Lynxmotion SES V2 Hexapod Robot

Lynxmotion Legged Robots
, , , , , ,
59

Hi @kurte

Unfortunately and as you already guessed, no. The Tx/Rx pins coming from an Arduino 3.3V Boards with the LSS Adapter connected as a shield are not level-shifted to 5V. With the switch in ā€œArduinoā€ position, the LSS Adapter acts only as a pass-through and it provides a direct connection from the Arduino Tx/Rx pins to the LSS Rx/Tx.
As you said, the only option to use 3.3V boards with the LSS Adapter is to go through the XBee headers with the switch in ā€œXBeeā€ position. Basically, a Teensy carrier board with XBee form factor would work but didnā€™t find any when I looked online.

60

Thanks, that is what I figured.

For the heck of it, I just hacked up one of my own test board designs to hopefully add two of these servo connectors. Note still have bioloid ones as wellā€¦ There are probably going to be issues with it, but I sort of built in two level shifters like the Sparkfun board bss138ā€¦ Ordered a set of 3 from OSHParkā€¦ Here is a 3d rendering from diptrace. This can in theory be used by most Teensy, although some features wonā€™t work with smaller versions like T3.2ā€¦ With T4, I have a similar board with T4 in it using a castellated add on board that a PJRC forum member set up to make the T4 to have the same form factor as a T3.6(5), (although not same USBā€¦). But hopefully should be pretty close for when PJRC releases a T4.1

T4-36-Lynxmotion-servos
T4-36-Lynxmotion-servos1216Ɨ798 89.4 KB

But just doing this for my own fun!

2 Likes
61

Sorry for my very late response. Personally I prefer the Teensyā€™s. But Iā€™m willing to try out RPi too, most for learning. I might be able to contribute more on the Teensy side though. Some years ago I started playing with my own gait algorithm/engine that might be easier to use on this hexapod using a Teensy to start with.

62

Time is certainly my biggest issue here. Iā€™ve told my wife I probably need to spend some hours in my workshop now and thenā€¦
She is pretty occupied her self working full time and studying for a degree of master. So I need to do a lot of household stuff.
I do have some parts already though, but itā€™s probably easier if we all go for the same configuration. I do like the look of your V2 brackets :+1:.
Iā€™ve several 3S LiPoā€™s of different sizes, also similar to the one Kurt have, also Deans T-plug. Making a XT-60 to Deans T adapter isnā€™t hard though (or just buy one).
When it comes to electronics, @kurte boards are always interesting, so I might join in and order one myself one time. Iā€™ve several T4.0ā€™s and a 3.6 + 3.5. The next question is how to operate them. Personally I prefer custom made remotes with 3-axis gimbals (XBee radio).

1 Like
63

We do have plenty of those. Maybe @cbenson can include one in the kits?

64

Oh! :slight_smile:
@dialfonzo

65

@kurte Weā€™re about a week away before we can ship the robots / parts, and we only have the Teensy 4.0 in stock (which seems noticeably better than the 3.X). We have the option to create and test prototypes internally - would you be interested in designing a board which might end up in production? In the meantime, not sure if @cmackenzie @xan @zenta have the Teensy you designed for. Open to ideas.

66

I have a Teensy 4 here already. :slight_smile:

1 Like
67

Sounds good!

68

I am always happy to share things like designsā€¦
I did put up the current WIP board I did a quick and dirty update to hopefully support these servosā€¦ Still supports Dynamixels as well. Received notification today from OSHPark that the board was shipped off to manufacturing. I also pushed up the Design files to my set of boards on github:

Again has things on it that ones may not need and may not have other things. Example has connections setup that I can plug directly in an Adafruit ST7735 or ST7789 display .

And temporarily we can simply adapt a T4 to your board through the XBee connector. Many options here. Could do a real simple version which is simply brings out an Arduino Shield connector layout and add in level converter for those pins that talk to your shield to convert 3.3v to 5v.

1 Like
69

@zenta - It would be great to try out your new walking gaits and the like, it sounded very interesting and if I remember correctly it would maybe be better for things like terrain adaptation. I believe it was converted over to use floating point math, which would work well with the T4 ad as well later with RPI.

As for controller devices, I see lots of possibilities. The Arduino Phoenix code up in (https://github.com/KurtE/Arduino_Phoenix_Parts)
was originally setup to be very similar to @xan BAP Phoenix code, where there is a simple interface that allows different Input devices to be used.

A few thoughts/possibilities here for using something like T4 or T3.6 and/or RPIā€¦

a) XBee communications - Like the remote control mentioned. I have some version of that sitting around, but as one with 10 left thumbs I never could things move the way you can :wink: So I often simply used the Trossen Robotics Input commander:
https://www.trossenrobotics.com/p/arbotix-commander-gamepad-v2.aspx
Which is nothing special, It has two thumb joysticks and 8 buttons. For many years this is what I mostly used.

b) Simple RC remote - I purchased one of the Flysky, where I had a simple receiver which I believe I could decode with one IO pinā€¦


I know that on Trossen @jwatte was using one or at least trying one. This gives you more range and less interference for those who wish to do things like Mechwar and not have issues of multiple robotsā€¦

d) USB controlled devices. The T3.6 and now T4 have a second USB port, where we have code to allow the Teensy to host some different USB devices like keyboards, mice, Serial Adapters, and Joysticks. I also added some support for Bluetooth devices. Some of the rudimentary support for this is in the current Teensyduino builds and some additional stuff is still in my own github branchā€¦ I need to get back to this, but got distracted when T4 was in beta now other distractions. But with this, we have tested out and I know other are using the support for things like:
PS3 controller, PS4 controller, XBox 360 with PC wireless Adapter, PS3 Move controller, PS3 navigation controllerā€¦

The parts of the BT support that has not been fully completed and tested fully included better support to work with multiple Bluetooth devices, like two PS3 controllers, like both a PS3 Move and PS3 navigation. It has been awhile since I looked at this, but I think the basics are there.

So earlier I was playing around with PS3 or 4 for controlling robots. And for many of us I think this would be a good starting choice. With the first Hexapod ROS stack (KevinOchs) that is what we were using. But again with ROS he was mainly interested in doing the ROS stuff and not as much about fine control of Hexapod.

d1) Side note: Robotis with their systems uses a real basic controller:


I would NOT recommend it. It has no logical joysticks, just something like 8-10 buttons. This is what they ship with TB3ā€¦ It connects through Bluetooth. Note: Their Bluetooth setup is through a BT to serial adapter, which we could do as well, butā€¦

Note: If we go with USB, I need to make sure whatever board I/We use supports USB for T4. My current one in fabrication I did not add the extra parts for T4 USB. It will support it on T3.6 and the T4.1 when it is released. The differences with T4 and T3.6 on USB, there is a 5 pin connector that is setup that you can simply use a some remote PC USB connector wires to use. It also has built in USB power limiting chip and two CAPS on the T3.6. The T4 does not, there are simply 2 pins that are often connected by POGO pins or the like and does not have the power chip/caps. Can work without those, but may be issue if you hot plug in deviceā€¦ Some of my other boards have it, but I removed those to make room for the Servo connectorsā€¦

Thoughts?

70

I like that you guys are talking about controllers. I was thinking I needed one for the biped soon enough as well and whatever you come up with I would like to adapt into the ROS2 ecosystem as well. ROS already has normal usb joystick integration. I was considering using an ESP8266 on Arduino platform which has built-in Wifi and add OLED, some buttons and joys. Would be pretty easy to code. Iā€™d go with the newer ESP32 but I have a few and the Wifi network response is 10x slower! Probably a firmware issue but thatā€™s where it stands ATM.

71

A controller which either Lynxmotion produces, or one which is readily available might be best from a corporate standpoint. Even a remote like the PS2 is (effectively) discontinued, and we have gone through many PS2 variations, each requiring tweaks, testing and troubleshooting. Sourcing has also lead to issues. A smart phone is very versatile, but maintaining an APP on Android will require quite a bit of maintenance (and is Bluetooth or WiFi control ideal?). RC remotes have never gone out of style. USB input can be interesting, though ideally a non-tethered approach.

72

Please Note: This is not a ā€œreplyā€ but some food for thought regarding moving away from a PS2 Controller environment. My comments here are added as a suggestion from Coleman at RobotShop and is my response to his update on PS2 Controllers. For context, it is an unedited excerpt from my reply to Coleman regarding this subject:

Here is some food for thought:

I own 8 Bots which are controlled via Apps by my Android Phone. 2 of these Bots no longer function as the company that manufactured the Bots no longer supports their Apps for updates to newer Android OS versions.

Besides this, Not one App allows for solid reliable control of Bot Functions and are ā€œsloppyā€ in control to say the least and suffer from time lag as well. This is the same for Bluetooth and WiFi enabled Bots even with very strong signal present. On a couple Apps any swipe near the screen edge (where many of the controls are) automatically closes the App and this is frustrating to say the least.

I fully understand the manufacturing ā€œcontrolā€ advantages of using an App vs. a physical controller but caution that you at least consider a dual path until all the bugs are worked out.

The Phoenix PS2 control interface has at least 14 buttons and 2 joysticks which would be a challenge to replicate functionally on a touchscreen UI.

The fact that PS2 is old is a clear advantage in price and lack of license cost (either low or ignored by the supplier). Before you abandon these take a look at just how many New PS2 controllers can be found on EBay.

As you know, we seldom see IFU manuals with Bots anymore to save costs. A few years ago there was a movement to move away from hand controllers to Apps specifically to reduce manufacturing costs. Even my Mavic Pro Drone provides a joystick controller but relies on the user having a smartphone for video image display and dashboard information.

The inexpensive Bots using App controls have products which a physical controller is a significant portion of the total product acquisition cost (I estimate this to be a minimum of 20% for a physical control interface). For your high-quality hexapod kits a $24 physical interface control is a fraction of the Botā€™s total cost. In my case less than 3% of the total build.

If you read reviews of App controlled bots (the thoughtful intelligent ones) you will see that few, if any, are satisfied with the App Controlled UI and I will remind you that these are from the perspective of mostly ā€œtoyā€ bots costing <$200. I also own an Alpha 1s and I would much rather have a physical controller than the crappy App it comes with.

Lastly, I spent over 20 years in marketing of hi-tech electronic and medical products. I would strongly suggest that before too much time and money is spent on App development and the severing of a PS2 (or any physical controller) product supply source, you can use your customer base and Forum to do market research and identify the Must Have Features any user would want and customer preferences. You could pose a simple question, ā€œWould you rather have a PS2 or App UI? And a space for commentsā€¦ Itā€™s amazing what you may learn. You could even select a committee of your most active and vocal customers, product developers and supporters directly or via your Forum. Make sure that you have a balance of Pro and Con regarding UI types and a good representation of customer types (include educational type and commercial types if you can).

Here is one last thought. Do you ever see Battle-Bot tournaments using Apps for controllers? You need to ask the participants why this is then listen (donā€™t speak, just listen).

Okay, thatā€™s my 2-cents on this subject and in the least I hope I may have expanded the scope of the conversation a bit (no pun intended). I do not have the robotic cred of the names I see on this thread but do have many years or RC (land and air) build and control experience coupled with product development participation in hi-tech electronics and medical devices.

Best Regards to All, this Forum has been a great help in my Phoenix Hexapod project!
Tobar8th (Bill)

2 Likes
73

@cbenson
Yes I punted a long time ago with PS2 controllers. They were too problematic!

Joysticks (ROS) - It has been awhile since I played it on ROS (http://wiki.ros.org/joy) , but there is/was a node you could install that can translate the Joystick axis/buttons from one joystick to another. For example I believe with the ROS Hexapod he set his up with PS3. Some of us used PS4, so we setup table for translating PS4 inputs into PS3 like valuesā€¦ (http://wiki.ros.org/joystick_remapper)

Joysticks with Teensy4/3.6 - Our first pass through was doing this with plugging the joysticks into the USB host adapter.
i.e tethered. Although did have wireless adapter for one of the XBox controllers. Some of the details are up in the thread:
https://forum.pjrc.com/threads/49099-T3-6-USB-Host-Joysticks

Later with the Bluetooth support, we have wireless support by plugging in a cheap USB BT adapter. More details are up in the thread:
https://forum.pjrc.com/threads/49358-T3-6-USB-Host-Bluetooth

As you mentioned at some point it might be great to have Android and/or IOS supported Apps, that talk through bluetooth, but that is maybe beyond my pay grade :smiley:

74

@Tobar8th (bill) Indeed, and welcome to the discussion! Appreciate the insights.

1 Like
75

@toobar8th I agree. Control apps havent been the best and it would be significant effort to code and keep up to date. Even with a good app you have to look at it since there is no haptic feedback. Nothing like some real buttons and joys there. It wouldnt surprise me if there is some IoT app out there already that a user could add buttons, controls and KPIs that could control the high-level stuff and accompany a hand controller.

1 Like
76

cmackenzie I appreciate your input and viewpoint. Iā€™m sure that from a advanced robotic development perspective the RC Controller advocates have valid technical points. However, from a specific product-kit standpoint (not R&D or development) you canā€™t beat the ergonomics of the PS2 Controller which SONY most likely spent millions on R&D and testing to get right (note that there is little change over time in the form, fit and function during their evolution) and we can ride their ā€œcoat tailsā€ for next to nothing. I would guarantee that there is no other RF Controller out there with even a tenth of the resource investment that SONY has made in their controllers. They have already done the heavy lifting for us and Bill Porter did us all a great service in decoding the PS2.

Earlier in this conversation there is a $30 RF ā€œbat-wingā€ controller identified with a link. It accepts different Tx modules for your choice of transmission type (which is cool and could then be used with multiple projects using RF, IR or Bluetooth). This could be a good compromise but it is difficult to replace 14+ buttons with 2 Joysticks for complex control functionality in such a compact ergonomic form. I believe that this $30 controller only has 10 buttons BUT there were over 1,000 button functionality combinations (if I understood correctly) which, I gather, means that you would need to also commit more paired button functions to memory than you do now with your PS2 . Change is always uncomfortable.

77

And then thereā€™s stuff like RB-Dfr-223:

image
image1350Ɨ1350 207 KB

image
I feel that controller (or something like it) may be a good middle ground. It has all the buttons, joysticks and ergonomics of a PS2 style controller with the smarts of a programmable microcontroller board (Arduino) with a replaceable Bee-socket compatible wireless module.
Iā€™m not saying it is the best solution, but it seems like a fair contender to me:
image

78

It is often needed the most when it is most uncomfortableā€¦ :smiley: