Working BB-8 Droid from Star Wars Episode 7

Thank you for your continued support. 700 and counting!

BB-8 has had his first trip to a show, to meet members of the Brickish Association in the UK.  Always a good time to test and find improvements.  Preparation for a show does take more time, so I posted this update later than I hoped.  For a show it is always worth taking spares - battery, charger, batteries for camera and handset.  There was plenty of interest and opportunity to demonstrate the features.

BB-8 managed a couple of test runs.  Need to improve counterweight attachment as they are difficult to put back on with the latest shell improvements.  Rolling is better on a soft surface than a hard floor, even with a thin mat taking some of the shocks.  I'm thinking about how the corners of the 7x7 areas on the 12 edges (grey and black parts on the diagonals above) could be less prominent but still give strength to the shell.

The 4th update to the head is a new design, using the angle joints instead of the flexible axles to make the curvature.  This allows the gaps to be smaller, especially near the top.  It also provides a steady mounting point for some orange parts.  The eye is less prone to falling off and I have added a light blue piece for the indicator that lights as the real BB-8 talks.

I had most of the tools on display; flame, arms, cables and panels.  Still quite a bit to do for the remaining tool faces.  The shell now has more orange parts at the corners of the tool faces.

Since these pictures I have completed two bits of the tool face that has the map drawer and 3 arms with some white parts.  This week I have changed the white tubes for orange ones to make the orange circles look more circular.  Pictures of that next time.

So far the videos I've seen of the real BB-8 indicate a single rotational axis for rolling any distance, a leaning mechanism for steering and a flywheel for spinning, rather than full holonomic motion (i.e. rolling in all directions).  I have done the first two of these mechanisms so far; the extra weight blocks I have just received from the latest order might enable me to add a spinning function, so I will look into that as part of strengthening the counterweights.

I'm also proceeding with magnet mounting experiments, looking more at the underside of the real BB-8's head.  The contact area is just 60% of the diameter of the head so I may reduce the self-levelling mechanism to a single smooth piece.  There are some wheels of the right size but their edges are not smooth.

Please join more than 700 people who are supporting this project.  Share it with your friends and help us reach 1000 supporters soon.  Many thanks.

Thank you for continuing to support and share.
A few pictures from here, from my Brickshelf gallery and from YouTube have started appearing on Google searches.

Since last time I have confirmed the order and orientation of BB-8's tool faces, by trawling through the videos of the real BB-8 and matching that with some diagrams that other (non-LEGO) modellers have drawn.

This meant I could start improving the faces and closing gaps in the shell.
I began with the parts between the orange circles and the silver-grey tool areas.  There are 48 of these and most are now in a better state.
Some are finished, others need more work.  Where a grey part does not extend towards the centre is it more difficult because a white piece with a round profile is needed, with support and no straight part.

There are several places where BB-8 has deployable devices that we have not seen yet.
The face that has the map drawer also has three long grey shapes.  I have speculated that these may operate like R2D2's arms.
There may also be another drawer opposite the map drawer because the shape and panel hinge is mirrored.

Another face has two long grey shapes and a hinged circular panel.  This face also has a cable deployment point; I may move that later when I have confirmed its location; it is hidden in some of the cable pictures.

It's possible the cable deployment point is on the right of this face rather than at the top in this orientation.

There are two more cable deployment points on other faces to make the total of three shown in Ep7.

The cables, which BB-8 uses for climbing and for holding position in a barrel-rolling Millennium Falcon, are deployed from some of the orange parts that protrude inside the circles.  There is a suggestion that the real BB-8 may use compressed liquid cables, which would be a CGI effect if true.  Since no liquid cable LEGO piece exists, I have found space inside the shell for some reels for the cables.

It was difficult to find space but these points protrude a little from the spherical shape so a thin-enough mechanism fitted!

I'm still waiting for more parts to arrive; that will lead to some more improvements.
The internal mechanism will need another update when they arrive but some shell parts will be easier to fit.

One face includes a ring that is half grey and half white or tan and recessed slightly.  For the moment I have used some white tubes that were bleached by sunlight for the tan part.  Swapping for either white or tan later would bring it back to using only legal parts.  In LEGO building, any opportunity to use bleached parts in either a hidden place or an appropriate visible place is valuable, restoring the value of the pieces.

Still plenty of work to do but we're on target for BB-8 to have similar functionality to Volvo Loader 42030, i.e. 4 motorized functions and several minor functions, at a similar price point of £170.
BB-8 branches out from the usual types of Technic model - car, truck, aircraft, farm machinery, construction plant and robot.
I hope that BB-8 might be the first of a new type of model in the Technic range, perhaps featuring animal movements.

Please keep on spreading the word.  Almost two-thirds of the way to our first 1000 supporters!
The smaller rolling BB-8 has reached 10,000 supporters now - congratulations to them.  I hope they will be successful in the review and that their success might pave the way for other ideas based on existing licences.
I hope also that a new, safe but versatile magnet piece can be created; it is one type of function missing from other models now that the buffer beam is the only piece with a magnet.
I have ideas on how to encase a magnet safely to avoid it being swallowable.  My BB-8 will need strong magnets to attach the head and manage the attraction distance.

Thank you, particularly to all our new supporters and those who have shared the project with their friends.

I have started testing the steering function.  When this works well, I'll do another video.
So far the sphere can steer with about 0.5 metre radius.  On the second test it turned successfully both ways round but then, with enthusiastic driving, it fell off the bed!  At least the rebuild took less than 10 minutes as most disconnections happened between modules.  I took the opportunity to charge the LiPo battery; performance tails off a bit when the battery runs low, as with most models.

Full holonomic motion would need smooth sphere.  With the type of mechanism I have, BB-8 will steer more like an RC car.  We're still on target to have similar functionality to the Volvo Loader set 42030 for a similar price.

I have done some more to the shell this week.  Several of the tool areas have white areas that could be made with similar sub-modules so that's a bit for each face rather than completing a single face.  I've started on the map drawer, which will need some non-integer lengths to make everything fit.  A door has to open before the drawer comes out.

I have done some more research for the other tools.  It appears the cables, which BB-8 uses for climbing and for holding position in a barrel-rolling Millennium Falcon, are deployed from some of the orange parts that protrude inside the circles.

I have also ordered some more parts for both shell and mechanism improvements.

Please keep on spreading the word!  Still a way to go to our first 1000 supporters.

Thank you to everyone who has supported and shared already.  We are well past the initial rush of enthusiasm; new supporters are needed. This happens to most projects so please keep on sharing with your friends.  I hope you will be encouraged by the progress; we can now replicate the iconic "Thumbs Up" scene with a tool that is entirely stowed in the shell - well worth sharing!

Having put in some new pieces last week, I did some more research and found that the orange circles on the shell should be bigger in proportion to the areas between them.  This week's first set of modifications has made the circles larger and extended the recessed black areas around the white 8x8 radar dishes.  This also provided an opportunity to remove some red and brown pieces that had been standing in for orange ones.

The second set of modifications this week added some black pieces that could support and provide attachment points for the tools and doors.  Then it was a case of looking at the drawings of BB-8's functional parts to see where to start building them.

The third modification this week has replaced one of the six radar dishes with the proper functional parts.  The idea is to have the appropriate tools deploy from the shell without getting in the way of the internal mechanism when they are stowed away.  Whilst I have just one droid to display both movement and tool deployment, the real BB-8 in the film is allowed to use multiple droids, some for movement and some for static shots.  The static models of the real BB-8 can have tools deploying from deeper within the droid, whilst the moving models might have just the opening sections of the shell with a representation of a stowed tool but no deeper items.  This allows the moving models to have a thin shell to minimise the magnetic coupling distance for holding the head on top.  It also allows the static models to have comprehensive mechanisms to do everything the tools need for deployment and action.  With a static model the props team can choose whether the iconic "Thumbs Up" shot should have a live flame or an electrical effect.  I have no such luxury with a single model so the tools of the LEGO Technic BB-8 have to be stowed within the shell.  I'm happy to say this was achieved for the first tool; the trans-purple cone makes a lovely flame.  This project will not be using any stuck-on tools that would need to be removed for rolling!

The most difficult part of the build this week was to make the door for the lighter arm, including making it hinge at the correct angle on the shell relative to other parts and giving it the correct sweep to get it out of the way when it opens.  The real one hinges through about 180 degrees and the hinge is at an odd angle to other things.  I used some small tubes to make the hinges, using techniques found in existing sets (all legal moves!).  Another tube provides a catch to stop the door falling open when the sphere is rolling.

Some comments have mentioned gaps in the shell; it has always been my aim to close them.  In the fourth modification this week, the new pieces have enabled some gaps to shrink or close in the lower part of the head; still much to do at eye-level and above.

On the shell, the expansion of the orange circles has opened up some gaps in the diagonals but allowed me to start covering the recessed black areas; one has been done this week but eventually all the black areas will be covered and all the 8x8 radar dishes replaced with functional items.

I have done some work on the internal mechanism but there is a lot more to do; it is even more complex than the shell so it will take a bit longer.  More counterweight blocks are on their way.

I will also be updating the other five tool deployment areas as I find out more about what tools deploy from where.  Having done the lighter, there is the zapper, the drawer for the plans and three locations for tethers, all of which are all used in the film, as well as other tools we might see in further episodes.  Please add your comments if you see pictures from the film of the other tools; they haven't come up yet in my web searches as the "Thumbs Up" one did.  I'd like to have each tool stowed in the shell for rolling and deployable when BB-8 comes to rest.

Many thanks for your support.  Please keep on spreading the word.
Remember the test video too.  The droid will still work similarly with the tools stowed:

All the pictures are also available in my Brickshelf gallery at http://www.brickshelf.com/cgi-bin/gallery.cgi?f=563009 (it may take time for moderation when I add more so please try again if it is unavailable).  It is easy to link to the pictures from discussions on community and public sites; I often use links to my model pictures as examples, sharing ideas to help others as they build.

Now moving up through 600 supporters, thank you everyone!

The last few updates have shown that particular pieces feature strongly in the design.
I have gathered more of those key pieces in the right colours and substituted them in for others in the sphere shell.

I have also closed a few gaps in the shell.  Some more to do, and some in the head too.

There will need to be more work to get rid of other red pieces later but this will depend on design changes too; no point buying parts in the right colour in one type and then changing the types!

Still to come are some weight blocks for the counterweight.  I hope to update the internal mechanism for the next update soon.

Some of the parts from recent set purchases look good for experimenting with deployable tools.

Interesting to see that at last someone else has a (smaller) BB-8 that is intended to move, though the power source is external.
We share the same magnet issues, since the old coupling magnets would not meet modern safety standards.

Once again thank you for the support and encouragement.  Please keep sharing with your friends and encourage them to support the project.
Still a long way to go but looking better and making progress.

This week I have some parts on order that will enhance the shell colour scheme and also allow improvements to the internal mechanism, working towards being able to steer the droid.

Unfortunately some other parts that I wanted are not available through the online ordering service.  I will examine the options for those later.

Now almost 550 supporters, thank you everyone!

A small but significant update this week.  The six 8x8 radar dishes used to stick out of the sphere a bit too much so I have recessed them.
You can see how the profile is rounder near the dishes.

This also needed modification to the 24 modules with the small panel pieces, adding a 3M half beam.  This in turn pushed out the tips of the panels a bit.  The "bit" became as much as 1M at the centre for the 8 segment modules, which is also where the internal mechanism drives the sphere from two of them.  So quite a shift of the shell parts.  If the Earth's plates moved that much (hence the title) then it would be serious for all living things.  The profile is a bit less round at the centres of the segments, more like the Himalayas!  I'm sure the shell will continue to evolve.  Worth getting the shape and parts mix right before I buy more parts in the right colours.

Recessing the dishes means that there might be room for some of BB-8's tools.  Studying the film:
- 3 or more nodes are able to release cables, which would be a metre long for this half-size model.
- 1 node has a drawer.  In full size this is big enough for a memory stick but about 2x4 brick size for my model.
- 1 node has a zapper.
- 1 node has a flame.  I will have to look closer to check whether it is the same tool as the zapper or not.
There may be other tools available.  I will have a look at the 6 patterns of grey on the sphere shell to understand more.
In the deployment of tools it may be possible to replace the dishes with a composite of plates, tiles and curved slopes later.

In the film it looks like some of the tools deploy from a place inside that is deeper than the shell.  This would be within the internal mechanism because the shell has to be thin for the magnetic head-hold function to work, so it would require lining up the mechanism with the shell before deployment.  This is where movies are able to cheat and have more than one BB-8!  One BB-8 can do the full movement for all the running around and another can do the tool shots with more basic movement functionality or limits.  I also noticed that it took two people to control the real BB-8.  I guess descending stairs in a controlled manner took plenty of practice!  There is the possibility that the real BB-8 includes some programmability, such as the "stay upright" function.

I found one more counterweight piece so I will have a look for others towards updating the internal mechanism to improve movement performance.

Once again thank you for the support and encouragement.  Please keep sharing with your friends and encourage them to support the project.
Still a long way to go but making progress.

Almost 500 supporters, thank you everyone!

This is the update many of you have been waiting for - the first video:

In the last week I have redesigned and rebuilt the sphere (hence the title).  It is now larger, the right size for the head.  All the distances change in the sphere but not all by integer amounts.  In particular the distance from the edges to the centre of the 8 segments includes a half stud, which is more difficult to fit and to make strong.  I expect there will be some improvements to come in that area in the future.  The sphere build was quite simple as modules:

• 6 vertex modules in black, behind the 8x8 dishes
• 12 edge modules in mostly grey and white
• 24 panel modules to fit to the 3-axle 120-degree pieces, two of which are where the torque is applied.
• 24 edge pieces between the vertex module and the edge module, centred on the tax 1x3 half beams.

This means it would be easy enough to write module instructions for the shell for a potential kit before final assembly; not so difficult to build.

I have made some modifications to the internal mechanism but not a rebuild.  That is for the next stage.  I decided that the motorbike wheel as a flywheel made little difference and I found that the stresses on the internal frame put friction on its drive shaft.  It could spin up to about 5000 rpm so it was easy for friction to reduce the speed and increase motor current; the train motors did cut out occasionally with the load.  For the moment I've left the motors in because they provide support for extending the structure and mass away from the drive shaft centre of rotation.  This means I can hang more weights further away from the centre and make better use of the counterweights before I add more.

Functionality with the head attached is currently limited to rocking by a modest angle, not too much in case the head overcomes the counterweights!  This could get closer to where BB-8 leans forward to look out from behind something.

Functionality with just the sphere is greatly improved from the first prototype.  The sphere can start away most of the time on carpet or on a bed duvet.  The sphere is able to accelerate but not too quickly as the video demonstrates - there is still a risk of sending the counterweights over the top!  More counterweights will improve this performance.

Once again thank you for the support and encouragement; I couldn't do this without you.  It's great to be able to post a video of something working; there is still a long way to go so there will be more updates to come.  Please keep sharing with your friends and encourage them to support the project in the meantime.

Now over 400 supporters, thank you everyone!

A small update this week, part way towards a new internal mechanism.

I have changed the L-motor and 2-stage gearing for XL-motors because less gearing is needed.  The gears now sit within some frames designed for them, reducing the risk of jumping, which was a problem on the first prototype.  Also two motors are used so there will be plenty of torque and less risk of driving one side of the sphere more than the other.  I will see if electrical load-sharing is sufficient to keep the two sides turning together.  The XL-motors use less space, leaving more for the other mechanisms.  A PF polarity reversing switch makes the XL motors turn in opposite directions so that both sides of the sphere turn in the same direction together.

The first additional mechanism is a gyroscope flywheel, hence the title.
The plan is to build the droid with Power Functions parts, without using an NXT or EV3.  Either of these programmable units would use a gyro sensor to feed the tilt of the droid internal structure into the equations for motor control.  Instead of this, the flywheel provides some resistance to the droid falling over in sideways or forward and reverse directions, just as bicycle wheels do.  Whilst a sudden change of flywheel speed might be able to spin the droid, as a full-size non-LEGO BB-8 home-made design has done, this is a wait-and-see extension to the function for my model.

I have incorporated one of my LEGO flight experiments into the droid by using two PF train motors to provide the flywheel power.  My tests have shown that two PF train motors geared up 5:1 provided more high-speed power than two PF medium motors geared up 15:1.  The flight experiment was to see if PF motors could make a Ninjago Airjitzu spinner (with a Technic axle but without the pod) take off under PF LiPo power.  Only the PF train motors were able to do this.  The spinner rose and hovered a few centimetres above the frame.  It is still a lot less power than pulling the trigger!  The resulting rotational speed of the output shaft, for the spinner or the BB-8 flywheel, is around 5000rpm.  I checked Philo's motor page to work out a ball-park figure.
As the ring of the sphere is rotated sideways the reaction forces can be felt; a sideways rocking results in force in the forward or reverse rotational direction.  I will see if this helps stability.

Safety First

Always think of safety first, especially for an idea or product shared with others.  With a fast flywheel there is a potential risk of it coming off the axle so it is held on with an extra wheel bearing.  The counterweights and batteries will partially surround the flywheel and help to contain it if it ever came off.  The flywheel has a rubber tyre and no sharp edges so it would not cut anyone.  This is why the counterweights are not part of it at this time.  Therefore the risk (both the likelihood and the consequence) has been reduced to an acceptably low level.  If LEGO Technic builders have had a childhood experience similar to mine then spinning a wheel as fast as possible is one of the regular experiments!  Hence the flywheel mechanism does only what many LEGO builders would be doing already, so there is no additional risk compared with normal use of the product!

The next step is to fit the batteries and counterweights and build the whole sphere at the larger size.  This will need a new shaping method so I will do part of it and then roll out a solution to the rest and test the result.  I expect it will also need more counterweights than I was using before.  There will be room to fit a head control mechanism in the top half of the sphere, and counterweights and batteries in the bottom half.

Again thank you for the support and encouragement; I couldn't do this without you.  The features will change over time but this is typical of real engineering.  I'll keep you posted as I reply to comments, and also on some of the LEGO forums and facebook groups.  Please keep sharing with your friends in the meantime.  I hope we will reach 500 supporters soon, half way to the first 1000.

Four days in and over 280 supporters, thank you everyone!  Thank you also for the suggestions and encouragement, much-needed as this is a difficult project.  Please continue to spread the word too; we need to keep growing the support in the idea in order to let the LEGO company know that we want a working BB-8 droid.

Head Improvements

This week I have been working on the droid's head, hence the title.  The previous prototype was built quickly.  The real one tilts and turns so I have made the turning easier in order to leave options open for later.  The head how has a more hemispherical shape.  I stuck with the ring of angle joints at the bottom of the previous version.  It is still open-frame because I didn't want to add too much weight just yet; the head weight has to be in proportion to the droid's ability to balance it with counterweights.  Some suitable panels are already included in my LEGO-buying plans for this year; I see a few new kits have them!

The updated head has a few technical features:

1. The casing, with the eye, is able to spin on its axis.  This means I could make a turning arrangement inside the head later; there is space to do so.  I have left it free to rotate for now.
2. The updated head has a self-levelling mechanism.  This allows it to cope better with the inevitable unevenness in the sphere, since there is no ready-made 20cm sphere segment piece!  The other part of this week's work has been to make the sphere smoother, see later.
3. The self-levelling mechanism includes magnets in preparation for other magnets in the sphere to attract them.  It is good for the mechanism for the weight (and in his case magnetic attraction) to be on the levelling pads.

Sphere Smoothing

The previous prototypes managed to fill in part of each of the 8 sphere segments with panels, whose shape is convenient, but this still left some large gaps.  Although the 8-wide radar dishes look good, they make the sphere rougher and less-able to roll, especially in a straight line.  This next prototype adds a pulley in between the panels to fill in a hole.  This also provides a mount for axles towards other holes.  Some #1 and #6 axle joints near where the dishes were, fill in more of the holes; these can be upgraded to orange instead of red later.

With these measures on 1 segment, the new head glides across that segment better than the others, so I have an incremental solution to roll out to the other segments.  I would have to do this before rolling performance on a hard floor (or carpet) would be significantly improved.

Counterweights

With the need to improve rolling performance in order to facilitate a video for the next update, I decided to add more counterweights alongside the battery box.  This has worked better whilst rolling on the bed (duvet).  They are black in this picture, the ones used in trains of old and they still appear in a few sets from time to time:

This was an area where I had to resist the temptation of using other methods.  It would be easy enough to make counterweights from a pack of ordinary metal washers on LEGO axles; this could be done without modifying any pieces but washers are not usually available to children (even if they need more iron in their diet)!  I notice that the read droid and other non-LEGO home-made ones have the whole lower hemisphere full of heavy items.  Clearly a lot of counterweights are needed; I do have a few more of the LEGO weight blocks.

Further work to come

The next task is to update the internal gear mechanism.  Although the motors have enough torque, the mechanism needs to handle it better.  I also have to eliminate internal things catching on the inside of the sphere to make motion more reliable.  I hope this will facilitate a video for the next update.

There are still options on a scheme to provide rolling in multiple directions.  This is attractive because I want to get closer to how the real droid works.  I did test it at an earlier prototype before raising the project here but I must get one direction of movement reliable first.

I might say more about how the mechanisms work in future updates too.

Given the size of the head, it would support the droid body being larger.  I can see that this may be necessary in order to do multi-directional control and fit in enough counterweights!  I am wary of making it too big because it would lose strength as it grew.  I would also have to acquire more parts in order to try it; I would like to have enough for two models so that I can improve one and do some relative tests.

Again thank you for the support and encouragement; I couldn't do this without you.  I hope some of you who were not so confident will be encouraged by this update; quite a few features will change over time but this is typical of real engineering.  I guess the internal mechanism work might take at least a couple of weeks.  I'll keep you posted as I reply to comments, and also on some of the LEGO forums and facebook groups.  Please share with your friends in the meantime.

Where's your head at BB-8?  It's here!