Grip Arm Files Drop!

[Steve Pendergrast]

Hello everyone,

We are going to ship out our pre-ordered grip arm kits on Monday at this point (sorry for being a few days later than originally projected but it took a bit longer than expected to get the documentation finalized.)

Anyway, we have started the roll out by dropping all the files today:

• Thingiverse has the STL files for the grip arm here: https://www.thingiverse.com/thing:3231634
• Code updates (V2r1)  to make it work with the gamepad are on Github but also now on the shared dropbox folder here: http://tinyurl.com/VorpalFiles
• Build instructions, gamepad instructions, and other info is now on the Wiki here: http://vorpalrobotics.com/wiki/index.php/Hexapod_Grip_Arm
• The kits will still be at the pre-order price until Cyber Monday (this coming Monday Nov 26).  Kit pre-orders are here: https://vorpal-robotics-store.myshopify.com/products/hexapod-grip-arm-kit
  
• A very short demo video is on our youtube channel here: https://www.youtube.com/watch?v=AnJ6JeqtUys  (Sorry the video is shakey, I was holding my phone with one hand and working the gamepad with the other!)

I'll get some better pictures and video shot next week.

Enjoy!  We'll be working on new activities that incorporate the grip arm in the coming weeks.

Happy Thanksgiving for those of you in the USA!

-Steve P.

[Dave Leiner]

Hi Steve,

I printed the parts and am looking forward to getting the kit today. Looking at the V2r1 release files, it looks like the Gamepad file is still at version V2r0. Were there actually any changes to the Gamepad code for the grip arm? I don't really see why there would be.

--Dave

[Steve Pendergrast]

There are no changes to the gamepad for the grip arm. The gamepad simply transmits a sequence indicating which button is pressed, it's up to the robot to interpret what that's supposed to mean.

When you turn the robot's dial slightly counter-clockwise from the RC position you'll hear a beep. Stop turning a bit past that beep. F2 fight mode will now control the grip arm. If you remove the grip arm, just turn the dial all they clockwise again.

This seemed like a better solution than having to reflash the robot every time you swapped out the grip arm. you could use these same controls for any other two-motor accessory you come up with (for example a go pro 2 axis gimbal mount, hmmmmm).

I am also considering a future software upgrade that allows chording of the 4x4 matrix buttons to trigger many more possible functions (i.e. pressing both W1 and W2 would access yet another walking mode). right now there is a concept of a long click on a matrix button to trigger a scratch-recorded set of motions, but I find myself needing more and more modes for future ideas and add-ons. The other option would be things like "double-click" or "triple-click".  The issue with that is that timing might be hard for people to learn and you'd not be able to tell in a noisy environment whether the doubl-click was actually recognized or not (i.e. if you couldn't hear feedback beeps from the robot).

[Dave Leiner]

The grip arm went together quite well and the parts were fast and easy to print. The only problem I encountered was that the included M3 screw was too big for the SG90 servo. Fortunately I had an M2 screw and washer on hand which worked well. I also had to give up the ultrasonic and light sensors which were using the grip arm's power pins but I suppose I could splice into power if I decide to add them back in.

The arm works very well and is a fun addition. Thanks!

--Dave

[Steve Pendergrast]

Hi Dave,

Yes it looks like the M2.5 is too tight a fit. In our test models we had first used the pointy screw that came with the servo before putting in the M2.5 screw and apparently that makes a huge difference, the pointy screw makes the hole a little bigger as it cuts its threads in. Sorry we didn't catch this!

The pointy screw does work though, so I've just now changed the instructions online to use that for the SG90 instead of the enclosed M2.5.  We'll do some testing against longer M2 screws to see if one works better than the other and will consider whether its worth it to switch in future versions of the kit.

Thanks for pointing this out!