Feedback on choosing the correct motor

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
Hi Folks, hope all is well.

I am planning on building an Electric motor powered garden cart.

I am looking into choosing the right type of motor.

The motor needs to have the 2 minimum items.

  • It needs to haul at least 30 pounds.
  • It should be able to move exactly 12 inches (or a certain preset distance) and then stop immediately without going over to 12. 5 inches or more. ( It is okay if its speed was only 6 inches per second )
  • The cart will eventually be automated; so I need a motor that can work well with Arduinos etc.

I am unable to decide between a regular DC brushless motor versus a Servo motor versus a Stepper motor.

Reading online about them didn’t help since I didn’t get enough clear information regarding which motor that I need to choose.

Can you guys please give me your feedback? Can you please also give your experiences when choosing a certain motor for a certain job? What variables dictates which motor that you guys would choose?

When do you choose a DC brushless versus servo versus stepper?

Thank you
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
How do you intend power it, i.e., power source voltage etc?
A regular DC motor may be the best option, I don't believe you would need accurate positioning, just a simple pulse counter, in order to count pulses.
 

Yaakov

Joined Jan 27, 2019
3,161
How do you intend power it, i.e., power source voltage etc?
A regular DC motor may be the best option, I don't believe you would need accurate positioning, just a simple pulse counter, in order to count pulses.
If the terrain is at all uneven, it might need an idler (not affected by wheel slip) with a tachometer or similar sensor to determine the distance actually traveled.
 

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
How do you intend power it, i.e., power source voltage etc?
A regular DC motor may be the best option, I don't believe you would need accurate positioning, just a simple pulse counter, in order to count pulses.
I want to power it using rechargeable Lithium Ion batteries. Yes, I am sorry for the initial post but position accuracy is not so importnat but i do need it to stop pretty quickly after it is told to stop.

https://www.amazon.com/Rechargeable...=p_72:1248903011&rnid=1248901011&s=hpc&sr=1-9
 

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
If the terrain is at all uneven, it might need an idler (not affected by wheel slip) with a tachometer or similar sensor to determine the distance actually traveled.
Yes, I am sorry for the initial post but position accuracy is not so so so importnat but i do need it to stop pretty quickly after it is told to stop.


https://www.amazon.com/Rechargeable-Batteries-Taken-1600mAh-Battery/dp/B08H7XPQ31/ref=sr_1_9?dchild=1&keywords=rechargeable+battery+liion&qid=1619636894&refinements=p_72:1248903011&rnid=1248901011&s=hpc&sr=1-9
 

Yaakov

Joined Jan 27, 2019
3,161
I want to power it using rechargeable Lithium Ion batteries. Yes, I am sorry for the initial post but position accuracy is not so importnat but i do need it to stop pretty quickly after it is told to stop.
You can use electric braking, so that shouldn't be a problem. You will probably want to use a gear box rather than direct drive.
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
Have you taken a any kind of simple torque assessment or attempt to measure same yet?
There are quite a few DC motor options that are automotive related.
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
The general procedure is to come up with the propulsion mechanism, then measure or calculate the degree of motive force/torque needed at the input.
 

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
The general procedure is to come up with the propulsion mechanism, then measure or calculate the degree of motive force needed at the input.
Ok. I will do that. I will be back in a few hours after doing the math. see ya soon.

BTW, Why didnt you ask me to pick a stepper or servo? Ty
 

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
I don't believe you need the accuracy afforded with a servo, and a stepper May do the job, but with much gearing.
I would be looking more to a DC motor with sensor feedback
a) You increased my curiosity. Why would the steper need more gears?
b) Do they sell DC motors with sensor feedback readymade or do I need to buy a DC motor and design a feedback system myself.
c) Do they sell these sensor feedback devices separately?

Ty
 

MaxHeadRoom

Joined Jul 18, 2013
23,115
One issue with steppers is they use the rated current constantly, regardless of load.
One advantage however is the stationary torque can be applied constantly to hold in place.
You can get motors with sensors, but they are relatively easy to make with either a slotted wheel or other non-optical types.
 

Thread Starter

bootloader9800

Joined Jan 12, 2021
27
I suspect that you wouldn’t want the cart to coast when not driven, or on power loss. Should this cart be towable?
On power off it should NOT be towable. It should act like a stepper motor where it has power, but impossbile to move until the correct signal is sent. I hope I was clear. Ty
 
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