Here is my entry for the 555 contest, a robot that can be set free on any ferrous metal structure. It has rare earth magnets for wheels (covered in hot glue for traction) attached to micro servos modified for continuous rotation. The bot closely resembles the Beetlebot by Jerome Demers, as it uses limit switches to change the direction of the bot. When the switch closes it shorts or opens the switch connections and causes the servo pulses to manipulate the direction of the servo. I used modified a Simple Servo Tester board from Gadget Gangster on each side, which uses a 555 timer in Astable mode to set up the 1.0 – 2.0 ms signal required for a servo to move one direction (2 ms) or the other (1 ms).
So I wish I can say everything turned out perfect.
After many struggles including:
-Finding out Hextronix HXT900 servos don’t jive with Gadget Gangster Servo testers
-Breaking a gear while trying to modify a HiTec servo for continuous rotation had to buy another
-Bought a HiTec servo that didn't work at all (luckily i had an extra on another bot)
-Staying up all night modding hardware and paying for it the next day
-Thought I blew up a couple 555′s turns out I just had a modified servo that didn’t run very smooth
-Having some intermittent issues (as you can see in the vid) when everything was put together, found I had the resistor in the wrong place on one of the switches
I finally actually pulled “something” off at the last minute, I wanted to keep it fairly simple and use 555 timers to drive servo motors, turns out I had to throw out most of my more complex ideas and keep it simple as I ran out of time. The mission of this robot was to “unlease it”, or “set it free” on a metal pole or building and watch it climb as high/far as it could, maybe even on a bridge. I was thinking you could always put a solar panel on it and maybe it could even sustain itself…but that’s wishful thinking. Dave Hrynkiw pointed out that the bot could fall from a height at any moment and could be a safety concern, he suggested a parachute…lol…it’s actually a pretty good idea!
Material List:
- Gadget Gangster Simple Servo testers
- Solarbotics Neodymium Disc Magnets
- HiTec HS- 55 Micro Servos
- Limit Switches
- 9v Aluminum Battery Holder from Digikey
- Antenna wire from Take out boxes (Wok Boxes)
- Female Header cables from Solarbotics
- Automotive Terminal Connectors
- LM2937 5V Voltage Regulator
- Caps for the regulator and 820 ohm & 15 kohm resistors
Climbs metal surfaces and avoids obstacles at the same time
- Actuators / output devices: 2x Hitec HS-55 servo
- Control method: autonomous
- CPU: 2x 555 timer
- Power source: 9v battery
- Sensors / input devices: 2 Bumper switches
- Target environment: metal surfaces
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/freedom555bot
