Weight Sensing- Dual rear Brushless Longboard Build

[creative_motorhead]

Hey guys, I am fairily new to this forum but i thought I should share what I have done and my next project.

First my traditional electric longboard set up. Its the typical 6s lipo with a hobbywing 150A esc and a 6374 brushless motor.

 

[creative_motorhead]

All right now here is What I am really exited about. The weight sensing all around amazingly user-friendly board.

What I want to create is a board that anyone can just jump on and go and you dont have to program the charger or watch your house burn down because they batterys explode. Here is what I am thinking.

-Weight sensing
-Dual rear (probably sensored) brushless motors , Yes like Boosted.
-Integrated projection head light, led tail light that are turned on by a light sensor
-Battery management system with regular laptop charger


Also a bunch of software stuff like
-The board will automatically shut off after 3 min of non-use
-A power cut off when you manual the board.
-a battery fuel gauge on the top of the board

Lastly, and this is way out of my league but the ideal board would have an app that does basically everything this does

https://www.kickstarter.com/projects/flykly/flykly-smart-wheel



Some people dont think weigh sensing is the best way to accelerate but here is what i found. I found when i was riding mine with the hand control that i was trying to calculate and adjust my body lean in realtion to my acceleration and stoping perfectly with the amount of throttle I gave it and it is nearly impossable to get perfect. So what I am trying to say is that although the hand conrol works fine I think ( and has yet to be proven) that the weight sensing system is going to be more intuitive. (Justin built one and from what I have seen it seemed to work well).

All right the build. I have the motors, Batterys, some boat ESC's and and Ardunio for the brain.

-Batterys - 12x Single cell 5000 MAH Lipo that i am going to make into 2 22v packs
-Motors Turnigy L3040A-480G Brushless Moto ( i am using these because they are 22v, 1000w and tiny
- ESC"S - 2x 120A Hobbyking boat ESC (they where out of 90A) - I am just trying these out because they are cheap but I am probably going to have to get some sensored Kelly Controllers to make braking more accurate.
-Brain - I got the Ardunio starter kit with tons of electronics unfortunately no Strain Gauges so i have to buy them.


I uploaded a couple pictures of what i am thinking for the set up and lighting positioning.

QUESTION - Here is a problem i was wondering about. I want to put the lights on the bottom of the board in the front and i was wondering if the fact that the lights will get blocked by small hills would be a problem. (like if you only had low mounted fog lights in your car, you would not be able to see over much because the light is at such a low angle). If thats the case I will have to move them up.

 

[LEVer]

so you're able to do all of this but your problem is you don't know where to mount your light? :|

 

[daverobson08]

Mount the lights on a piece of metal plate which sits where the front riser would, extending forward and bending up 90° in front of the nose.

Best of luck with the rest, it sounds like an ambitious process. How will you go about implementing the 'manual shut-off'? Hinge switch? Gyro? Pressure switch? This bit sounds like it could be tricky.

 

[creative_motorhead]

so you're able to do all of this but your problem is you don't know where to mount your light? :|

Sorry, I must have been unclear about why I was asking the question. If there is someone who comes across this build who has lights on their board it will just save me a bit of time of testing. It probably wouldn't take long to figure out once I have the lights but if someone else all ready knows why not ask.

 

[creative_motorhead]

Mount the lights on a piece of metal plate which sits where the front riser would, extending forward and bending up 90° in front of the nose.

Best of luck with the rest, it sounds like an ambitious process. How will you go about implementing the 'manual shut-off'? Hinge switch? Gyro? Pressure switch? This bit sounds like it could be tricky.

Hey, thanks for your interest. For the manual shutoff I am going to put a couple switches under the kick tail. Then program the ardunio to shut off then any of them are hit. I think it should work fine. I will just have to make sure the switches are not hit then you are ridding the board normally, but it shouldent be a problem.

 

[beto_pty]

yes... the arduino programing.. and the lights.. and the gyro, and the torsion sensing bars... and the breaking mechanism, and the gps alert signal, the microwave charging impedance detector, the 6.6 Gigawatt flux capacitor...

BUT WHAT COLOR IS IT GOING TO BE ?

Dont take it the wrong way guy, welcome to the forum, it is just that it seems you might be trying to run the 100 meter dash before learning to crawl, or even knowing where your feet are...

Get your mounts to work, your motor to turn, your sprockets to fit, eliminate the wobble from the wheel gear, your esc to go "tata", your receiver to bind, your lipos to balance and then worry about all the awesome stuff you will add to this... Your first and formost goal should be to have a rolling motorized board. Once you have that the rest will be either apparent, or a matter of ducktaping it to your board and trying it out. Also it might make other people less "ejem" skeptical if you mention you are an arduino genious, or a bluetooth programer, battery/bms tecnichian, or a cell-phone app maker...
or very rich and generous... that will also make new friends...

 

[lpbug]

^Agreed with beto. Even supposing that you have experience with all those electronics you mentioned- integrating it all at one time is still very difficult. I think it'll be wise to prototype one step at a time and perfect each step as you go along. Also- intuitive control stems from well coded software not necessarily from hardware so keep that in mind. Balance between intuitive control and reliability is also something to consider.

Best of luck!

 

[creative_motorhead]

^Agreed with beto. Even supposing that you have experience with all those electronics you mentioned- integrating it all at one time is still very difficult. I think it'll be wise to prototype one step at a time and perfect each step as you go along. Also- intuitive control stems from well coded software not necessarily from hardware so keep that in mind. Balance between intuitive control and reliability is also something to consider.

Best of luck!

Thanks a lot for your input guys, I really appreciate it. You are totally right that what I am doing is ambitious. And also completely right about first getting the basics figured out. I guess i should have maybe said this a multi-year project that in the end will hopefully look something like what I have described but probably will be slightly different. I am going to do exactly as you guys recommended and do smaller stages and test as I go. The first stage is to get the drive system working and I will just use a hand controller. Then start with the weight sensing system, and so on. It may be a little ambitious and I may drop a few features as I go but its good to be ambitious.

 

[beto_pty]

Awesome we might still make an eboarder out of you yet!

Any idea what motor mounts you will be using?
Also why did you decide to assemble a 6s 5000 out of 12 packs? cost? size? Bms compatibility? torque always goes with his trusted 2x 3s 5000 in series, i tend to go with 2x6s 2650 in parallel... just curious why you went the multiple 1s route...
Also love the little demons. Minimotors are a blast.. not so cool and exciting is getting the motor sprocket... you are stuck with small tooth belts, the bigger tooth belts (htd5 etc) are usually unavailable in 5 mm bore sizes.. in my experience (probably due to my inexperience and poor craftmanship) belt slip was unavoidable and annoying as hell... Had to move to 8mm shafts, and the larger teeth they support. Other than that they are feisty little buggers and quite strong too...

 

[creative_motorhead]

Awesome we might still make an eboarder out of you yet!

Any idea what motor mounts you will be using?
Also why did you decide to assemble a 6s 5000 out of 12 packs? cost? size? Bms compatibility? torque always goes with his trusted 2x 3s 5000 in series, i tend to go with 2x6s 2650 in parallel... just curious why you went the multiple 1s route...
Also love the little demons. Minimotors are a blast.. not so cool and exciting is getting the motor sprocket... you are stuck with small tooth belts, the bigger tooth belts (htd5 etc) are usually unavailable in 5 mm bore sizes.. in my experience (probably due to my inexperience and poor craftmanship) belt slip was unavoidable and annoying as hell... Had to move to 8mm shafts, and the larger teeth they support. Other than that they are feisty little buggers and quite strong too...

Hey, thanks for the response.
Ya, i decided to go with the individual cells because they where the best power to size ratio i could find and because I want the bottom of the board to be completely flat (no block sticking off the bottom). I posted a drawing in yellow, that is what i want the bottom to look like. just flat except the lights. I am going to do it by covering the bottom with a plastic sheet. the plastic sheet will be about 11mm down from the deck and I should be able to fit everything in there. I know that just putting a sheet on the bottom will not look that great so the plan is to thermoform a 1/16th sheet of acrylic to fit. (I have access to a vacuum forming machine).

For the motor mounts I am making them out of 1/8th thick aluminum and welding them on the hanger. The reason I am making my own is because I want to protect the motors more so I can ride it in wet weather and over stones and I dont have to worry about damaging the motors. I have decided to weld it because the way I am designing the motor bracket I have a kind of skid plate on it, and it would be difficult to screw together,and less strong, and if I have to weld the skid plate on then why not weld the rest. I am using 150mm Paris trucks with a 43 degree baseplate in the back and a 50 degree baseplate in the front. As for the motor sprocket you can actually get stock HDT3 and HDT5 rollers and my plan was to just bore out the middle to size. Right now I am debating between the 15mm wide HDT3 or HDT5. The problem with the 3 is that you can not get a 15mm wide wheel pully. So the only options are again buy a stock roller (like 50$) OR weld 2, 9mm pullys together. So the HDT5 seems like a better system but there the problem is that the motor pulley can not be as small and the wheel pulley will be closer to the ground and as the wheels wear down the belt may hit the ground, but i am probably going to do this since its not that big of a deal.

 

[beto_pty]

Maybe 1/8 inch alum might be on the thin side... ive torn apart 3 different 1/4 inch mounts and totally twisted the hell out of 2 1/2 inch ones... the 1/2 inchers failed due to design errors on my part.. however 6s will pull...also after welding there is no going back...and you loose the trucks. .

 

[torqueboards]

Maybe 1/8 inch alum might be on the thin side... ive torn apart 3 different 1/4 inch mounts and totally twisted the hell out of 2 1/2 inch ones... the 1/2 inchers failed due to design errors on my part.. however 6s will pull...also after welding there is no going back...and you loose the trucks. .

Yeah, 1/8 inch is going to be quite small. 1/4 I think is fine as I use 1/4" thick aluminum for my mounts and they hold fine. Beto, how did you twist 2 1/2" and 1/2" motor mounts? I would imagine you would need a massive amount of force for that. I can't even twist my 1/4" thick or 6mm mounts.

 

[beto_pty]

Sorry if i was unclear iI twisted two one half inch mounts... not a two and a half inch...
The bolt runners were too close to the edges..but still it was a half inch man....

Then had to cut them off the trucks.... now my non motored board (my transportation inside the factory) is like a little gimp-board lol
Now I leave a quarter inchwide half inch thick rib around the whole thing and get no beef evn from my 12s setup...

 

[creative_motorhead]

Maybe 1/8 inch alum might be on the thin side... ive torn apart 3 different 1/4 inch mounts and totally twisted the hell out of 2 1/2 inch ones... the 1/2 inchers failed due to design errors on my part.. however 6s will pull...also after welding there is no going back...and you loose the trucks. .

Hey, thanks so much for your insight. Ya, I am supporting the motor mount on three side by connecting to the opposing motor mount so it might hold but your right, its probably a better idea to make it a bit stronger just incase.

 

[creative_motorhead]

Here is a very rough shape of what i am thinking for a motor mount (I have to make everything line up and add a holes and such). Thanks for all your input. I am thinking of going with a bolt on now.
The shaft is suppose to be a threaded rod and you can tighten it to tighten the belt. The smaller piece gets held on by the motor clamping it on the other side. The motor shaft larger hole is for a bearing.

View attachment 3

 

[beto_pty]

I like the pulling bolt design.
Very industrial and efficient... will not permit your motor sprocket from moving once you have tightened your belt...
8)

 

[Hummina Shadeeba]

Wow that's a weird mount. I still keep looking at it imagining where it's weakness could be. Ur going to add a bolt to the top n thread it I guess. How's it coming?
U cutting and drilling it all by hand?

That bike wheel is awesome. 800$.

 

[creative_motorhead]

View attachment 6View attachment 5View attachment 2View attachment 1View attachment 1View attachment 2View attachment 3View attachment 7View attachment 6View attachment 5View attachment 8

Wow that's a weird mount. I still keep looking at it imagining where it's weakness could be. Ur going to add a bolt to the top n thread it I guess. How's it coming?
U cutting and drilling it all by hand?

That bike wheel is awesome. 800$.

Hey man,
Thanks so much for looking at my stuff. I have actually been doing quite a bit of design work on it. The current mount looks nothing like that one. As for tools, I have access to a cnc milling machine and a lathe so I will use those. Also the current design is going to use some waterjet cutting, (which i have never used, but I have been told is reasonably cheap). Here is the current Design which I did just as a rough draft and has yet to be though out. Also for kicks here is a more though out version of the one I posted before.

Ok so First is my current idea. It is held on by u-bolts which are not in the renders.

 

[creative_motorhead]

So the pictures kind of screwed up, The very last one is suppose to be viewed first then go in order.

 

[Hummina Shadeeba]

I looked at the photos. I don't see how it's bolted on but see bolt holes on the plate. That's a lot of computer designing. Theres so much material I wonder how it'd hold up in polypropylene...maybe u could get it printed

 

[Martynas]

Looks nice, all i can say is good luck. I myself always wanted a weight sensing skateboard ,but i have 0 programming skills, maybe you are going to share your code with everyone so other people could also use it and make it better ?

 

[creative_motorhead]

Ya, it took a while to to do all that designing. As for printing, not sure if that would work but for now I want to make it out of metal just to be sure its going to hold up.

About the code, Forsure I am going to share. I couldn't build the board without everyone on here sharing what they have done.

 

[creative_motorhead]

Hey

Here is my latest prototype set up for Dual rear. This is only meant to be a prototype control experiment so i can make sure it is going to work and then i will take parts off and thin stuff out untill i am left with only what i need. So I know it looks overbuilt. You cant see it here but on the flat piece of metal connecting the motor to the hanger there is actually a gap were shims are going to go. The reason I did that is so that if I hit a curb or something there is no chance it is going to break off.