Hi!
I am about to tackle my first Arduino project and would like to make a self balancing robot to get into the swing of things!
I have a few questions about the motors and shield needed. Firstly I'd like opinions of this motor:
I would like to get this bot to handle small jumps, short falls and maneuver uneven terrain.
Also I am not sure how to control them sufficiently, can I get some advice on shields/ESCs etc?
I would like to get this bot to handle small jumps, short falls and maneuver uneven terrain
Which bot would that be?
The motor's rated at 7.2W which is quite small - if the bot is small it might be enough.
does not appear, but these engines are strong for their size ...
They have enough reduction, of course you will not be able to move a person. My guess, with small wheels (7cm), a robot up to 2kg
For Driver (Controller), my suggestion is "Arduino 2A High Power H-bridge Dual Motor Controller".
You can find it at eBay, or, "L298N Dual H Bridge DC stepper Motor Driver Board module" (need more pins and is a bit more complicated, but cheaper).
@ AWOL, A typical self balancing bot, 2 motor powered wheels and a upright body.
@ MarkT, It will probably weigh approx 1kg, I haven't ordered the parts so it is impossible to give an exact estimate.
@xanok, I will look out for those, also glad to hear they are strong enough but I'm also worried about reaction speed, I have read numerous reports of ones struggling to find equilibrium and blaming it on motor speed?
Thanks guys
@ AWOL, A typical self balancing bot, 2 motor powered wheels and a upright body.
small jumps, short falls and maneuver uneven terrain.
"typical", "small", "short" and "uneven" are all a little imprecise, wouldn't you agree?
GregN:
@xanok, I will look out for those, also glad to hear they are strong enough but I'm also worried about reaction speed, I have read numerous reports of ones struggling to find equilibrium and blaming it on motor speed?
Im not expert, but I bought and search a lot of these motors on internet.
As you can see, it's says '270rpm'. a simple math problem.
60s = 270turns
1s = x
x = 4,5 turns per sec
4,5 turns take 1000ms
1 turn take x
x = 222,22ms
in degree:
1 turn = 360º
360º = 222,22ms
1º = x
x = 0,61ms per degree
If you control by time, I think you can use 0,61ms per degree.
Speed can be calculated with:
270rpm / 60 * d * 3,1415
If your wheel has a diameter of 5 cm (d), your speed is 70,68 cm/seg
If your wheel has a diameter of 1 m (d), your speed is 14,13 m/seg
Speed is inversely proportional to torque.
More and more speed, less weight you can carry.
Im not sure about torque equation...
I think if it's says "torque 2KG.CM", it means...
If you have a wheel with 5 cm (diameter), you can use this equation:
torque/(d/2)
or
torque / (r)
2kg / 2,5 = 0,8kg per motor
If you have 2 motors, you can carry 1,6kg.
The problem is, I do not know if this torque is the total limit of the engine, or is the limit to keep the engine specified RPM.
@ AWOL, I want it to stand about 40cm high, weigh approx 1kg with wheels about 15cm in diameter (I still need to find a pair). I will use PID control to keep the 'body' upright, with an accelerometer/ gyro combination board. By uneven terrain I am aiming at grass, soil and gravel with slight slopes and descends. And maybe sudden drops of about 20cm max, the drops will not be in sequence, just one at a time.
@xanok, Thansk for the info.
Thanks again
Here is some good reading for the subject. http://arduino.cc/forum/index.php/topic,60170.0.html