Lynxmotion SES V2 Hexapod Robot

cbenson · May 14, 2020, 12:39pm

Looks like there’s a tracking number (10 minutes ago) so a bit too late to include any free items. We would have been happy to ship the correct brackets free of charge and include the plastic clips. If you have any issues with the servos, we’ll handle the exchanges. No spare (free) 3D printers to send unfortunately

Do you have any options for the bottom of the feet so the rubber doesn’t flatten and impede motion? Even a suitable marble might work, or rolled and cut paper or popsicle sticks cut to the right length forming an X?

kurte · May 14, 2020, 7:03pm

@cbenson - no spare free 3d printers I know that I should probably try to see if I could rewire the one I have, the USB connector broke off the circuit board, which I saw they had problems with. They since went defunct, but another company is/was selling a replacement board… Maybe should build my own but…

Anyway playing some with the code. Right now have it laying sort of flat on the table as you can see in this mess:

I have the code doing junk when idle of cycle through all servos changing color of LEDS… I added something like this earlier on others, as I would do something (turn off commander which makes robot go limp) forget to turn off the power and kill a Lipo… Right now running off of wall wart.

Wondering what others are doing for power harness. Currently Gerry rigged using Trossen HUB to plug in wall wart, plus cut off battery connector off old dead lipo to adapt.

Sketch updated on github…
One of the things in testing code is showing current positions.

Serial Cmd Line:p<eol>
Servo positions shown by leg joints
(Rear)
    T     F     C |     C     F     T
 -712   177   -16 |    -7  -228   699
 -725   172   -26 |    95  -198   629
 -730   153    -6 |   -12  -221  1061

I am getting a reasonable number of Read fails, so will debug that some more.

xan · May 17, 2020, 9:18am

@cbenson

Yes, perfect

I do have the clips with the magnets. But the ones in the photo are different.

Unfortunately I do not have a 3D printer. It is on my wishlist though. It would be nice if you could add them.

I think I have all cabling needed. The cables in the boxes seem to be long enough and I received some extra long ones. I’ve already ordered some XT60 connectors since it is time to switch away from the Tamiya connectors.

Could you add some plastic offsets to mount the electronics?
Might it be possible to drop in a Teensy 4?

Since we’re all talking about Teensy here, I was thinking of joining the club.
@kurte I saw a lot of nice adaptor boards for the Teensy4.x. Are you using one? Is there a way I can get my hands on one of them?

cbenson · May 21, 2020, 11:49am

@xan

So far in the list for Xan:

1x Teensy 4.0 (RB-PJR-18)
3x SES V2 C-Bracket Pair (RB-LYN-1006)
6x CF Tube Hemi (RB-Lyn-1059)
? Standoffs & Screws

For the last one, can you browse the site to see which you might use?

@kurte

Can the Teensy 4.0 use identical code to the new one?
3x SES V2 C-Bracket Pair (RB-LYN-1006)
6x CF Tube Hemi (RB-Lyn-1059)
… anything else?

xan · May 21, 2020, 1:04pm

@cbenson

I’m talking about the following standoffs. I noticed that you have different lengths in stock. If you could include some different lengths so I can experiment on how to mount the electronics that would be highly appreciated.

Thanks in advance!

kurte · May 21, 2020, 2:28pm

Good morning @cbenson and others,

Sorry, been a bit distracted this week. It is spring time with lots of outside projects. Plus also distracted on finishing up some system code support for the Teensy. Trying to help out there as with the current Covid-19 quarantine they are down to just (Paul J, and Robin C).

T4 and T4.1 are very much compatible with each other. They have the same processor and the like. In fact very close to the same thing as T4 with the FRDM4236. There are differences like additional Pins, built in SDCard instead of pads for it on bottom of T4. USB Host pins have same setup as T3.6, and most of the ethernet setup (minus magjack… ). But in addition to this, there are some additional unpopulated chips SMD pads on bottom of T4.1 which can be 7 IO pins or setup for one or two memory chips. I have one now with 8MB PSRAM and 8MB of Flash memory. I have a second one with 16mb of PSRAM… And the T4.1 comes with 8MB flash where T4 comes with 2MB…

But unless you make use of some of these features. they are totally compatible.

My package of stuff I bought last week arrived yesterday, so over the next few days will replace those brackets. Will play with some of the other pieces as well.

Software wise I have not done much in the last week. Need to get back and figure out the differences in leg design versus the PhantomX V2, to see where some of the calculations need to change (180 degrees versus 135 versus ???) Obviously if someone beats me to it that would be great.

My T4.1 board - had some issues, where the RX, TX pins to servos were swapped. I ordered another version with this fix. After that I figure out the XBee connections was a bit wrong. Easy to jumper around, but I updated the board, and will order a new one of it soon. I will probably again use PCBWay, which is cheap ($5 for 10), plus something like $18DHL and you usually have them back well under a week.

I still have not done anything for the bottom of the feet yet. Will look around here to see if I find anything. I am avoiding going to store (have not been to any since early March).

As for mounting PCBs. I have purchased from Amazon a few of the different kits of standoffs. They are usually pretty cheap. I do find with the Robotis stuff I sort of like their simple offset setup:

Where on some of their systems like the waffle boards, you put nuts in bottom area screw through top slider area, the round part has setup to hold a nut and you screw through board to that nut, and then it adjusts to fit your board,
and hole pattern. I will probably see if I can find some of these… But my board has I believe same hole pattern as yours so should just be able to work with standoffs.

kurte · May 21, 2020, 11:39pm

Quick update: I ordered a new set of the V0.3 of the boards, which I hopefully fixed the XBee issue, plus made the mounting holes bigger as to work better with your standoffs, plus I added two small buttons to the board that can connect to the PGM and ON/OFF signals. Note: these are in the T4.1/T3.6 setup (ON/OFF on 3.6 would be Reset).

Again this board is setup to Hopefully work with most Teensy processors, with some differences in limitations.

That is, I will use a 4.1 maybe with some extras, although also tested some of it initially with T4, mostly with an FRDM extension… A member up on PJRC setup the castellated solder on the bottom extension that makes the T4 into something close to the T3.6 and now the T4.1 setup.

Again details up at:

http://www.trainer4edu.com/edubase_teensy/frdm_4236.html

Which I setup a few. For awhile (not sure if still there) you could order from OSHPark. Which I have done. Can be problematic, and then you still need to extras to get Host USB to work. On the above image, there are two pads that for T4 are setup for POGO pins, to get to the USB connections on T4. The chip to the right of it is to add the power management that keeps the Teensy within USB spec for power usage when user plugs in new device while running… Plus there are a couple solder jumpers to route these in. All of this is not needed for T4.1 or T3.6

Again warning, I am a retired Software Engineer who only dabbles in electronics, so no guarantees of anything.
But I did push up the diptrace design files plus the zip file I uploaded to PCBWay.com to the project:

Anyone is free to play with the design files and/or can also simply upload the zip files to PCBWay.com or OSHPark.com or Seeedstudio… For smaller boards I often use OSHPark, as they are reasonably local but they get relatively expensive for anything larger. Where PCBWay for these size boards is something like $5 for 10 of them plus shipping, which in this case was $18 and they usually ship within a day or two.

bdaouas · May 22, 2020, 2:15pm

Nice to see the Teensy/LSS Adapter V0.3. I like your routing job
Quick question, are the mounting holes connected to the GND pour ? I can see that they are plated and in the picture they don’t seem to be connected. I ask because there are some traces that seem to pass very close to the mounting holes and screw head can wear out the soldermask and mess with the signals. Adding plastic spacers would resolve this, but not sure if they’ll fit, as there are close header pins to the mounting holes.

kurte · May 22, 2020, 5:45pm

Thanks,
As you noted the mounting holes are not connected to anything, sometimes I think they should, but other times not…

I also ordered a set of these:

But for sure there are parts on this I have not tried out yet!

kurte · May 27, 2020, 2:07pm

Quick update,

Both of the recent pictured boards were fabricated and should arrive here I believe Thursday.

My order from Robotshop arrived. So need to take some time and swap in the newer brackets and use the new wire straps…

Software, I have played around some more, with some of the servos to get a better idea of how to use them.
Still need to work on the LegIK stuff as I know much is wrong with it with these leg configurations.

Also may work on using the option to tell servos to go opposite direction (GYRE).

Wondered about being able to tell servos their valid range, but not sure will work the way I would like. That is if a valid range for one servos is something like tibia, maybe hardware ways could go -100 degrees to to 75 degrees, I am not sure there is an easy way to use this as a limit. I guess we could setup a software offset of -125 as a offset such that we could then set a limit of 175. Although I need to experiment more to see does the default of 180 degrees already limit me? Or is that only in other modes?

Again sorry it is taking me awhile, but it is too nice to be inside and lots of stuff that needs to get done!

Hope everyone else is doing well!

kurte · May 29, 2020, 9:06pm

Looks like, I need to order some more short c brackets if I want all of them to be the same.

I goofed and when looking at other short C brackets came as a pair… New ones only 1… So I ordered 3 thinking I was getting 6… (oops)

Need to get back to playing with code

zenta · May 29, 2020, 9:52pm

Sorry for my absence lately @kurte and others. I’ve been busy with lots of things in life. Doing fine though. I hope soon to be able to join in. I’ll be using the T4.0. Probably use your old board at first. What remote are you using kurt, or just testing without? I’ve also bought a PS4 remote if we are going to test this to. I might need to replace my old PC soon still running Win7…

kurte · May 30, 2020, 1:14pm

Good Morning @zenta and all of the others,

I hear you about being busy… This time of year I spend a lot of days doing stuff outside, like gardens, mowing… So less time for working on this.

Glad you are doing fine. We are hanging in there as well and doing our best to stay safe.

Yesterday I received (picked up from our mailbox in town), a package from PCBWay with my updated boards. I may try to assemble one of them soon. Or at least enough of them to see if I have the different bits and pieces working and to see what parts I have in stock and if I need to make an order to Digikey or Mouser.

My current testing, was done with Arbotix Commander (XBee), as I could simply lift all of the code from current code base I was using to play with PhantomX. I am connecting the XBee and Servos through their shield board, where I have 4 TTL level converters built into mine to handle servos and XBee connections.

But once I have some of the things working, like turning it on does not cause the servos to want to turn the legs into a pretzel, then I will then concentrate on probably convert the code to use the USB with Bluetooth and either PS3 or PS4. I will probably start with PS3 as I have several of them that work. My PS4 from testing appears to now have dead battery that won’t charge. Will try new battery again, but had previous one and new battery did not help then.

One of main issues is my Math skills have are so rusty, that they are more or less non-existent anymore… Maybe has something to do of getting to the end of my 0x30s

So would be great if someone did the updates to the IK code (hopefully convert to floating point. My main things these days is more into the low level stuff!

dickel · May 30, 2020, 10:26pm

I’m following this thread for a while… excited with every new reply.
As I’m getting good progress with my mechDOG, I would love to join the hex crew and try my stuff with it (but a version without ROS, only Arduino)… I think I could contribute to this project. What does @cbenson think?

cbenson · June 1, 2020, 11:07am

@dickel You’re of course welcome to participate, and we can look into providing you with a discount on the parts as well.

cbenson · June 9, 2020, 2:30pm

@kurte @xan @zenta You should have each received an order confirmation for parts - please verify the details and indicate if there are any issues ASAP before they ship.

Sorry for the delay and thanks again!

kurte · June 9, 2020, 3:19pm

@cbenson looks good

I was going to also order 3 more of the newer short C brackets as I made the mistake of thinking they came 2 in a package… But that is not at all critical. I was just updating it to be closer to I saw.

Thanks again.

zenta · June 9, 2020, 3:35pm

Thanks. Not sure if made myself unclear, since I have the parts I need… But always appreciated.

If we all go for the same T4.0 board it would be more convenient, since I don’t have the 4.1 kurt made a board for. At the moment I’m thinking of the best way to connect up my T4.0. Also a bit delayed on everything since I’ve just bought a new PC for my workshop.

kurte · June 10, 2020, 11:21pm

Hi @zenta, @cbenson and others,

Today I populated one of my new boards, that I have setup for T4.1, although would work to some extent for most any Teensy, like T3.6 or T4 with our without the FRDM, and probably the T3.2 as well although again some functionality won’t be available.

Right now I have the T4.1 beta board in it, will be swapping in a different one soon. As you can see, I have not populated the speaker part of the circuit, but have populated the connections that are setup to allow an Adafruit ST7735 or ST7789 display to connect in. The one end though does overlap some of the three pin header plus the QWIIC connections for the Wire buss. I did not find my right angle versions of these connectors so used what I had. Also you can see that the display works (This is one of their Small ST7789 displays.

Next up Test the connections for servos, will first ring out the TX pin to make sure that signal come out properly. I don’t want to fry any of the servos as I don’t have spares!. Then test the USB Host connections. That should be no problem as it simply runs the 5 pins from T4.1 to the connector.

I will also for the heck of it check out that some of the QWIIC things work, like maybe their keypad or button.
Anyway a little progress.

kurte · June 11, 2020, 4:46pm

Quick update: I connected up the three servos of one leg and they are talking…
So will solder in the other 4 connectors.

Need to get back to fixing the math of the IK… But probably first may see if the USB connection is working and maybe create a simple PS3 input controller.