Power Wheels Racer Post-Race Update

So I did not really keep up with posting about all that has happened with the car lately but now that we are back and unpacked from Maker Faire I am going to update everyone on what we did. As far as the race goes in Orlando we had a great time up there and all the cars everyone brought were awesome. Here is a short video of the race so that you guys can see all the cars!

Although our car had some speed we actually were not able to finish the race due to burning our speed controller. Basically what happened was the connector that was between the forward and reverse and the speed controller melted from the motor running as long as it had to during the race. As that plug melted the two copper lead got closer and closer together until the shorted the wires running out on the speed controller this short then caused the speed controller to burn up. Here are some pictures of the damage. 

So after we really didn't think we had any chances of racing again. We had no replacement speed controller and after calling a few places in the Orlando, the internet was really the only place that we were going to find a 36V 1000W motor controller, but we didn't have time to wait for shipping. Then after talking to some of the other racers the guys over at Familab told us they may have a spare speed controller at their makerspace and they would let us borrow it if we came by to check out the lab. We took them up on the offer. They have a really cool setup over there with a lounge and hangout area plus some really awesome machines in the back. They had a manual mill and lathe, a CNC mill, one really big 3D printer, and lots more. I would highly recommend giving their lab a look if you are in the Orlando area.  And they let us snag a Kelly Controller 24V 400A speed controller to try to rig up on Sunday morning. We found a wiring diagram from Kelly controllers website and tried to follow it as best we could. We actually had to drive back to their space to grab a few extra parts. There was a main contactor, a few diodes, and a precharge resistor. After we had all we needed we still weren't quite able to get it back up and running that weekend.

Since Maker Faire, we ordered a new speed controller and decided to add a voltmeter and ammeter to the car so the diver might have some idea of what is going on back there. While I was driving I really had no idea that something was wrong until the motor locked up from the leads touching. Here is a link to the one we got below.

https://www.amazon.com/MICTUNING-6-5-100V-Digital-Voltmeter-Multimeter/dp/B01JOUZELG/ref=pd_lpo_469_tr_t_2?ie=UTF8&psc=1&refRID=V1PWGVGCC9264MT29MXX

That shunt that comes with it is basically just a really tight tolerance, low resistance resistor so that the meter can measure the voltage drop across it to get the current. If you want to know more about that resistor look up manganin resistors, they were actually used in determining the standard for the ohm back in the early 1900's. Also, Bryan made an Arduino circuit with a few temperature sensors so we can display the heat at a few different places in the circuit on the dash too. With the temperature, voltage, and current readings we are going to hopefully be able to diagnose any problems the vehicle has in the future faster and catch them before a controller looks like it got left in the oven too long (see picture above).

Power Wheels Racer: Car Updates Before Maker Faire

So as I talked about in the last post there are a few things that needed to be done to the car before it is ready to race up in Orlando. We read over the power wheels racing rules and found some things that we needed to comply with. First thing was the bumpers. We needed bumpers that covered 75% of the vehicles front and rear and covered a 1" space between 4-6" off the ground. So we ordered some aluminium tubing from Mcmaster Carr that already had holes in it and they even gave us the option to buy hardware to join them. After the tubing came in I took the stuff over to FAU and cut it to size on a circular saw and assembled it.

Front Bumper

Rear Bumper

Then we wanted to make sure that it wasn't going to tear up other people's cars while it was on the race track to we opted to just buy some pool noodles and tie then on the bumpers. In order to keep the colors right though we ended up painting them at maker faire. We also added some stickers to the car to make it fit our theme of hitchhikers guide to the galaxy, with the number 42, since it is the answer to everything.

The next update was the steering. We had a pvc steering wheel on there but there were a couple of things about it that weren't as good as they could be. For one the pvc is not real strong and could break. Also the hole through the steering column is not the same as any size screw you can buy at 0.3340" so no matter what bolt went through it there was some play in it. And finally, the steering wheel design made it tough to sit in the car because it took up a lot of space. Really the only way to get your feet inside of that thing is to pull your knees to your chest and if the steering wheel is there there would be no room for your knees. We decided on just making a joystick for the steering. We bought some aluminum rod, a smaller stainless steel rod, and a 10-24 Wingnut then I took the stock to the lathe. Here is what we were left with.

So the small stainless part was machined so that it would barely fit through the hole with about 20 thousands of an inch clearance. Then I 3D printed some couplings that would fit tightly around the shaft of the car and would house the aluminium rod and the wingnut. After we printed those the joystick was assembled and we wrapped it with some bike tape for grip. But when we put the throttle on there the aluminum rod was a little too big and tore up the hall effect sensor in the throttle so we had to order a spare and print a coupling from the shaft to the throttle. This kinda worked out for the better because the longer the joystick the easier it should be to turn. 

In the picture above you can see the forward neutral and reverse switch that Bryan added. He found one that used to be on a golf cart for pretty cheap and we wired it up so that the motor leads from the speed controller ran into it and then to the motor. It basically works as a mechanical switch so that the voltage applied to the motor is either forward or reverse or the leads aren't touching.

The last two things that we added were the kill switch and the fog machine. We 3D printed a coupling to go from the kill switch we bought so that it would be secure on the back of the car. The way it works is when the red key is in there is connection and the vehicle will operate. When the key is removed the speed controller will not allow any voltage to the motor. The fog machine is a dry ice container under the 42 on the front of the car and has a cap where you can add hot water to get the smoke going. Then the pipes run out to the back where the smoke would come out. I do not have any video of the fog machine yet but I will get some to post soon.

Power Wheels Racer

So we are nearing race time for the power wheels racer and trying to get it race ready so that we can get a driver some practice time around the shop before we race it next week. It got a new paint job today and a motor cover but there are some more fixes to be done before it is ready to go.

Updates to be done to be race ready

• Front and rear bumbers
• Kill Switch
• Paint Steering Wheel
• Cut and mount extra PVC piece on steering wheel
• Reverse
• Obtain 1 1/2" wrench to tighten back wheels
• Driver foot rest
• Chain Guard

Pi Zero Drone Post 7: Modular Body

Quadcopter Post 7: Modular Design

To the reader who has a smaller print bed and wishes to print this part I have designed a modular frame that will hold all the same components as before. Each print will not exceed a 114mm x 114 mm

I have attached the STL files with this post 

Here is a link to the STL Files:

http://www.thingiverse.com/thing:1795928

Nano Blade QX2 Repairs

We have two of the Nano Blade QX2 drones at the Boca bearings workshop and I have to say they are a really great option for someone who wants to get into FPV flying/racing. Horizon Hobby sells them for $159.99 and they are sold as a BNF (Bind and Fly package). Only thing about them being bind and fly is that they have to be controlled by a Spectrum transmitter or any other transmitter that has DSMX or DSM2 protocol. However it seems to be mostly Spectrum radios that have it. And we have been using the Skyzone and Fat Shark Teleporter headsets to fly the drones.

We actually only had one of them at first though. But per usual we ran it into something and the drone broke. But that is part of flying drones. I wish I had a picture right after the crash but basically what happened was the camera case on the front of the drone broke and the camera split in half. We began looking around online and we really could not find anywhere that had the replacement parts.

Here are a few of the websites we found:
https://www.hobbytown.com/blade-nano-qx2-fpv-replacement-parts-racing/c10178
https://www.amainhobbies.com/blade-nano-qx2-fpv-replacement-parts-racing/c10178

The only thing missing from the replacement parts list above was the camera and camera case. But we did manage to find that online too.

Camera Case:
http://www.fpv-direct.com/blade-camera-mount-inductrix-200.html?utm_source=google_shopping&gclid=COqG8qCZoc8CFYdZhgodrysPgA

Camera:
https://www.amazon.com/gp/product/B01EZLYT24/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

But instead of ordering the camera case I figured it wouldn't be too much to draw something up in CAD to replace the case instead of ordering it. And I wanted to get more familiar with Onshape. Although I am more fluent in Solidworks from using it at school Onshape is a pretty awesome program because it is all cloud based. That means that you can pretty much use it on any computer you have as long as you have pretty good internet connection. I even have it on my phone, which totally blows my mind. Because you could have a $500 dollar laptop with a 2.0 Ghz processor 4GB of RAM and still be struggling to run Solidworks. And Onshape makes it pretty easy to collaborate with other people on the same project. Here are some screenshots of the parts I made in Onshape.

Now the real tricky part of repairing the cameras on these drones is that the wires connecting everything are super super tiny. And when I say that I mean 4 stands of braided wire tiny. Which means while you are soldering them you have to be real careful not to pull them out (which I did multiple times). Here are some pictures of the iron and microscope I used to solder it back together.

 Had to scrape the adhesive off to reveal the pad I was going to solder it to.

So after that was done I 3D printed the new camera holder out of ABS and decided to use acetone to "weld" the two pieces together. That is one of the cool parts of using ABS not only is it stronger than PLA but it dissolves in acetone so you can glue two pieces together by melting the two pieces a little bit and holding them together until the acetone dries which happens pretty fast. The bottle below has the acetone is it and I use the sponge on top to wipe it onto the plastic and melt it.

And here is a picture of both of the drones. Now that we have two of everything we will have to get some races going soon. Hopefully we can make that happen and I will have a video to upload.

Luke Ridley

Pi Zero Drone 6: After First Flight and Mods

Quadcopter Blog Post #6: After first flight and mods

After the failed test, instant modifications to the design must be made. The most importantly was to protect the hardware so that no more time and money is lost waiting for parts. I have added a 3-D printed ABS cover that will protect the PXFmini connections and also add some style to the quadcopter. The design of the cover can be seen in the picture below:

CAD MODEL OF ABS COVER

In addition to protecting the quadcopter brains, the controller of the quadcopter has not been as responsive. Some research lead to a possible solution, the APM software that I am connecting to via Wi-Fi was interfering with the signal of the RC controller. The theory is this the Wi-Fi of the PXFmini operates at its own frequency band and the same goes for the RC controller. If the PXFmini comes close to the same band the PXFmini signal will be distorted and must be changed. In the US, a certain frequency band must be used for operations set by the Federal Communication Commission (FCC). Without getting too much in depth, you must choose the channel bands if you are operating in 2.4 GHz (Channel 9) or 5 GHz (Channel 40). Check out the chart below:

CHARTS OF FREQUENCY BANDS (2.4GHz Bands & 5 GHz Bands image)  

To check if the PXFmini is operating in the right channel use this command:

WIFI HOTSPOT COMMAND

Check the channel # in the following file:

WIFI HOTSOT SIGNAL FILE

Make sure that the channel # is 40.

Now check the signal strength using this command:

WIFI SIGNAL CHECK

After it is changed, connect to APM and turn on the controller. The interference has now been fixed.

Pi Zero Drone: Test

Quad Post 5: Test

Check out the video to see how to arm the quadcopter.

Arming Video:  https://www.youtube.com/watch?v=9BmgpX3vKM0

Quad copter test 1….. FAIL

Crash Video: https://www.youtube.com/watch?v=GUAmSo_e-a0

Crash Picture

After this test the PXFmini GIPO pin connection sheared from the PCB board and became useless. But from the video evidence I suspect that the trim on the remote may have been to an extreme right and also a bad ESC calibration. I am waiting for a new PXFmini to come in and I will retry.

There have been some modifications of the design on the quad:

• Shorter legs with Lipo Battery slot made from ABS plastic.
• Roll cage that will save PXFmini from future crashes.