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Upgrade servo and/or steppers
03-06-2017, 03:50 PM
Post: #1
Upgrade servo and/or steppers
I'm working with the BRobot 2 EVO model.
The servo does not seem strong enough to lift up the robot. The arm hits the ground and stops. Tried fresh batteries. Has anyone upgraded to a stronger servo in the same size, or a bigger servo overall?

Also curious if anyone has swapped to bigger steppers/controllers to work around stalling the motors and/or for a bigger platform.
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03-08-2017, 10:14 AM
Post: #2
RE: Upgrade servo and/or steppers
I thought the same but the servo can handle the weight. Be careful how you set the arm in the "centred" position and if you have enough grip on the wheels.
Anyway, I got an email from Juan (jjrobots) telling me they will release a new version of the code within days, this code will allow the Brobot to stand up without problems no matter the surface and with the new Google Blockly control feature already working (cool!)
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03-08-2017, 05:30 PM (This post was last modified: 03-08-2017 05:30 PM by jpedroc.)
Post: #3
RE: Upgrade servo and/or steppers
Hi!
We just released the latest code for the B.robot EVO 2: https://www.jjrobots.com/wp-content/uplo...VO2_17.zip
Changes:
- Now the B-robot will start to "stand up" from a lower angle (spinning the motors sooner): this will allow the servo to work less and push less against the floor.
- Google Blockly ready: we will post info about how to use it asap
- Ready to send telemetry: the same, we will update the control APP asap in Google Play

I have left this message here before we make everything official ;-)
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03-09-2017, 03:51 AM
Post: #4
RE: Upgrade servo and/or steppers
(03-08-2017 05:30 PM)jpedroc Wrote:  Hi!
We just released the latest code for the B.robot EVO 2:

I tried this code and it works great. It's running with my big buggy wheels at the moment. Very fast, twitchy if you can bang your thumbs around, handles bumps and crashing well. Congrats and thanks!

However my servo problem still persists. I'll try centering it again tomorrow to make sure, but even if I flip the bot over it still does not pick up. I'm thinking of making a shorter arm that will get better leverage/shorter throw.
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03-09-2017, 09:43 AM
Post: #5
RE: Upgrade servo and/or steppers
(03-09-2017 03:51 AM)jefm Wrote:  
(03-08-2017 05:30 PM)jpedroc Wrote:  Hi!
We just released the latest code for the B.robot EVO 2:

I tried this code and it works great. It's running with my big buggy wheels at the moment. Very fast, twitchy if you can bang your thumbs around, handles bumps and crashing well. Congrats and thanks!

However my servo problem still persists. I'll try centering it again tomorrow to make sure, but even if I flip the bot over it still does not pick up. I'm thinking of making a shorter arm that will get better leverage/shorter throw.
Yes, try another length for the arm. The original arm was calculated for the "regular" wheels, another slightly different diameter can make the arm not working properly (and let us know how it goes!) :-)
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03-20-2017, 01:23 AM
Post: #6
RE: Upgrade servo and/or steppers
Here are some vids of my arm progress. I still think I need a better motor, it just hits the ground and stops. Any ideas?

One of the original arms. I know the angle is off, but when it's on the ground like that it should be easier for it.
https://youtu.be/fTYjDaZKXSA

Here's a metal arm that allows two leverages to be attempted, but it did not work in either position.
https://youtu.be/uXyWwsi-0_E

Went nuts and tied a big chunk of plastic to the metal arm.
https://youtu.be/qiChbW6DVk4
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03-20-2017, 05:56 PM
Post: #7
RE: Upgrade servo and/or steppers
Hmm... Are you adding more weight than the "official" to the top of the Robot? It seems the servo you have is not capable of handling the weight Huh

I have attached a short video of the regular behaviour of the B-robot standing Up (as a reference)

Contact us at: info@jjrobots.com (we will send you another servo if you want) Wink


Attached File(s)
.mp4  standing up.mp4 (Size: 7.32 MB / Downloads: 25)
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03-22-2017, 01:15 PM
Post: #8
RE: Upgrade servo and/or steppers
(03-20-2017 05:56 PM)jpedroc Wrote:  Hmm... Are you adding more weight than the "official" to the top of the Robot? It seems the servo you have is not capable of handling the weight Huh

At present there is a GoPro mount and a USB cable. I will try removing those and see what happens. Thanks for the video. Is that robot running the same code that was release a couple weeks ago?
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03-23-2017, 07:46 PM
Post: #9
RE: Upgrade servo and/or steppers
Yes, running the same code. If there is too much weight that could be a problem. Contact us at info@jjrobots.com. We could provide a more powerful servo if you need it.
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