle leg on each side is connected on an 8-tooth gear and attach
> an 40-tooth gear. This serves as a crankshaft for moving the middle leg.
> Two light sensors are used for detecting the black line, one on the left,
> one on the right. It walks very well as going forward and backward. It did
> turn on the port by moving legs in opposite direction, ie. left side goes
> forward as right side goes backward, and vice versa. As it turns, it turns
> pretty well .
>
> The robolab program:
> - The light sensors detection are done in 2 different tasks, and each has
> its container/variable. Each task increments the variable as it reads black.
> - The main task is to move the legs . The movement of left and right are
> all serialized.
> - psuedo code for the two sides movement for handling the detection of the
> black line:
> a) loop if left light variable>0
> --> do one turn (ie. left side walks back & right side walks forward)
> --> decrement the left light variable
> b) loop if right light variable > 0
> --> do one turn (ie. left side walks back & right side walks forward)
> --> decrement the left light variable
>
> I have 1 major and 1 minor issue:
>
> MAJOR: it turns well as long as it does not involve multiple reverse turns,
> e.g. right ...left ... right ... left... etc. Sometimes, some turns are
> either too much or too little?!
>
> minor: the light seems to be susceptible to a slight light variance. The
> light sensor may give a value of 32 to 36 for the same black spot if the
> light sensor is elevated about an inch. If this bot is using wheels, this
> issue will not arise because the distance of the light sensor to the test
> platform is constant. But for a walker, the light sensor goes up and
> down... Now if the platform only has black and white, this slight variation
> does not matter... but with some green at some spots, it becomes problem.
> I perhaps could reduce gear size from 40-tooth to say 24-tooth... but I'm
> afraid the reduction of torque may make the walking difficult.... Input?
>
> Input is very much appreciated, especially for the major problem...
>
> --
> thanks,
> Elizabeth Mabrey
>
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