PiCamera 2 mount and electrical setup for UR3e

[sgbaird]

Hardware

Since the joint isn't a continuous rotation joint, having the camera to the right of the joint (i.e., fixed to the reference frame of the gripper/fingers) would be ideal. The power cable just needs to be a good length to not get pulled or be too long and get caught on other things. (NOTE: see Xiaoman's reply below, also including link to private video for my own reference)

Electrical

Requires getting 5V / 1.5 A to the Pi Zero 2W (micro-USB port). See ground symbol above, would likely pull from the gripper power, and may need to use a step-down voltage regulator - see voltage regulator links at https://accelerated-discovery.org/t/improvements-to-the-digital-pipette/236/11?u=sgbaird. You will also probably need a custom adapter to function as a power splitter, so that you can still power the gripper, but you can redirect a bit of the power to the camera. UR or someone who's worked with UR arms might have some kind of power splitter (probably an M12 power splitter, with then an M12 male to micro-USB male based on a quick search).

EDIT: I found specifications on https://www.universal-robots.com/developer/hardware-and-motion/electrical-interfaces-tool-connector/ for M8 and at first glance looks like SDL2's is an M8 male tool connector.

@xiaomguo doing something similar for powering the pH unit. Ideal would be pulling power directly near the gripper, but some cable management could also be done with a long cable powered from a wall outlet instead of the UR arm (or at least for testing/prototyping).

Link to CAD file for the picam equipment monitoring mount is here: #158 (comment)

[xiaomguo]

The joint position has been updated. Since the cable rotates with the joint, we don’t need a long one. Just make sure this joint stays fixed during pick-and-place so the camera stays level.

[sgbaird]

Thanks for clarifying! That really simplifies the setup. I also came across https://www.universal-robots.com/developer/hardware-and-motion/electrical-interfaces-tool-connector/. Could you or Yaseen follow the instructions there to see if you have the 12V or the 24V setup? (maybe you know already). Likewise, I'm having a hard time telling if you guys have the M8 female tool connector or the M8 male tool connector (latter maybe?).

[xiaomguo]

We have the 24V female tool connector

[xiaomguo]

I have designed the 3D printed parts and mounted the camera and Pi Zero 2W on the UR3.

[sgbaird]

Wow, so fast!

The following is the wrong size (M12, not M8) but is similar to what we'd want: Circular Connector Distributor Y-Shaped 8/8 (2) Male Pins/Female Sockets (2) Free Hanging (In-Line)

Robotiq seems to have the specific part we want ACC-SPLIT-M8-2:1 (EDIT: see note about the updated part), we just don't need the corresponding dual gripper setup.

I think we're looking for an M8, 8 position splitter with one male and two female sockets. It looks like DigiKey doesn't stock one with these exact specs).

The one from Robotiq seems a bit pricy (~$100's), will look for a suitable one from Mouser.

[sgbaird]

Finding something (mostly) off-the-shelf other than the one from Robotiq seems pretty bleak - #339. While we can still test in interim powering separately via USB (or maybe adding a small battery), @xiaomguo might be worth getting in contact with your Robotiq supplier to get a quote and check leadtime.

Also maybe worth getting a quote for a custom device through Phoenix Contact or similar.

Regardless, we'll also need to get that connection to the Zero 2W once it's been split (i.e., male M8 8-position to wire leads for example). EDIT: https://www.digikey.ca/en/products/detail/phoenix-contact/1404178/4080372 or one of the others listed at #339 (comment) should work for a wire lead option

[xiaomguo]

Thanks for looking into all of this! I’ll go ahead and send the ACC-SPLIT-M8-2:1 quotation email to our Robotiq reps, and look into others at Phoenix Contact.

I just came across this post— the user mentioned that the Tool I/O signals are included in the splitter. Not sure if that’s still an issue with the current version, but I’m saving it here just in case it helps with future troubleshooting.

Also, aside from the wire connection, I think we might need a 24V to 5V step-down converter for Pi zero as well, right? If that’s the case, we’ll need to find a way to mount the converter somewhere on the UR3. Feels like we’re adding quite a bit of hardware just to get around one cabling issue 😅. So far the shopping list looks like: splitter + 8P to wire cable + 24V–5V converter.

Alternatively, if we skip powering the Pi through the UR3 and just stick to the original power supply, I’ll try tomorrow to secure the power cable along the arm joints and run a workflow to see if it interferes with the motion.

[sgbaird]

Nice find on the post!

The support team sent me an email to schedule a call but I have not heard back for 24hrs. In the mean time, I was able to figure out that the ACC-SPLIT-M8-2:1 must only use traces for 24V, GND, RS485+, and RS485- because I was able to bypass it and turn on the Tool Inputs. You would think for the price that they are charging for the splitter they would include the other 4 signals for the Tool I/O, but I guess not. It seems like I will need to make a custom splitter on a PCB

Good to keep in mind for later.

Feels like we’re adding quite a bit of hardware just to get around one cabling issue 😅

More from a long-term perspective (rolling out same solution internally and externally, ~5-50x). It also might open up other possibilities for custom additions, though I think a camera is the obvious one.

Agreed though that powering directly from the original power supply is an easy interim, especially for trying out the workflow.

[xiaomguo]

Some M8 8pin connectors

https://www.elecbee.com/en-77397-m8-t-type-adapter-waterproof-m8-8pin-one-male-plug-to-two-female-plug-connector

https://www.elecbee.com/en-77395-m8-y-type-adapter-waterproof-m8-8pin-one-male-plug-to-two-female-plug-connector?utm_term=&utm_campaign=&utm_source=adwords&utm_medium=ppc&hsa_acc=9958698819&hsa_cam=22396437734&hsa_grp=177935010432&hsa_ad=743285203352&hsa_src=g&hsa_tgt=pla-2265612554879&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gad_source=1&gad_campaignid=22396437734&gbraid=0AAAAADGHwHbFHmt0-Cm4UDbkcxZ1vobUV&gclid=CjwKCAjw6s7CBhACEiwAuHQcksWNHR5nO0IFxqaTZZiEi_nOpqk3LCHQlM1ewGxdCdATw6BFVXRwJBoCeK0QAvD_BwE

https://www.elecbee.com/en-5658-10-pcs-m8-8-pin-connector-circular-waterproof-m8-panel-mount-solder-socket-with-1m-26awg-wire?search=M8%20Male%20to%20wire%20cable&page=2

https://www.elecbee.com/en-5680-10-pcs-m8-waterproof-b-coding-m8-male-panel-mount-solder-type-with-1m-26awg-wire?search=M8%208pin%20male%20to%20wire%20leads

[sgbaird]

Oh wow, nice find! That + https://www.digikey.ca/en/products/detail/phoenix-contact/1404178/4080372 + https://www.pololu.com/product/4091 + https://www.pishop.ca/product/piz-ezconnect-terminal-block-hat-for-pi-zero/ was the best off the shelf setup I could find, but still requires soldering terminal blocks (https://www.pololu.com/category/175/screwless-terminal-blocks) to the converter.

@kelvinchow23 any thoughts?

[kelvinchow23]

not a lot of great thoughts, but i can throw something in here. If this is dealing with power management, maybe we need to find a better solution. Based on skimming this thread, I'm assuming we have 24V/GND from the M8 connector, and i'm looking for a step-down converter that had a usb output connector that you could plug into the pi directly. Here are a few things I'm thinking about, but it probably needs to be a more legit option:

• https://www.amazon.ca/XMSJSIY-Step-Down-Converter-Adapter-Regulator/dp/B0BJZ8XHBB/ref=asc_df_B0BJZ8XHBB?mcid=143fc073761732be937e048b8e9fd8c7&tag=googleshopc0c-20&linkCode=df0&hvadid=706724917107&hvpos=&hvnetw=g&hvrand=4527165058803826676&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9197976&hvtargid=pla-2064748017596&hvocijid=4527165058803826676-B0BJZ8XHBB-&hvexpln=0&gad_source=1&th=1
• https://www.mouser.ca/ProductDetail/DFRobot/DFR0884?qs=pBJMDPsKWf3ZdM74MAgUoQ%3D%3D&mgh=1&utm_id=17633666059&utm_source=google&utm_medium=cpc&utm_marketing_tactic=amercorp&gad_source=1&gad_campaignid=17632709511&gbraid=0AAAAADn_wf0jo4nwBeyQge-QKES7DM5O5&gclid=Cj0KCQjwjdTCBhCLARIsAEu8bpLi20w0vepyV8lunZQOHqcIf5uLuINmTiY7iLbAFiKyGVtw9tJjS9kaAjp6EALw_wcB

[kelvinchow23]

I know @Seth-Winton was looking into pulling power off the m8 connector, maybe he has some insight?

[xiaomguo]

Here is a reply from our Robotiq reps regarding the splitter