Robotic Arm Project #1

Robotic Arm Project #1

2018-08-10

I have begun partial assembly of a small robotic arm from a kit containing the mechanical parts and the body pieces and the servos. I have been test fitting parts and have already discovered an issue with the servo wheels which are cogged for gears aren't fitting well on the gear on the MG996R servos. I checked how well the Hexfly servos fir the servo wheels .

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Servo Replacement
From advice gleaned from various places I will be replacing (4) of the original servos MG996R (I have already obtained two replacements) which are much better quality but need to locate a couple more Redcat Racing Hexfly HX-15S servos (will be replacing 4 of them. They seem to be out of stock everywhere I have checked. I can re-use the original servos in some less critical application so the MG996R won't be wasted hopefully.

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I attached the servo wheels to the two Hexfly servos and the gears are incredibly tight. I checked the MG996R servos and they were also unbelivably tight so I think there is a slight mistake in the servo wheels as two different brand of servo was almost too tight to work. I really had to struggle and use a lot of pressure to get them on.

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I am waiting on the arrival of (2) servo controllers, one of which will be used to calibrate the servo motors. I am only test fitting everything right now as I can't move forward until I receive the servo controllers.

The Arduino code to calibrate the servos is provided by the vendor but I did a lot of research before buying this particular model because I tracked it to 5 or 6 vendors all selling chinese hardware and designs. I found a duplicate on eBay that was exactly the same as the vendor model so I ordered a second robotic arm to work with. I am building the current one which I have called Project #1 using higher quality servos and plan on making this a precision device.

That could mean writing more of my own code and searching for better servos if the Hexfly models aren't precise enough. I hope to also work with some machine vision designs to see if the arm can be made to do something useful.

I am sure there is a lot of work to do before that.

32-Channel Servo Controller

I was able to obtain a lot of software to control the robot but using a specific 32-channel servo controller which is why I have to wait but I am going to archive everything here so that perhaps someday it will become useful when the originals vanish from the net.

It seems I can't upload it all here as one of the files is around 60MB which seems to have hit a wall on file-size during the site upload. I have a ticket in with the wiki provider to ask to be able to upload larger files I used to be able to store CD images which were over 300MB so something has changed lately.

Meanwhile I do have the Linux code for this see SUTD_Linux_2.1.0_X64.tar.bz2 MD5 e5bd7c9457b5c378824ae38a9c20fb2e however I found software for Windows, MacOS, Android!

I will try to find out some way to get it all archived here. I got the software and the manual for the 32-channel servo controller from http://www.rtrobot.org/software/ and the manual is located here see http://www.thanksbuyer.com/download/38641-manual-english-V3.0.pdf

I have a local copy 38641-manual-english-V3.0.pdf

The Windows version is https://rtrobot.org/software/ServoController_Windows_3.2.8.zip MD5 bdc5e2a2ee00114acf723ed8d4c0d102

The MacOS version is https://rtrobot.org/software/ServoController_MacOS_3.2.8_X64.zip MD5 b7b22fef5d4d85bf48d9c09a1a7063b0

The Android version is https://rtrobot.org/software/ServoController_Android.zip

The card is available from all the places that sell all the generic Chinese hardware that we all seem to be able to get from different places that may even have a different brand name but it is exactly the same as the next one. The Generic 32-Channel Servo Controller! I have found it at NewEgg, eBay (various vendors), I found it on Amazon as well.

I found several tutorials even one on Instrictables. See https://www.instructables.com/id/How-to-Use-32-Channel-Servo-Control-Board/

I found more documentation

http://letsmakerobots.com/files/32_Servo_Controller_Manual.pdf and http://github.com/RTrobot/Servo-Controller-for-32/archive/2.5.2.zip

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