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Full Version: B-robot EVO. OFF ROAD version
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(12-29-2017 09:33 AM)JJrobots JP Wrote: [ -> ]Thanks for this Monty. Got a pair
:-D

I am still having intermittent issues with my kit:
- bot just falls over while driving straight
- intermittent bot won't power up

I have followed the B-Robot recent thread, where it was suggested to check the IMU, shield and Leonardo solder joints. I have reflowed the IMU, shield IMU i2c connections, and checked the Leonardo solder connections. It appears my issue is similar to the other post - if I just touch the IMU cable - I can sometimes get the bot working for a while, but if it falls over - it may not respond (arm doesn't work, and if I pick it up the motors don't spin to balance the bot again).

Monty
It is probably a IMU problem. If the robot suddenly falls that means:
1) low battery (discarded)
2) Incorrect angle value coming from the IMU: cable disconnected/ faulty IMU
I will stick with the second option as you have already indicated that the B-robot sometimes does not power up.
Please check the IMU headers (back face) are not touching the metallic case of the WIFI module. If you want you can solder the i2c cables to the IMU. Alternative: let us know a delivery address and we will send you a replacement of the IMU
(01-02-2018 11:30 AM)JJrobots JP Wrote: [ -> ]It is probably a IMU problem. If the robot suddenly falls that means:
1) low battery (discarded)
2) Incorrect angle value coming from the IMU: cable disconnected/ faulty IMU
I will stick with the second option as you have already indicated that the B-robot sometimes does not power up.
Please check the IMU headers (back face) are not touching the metallic case of the WIFI module. If you want you can solder the i2c cables to the IMU. Alternative: let us know a delivery address and we will send you a replacement of the IMU

Thanks - I sent PM with my shipping address for a replacement IMU (and cable too)

Monty
I just installed off-road wheels on my slightly modified B-Robot EVO 2 chassis which has been widened from the original to allow space for a second servo (if you want to try my modified chassis: https://www.thingiverse.com/thing:2858220 ). The added benefits of wider wheels are more stability and also since the wheels are securely fixed to the motor shaft with hex coupling, the robot motion is more accurate in a straight line and also when steering. Smile

In case some of you might be interested, i bought them from aliexpress - a pair for about USD 10, currently available in 3 different colours. Search for "83mm RC wheel" and select "5mm Extended Hexagonal Coupling", as that's the diameter of the stepper motor shaft. BTW, 83mm is the diameter for off-road wheels recommended by JJrobots but maybe other 'slightly' different sizes could also work without having to modify the code. But with 83mm wheels, the robot balances and can be controlled without any issues.

[attachment=288] [attachment=289] [attachment=290]
Wow! Upload a video or link a youtube video. We really want to see it rolling!
Have started planning my robot (waiting for the controller and other parts)
I plan to use 120 mm wheels
https://www.ebay.com/itm/4pcs-AUSTAR-502...2749.l2649

+

https://www.ebay.com/itm/1pcs-HUB-12mm-H...2749.l2649

Any point using Shock Absorber Stepper Motor Vibration Damper to reduce vibrations from the stepper motors?

https://www.banggood.com/Shock-Absorber-...rehouse=CN

I plan to use 3S LiPo battery on mine

Started my design (using Fusion360) - is there a electronic brain shield v3.1 3d model (step format..?)
[attachment=291]
(04-16-2018 12:14 PM)JJrobots JP Wrote: [ -> ]Wow! Upload a video or link a youtube video. We really want to see it rolling!

I plan to upload a good video when i have my tripod so i can film it properly. Big Grin

I'm also working on a new chassis idea where the cables for the motor are no longer visible on the side of the robot. So, the robot can have a cleaner look with the cables going straight up from the motors through holes in the top plate to connect to the shield.

Also, i'm thinking of swapping the current 6 AA flat battery holder for a more compact one which can fit in the empty space between the stepper motors - this could make the robot even shorter in height or fit more layers/components within the same height.
[attachment=292]
Well, lowering the center of gravity will make the B-robot even faster. Keep us updated!
I just got my latest EVO2 Off-Road MEGA 2560 working tonight.

I wanted more I/O and program space - so replaced the Arduino Leonardo in the kit with an Arduino Mega 2560.

Since the Mega 2560 is over an inch longer - I used Meshmixer to cut the Stealth files and Simplify3d to stretch and merge the pieces to extend the width of the chassis to 130mm.

I had to modify the Leonardo program files for several things that are different in the Mega 2560:
- Mega i2c pins are outside the EVO2 shield - so I plugged two long header pins into the Mega i2c pins and plugged in the i2c CLK and DATA pins from the Gyro cable into the Mega.
- Mega Serial0 (console) is on pins 0 and 1, so I bent the shield pins 0 and 1 out and jumpered the pins to Mega TX1 and RX1.
- I changed the servo code to use the SoftwareServo library. The Servo library conflicted with the Wire library. Then I changed the servo code to make library calls. If I was more proficient at Arduino timer code - I might have been able to not use the softwareservo library and initialize the Mega timers.
- I changed the PORT and bit from Leonardo to Mega 2560 to get the stepper motor code to work with the Mega.

Here is a photo of the front and back of my Off-Road EVO2 MEGA. I'll get someone else to make a video later - as TouchOSC on my phone stops the robot when I stop touching the screen.

[attachment=311][attachment=312]

I ordered the same wheels Vaygr posted - and although I love the brass coupler to the servo shaft - I don't like this size wheel as much as my bigger wheel.
I'll have to make a 17mm hex to 12mm hex adapter - and bolt the bigger wheels to the brass couplers. I found the bigger wheels were easier to drive on carpet.

Monty
(05-08-2018 03:30 AM)nikola-wan Wrote: [ -> ]I just got my latest EVO2 Off-Road MEGA 2560 working tonight.

I wanted more I/O and program space - so replaced the Arduino Leonardo in the kit with an Arduino Mega 2560.

Since the Mega 2560 is over an inch longer - I used Meshmixer to cut the Stealth files and Simplify3d to stretch and merge the pieces to extend the width of the chassis to 130mm.

I had to modify the Leonardo program files for several things that are different in the Mega 2560:
- Mega i2c pins are outside the EVO2 shield - so I plugged two long header pins into the Mega i2c pins and plugged in the i2c CLK and DATA pins from the Gyro cable into the Mega.
- Mega Serial0 (console) is on pins 0 and 1, so I bent the shield pins 0 and 1 out and jumpered the pins to Mega TX1 and RX1.
- I changed the servo code to use the SoftwareServo library. The Servo library conflicted with the Wire library. Then I changed the servo code to make library calls. If I was more proficient at Arduino timer code - I might have been able to not use the softwareservo library and initialize the Mega timers.
- I changed the PORT and bit from Leonardo to Mega 2560 to get the stepper motor code to work with the Mega.

Here is a photo of the front and back of my Off-Road EVO2 MEGA. I'll get someone else to make a video later - as TouchOSC on my phone stops the robot when I stop touching the screen.



I ordered the same wheels Vaygr posted - and although I love the brass coupler to the servo shaft - I don't like this size wheel as much as my bigger wheel.
I'll have to make a 17mm hex to 12mm hex adapter - and bolt the bigger wheels to the brass couplers. I found the bigger wheels were easier to drive on carpet.

Monty

Great work, Monty! You've done quite a lot of modifications. The extra pins of the MEGA can always come in handy to connect more components, such as additional servos, etc. For example, it would be cool to attach a small/simple robot arm on top of the B-Robot to pick up stuff. Could you post some close-ups of the wiring on your MEGA or maybe some schematic if you made one? Maybe you could even consider sharing your work on GitHub. Big Grin

What is the diameter of your bigger size wheel? I also realized that the 83 mm wheels didn't leave much space between the bottom of the chassis and the ground surface, especially for off-road. I ordered some new wheels: https://www.aliexpress.com/item/2pcs-Wil...0.0.US6LXX
Diameter 125mm
Width 70mm
Hexagon adapter 12mm
Brand: GWOLVES (since it's branded, i'm hoping that the quality will be better)
I'll post some pictures and video of my upgraded B-Robot setup when i receive the new wheels in a few weeks.
I also have some larger wheels but with 17 mm hex and i just ordered these adapters (although you can design and 3D print your own): https://www.aliexpress.com/item/12-17mm-...40979.html

P.S. I see that the automated anti-spam forum system banned you (undoubtedly, for editing and submitting several times and too quickly - it happened to me too) but i don't have the forum privileges to unban you, so let's wait for the admins. Sad
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