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DPRG: All robot builders know this....

Subject: DPRG: All robot builders know this....
From: Jim Frye jfrye at lynxmotion.com
Date: Thu Jan 1 22:07:20 CST 1998

Hello all,

In light of the recent thread concerning DOers, I thought it might be a good
idea to give a progress report of my personal hexapod project.

Goal: 
 Build a small 3 servo remote piloted hexapod.

Features:
 Standard Lynxmotion Hexapod Walker (with camoflage paint of course).
 Futaba 4 channel RC set (left stick = motion control) (right stick = CCD
camera)
 Full pan and tilt of CCD camera (B/W)
 PIC processor to convert RC signals to stick position TTL for basic stamp.
 Basic Stamp control for walking gait.
 Video / audio transmitter on board.
 LCD "TV" for monitoring walking progress.

Progress:
 So far I have the bug built, 3 standard servos installed, pan and tilt is
built from 2 micro servos, basic stamp is wired and installed, RC receiver
is installed, PIC processor to intercept the left stick pulses is prototyped
and installed. The CCD camera is not installed yet, The LCD display has not
been purchased yet. I have a video / audio transmitter that runs on 9V but
it needs to be put into a smaller enclosure, and is not installed. 

Sucesses:
 The thing will walk under RC control and the pan and tilt works great. The
robot weighs in a 1.2 lbs now with a bit more circuitry to add, the weight
should not be a concern. I have tried sevel Futaba RC sets with great
results. I will be trying a Hitec set when it arives. 

Failures / Fixes:
 The thing is sucking the nicads dry real quick. I have measured up to 800mA
spikes when walking. This is not acceptable so I am trying to optimize the
setup to reduce the current consumption. I have adjusted the servos for the
legs to maximum throw for the required leg throw and lift to give the max
torque which resulted in some pushrods bending under the large load. I have
ordered hobby ball joints and will replace the wire pushrods. I have found
the servos have a greater torque at 6v rather than 4.8v. So I am putting
together a 5 cell AA pack to replace the 4 cell pack. I may need to go to
the Nickel-Metal Hydride (1200mAH) but am not anxious to spend $29.00 for a
small battery. 

Future:
 I will be ordering the CCD camera soon and installing the whole mess onto
the robot in the next few weeks. I antisapate a simular problem with power
for the 9v side as it powers the basic stamp 2mA, PIC 2mA, CCD camera 20mA,
vid / aud transmitter ~50mA I also expect the video transmitter range to be
a dissapointing 100 ft. 

Closing:
 I don't expect this to be a great performer... I hope it suprises me. It
will be somewhat slow (a few inches / sec.) and the operating time will be
only 1 to 2 hours. However it is a great learning project for me and I am
enjoying the oppertunity to overcome some huge obstacles. DO give me any
feedback you may think is appropriate. Lets get the thread back on track and
talk about real robots for a change. :) Thanks, Jim


Jim Frye                             ---------
Lynxmotion, Inc.                   /   (o\ (o\)----
104 Partridge Road                +-----\ \-\ \   o \
Pekin, IL 61554-1403 USA        GET A   |\o) \o)     |--------
Tel: 309-382-1816               GRIP!   |/o) /o)     |--------
Fax: 309-382-1254                 +-----/ /-/ /   o /
jfrye at lynxmotion.com               \   (o/ (o/)----
http://www.lynxmotion.com            ---------

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