Biomimetic Bionic Hand: Build & Control Guide

[00:00:00][Music] [Music] welcome cogs in this video I'll be laying out everything you need to print assemble wire and control your very own nilheim megatronics bionic hand Delta 1.1 if you don't want to build your own I've put a lot of work into these hypnotic blender assembly animations so hopefully that'll be entertaining whether you intend to build your own or not firstly there's a few things that I wanted to mention first and foremost this channel has reached 100,000 subscribers I posted my first video of my fire side in 2014 and since then I've worked on robots sculptures jet engines accordion lasers drones and of course the bionic hand and I hope that I've educated and inspired some of you guys and had some kind of positive impact I want to extend the biggest thank you to everyone who's watched my videos being a part of the community and supported me on patreon second order of business my website has been deteriorating with dead links missing projects and neglect several people have told me that they've struggled to find certain files and parts so I've switched over to a new notion based project archive I fixed all of the links and put everything in an easily accessible database ranked by difficulty and cost so hopefully it's easier than ever for you guys to build my projects at home find that link in my description along with my patreon page and Discord so there's a few things about this project I want to make clear before I get started first of all this project is not complete in truth I don't think it's really possible to complete a project of this scale and undefined scope but I decided that now is the best point in this Project's life to open it up to the wider world so that it can properly flourish there will be mistakes and bits that could be improved secondly this project is difficult I've crammed a lot into some really tight spaces I have mechanisms on top of mechanisms and all of this is buried under A Rat's Nest of cables be sure you know what you're getting yourself into before you embark on this project thirdly I might not be available to answer all of your questions as much as I try and respond to every email and private message sometimes things slip through the net so I would recommend the best place to get advice would be my nilheim megatronics Discord server I've added a bionic hand builder channel for everyone doing this project to share progress ask for help and so on the server is full of wonderful people who are already sharing their knowledge and Innovations so without further Ado let's get onto the hand you'll need to do quite a bit of 3D printing to get the parts ready and while I've experimented quite a bit with printing techniques I'm pretty sure you can print everything on an fdm printer my fingers are in fact resin but there's nothing about their design that I don't think would be achievable on an fdm print printer if you're looking for a recommendation I can recommend the bamboo lab X1 Carbon series which I began to use towards the end of the project after having used lots of different printers over the years to put it simply and keep it brief the quality is awesome the speed is awesome the slicer is awesome and it's especially easy to use currently my design uses two separate printed circuit board designs which I have had assembled by the manufacturer because it saves a ton of time and my soldiering skills are pretty bad if you want to solder them by hand you totally could there are surface mount components on my boards but they're still pretty simple in any case I've uploaded the PCB files and the assembly files which I configured with jlc pcb's system and I'll also include the rest of the files so you can manufacture them however you like there are other components you'll need and all of these can be found on my alha mentioned project archive page with components like the servers power supply Etc take these as a suggestion rather than gospel as a lot of small form factor servers have the exact same dimensions and can easily be swapped out and I know for sure some of you guys have more knowledge of electronics and control than me so now we can begin assembly hopefully this video will be enough of an assembly guide but you may want to keep the cad open on one screen so you can reference it as you build the first thing you'll need to do is to alter your servers to take an external sensor reading and enable them to rotate freely different brands of servers will have different constructions and so the method may be different but if you're using these Corona ds939 mg servers the process is this firstly take off the server casing by removing the screws and popping off the top cap you'll need to remove the final gear and chop off the plastic block which limits its rotation inside the small hole there's some geometry which locks the rotation of the gear to the potentiometer below so you can either use a tiny drill in a pin Vie to make it a round hole or do as I did and simply Force the gear around to break the internal plastic off I would however recommend that you use the drill to reduce friction you'll then need to disconnect the server's potentiometer which is the rotary sensor which allows it to work out its position take note of which wire connects to which part of the circuit board doesn't make a difference to wire the positive and negative terminals the opposite way around other than that it will invert the signal but it is really important you keep the central wire in the center snip the wires and make sure they're as short as possible and out of the way then take a female three pin dupoint connector which is the standard 2.5 mm pitch connector on arduinos and basically every circuit board and sold on one end to the wires you just desoldered making sure you do them the right way around you can now reassemble the servers and you may find you need to snip a small extra slot out of the base to make space for the new cables you'll need to do this 15 times you can then drop in all 15 servers into the front side of the foram you'll notice which way around they're supposed to go because there's a little slot where the wire is supposed to pass through each row of servers is held in by a retaining strip that fits on the back and accepts an M2 screw to make these you'll need to add a pause in your 3D print in G-Code pop in a M2 nuts and resume the print these are designed to slip in behind the servers and snap into place they don't need to be held to rigidly because they're only there to hold the nut in place finish securing the servers by firstly placing the cable housing retaining blocks and passing the screws through this the server the housing and finally the nut held in the retaining strip now put the back half of the forarm frame in place and feed through the servo cables the forarm feet also have a print in place note so using a G-Code Paws drop in two M3 nuts per foot you can put these in place and fix them with a 20 mm screw on each side and then attach the circuit boards with some standoffs of around 15 to 25 mm you may want to do this before putting the whole back panel on although it will be trickier to feed the cables through it's entirely up to you take note of the block which goes at the top of the forearm and will connect to the wrist you don't need it yet but you can put it in place now we need to build the wrist first take the core wrist server housing and pop an mg996r server or similar into the Gap there are two servers in this part of the arm and you'll need to make sure they're both roughly centered so use a server tester or just the basic uo server example sketch to Center them you may need to unscrew the base of the Sero to get into position without bending the wire too much secure it with M3 screws threading directly into the 3D printed material then put the three bearings in position take the front side of the wrist and assemble The tensioning Idler with a triangular piece followed by an M4 Square nut washer M4 plane nut m3x 6 mm screw to keep the wheel in and two m4x 6 mm screws to lock everything in position this is a mechanism you'll want to refer to the Cat build or just rewind a lot of times onto the back side of the wrist you can place the server assembly we built earlier a second server with a printed pulley and retaining m3x 12 mm screw a roughly 210 mm GT2 belt and 4 16 mm M3 screws with nuts to hold it all together also put on the wrist Palm adapters but not before setting your server to its Center position attach the wrist to the forearm using nine M3 nuts in the wrist block and M3 screws of various lengths to connect it all up onto the Palm now this one's pretty straightforward just put five DS 843 mg servers into the hand again you might need to unscrew the base to be able to get the wires through also make sure you've set the servers to their neutral middle position as before secure the servers with m3x 8 mm screws and on each knuckle you need to put a bearing and then you can attach both Sid of the mCP link component these are held together with 4 6 to 8 mm M 1.6 screws threaded straight into the plastic attach the Palm onto the wrist Palm adapters with two long 35 mm M3 screws and nuts on the end now we can move on to the fingers the fingers are actually really simple they good together like this did you get all of that all right maybe I should delve into some specifics the first part I'd recommend you make is the potentiometer boards now I had these assembled by the manufacturer with the jst S connector already on the board but since I couldn't find a supplier for the potentiometers I wanted to use I just solded them myself the company bonds makes this flat pot which I've used for years I do think it might be time to explore other options but the form factor is just so perfect that it's hard tol these just clip into a 3D Plage harzin one type for IP joints and another for mCP joints you you may want to plug in the sir cable now or you may find it less fiddly to do it once it's fully assembled although you will probably need to use tweezers if you're doing it that way you can also prepare your pulleys by feeding some fishing line through and making a knot I've designed them so you use a tiny pin like a Sim tool to poke fely into the hole and then out of the adjacent hole knot it and trim it close you want the knot to be flush with the side face of the pulley I used a lighter to tidy up the freay ends but for safety reasons I can't recommend you do the Sim the mCP pulley Works in much the same way but the cable passes through the PCB also I recommend using much more wire than you think you need to complete the fingers it's just a case of putting each component together in a stack and securing with a central axle rod and snap fit end caps this is going to be one of those parts where it's easier to just look at the card model while you're building I also have been inserting a single core wire and bending it around this keeps the pcbs Align mind but a big Improvement would be to Simply add a registration feature between the PCB housing and the structural parts of the falles and then there would be no need for this wire place your fenge onto the palm and now Begins the most fiddly and painful part of the whole build so now we need to thread the fishing line through all of the pulleys it can be very awkward but after doing it a few times you'll get the hang of it make sure that the cable does one full loop of each pulley and you may need to use something small like a piece of wire tweezer or something else to help you thread the fishing line through you've got to do this for every pulley in the hand so it will get a little bit tedious now you can cut a length of extension spring wire housing to sheath the tendon cables make sure you cut a long enough length to accommodate the wrists full range of motion this can be tricky to get right feed the wire through and into the pulley block holes in pairs then feed your pairs of wires into the pulley I have a specific technique for this feed it through rotate 180° around the Zed AIS and and then 108° around the xais I'd actually recommend doing this twice for two total Loops but it was really hard to animate so you'll just have to visualize it press the pulley onto the server it should be tight but not too tight and pull the cable slack through the hole add the M2 server screw and locking screw but I would recommend again trimming the cable until you're sure that everything's working this extra slack makes it so much easier to work with to finish off with I also have this fancy armor shell it's not really finished yet some parts just attach with adhesive but I've decided to leave this as a treat for my patrons only for now check out my patreon page and consider supporting me if you want access now mechanically speaking the hand is essentially finished on to programming my control system is very bare Burns because I wanted to focus on the mechanical side and not spend too much time with electronics and programming the most important next step in this Project's life right now is to improve the electronics and programming so I'll show you what I did as a reference point or if you just want to get things up and running quickly but I really would recommend you look into a better way to drive the servers my first job was to plug in each joint and find out the limits so for each server you will need to connect the potentiometer wire that you soldered earlier to connector on the switchboard you need to find the finger potentiometer that the server corresponds to and connect its potentiometer cable to the same switchboard number for that server I would then plug it into a port on a PCA 9685 server driver board and use a very simple Arduino program to oscillate between two positions and gradually increase this range to find the limits I'd also take note of which direction was flexion and which direction was extension I then wrote everything down in this big chart so I know how everything is wired I found it helpful to drive all of the previously wired servers at once so I knew that they were behaving correctly when working together with other servers to drive everything I used a Unity program which uses either a Leap Motion controller or a simple combination of Sliders and it connects using a PID extension called udina there's some corresponding code that you need to upload to the Arduino but you should just be able to connect with the Arduino validate that uino has connected and start control in the hand depending on which control method you're using you'll need to update either the mapping functions in the joint angle getter script for leap motion or the ranges in the poser slider script I also added a feature recently where you can move to predefined poses using this poser slider you can also put this on the timer and cycle through them to animate the hand so that's just about the limit of all the knowledge I can impart about this project right now I really hope this can get more people on board and started with this project because I really believe that as a community we can work together to make this a truly awesome project a big thank you once again to all of my patrons and I'll see you guys in my next video I'm