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Anyone building a robot dog? I am looking for Servo's to build one that will work with ARC...
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Just be aware...these are 1/5th scale servos...so they are not the same size as a standard servo...must bigger.
Here's a picture of the $350 servo I'm using now. (It's no longer available)
http://www.hobbyclub.com/index.php?main_page=index&cPath=24_225
The servos from my hexapod and the drink droid: 60 Kg/cm servo from Ali Express
I'm pretty sure this servo is not strong enough to lift the bubble section...maybe two working in tandem?
i have a dog on the drawing board...you’ve never seen anything like this before. I am experimenting with the CANBUS 3 phase motors. They are pricey but even with these Motors and controllers ($400 per axis) your looking at about $5000 for the project.. well below $70,000 and even some of the smaller dogs that are about $30,000 from other manufactures.
https://www.desmos.com/calculator/rpnk0wnpvj?lang=de
[/u]
Edit..some places it says $3250 and others says $6000 to $7000 lol never a good sign!
Maybe assembled vs unassembled...?????
Watching that Cheetah vid was interesting. Ont thing I have never seen in a walker happens at 2:26 when the knee joints invert and the robot swaps orientation from front to back. Seems so easy to get out of a situation rather than walking backwards until you are clear. That was cool.
Those motor servos are amazing there is even a couple of bipeds being developed based on them.
Be nice if ARC had a driver for them :).
This is a great time to be interested in Robotics.
We can control these motors with a little third party help. They run on CANBUS, which is the system built into your car electronic system. The motors are 3 phase and they use Field Oriented Control (FOC). This creates a sequence for the coils in the motor they kinda fire off in sequence to get the shaft to turn. Because there is no gearing only electromagnetism holding a position there is compliancy in the shaft..that means it has a little bit of spring..like a shock absorber and keeps from tearing apart something like a dog that impacts with such force on the ground.
You can control these motors using many control boards available like the Flipskys that I used on the hoverboard hack on my channel. Those are similar to the robot dog motors. These controllers allow you to connect to the EZB or IOTINY or anything ARC supports using serial or you can use standard PWM like a standard servo control. Without an encoder they are only good for rotational movement, but with a hall effects encoder you can control positional. Then you have a massively strong servo to build a robot with.
$300 for motor $100 per flipsky or other FOC controller , so about $400 per DOF.
Here is an example with a very cheap ($20) FOC controller and an Ardurino with a sketch controller....this acts as positional motor/servo.
EDIT: Seems this board is no longer available..and limited by the Atmel onboard.
That is a nice Christmas present!!
MIC-01A $6500
The MIC-01A has stronger motors and can last 1.5 hours, has the ability to add a realsense D435 (not included) and a Jetson NANO TX2 (not included).
Neither the D435 or Jetson Nano are supported today by ARC.
There is a sample? for the MIC-01A for $4545 US but actual $6596 CAD (Robot+ Transaction Fee + Credit card Fee) +13% Tax =$7453 CAD
https://www.alibaba.com/product-detail/Medium-Electric-Driven-Robot-Dog-Based_62491310900.html?spm=a2700.galleryofferlist.normal_offer.d_title.12e06784Vbvz5z
MIC-01B $3250
The MIC-01B has smaller motors so can handle less payload and walks slower, It runs linux and MIT opensource software but it does have an intel ATOM PC but not sure how much RAM. I guess you can hack it and add your own sensors and get it to work with ARC but that is a lot of money to drop down if it doesn't work.
The MIC-01B for $3250 US but actual is $4872 CAD (Robot+ Transaction Fee + Credit card Fee) +13% tax = $5505. (Ontario sales tax).
https://www.alibaba.com/product-detail/Medium-Electric-Driven-Robot-Dog-Based_1600144281544.html?spm=a2700.galleryofferlist.normal_offer.d_title.e8646784EXWv1u
Takes 3 weeks for delivery.
@DJ you only pay 5% sales tax :-)
If anyone buys one please post
Messaged seller and got this response. Looks like they are building a new range.
You need to be very careful with internet shopping. I ordered a German shepherd and now this man is living with us.:
If you watch his November update video and follow along with his blog you can see his journey, he developed his own motor driver controller board and motors as well.
Josh is amazing and has really come a long way and is an excellent engineer and developer.
Dog,Spot
The moteus r4.5 controller looks good and seems to be easy to setup...this clip above is just some nice explanatory stuff on FOC!!
Looks like there is more stuff on the way... 2021 will be full of surprises I guess!!
Bu this board is limited to 24v max
So to get FOC motors to work like a servo and with skills in ARC, it would be nice to have a controller that can control precision position not just velocity. I found a card called the NearZero. Its home brew but open source. They don't have any cards available at the moment..as they are moving onto ver 2. Only draw back with current board is a fairly low max current at 3 amps per channel (2 ch per board). I've shot off an email to see what the specs are on V2 (due in Feb).
Start at 11:30
This is another one to check...
@all I ordered two of those Simple FOVs now, and will compare them to my ODrive...it seems like the Simple FOV is designed with small BLDCs in mind, but that would no worry me too much! Could be nice for anything not needing a massive amount of torque!!
post #30
https://mjbots.com/products/moteus-r4-5-developer-kit
I'm playing with dev kit and so far is working out of the box on Linux and Raspberry PI, the overall design is very good, the controller interface is CAN FD, single motor and the pcb has an absolute magnetic encoder so the idea is to pair a controller with a magnet attached to a BLDC motor.
The dev kit has everything included to start: 24v Power supply, USB-CANFD, Controller attached to BLDC motor.
The solution allows to control a BLDC motor like a 360 multi turn servo, plus all the other stuff: torque, velocity.
I'll create a plugin to interact with controller.
Thank you for introducing it to me, did you manage to test it ?
This is just a POC to show how a BLDC motor on closed loop can be controlled with ARC, the firmware basically sends all servo input from ARC straight the M0 on the Odrive, it is more or less just a starting point and meant to be developed further!
I thought it might come in handy...
https://github.com/SwannSchilling/ODrive-for-ARC/blob/main/ODriveArcArduinoTest.ino
Nice!
You can use the AS5047P absolute encoder:
https://www.digikey.com/en/products/detail/ams/AS5047P-TS_EK_AB/5452344
with odrive.
https://docs.odriverobotics.com/encoders
Using an evaluation board simplifies the integration.
The AS5047P is also used by the moteus controller.
Great job on the ODrive set up....you should make a video on your set up!
The dev kit worked fine in ubuntu but I couldn't get it to work properly in windows, I posted in the discord. I saw above you are looking at making a plugin NICE that would be very helpful (You are amazing).
@Mickey666
Nice work and demo on the Odrive working with Arduino and ARC. Very cool.
The reason I went for the Moteus was he had made the opensource dog and I figured that would be the easiest way to get one working with ARC ( I still am not able to buy a dog, so only choice is build at this stage unless someone wants to give me 75K for Boston Dynamics Spot) . I like the nearzero idea as it uses standard PWM or I2C so it should just work out of the box with ARC.
All options have pros and cons!
I went for the Cycloidal because of the low/zero backlash, but it is taking some effort and money to build with all those bearings and other parts!
Planetary Gearboxes on the other hand can be easy to print, but they might have some backlash and I don't know how good those teeth will hold up, when exposed to a lot of torque.
The choice of the right gearbox is as important as the motor/driver solution, it might be strongly dependent on the scenario of your application!
If there is a cheap option available that is assembled and ready to use, please share!!
The Moteus is a very good find, I am more than tempted to give it a try.
Both the Moteus and the ODrive have pros and cons...
The Moteus is very specific for being used on a robotic joint and to be used straight out of the box...eg encoder is on board!
The Odrive has a bigger form factor, but lets you choose the encoder and is more a general purpose dev board!
Odrive setup for ARC is pretty straight forward, I dont own a Moteus (yet?)...so lets see where this takes us!!
This guy has a very easy to understand series on YouTube and shows different use cases and set up for open and closed loop examples... yup you guessed it with HIS version of a controller he developed...its got two channels for $45USD but again limited by max current (about 6 amps with 30A short bursts). Also has a built in Arduino. So definitely depends on the size of the project you are building. Watch his whole series..!!! Good info.
Mickey666Maus#3529
Btw I posted a video of exactly that guy #45
It is more or less the same like the SimpleFOCShield, both are using the L6234 IC and just come in slightly different form factors!
The SimpleFOCShield is, as its name says, a shield to be used on an Arduino or compatible board...
Random Access Projects is having the it all on one board which might be nice since it is more compact!
So again, its the same choice, one is more a def board since it allows Arduino, STM32, ESP32 and Teensy boards to be setup.
The other has a pretty nice overall package but you are set to what it is...
It might boil down to your application or maybe hardware preferences!
Btw, if you are interested in driving bigger BLDC motors with the SimpleFOClibrary, it is also quiet possible...
I def interested trying out the Near Zero2 when it comes out.
Both seem to offer very good documentation so its pretty easy to figure out what to send to those registers if you want to write up some code!
Both seem to have a vivid Discord community, so these are pretty good options!
The other boards are very tempting because they offer a low cost option where you don't need a ton of torque, but some of those advanced control options and high speed might come in handy!!
Super interesting, I am happy this is still hot gossip!!
http://www.thecatalystis.com/gears/
Plus the plugin for Fusion 360
https://apps.autodesk.com/FUSION/en/Detail/Index?id=9029586664984391977&appLang=en&os=Win64
https://www.thingiverse.com/thing:4604783
I think the best way would be to have some form of sensor platform and you can mount on the sensors required for the use case you need.
Back to the FOC here is a good MATLAB on how FOC works with BLDC and PMSM motors. (You can go back to episode 1 to 3 for BLDC PMSM differences, PWM, Brushed motors etc)
Good find!!
https://synthiam.com/Community/Robots/BLDC-Control-ODrive-for-ARC-20199
https://tinymovr.com/collections/all
I am working on a joint for the use with those Tarot 4108 BLDCs, got it working and will post once I can tell more about the progress...
https://apps.autodesk.com/en/Publisher/PublisherHomepage?ID=HNK2PN6ZY74X
I mean we are in the robotics department and not up to be driving a remote controlled car, right?
But I guess @ptp will know...I am really bad with this kind of hardware evaluation stuff!!
Btw...I just finished the assembly video of my gearbox, and will put all the files up somewhere, just in case anyone wants to follow along!!
https://www.prusaprinters.org/prints/53681-cycloidal-drive-3d-printed-gearbox-401
I thought I'd add what I've learned researching these BLDC FOC motors and controllers.
___________________________________________________________________________________________________________
1) Most of the BLDC FOC motors we are talking about, are built for drones. Their main purpose is to spin props at high speeds.
2) The controllers we've talked about here, are to convert these motors into low velocity and closed-loop positional motors so we can use them like servos.
3) These motors are rated in KV. KV refers to the constant velocity of a motor. It is measured by the number of revolutions per minute (rpm) that a motor turns when 1V (one volt) is applied with no load attached to that motor.
4) Torque is determined by the number of windings on the armature and the strength of the magnets. A low Kv motor has more windings of thinner wire. It will carry more volts at fewer amps, producing higher torque. A high Kv motor has fewer windings of thicker wire that carry more amps at fewer volts.
5) We will most likely be using these motors as actuators, so look at a lower KV value (100 KV or below). This will give more torque to move heavy objects/robot parts. If you go with a gearbox, you can pick a higher KV rating, which has a smaller physical size compared to the larger lower KV motors and can often deliver more torque. But you gain backlash and noise in the gearboxes.
6) Cogging. This is something to avoid and is due to fewer poles and magnets in a motor. The result is chunky moves at low speeds and the inability to makes small incremental degree movements. But, some developers are writing software for controllers to avoid cogging on these lower pole motors! A fascinating workaround.
Anyways hopefully this is helpful.
There will also be a mount for the AS5047P-TS_EK_AB...
Everything is looking good. I look forward to seeing all axis work together. Is there much noise when they work together?
I will try and make a torque, speed and precision test asap!!
But today I was having to deal with a clogged nozzle, you know the drill!!
Man am I happy, I did not lose some screws on the way...
Just had to throw this one in here...its so well filmed, sometimes you'd almost think it is CGI!!
Maybe we should just short GameStop. You go first.
If your project is large like a dog..make sure you pay attention to the voltage requirements for that motor because you will get better performance with max volts. As an example...drone motors are using standard hobby lipo batteries..but depending on the size of the motor voltage can go way up. Try to match the battery for your motors.
Standard lipo battery voltage for drone motors:
3S is 11V
6S is 22V
12S is 44.4 V
14S is 48V
How long your robot runs will depend on how many amps you can feed it. Remember If you have a 1 amp/hour battery (1000mil/amps) you can run a 1 amp motor (no load) for about an hour. If you put that motor under load and it pulls 2 amps, the battery would only last for 1/2 hour and so on. On a dog if you had 12 motors, pulling 1 amp at idle, that's 12 amps/hr. So if you had a 12 amp/hr battery you could run it for an hour. But we know the dog will be jumping running and the current draw will be different every time you take it out. Just get the max Amp battery you can afford...they get pricey the larger you go!
You can also get 2 batteries and combine them in parallel or in series for more volts/or more amps whichever you need.
Here's a 10amp 24 to 12 one: https://www.daygreen.com/collections/24v-to-12v-13-8v/products/24v-to-12v-10a-120w-dc-dc-step-down-converter-voltage-regulator
And 30 amp: https://www.daygreen.com/collections/24v-to-12v-13-8v/products/24v-to-13-8v-30a-414w-dc-dc-step-down-converter-voltage-regulator-1
You can now change the ratio of my gearbox on the fly...
https://build-its-inprogress.blogspot.com/2016/01/motor-characterization-for-small.html
I have been looking at the API and the ROS integration with Spot and I think a ARC plugin could be written fairly easily to provide some basic functionality. Also SPOT has a sensor platform where you can add OEM sensors (Lidar, Robot Arms etc) so ARC would provide a lot of value.
So who has $75,000.
Adding a few more bearings and now also a second encoder per joint...
I need to do a testing rig, but it is looking pretty good so far!
These guys managed to get very precise with their Cyclodials...
Its just a bit pricey for prototyping that's all!
http://www.dizzy.ai/
The controller is only 35$ and it looks pretty amazing...with the encoder build in an hollow shaft being supported by design!!
I am following the guy on YouTube but never realized, he is also selling products!!
Great...this could help to reduce the per joint cost! Quads are getting exponentially expensive...just way to much joints!!
Edit: Also looks like he is sold out of everything....and not been any for awhile...he has posted everything open source so you can build your own board....sigh
I would not mind to get those PCBs made somewhere, I mean you'd need a few anyways. So the price might be OK?
But if there are any issues, there is no one to give a helping hand and you'd be there by yourself...
So I guess, unless there is someone with enough knowledge popping into this adventure, it would be not the very best option!
But man, the ODrive and the Moteus will cost a lot of money if you are going to build a quad!
For a 4DOF arm it is fine, but a quad will be much much more!!
https://twitter.com/HomeiMiyashita/status/1335856042509365250
Unitree A1 vs Spot
what amazes me is you can buy a cheap TOF laser sensor for $10 so putting 1 on each leg isn’t exactly going to break the budget of a $10K dog.
Spot comes standard with five stereo cameras with global shutter, greyscale image sensors embedded into the body two on the front, one on each side, and one on the back. So is 5 "realsense" depth cameras.
I'm guessing the Spot's front maps a wide area with much more detail (2 depth sensors).
Spot can climb down using a single 3d sensor so I believe the difference is their software and expertise.
You can cut corners and costs but in the end the software is the key.
Keep us updated on your progress!
I guess for a quad you will end up with a belt and pulley plus gearbox combo...at least that's what Josh is using for his dog!
I really like those planetary reducers he is machining!
The motors I ordered are for a gripper, lets see if I can get it to work too!
They have a website here.
https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware/blob/master/mechanics/actuator_module_v1/README.md#brushless-actuator-module-v1
Here is their main page
https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware
I guess the robot arm would need 3 of these actuators, the base if mounted horizontally won’t have a lot of vertical torque so could base just use an ungeared BLDC? The wrist and gripper will only have to lift the weight of the load so I guess I could use common hobby servos.
I have decided to base my robot on the TJBOTS quad build as there is a strong community and lots of support, although the price for parts is steep, especially if you use Josh expensive motors. My logic was to use the supported JSON to communicate with the quad so I don’t have to fork the base design and use a payload adding an SBC to handle all the sensors, additional actuators as well as command and control with ARC.
I will need to make a robot arm and gripper for it, but I don’t think the dog can carry a heavy load so what ever I do needs to be light weight and easy to attach / remove. Hopefully I can use USBCANBUS to drive the robot arm with the added SBC and ARC
I am about to finish the design for my end actuator...it will be driven by 3 small Gimbal BLDCs, hope I can get it all to work soon!
Will throw it to the printer now!!
But my setup is meant to be for a stationary robot arm and not for a quad! I guess for a quad you would have to go for a combo of planetary and belt or cyclodial and belt! Paul has done some nice Capstan Timing Belts lately!
This one looks great btw...but I dont know if I can do the math to get it right!!
If you read down in the description there is an expired patent on a similar design with only three points like a planetary alignment.
[url=https://patents.google.com/patent/US5954611]https://patents.google.com/patent/US5954611
https://tinymovr.com/
https://github.com/cajt/list_of_robot_electronics
Could be fun though!!
Just had to put this here...its too sweet!!
I really want to get into 3D printing and probably pop for a nicer one I'd have to put together for the reasons Perry_S mentioned. However fear of constant maintenance, adjustments and the learning curve scares me.
First print
Don't get scared by the learning curve. Once you started printing, you will get hooked anyways... and maintenance is really marginal!!
https://www.blackmagicdesign.com/de/products/davinciresolve/
@Nink OMG that fresh printbed makes me instantly fall in love!!!
Thanks!!!!!!!!
The rest of the gearbox is PLA, Bearings added to fix some of the original design wear zones. The worm support is really bad out of the box.
We all know resin printing from the awesome miniatures with incredible high detail. They were $2000 one Christmas and $220 the next. They were almost all made for the miniatures markets. Some time has passed and there is a growing movement to develop higher strength resins and processes. You are completely right about the brittleness in parts printed with regular resin. Mine are too, compounded by the fact I am usually printing thin parts at the time. But these thick heave parts printed non-hollow have held up well. I am noticing they do not have the same lubricity from the material I get with PLA gears so we will see how this new resin will perform. It is a ceramic no-fire resin with high surface hardness which I believe will help with galling and a much higher modulus of elasticity which will yield a better stress/strain profile. As I said, all words until I run it rough for a while.
Resins are coming along. Here's an example
I'm so slow some time
Reading https://www.3dhubs.com/knowledge-base/sla-3d-printing-materials-compared/#standard
Man I can can make flexible tires!
I got a Mars Pro for Christmas. Really happy with it and a lot of online support.
Yes FX Artist. You got it!
I just repaired my damaged BLDC, so I thought the clip fits perfect into the thread...
Its amazing how simple and elegant the whole concept of BLDCs is!!
Anyways, You did an awesome job rewinding it.
Here's a pic from my day job, installing a 2.1MW BLDC used as a generator on a wind turbine. The team I work on did the design and prototype testing.
Edit: I missed you were using a blend.....these suggestions are for PC by itself. Not used a blend..what is the other component?
https://shop.prusa3d.com/en/prusament/1258-prusament-pc-blend-natural-1kg.html
Here are some good ideas for enclosures...they will help to prevent the crazy warping of your prints!
https://www.amazon.com/Creality-Enclosure-Temperature-Soundproof-Dustproof/dp/B0852TT63F/ref=sr_1_5?crid=192PLBHEPZPI0&dchild=1&keywords=3d+printer+enclosure&qid=1615326083&sprefix=3d+printer+%2Caps%2C241&sr=8-5
But both Moteus and ODrive are top choice boards!!
The poor mans robot dog!
Link Here
https://shop.m5stack.com/products/odrive-13-2-module-drv8301dca
I thought I'll bring the thread back to life with some progress I made on my actuator...