Servo layouts in the V1 DexHand - open,

Описание: 19 servos drive the #V1 #DexHand.

The fingers are moved in pitch and yaw at the knuckle by the pairs of servos located in each palm section.

The long tendons of the fingers can be connected to any of the forearm servos. Here they are connected to the four distal servos nearest the wrist.

The thumb is driven by the other four micro servos in the forearm nestled in with the wrist pitch and yaw servos.

The Dexhand is part of the Open Humanoid Robot Project - an #open #alternative to the commercial #humanoid #robots being developed by tech giants like #Tesla #Optimus

If you’ve always dreamt of having your own humanoid robot that dream is within reach and uses only 20k USD of components.

We are now looking for participants in the production of the first batch of DIY robots to feature 19 DOF hands, series elastic actuator driven arms and an articulated body that can stand, balance and move at over 25 km/h!

Want to see if you've got what it takes?

The V1 #DexHand is freely published and available for download at https://github.com/TheRobotStudio/Dex....

The parts can be printed on any extrusion printer and the hand uses less than 300 USD of components.

The parasolid CAD model can also be viewed and downloaded for free on the cloud platform Onshape: https://cad.onshape.com/documents/16c...

Designed and tested for high speed printing using a 0.6mm diameter nozzle and 0.4mm layer thickness except for the tendon spools and split parts of the palm sections which benefit from printing at 0.3mm layer thickness or better.

Tested in PLA, PETG and CF nylon. ABS is not recommended for the large pieces due to warping.

To finish 3d prints to a high standard requires a fine sandpaper or emery board.

Diamond coated steel nail files are a handy tool: https://amzn.to/3VBBsOX

Though my favourite diamond file is actually intended for maintaining whetstones, just a nice big expanse of diamond dust to use :-)

Amazon US: https://amzn.to/3eN3bvo

Additional components required are listed below.

Please consider buying via the Amazon links where available to help fund the robot development.

The biggest cost item are the 16 slim micro-servos that drive the fingers and thumb.

In the US the discount code ROBOTSERVOS will take off 10% from the official Emax webstore: https://emaxmodel.com

There are four variants at this size with plastic or metal gears and using either digital or analog control technology.

ES3301 (approx $6.6)
ES3302 (approx $9.2)
ES3351 (approx $8.5)
ES3352 (approx $12)

2 standard micro servos are needed for wrist flexion and extension.

Feetech SCS2332 - https://feetechrc.com/product-name_55... are recommended.

These are serial bus driven servos over allowing a greater range of controlled rotation.

They cost around 35 bucks each plus delivery.

If you prefer to use a standard PWM servo for simplicity they can be substituted by any servo that fits inside the envelope 23.2*12.1*28.5mm.

The trade off is the reduction of the powered range of motion of the wrist to about half.

1 standard servo needed for axial wrist rotation (optional)
Feetech SCS15 - https://feetechrc.com/6v-15kg-digital... or any servo that fits inside the envelope 40*20*40.5mm.

Reduces powered range of motion to about half and the loss of a continuous rotation option.

The rest of the components are relatively inexpensive:

2mm diameter steel pins - alternatively cut lengths from a wire coat hanger or in Europe order direct from https://www.visseriefixations.fr/goup...

Otherwise kits are available on Amazon US: https://amzn.to/3VYrnfh

M2 screw and washer kits, or also in Europe from https://www.visseriefixations.fr
Amazon US: https://amzn.to/3sf4NkE

M2 brass threaded inserts M2 * 4mm long * 3.5mm
Note that the type required has a plain section between the knurled ends to allow attachment of the tendon in the fingertip.
Amazon US: https://amzn.to/3yYl1lY

Kite or fishing line for finger tendons - Sufix 832 is the best I know of for longevity, the 80lbs breaking strength is stiff enough to thread easily and most readily available on
Amazon US: https://amzn.to/3DgjNoF

Slightly thicker 0.8mm kiteline for the finger ligaments and wrist tendons.

Amazon US: https://amzn.to/3GMKQJL

Ball Bearings 6*10*3 - Need 50 for a hand, packs of 10 available which are enough for the sample finger.
Amazon US: https://amzn.to/3Dj7cBn

Ball Bearings 2*6*3 or 2*6*2.5 - Need 6 for the wrist
Amazon US: https://amzn.to/3yYlTHg

Ball Bearings 15*21*4 - Need 4 for the wrist
Amazon US: https://amzn.to/3TsMSTO

Ball Bearings 3*8*4 - Need 6 for the wrist
Amazon US: https://amzn.to/3VyE28O

M3 * 70mm caphead bolt (grade 12.9 ideally)
Available from Amazon US in packs of 10: https://amzn.to/3HM0Rjx

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