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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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