This instructable was created to be entered in the Robot Challenge. If I win, the parts will of course, go into robots like this one. Notes on how to include some of the very components in the prize packages are given in the last step. I am 28, so of course, I'm not going for the student prizes.
I created this as a simple project for those just starting out in robotics. It is relatively inexpensive, requires minimal tools and is easy to build. Once finished you have an expandable robotic platform that fits in the palm of your hand and can be easily programmed in the Arduino environment.
Here is is driving in a triangle, without any special add ons
In the instructions I'll walk you through how to:
For the basic platform the following supplies are needed:
an Arduino nano
a small rechargeable battery
a pair of 9 g servos, modified for continuous rotation
part of a Tamiya track set
a 40 pin dip socket
a rubber eraser
some zip ties
I created this as a simple project for those just starting out in robotics. It is relatively inexpensive, requires minimal tools and is easy to build. Once finished you have an expandable robotic platform that fits in the palm of your hand and can be easily programmed in the Arduino environment.
Here is is driving in a triangle, without any special add ons
In the instructions I'll walk you through how to:
- Modify the servos for continuous rotation
- Fit the track hubs on to the servos
- Make a custom battery pack
- Wire it with a few connections
- Assemble it
- Program it
- Customize
For the basic platform the following supplies are needed:
an Arduino nano
a small rechargeable battery
a pair of 9 g servos, modified for continuous rotation
part of a Tamiya track set
a 40 pin dip socket
a rubber eraser
some zip ties
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Signing UpStep 1: Construction: Modify the servos
Micro servos modified for continuous rotation are the heart of this design. They give you so much of the hardware; the motors, the gearbox, the driver and control circuitry, all in a tiny cheap package, and in this implementation they also act as the frame of the robot (seen in the next step). There are many instructables on modifying servos for continuous rotation. But here is how I did it for the micro 9g servos I am using.
Pictures:
Pictures:
- Remove the tiny screws and open the case
- Cut the potentiometer wires, these are where you will attach the resistors
- If you have surface mount resistors, place a 5k (1k to 10k should work) on the pad from each of the side pads to the middle pad, if you don't twist a pair of through hole resistors like this
- Break out the stop on the potentiometer with some small pliers, you need the pot for its use as a rotational bearing
- solder on the resistors, if you used the pair of through hole ones, I recommend bundling them in electrical tape like so. For the servo that will go on the front, cut a notch for the wire to exit through the side so it doesn't come from under the robot.
- (not shown) Before you close up, put a hole in the back part of the case opposite the spline to mount the idler (wheel with no teeth).
- Use some angle cutters or pliers to remove any mounting flanges from the cases and file or sand down the ridges they leave, these can get in the way later.
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Really, really neat!
It's hard to make a narrow robot when you're using continuous rotation servos because of the gearbox height, but you've overcome this with the tracks and the asymmetric mounting method.
Just to clarify, you've drilled a hole for the idler pinion in the servo bottom cover in line with the spindle? Must have been pretty tight in there - the boards in those 9g servos don't leave a lot of room.
Here is my version.
By the way, how did you do in the competition?
I tried to program a similar (but again, bulkier & uglier) bot to map the room so it could always choose the longest path and avoid crashing with solid objects. Problem was I did not have a direct way of relating the current sent to the motors with its change in position(gears jump, electrons blip in and out of space etc) so i could not feedforward, so now I am working on feedback lol
I like how the use of servos makes motor drivers unnecessary.
Great instructable.
1. no Arduino nano
2. no battery
3. no 40 pin dip socket
and the question would be how to MANUALLY control basic 4 direction movement via an attached multi-wire light cable (CAT type?) let's say 100 ft long.
Power of course should be supplied at the controlling point via de cable.
The mounting, feeding and powering the tiny CCTV camera would be my job once the vehicle is manually operational.
Any inputs or help, online or off-line at ron.dacosta@gmail.dot.com?
Many thanks anyway. Ron
To drive by wire there are a few approaches you could take, you could send a servo signal through the line (0.5 ms to 2.5 ms pulses spaced 20 ms apart) or you could pull out the board and just give -5 to +5 Vdc, or a duty cycle PWM signal to the motor directly.
Wonderful project, great Ible. Truly inspiring!
When I first saw this, I thought it was a version of ChrisTheCarpenter's Tiny Tank (http://www.instructables.com/id/Rocket-Brand-Studios-Tiny-Tank/) but I see now it's all original. Good job!