Project robot lawnmower

[Raess]

Testing the new BLDC motors running VESC.
https://www.youtube.com/watch?v=ha5ucyqyUr0
Read full post here: http://valify.se/2018/03/20/the-new-bru ... ors-spins/

[Raess]

Jetson TX2 mount and SSD mount 3D printed.

[Raess]

Tested to control the motor with VESC over ROS and Differential drive, ROS controller and keyboard_teleop.
https://www.youtube.com/watch?v=f4ZobjZOBfo

Lets try both motors tonight.

Read full post here: http://valify.se/2018/03/21/differentia ... -ros-vesc/

[Raess]

Tonight Part 10 was finished, the second wheel for the Valify Robot lawnmower. The print took around 44h and conusmed approximately 550grams of PrimaSelect PETG filament.

I just order a tachometer so I can measure the RPM easier. For low RPM the motors are working quite good. No problem with torque, as i wrote earlier I can't even hold them. So I need to measure how low RPM the motors can handle before calculating gearing further. I will order encoders for absolute rotor positions improving low RPM start and torque. The encoder I am looking at is the AS5047P (which seems to be hard to get) I also looking at the AS5048A which can support 16384 positions per revolution.

Yesterday night I continued to work with brushless motors, VESC and ROS. The Differential drive works. I hooked up a DS4 running turtlebot_teleop_joystick In order to control the motors with a joystick
https://www.youtube.com/watch?v=zs_l-jMn2cI&t=3s
read full post here: valify.se/2018/03/24/brushless-motors-vesc-and-ros-second-test/

[Raess]

My printer had no tasks in the pipeline for tonight, So I 3D printed the mounting bracket I designed a couple of days ago. The mount was 3D printed with PrimaSelect PETG, 3 shells and 10% infill. Due to the different surfaces I needed to print with support. The mount came out great and everything fit perfectly. The Scanse Sweep was mounted with 4x 2.5M screws on the bracket and there are two different ports at different orientations which may be used to interface the serial port to USB using a FTDI serial to USB converter. Scanse Sweep plugs into a USB hub which is in turn connected to the onboard Jetson.

First test of Sweep: https://www.youtube.com/watch?v=k9m85NCLcu4

Read full post here: http://valify.se/2018/03/24/scanse-swee ... g-bracket/

[Raess]

3D printed wheels, Drive shaft nav and wheel nav. Everything fits perfect.
8mm Drive shaft in Silver steel, Ultra silent F688ZZ bearings, 8mm clamping ring in alu. Clamping element 8 x 15. The wheel nav is only a quick and dirty concept, need to improve the looks so it follow the same lines as the wheels.

[Raess]

Today I received the touchscreen for the robot. Did a quick and dirty prototype of the mouting bracket and printed it.
Here is how how it looks mounted on the robot. (Did not have 90-degree HDMI connectors at home, thats why is lifted when powered on).

Read full post here:
http://valify.se/2018/03/26/capacitive- ... n-running/

[woofy]

Wow, you are steaming ahead with this. Impressive.
What are you going to drive the display with, a raspberry pi or similar?

A couple of years ago I started work on a robotic lawn mower of my own. It would have been smaller than yours with maybe an 18-20cm cut. However we moved before I'd finished and as I now have about 1.5 acres to cut, I have a ride on mower.

[Raess]

Thanks. But still a very long way ahead.

The display is driven buy a Nvidia Jetson TX2.
More info here: https://www.nvidia.com/en-us/autonomous ... s-modules/


You can see the display in action here
https://www.youtube.com/watch?v=TBCq1r_XWo4

Cheers

[Raess]

A quick Drive system/wheel assembly.

Things are coming together quite nicely.
Here is a small video on the drive system in action with wheel:
https://www.youtube.com/watch?v=tMZNToO2TvU

[Raess]

The appearance grows part by part. The Wheels made a huge difference on the size and the contours of the body.

[Raess]

Friday fun!
Testing the AS5048A encoder with 16384 positions per revolution and with the temporary drive system. Motor brackets are 3D printed and not perfect, therefore some annoying noises! Running VESC FOC Mode @10% Duty.

With the rotary position sensor I get a very smooth start and better torque. Before the start from standstill could be a little choppy and the sensor took care of this issue.
https://www.youtube.com/watch?v=h7JsRsa5fl8

[Raess]

This week, CNC milling of motor brackets begins.
Here are the final brackets and the plan for gearing

a quick render on the drive system

In the meantime I keep the printer busy with printing pulleys.
Sizes printed today is XL 10T, 50T and a 55T. Took a few test prints before I could find the sweet spot for the settings for a maximum belt grip.

[Raess]

New AS5048A encoder mount printed. HE-14 header fits great and I installed pull relief for the cables on the back.

[Raess]

Testing to print with PrimaSelect Carbon. A PETG mix with 20% carbon fibers. This Filament is a bit stiffer then the normal PETG. But I am not sure it´s worth the extra bucks compered to PETG. a whopping 95USD/kg VS 35USD/kg

This was my first print running almost same settings as the Normal PETG, I went down to 235C from 240C.

[zemlin]

Testing to print with PrimaSelect Carbon. A PETG mix with 20% carbon fibers. This Filament is a bit stiffer then the normal PETG. But I am not sure it´s worth the extra bucks compered to PETG. a whopping 95USD/kg VS 35USD/kg

This was my first print running almost same settings as the Normal PETG, I went down to 235C from 240C.

IMG_2857.JPG

I have very limited experience with CF filament. I compared a eSun ePA with their CF ePA recently and was not impressed. More rigid in heavy sections, for sure, but thin sections could tear like paper where the straight ePA was much tougher. I don't think the fibers are long enough to add strength to the matrix so it's just a filler which reduces the overall tensile strength.

[Raess]

@zemlin I am sure you are right. This was the first time for me printing Carbon. But my conclusions are that is not worth spending these extras bucks because the overall strength is not as good as one should expect. :/

[Raess]

Saturday's fun. Printed mounting brackets for the front wheels (Please note that this is only test wheels before I make an effort the design some new ones with bearings etc.
The brackets came out great. Following the contours of the body and blended in quite good. This parts was also printed with PETG.

And a quick assembly with all wheel mounted.

[Raess]

Testing the 3D printed front nose. Looks quite good. Minor adjustments needs to be done.
Printed with PrimaSelect PETG @240C, 85C bed, 3shells and 15% infill (Very solid outcome).
Countersink need to be adjusted to cut the body.
The Integrated ZR300 camera need some cover on the back.
Check if one can use a 90 degree USB instead of a normal USB head.

[Timber Haint]

Great work! I always like to see people who are using their printers for engineering projects. Keep the updates coming.