Commuter Booster - <1kg Friction Drive

[Kepler]

Thanks Adrian,

I really believe the interface is the missing piece of the RC based friction drive puzzle

[adrian_sm]

Totally agree!

..... and when I find a bit of spare time on a weekend, I might just give you a bell and drop around for a go.

Keep up the good work.


Update:


On a seperate note, testing has slowed down due to work commitments, family staying with us, and a dodgy 5s5000mah pack from hobbycity.

I order two, one was fine, the other had a dud cell at <1.0V.
Shipping back to the warrenty centre was going to be $23, so I decided to charge it up and give it a chance instead.
Currently on the charger, and looking okay, slowly balancing the pack, no excess heat, puffing, fire etc.

Time will tell.

- Adrian

[adrian_sm]

I had some musing time on a plane last night and realized I am chasing too many things at once with this build. Trying to debug multiple things at once.

So I will be getting my hardtail mountain bike back on the road as my test mule. This will let me use a standard throttle which will make it much easier to get to know the drive.

Since the Avanti MTB has a larger seat tube I'll probably just build a second unit with the larger motor. This will let me work out a few differences in the deadstops, springs etc that a longer motor creates.

Looks like I may have to order a few more things from HobbyKing so I can have two units up and running.


Now if only I wasn't on holidays, I would start making bits.

- Adrian

[umejopa]

Well Adrian now you have same setup as I have
Have make the current controll running better now and add a pot to set the level wene it with powerup.
Even more more snow here now so hard to test for me..

If you have time you can rebuld your Wattmeter and make it to RC-tester with current limit .

Current limmit wattmeter

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Upload the hex code for the flash Watt1.hex and the EEdata Watt1.eep and assebler code if you want to change some.
The setting for current can ben set by the computer but for test it is better to have it adjusted on the road.
I think 1000W input may be a good limmit... (22V x 45A)

//Jonas

[adrian_sm]

Great work Jonas.

When I get back from my holiday I'll give it a go.

Thanks again for sharing.

- Adrian

[deVries]

Here is a review and testing thread on the drive http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=22026

Sorry, no plans for a high powered version. The interface is really a means to an end so the drive can be sold as a complete unit. Happy to get it out to ES members in the near future though.

Ok, when are you going to start a new thread on your new "Avatar Design" ???

Obviously, you've been working on an idea that went through my head from the beginning of your first prototype design. Two speeds or a two geared drive...

Let's check it out...

When will you post about it? Christmas is coming...

Thanks

[adrian_sm]

Back from holiday now, was an awesome trip to Cradle Mountain in Tassie. Here is a few pics from the trip.

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UPDATE: Throttle
After being frustrated with the dodgy excuse for a thottle that I knocked up before, I thought I better get something more conventional while I get this drive up and running. So Before I embark on making use of Jonas' work on modifying a Watt Meter to do the job, I decided to follow Hillhater's version of a modified servo tester with a hall throttle input. Thanks Hillhater.

Seems to work fine getting full throttle range. Only issue is the cheap thumb throttle I am using is a bit sticky, so it wasn't as smooth when I slowly adjust the speed.

Here is a few pics of what I did. And the bench test parts, which will be getting put together on my old Avanti hardtail mountain bike soon.

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- Adrian

P.S. @Kepler.
John, you have to admit you are a bit of a tease. Updating your avatar with unreleased products. Dropping tasty little tid bits about your throttle interface, without let people know when they may be able to get their hands on it. Come on already.

[adrian_sm]

Since I am building a second unit, I thought I would get a second ESC to try out.

This time I went with the $60 TURNIGY K-Force 100A Brushless ESC, rather than the $36 Turnigy Brushless ESC 85A w/ 5A SBEC which has been fine so far.



Unfortunately the new 100A ESC doesn't have the ON/OFF switch that the cheaper ESC has.
But it does apparently have USB programmability, and firmware upgrade. But I don't see no USB port on it. From reading the comments on the HobbyKing site it looks like you need to buy some seperate progammer, that also allows you to connect it to the PC via USB. Great. How handy.....
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8996

[HAL9000v2.0]

Instead of programmer you can use USB linker for 8$.
http://www.hobbyking.com/hobbyking/stor ... duct=10628

[rearengine]

Hal!! What more can you tell us about the linker, Sounds really cool.. Are you using it , and how does it work ? Thanks for posting it ... Bill

[rearengine]

Adrien! Very interesting thread, Pictures worth a 1,000 words... I've been following your build all along , with Keplers, EvTodds , and a host of others.. I'm still working on Rearengine Hill Helper, friction drive With a whole lot of help from Spinningmagnets.. Enough of that on your thread... Bill

[deVries]

Back from holiday now, was an awesome trip to Cradle Mountain in Tassie. Here is a few pics from the trip.

Thanks for the pics... beautiful.

Good find on that 150burst amp ESC... somehow I missed that one, and it should give you plenty of headroom to not fry it. Will you add caps?

P.S. @Kepler.
John, you have to admit you are a bit of a tease. Updating your avatar with unreleased products. Dropping tasty little tid bits about your throttle interface, without let people know when they may be able to get their hands on it. Come on already.

Please note, he has now de-updated the avatar putting his two speed roller design, I guess, in the top-secret cave??? ...Hmmm.

Well, just open a thread on it, and be done with the surprises in store. After all, ES is a prototype, feedback, open-source idea community.

At least get the throttle thread going soon???

[Kepler]

P.S. @Kepler.
John, you have to admit you are a bit of a tease. Updating your avatar with unreleased products. Dropping tasty little tid bits about your throttle interface, without let people know when they may be able to get their hands on it. Come on already.

At least you know I am not sitting on my hands doing nothing
Just a quick up date (I don’t want to hijack this fine thread) The dual speed setup is on the back burner at the moment. I really question if two speeds are necessary for a friction drive that is used an assist as apposed to a primary drive. However, I do have some designs drawn up for future development.
The latest design has grown a little so it can accommodate the battery (5S 5ah) as a complete package. I had been trying to make the drive as small as possible but I have now moved a little in the opposite direction as I think the 20% extra bulk is worth it seeing you no longer need some method to carry the battery. Also the battery gets well protected between metal side frames.

Interface boards are being built at the moment. The main processor is now mounted in a small box on the stem or the handle bars. Accessories are then plugged directly into this box. Lots of flexibility here including options for LCD screens, simple low cost SunDing bike computers, throttle, brake, pedlec, voltage taps up to 18V to power lights and accessories. There is a second slave board back at the drive that takes the ESC input, current sense, and volt pickups.

Enough of cluttering up Adrian's thread (you did ask though ) I will get a stand alone thread running in a few weeks time for some serious discussion on this stuff.

Adrian, offer is still open to test ride the button throttle interface.

[Hillhater]

This time I went with the $60 TURNIGY K-Force 100A Brushless ESC,
But it does apparently have USB programmability, and firmware upgrade. But I don't see no USB port on it. From reading the comments on the HobbyKing site it looks like you need to buy some seperate progammer, that also allows you to connect it to the PC via USB. Great. How handy.....

Adrian, you are aware you can reprogram all the key variables on that ESC using just the servo tester/throttle actions ??
Its explained in the handbook.

glad you found the throttle mod useful too.
HH

[damonjackson_spl]

I thought i recognised the pics of cradle mountain!! beautiful walk..

the worst thing in, cradle mountain is only a 3.5hr drive from hobart and most of us have not done that walk :O

pity as it is a great spot!!

i think the friction drive would love those winding timber tracks!!

D

[adrian_sm]

Instead of programmer you can use USB linker for 8$.
http://www.hobbyking.com/hobbyking/stor ... duct=10628

Thanks for that Hal. That is cheaper, but I guess I was just expecting a mini-USB port right there on the ESC.

Adrian, you are aware you can reprogram all the key variables on that ESC using just the servo tester/throttle actions ??
Its explained in the handbook.

Yep. I used it to originally set-up the ESC, but found it annoying. It is slow, requires you to have the manual right there with you to make sense of it all. Generally just a royal pain. That is where the Pro Programmer Box I linked too would actually be worth it. As it displays all the settings nicely on a screen, and you can then reprogram quickly and easily in the field. Great for trying out different settings quickly while out on the road.

The cheaper USB adapter thing Hal linked too, would be great if I had a computer in the shed where I park the bike.

I'll probably stick with the throttle adjustment of settings, as it is not something you change very often. But thanks for everyone's input.

- Adrian

[adrian_sm]

Adrien! Very interesting thread, Pictures worth a 1,000 words... I've been following your build all along , with Keplers, EvTodds , and a host of others.. I'm still working on Rearengine Hill Helper, friction drive With a whole lot of help from Spinningmagnets.. Enough of that on your thread... Bill

......
Enough of cluttering up Adrian's thread (you did ask though ) I will get a stand alone thread running in a few weeks time for some serious discussion on this stuff.

Adrian, offer is still open to test ride the button throttle interface.

Thanks guys. Don't feel like you are cluttering the thread. It is great to have others drop by. Especially those working on similar set-ups, and new innovations.

Keep up the good work.

- Adrian

P.S. John, I will take you up on that offer one day, but I am struggling to find time on weekends, and the few spare minutes I do get I want to focus on getting my drive up and running.

Then I'll drop around, and we can compare. Or more likely you can help me fix it, when I burn something else up.

[adrian_sm]

Major Update: Commuter Booster - Proto #2

Amazing what you can get done, when you find a spare 4 hours to work in the shed.

Behold Commuter Booster - Prototype #2
- Turnigy 6374-200
- single swing arm design
- easily adjustable (spring preload, engage deadstop, and disengage deadstop)
- suits 34.9mm seat-tube.
- weighs in at 1.2kg, 0.9kg of which is the motor itself. Not bad since I have made no effort to shave weight down.

1.2 kg. Not bad since the motor weighs 0.9kg

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Left Side

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Right Side

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Really happy with how this one has come together.
The single swing arm is defintely stiff enough, and the motor has a skirt bearing so no stress issues.
The deadstops are adjust via two M4 screws. So it is ultra easy to adjust how far the motor sits from the tyre, and limit how much it will rotate in to the tyre as well. So it will be really easy to tweak the amount of engagement to minimise losses. I will need some method of locking them in place once adjustment is done. i.e. lock nut. And I will probably add some rubber to soften the blow when it hits the deadstops.

The dead stop arrangement. Note the dodgy work with a dremel because I don't have a mill.

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I have also made the spring that takes the weight of the motor easily adjsutable too. So this will allow for more subtle tuning of the drive engagement. All you have to do is rotate that little collar that retains one end of the spring, then tighten the grub screw. (Note that little collar comes with the motor)

The motor counter balance spring.

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Here is a pic showing all the parts that make up the drive. On the left is the fasteners, in the centre the custom parts, and on the right the parts required from hobbyking. A total of 7 parts (4 custom, one modified), plus 10 fasteners (6 new, 4 came with the motor). Definitely happy with that. Can't see any way to reduce that while keeping the level of adjustment I have.

The Commuter Booster Drive in bits.

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The custom parts:
- The main clamp/pivot block. Made from Acetal with a drill press, hole saw, various drill bits, M4,M5 & M6 taps, and a dremel. Size and shape is still totally un-optimised. I just used the blocks that I had laying around.
- The swing arm. Made from aluminium with an angle grinder to cut to size, drill bits, & M4 tap. (Note the centre clearance hole is too big as this was originally a right hand swing arm that took a bearing.)
- A spring. Repurposed from an extension spring using a dremel to cut to size, then lots of swearing to bend it into the shape I needed.

The Custom Parts

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The fasteners:
2x M6 screws to clamp it to the seat tube
2x M5 screws for the dead stop adjustment
1x M4 screw which is what the adjustment screws act on
1x M4 grub screw to lock the shaft to the swing arm (should probably have two)

The fasteners

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The OEM parts
1x $60 Turnigy 6374-200
1x $8 Turnigy AerodriveXp 63-74 SK Series Shaft

The OEM parts

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Now I just need a chain ring, and brakes on the Avanti then I can mount it up and give it a run.

Mounted on the bike

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- Adrian

[recumpence]

The parts look well made!

My only concern is the use of the Acetal (Delrin) as the frame mount clamp. It may turn easily. Also, Acetal breaks easily when under tension.

I may be wrong, however. It is just a thought.

Matt

[adrian_sm]

Thanks Matt. I really didn't put much thought into materials just grabbing what was laying around, so your comments are welcome.

For the final model I'll probably just make them in ally, and use some Nyliner bushes. That should do the trick.

Cheers, Adrian

[recumpence]

Cool.

One simple method of reducing the tendency of Delrin from twisting when used as a clamp like that is to use a thin piece of rubber (inner tube?) as a buffer inside of the clamp. That rubber will protect the paint as well as reduce the tendency of the drive to twist on the frame because it has a "Tacky" surface.

Matt

[jbond]

This is turning out really sweet. One suggestion. Now you've gone to a single sided swing arm, you migh think about putting the pivot on the other side of the seat tube. Having a longer pivot arm will make the arc that the motor moves in shallower. This might make the end stops less critical as the motor con't cut into the tyre at such a sharp angle.

[Kepler]

Looking good Adrian. I have built a few prototypes out of Acetal. Works really well as long as you give it plenty of meat around any stress points. I think you might have some issues with the threaded stop screws breaking out but time will tell. The Acetal is great for proof of concept.

I presume you are putting a second swing arm on the other side. Looking forward to seeing the road test

[adrian_sm]

Looking good Adrian. I have built a few prototypes out of Acetal. Works really well as long as you give it plenty of meat around any stress points. I think you might have some issues with the threaded stop screws breaking out but time will tell. The Acetal is great for proof of concept.

Yep, the threaded screw stops are definitely the weakest link in this design, especially being in plastic. The location doesn't help much either. If I want it to last I will need to add some rubber to soften the blow.

It was all a bit of a by-product of only limited time to make this one up, so I just re-used the swing arm I had which stopped me from putting a bigger 'lever arm' on the dead stop.

I presume you are putting a second swing arm on the other side. Looking forward to seeing the road test

I was originally planning on this too. But once I put this together it seems pretty damn strong. It has a pretty good light press/sliding fit between the pivot arm and swing arm, so no slop, then the grub screw gets done up to take the fairly minor spring torque load. It also makes the assembly really straight forward, and as a real bonus provided a super simple method to adjust the spring tension. Previously I was going to put another screw in to adjust that force, as you wouldn't have had access to the end of the spring like you do on this single swing arm design.

I really like the single swing arm design. I'll be keeping it unless things go drastically wrong in testing.

This is turning out really sweet. One suggestion. Now you've gone to a single sided swing arm, you migh think about putting the pivot on the other side of the seat tube.

What advantage do you see with that? Geometry is pretty similar either way. Clearances to pedals is the same. Motor can is fixed in position with radial screws so no issue there. With the spring I have used it is currently winding it up (i.e. reducing it's size in diameter when under load) which is a better then unwinding in my experience. Apart from that it would be easy to flip over. I just don't see the advantage at the moment.

Having a longer pivot arm will make the arc that the motor moves in shallower. This might make the end stops less critical as the motor con't cut into the tyre at such a sharp angle.

You might be right, I haven't put a lot of effort in tuning this. Kepler has. I am running on the lower limits of the arm lengths that he found were good. The first prototype I made had the same pivot arm length and the engagement was fine once tuned, and dead-stops were not that critical. In fact thinking about John/Kepler's eBoost design I am not sure if it has this type of adjustment, and people seem to be able to set them up just fine.

The reason I have been keeping it short are to make the drive suit a larger range of bikes. The longer the pivot arm, the bigger a space you will need in this region of your bike. Obviously not a problem on my Avanti frame in the picture above, but try and put it on a modern road bike, and the is not much room in there, especially with this big motor. I think it will only just fit my road bike with this motor, as I have a large frame size. For smaller frames with less space, you would need to stick with the smaller motor size.

- Adrian

[Hillhater]

really neat, clean design Adrian.
..but i think you really need to thoroughly test it with that single arm mount as it is now relying entirely on the internal motor bearing locations to resist the "bending" forces and hold it together,.... and i have had instances of those not holding up too well !
I hope it does hold up, but the second support arm sure gives it much more support for only a few grams more weight.