I am a student from the TU Delft in holland and basically stuck on my project. We have to build a walking beer crate. Our specific goal is to make it as fast as possible. I am educated as a mechanical engineer, so my knowledge about electronics is very low (It's just my first year). My job is to program the DC motor in such a way that we can accelerate and decelerate it via bluetooth.
It can deliver a maximum torque over a short instance of 16 Nm. It runs on 24V.
My initial plan was to connect a bluetooth module to a basic arduino unit, an ESC, powersupply and the motor. I asked for some help, but the comments I got only made it harder vor me to understand the project.
My first question: can I use an ESC with a brushed DC motor?
How do I choose modules which will fit and correspond with each other?
I got information about an H bridge, motor controller unit, octocoupler, PWM and all kinds of info about maximum Amps, etc.. But honoustly, I don't know what to make of it. Any help would be appreciated!
Something as in the commercial: a walk'in fridge with beer.
Are those legs like the "strandbeest" ?
The hardware for a normal brushed DC motor is often called a "motor driver". That's just a H-bridge in most cases.
The name "ESC" is used when there is some intelligence on the board, as would be needed for a brushless motor.
This is a simple one.
You have to know the stall current of the motor, and find a motor driver that can handle that current and voltage.
At pololu are a number of motor drivers, like this one:
Yes it's something like the walking fridge. The leg design is also based on 'the strandbeest', as you noted.
I don't know the stall current. It is not given and we can't measure it, because we don't have the motor at home, yet.
Only the needed power (58 Watts) and the required voltage (24V) are given. Can I make a brief calculation of the max amps based on those numbers?
and about the bluetooth module:
Does it really matter what I buy?
And can I connect your given motor control unit to any basic MCU?
The peak current could be 10 times the average running current and the motor will briefly draw the peak current when it starts up. It would be best to know what it is!
This is a perfect example of good selection of topic title. With the title of "acceleration of walking beer crate" you will get hundreds of people helping.
It can handle a peak amp of 30 A. Am I right that this will give us more room to pull up quicker without burning the arduino or motor? That is very important as we are doing a timed race.
So what parts do I need to complete the circuit? I'm still missing out on the MCU and bluetooth module.
OldSalt1945:
This is a perfect example of good selection of topic title. With the title of "acceleration of walking beer crate" you will get hundreds of people helping.
It's DUAL 10A FULL H-BRIDGE. You can run BOTH DRIVERS IN PARALLEL. Connect the motor to both outputs. Connect both DIR
inputs together and BOTH PWM inputs together. The heat will be distributed between both drivers. The dimensions are 4.2" by
2.2" . The price is only slightly more than the other one and it can take 60A peaks /per single drive. In parallel it could take 20A continuous or 120A peak. The driver will only dissipate what the motor draws so this driver will never burn out. The other one from
Pololu looks very wimpy by comparison. This one is cheaper and looks beefier. (13A) http://www.robotshop.com/en/cytron-13a-single-dc-motor-controller.html
Recommendation: put a false bottom in the beer crate and put all the motors, batteries, etc. in that. Of course, you already thought of that. I don't drink beer, but I remember some time ago seeing short beer bottles. I think they were called stubbies. They could sit on top of the raised bottom and look like the full sized bottles.
This isn't going to shake up the beer is it ? I hate when I open a beer that somebody shook up and it sprays all over the place....
That's not funny...
Yes we have thought of that. We constructed a frame in which al the components fit. De whole crate kan be simply clicked in position. That way we can interchange the crate without a problem.
I will take the more expensive motor driver. We are really going to push the limits so a little extra safety is welcome.
We have got 2 12V batteries to connect to the 24V motor. Can I also connect one of those those to the arduino for power supply? Or should I create another 5V circuit with different batteries?
If you have a secret pipe that allows you to drink the beer from the bottles in the crate the reducing mass will automatically result in acceleration ??? F = M x A
The power jack on the Arduino Uno board can have 7 to 12V. About 7.5V is the best.
You could use a DC-DC converter to make 7.5V out of 24V.
You should have a look at DC-DC converters, They are fun to use (in my opinion).
The bluetooth module at Adafruit is working and is compatible with the Arduino.
Cheaper modules from Ebay have to be tested first, and the range might be very disappointed. I think it is easier to start with something that is working.
There are many motor drivers. The size does not really matter, and most "dual" drivers can be uses in parallel mode.
Modern mosfet drivers (or chips with mosfets) have a very low Rds(on) of a few milli-ohm, those can use small boards.
Older drivers without those modern mosfets need to be bigger.
My next question is about how to connect the motor driver properly to the the DC motor.
We have two 12V batteries which we will connect in serial to supply the motor with 24 volts. We will connect the arduino, as you noted, parallel with one of the batteries to supply it with 12 volts.
The problem is however, If I connect my motor driver together with my battery to the engine it will obviously not run entirely through the motor driver. In example situations I found on the internet it does.
How will this effect the working of my scheme? If I didn't explain it clearly I can draw it if you want.
