Construction history and operation: The objective
of this project was to develop a two legged, walking robot. To this end
ARBi was rebuilt 9 times, using different sized servos. The final design
(pictured) was constructed using 3/8" Acrylic rods, micro servos (15), and SSC
II servo controllers (2). ARBi's motion and balance was determined by
configuring the position of each servo using a desktop computer running a
Visual Basic program specifically designed to interface with the SSC IIs
through the Basic Stamp. 14 "snap shots" were taken of 2 steps. These shots
were attached together in the stamp programming using the proper time
intervals as glue. Using this method produced two steps that the robot could
take, but these steps could not be duplicated, so sometimes the robot
walked, sometimes it fell down.
The obvious solution would be to use some sort of sensors to balance the
robot. Strain gauges would not work because the plastic flexed too much.
Flex sensors looked promising, but the pressure scale was logarithmic with
an error margin that was too great. Switches did not produce enough
resolution. Another problem was that the servos were too "spongy" meaning
they could be pulled a few degrees out of position before they would
respond. These few degrees multiplied by 15 becomes quite an error factor
and is probably the real villain in this project.