Building RoboGator®
We here at ColorBAT have embarked on a project to animate a fake, plastic, floating alligator in an effort to create a device that will act as an effective deterrent to herons and other predators that would feed on the fish in our water-garden pond.
The goal is to have the 'gator detect, via built-in infrared detectors, the presence of warm-blooded things near the pond, and then slowly swim TOWARDS them!! The hope is that if the 'gator will swim towards a heron or other predator it should scare the critter enough to cause it to flee.
We plan on posting.. here... our adventures in this project. We'll include pictures when we have them. If any of you are interested... have ideas that might help... or would like to buy a finished, working, RoboGator for your own pond.... send us an Email and tell us a little about yourself!!
Feb 19, 2004: The project has begun with a study of various IR detectors and how they operate. We are in the process of building a bread-board working prototype of an IR detector so we can determine which models of detectors will be adequate for our needs. We want a detector that can identify anything as small as a cat (and for sure, a heron) as far away as 10 - 15 feet. We are planning to use a Fresnel lens over the detector to increase its sensitivity and range as well as its viewing angle.
Feb 29, 2004: Finally got the LM324 wired up and running. I managed to miswire the power connection on the first try and had to get another one. I'm going to rig a bracket to mount the IR detector and lens so I can get an idea of the range of detection. Will rig an LED to give a visual response to anything that is detected.
Wired a bread-boarded 555 timer to alternately turn on and off the two propellers on the head (to make the gator swim in a zig-zag path). Got both output LED's blinking alternately. Will later substitute transistor power switches for the LED's. Then started playing around with resistor and cap values to alter the blinking rate and burnt out the 555. So, now, I have to start all over on that project and be a bit more careful.
March 10, 2004: Got the 555 timer circuit to work correctly. I had not burnt it out after all... just needed a few adjustments! We are continuing to work on the IR sensor circuit. Finally received from Taiwan some small, round, domed, plastic, Fresnel lens for use over the end of the IR detectors. The lens is supposed to give each detector a 110 degree field of view and enable the detector to work at about 6 - 8 meters (yards). We are now in the process of building a bread-board circuit to test all of that out and determine the exact circuit design to deliver the greatest sensitivity for our IR detectors.
March 13, 2004: Attended a Radio-Controlled airplane show at Lebanon to see what might be available in small hardware items..... boat propellers, electric motors, battery packs, etc. Came away with a lot of good information and ideas. Also talked with some folks about fiberglass lay-up molding of parts. Am now considering making RoboGator as a fiberglass lay-up molding instead of using plastic foam. Need to study all of that a bit more.
March 15, 2004: We've decided that it will not be too good of an idea to use a long umbilical cord plugged in on shore as a power source for RoboGator. We think it will be too difficult for him to drag such a power cord around in the water as he swims after targets. So, we are now planning on using a battery pack to provide power for him. When he is not out chasing an IR target, he will "dock" himself in a battery re-charging "dock". We'll build a pile of "rocks" out of plastic that will float near shore. The "rocks" will have a "V" shaped opening in them that RoboGator will stick his tail in when he is not chasing IR targets. In his tail will be some coils of wire that will act as "receiver" coils for electrical energy to be transferred from matching coils in the rocks. The batteries in RoboGator will get trickled charged by electrical energy radiated from one coil to the other. Both coils... the transmitting and receiving coil... will be embedded in the plastic to make them water-proof. In order for RoboGator to know how to "dock" his tail in the "rocks", we'll put a small ultra-sonic transmitter in the "rocks" and a small ultra-sonic receiver in RoboGator's tail. The "tail" section will have two small motors and propellers which will allow the tail section to seek out and swim towards the ultra-sonic transmitter in the rocks. In effect, RoboGator will be swimming backwards as he moves into the re-charging dock. As the tail moves back into the "V" section of the rocks, the "V" shape of the rocks will guide the tail into position for the coils to match up and allow the transference of energy to RoboGator's batteries. RoboGator will spend most of his time with his tail back in the rocks getting charged. When ever the IR detectors in his head "see" a heron, RoboGator will turn off the ultra-sonic receiver in his tail (which will act to keep him in the dock) and slowly swim towards the heron. After the heron leaves, RoboGator will turn "on" his ultra-sonic receiver and swim backwards to seek out the pile of rocks and once again, dock his tail in the rocks to resume re-charging his batteries. By having his tail back in the "rocks" his head will be facing out to allow the IR sensors in his head to be constantly "looking" for an IR target. We'll use a small remote control (like a TV channel changer) to turn RoboGator "off" when we want to sit around the pond. Otherwise, he would "see" us and want to swim towards us.
We are also keeping open an option of building a small water pump into RoboGator's head that will allow him to "spit" a small stream of water at the offending heron if needed.
May 2006
Well, we've given
up on building a motorized alligator. Honestly, we just don't think
there would be much of a market for one. However, we ARE selling the
regular, floating, type! To buy a real, (fake), floating alligator (no
electronics.. no automation..))... CLICK HERE.