Motors choice

[sade54]

Hi !

Im new to ardumower and want to build a version with IMU/GPS/Pathtracking because I just bought a house with 1500m² of not so green) lawn

But as a electronician and RC modelist , I'm curious about why a brushed motor is used as the mowing motor. Due to the conception of the blade , which partly relies on centrifuge power, a 'low' power brushless could be used with a better energy efficiency ?
Just a guess

Moreover what is the exact ref and manufacturer of the motors used for wheel drive ? The pdf found on the shop does not point to the good datasheet !

Yann

 

[markus-lbon-facebook]

The drive motors can be identical in construction to those engines.
DSMP420-24-212-BF

Not everyone mows every day.
1 week holiday and a motor without power fails.
[video width=425 height=344 type=youtube]Ccpqt9mn5HI[/video]

Attachment: https://forum.ardumower.de/data/media/kunena/attachments/945/20150130_0846021.jpg/

 

[sade54]

Thanks for the answer !

Do you think this one could be OK ?
http://www.superdroidrobots.com/shop/item.aspx/ig42-24vdc-right-angle-024-rpm-gear-motor-with-encoder/1829/

 

[fredericg]

I am in the same situation as Yann; my main hobby are RC planes and copters. I am also wondering about the usage of brushless motors. I would like to find out if one of the (older) motors I have laying around could be used.

I have made this (see picture) to mount on a motor for testing. The size is based on what I have found (disk is 119 in diameter) and pictures I have seen on the knifes. But is look small to me... Who can help me, what is the exact size?

Thanks a lot!
Frederic
Attachment: https://forum.ardumower.de/data/media/kunena/attachments/1727/20150420_222204_resized.jpg/

 

[marco]

Hallo Frederic,

sorry, my english isn`t good. Do you built your mower like the ardumower of the shop? You search for the diameter of the mower blade? Diameter is 190mm.

Marco

 

[fredericg]

Hi Marco, thanks for the reply!

Indeed, I would like to build an ardumower. I am however looking to make it cheaper by using some parts I have laying around like brushless motors and controllers I no longer use.

Right, the 119 mm seems too small :cheer: don't know where I did get that value from...

Any idea how much the standard ardumower mow motor consumes?

Thanks a lot!
Frederic

 

[fredericg]

I made a bigger disk. I tried it one a brushless motor (still conveniently mounted on an RC plane ) . At 3550 RPM it draws about 3A at 12V. This should be representative I believe...

Frederic
Attachment: https://forum.ardumower.de/data/media/kunena/attachments/1727/20150422_105343_resized.jpg/

 

[hippp]

Hi. Can I use this stepper motor for my ardumower?

Electrical Specification:

Motor Type Bipolar Stepper
Step Angle 1.8°
Holding Torque 3.0Nm (425oz.in)
Rated Current/phase 3.5A
Phase Resistance 1.2ohms
Recommended Voltage 24-48V
Inductance 5.0mH±20%(1KHz)

Price: US$ 30.54

 

[fredericg]

Hi Toly,

IFAIK, stepper motors are not supported in the current firmware, just as brushless motors are not yet supported.
In addition, IMHO, stepper motors do not provide added value in this application. The wheels can slip at any moment and the exact steps do not mean anything. I also believe that the power consumption of stepper motors is higher.

So, I wonder if stepper motors are a good idea for this application...

Hope this helps,
Frederic

 

[hippp]

IMHO, stepper motors do not provide added value in this application.

IMHO, the pros of using stepper motors may be:
- it is cheaper in 3 times;
- does not need a gearbox (torque 3.0Nm);
- does not need a hall sensor.

 

[fredericg]

Hi Toly,

IMHO, the pros of using stepper motors may be:
- it is cheaper in 3 times;
- does not need a gearbox (torque 3.0Nm);
- does not need a hall sensor.

I fully agree on the 2 first advantages. However, not sure how important the last advantage is. The exact amount of revolutions looses its importance when wheels slip. In different video's I have seen wheels slipping, which brought me to the conclusion that IMU is the way to go. But, I have no experience yet :blush:

As said, I suppose the (only) disadvantage is consumption, but I don't know how high the consumption penalty is. You can give it a try and let us know

I have considered stepper motors for a while, but finally went for brushless motors; without feedback, hoping the IMU will provide the needed feedback. And yes, quality gearboxes are expensive

Frederic