Introduction: Halo Scorpion Tank
This instructable was created in fulfillment of the project requirement of the Makecourse at the University of South Florida (www.makecourse.com). This is my step by step process on designing and making a fully functional Halo Scorpion Tank.
The link contained below is a public google drive link I made containing the arduino code and the Cad files.
This will involve mainly 3D printed parts, a hot glue gun and a some hardware to assemble the project together.
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Step 1: The Physical Model of the Tank.
The design is modeled on Solidworks 2019, It features the full chassis. The main design features the chassis split in half to be print on the Ender 3 printer. the rest of the parts include the upper aft armor plating and the upper starboard plating. two connector plates used to bolt both halfs of the chassis together. The turret and cannon are printed separately as two pieces. The final piece being printed are the two front wheel axles. please note that teh modeled wheels in CAD are just for show, the actual wheels are bought parts.
Step 2: Electrical Interfaces
The control system I decided to go with utilizes two DC motors and one servo motor. the servo motor controls the turret with three predetermined positions at 0 degrees, 90 degrees and 180 degrees. The two DC motors make up the drive train of the entire system and are positioned in the rear for a rear wheel drive tank. The control scheme itself utilizes the arduino UNO and parts from the UCTRONICS store. The parts received from UCTRONICS store are the motor controller (second pic), the battery pack, the servo and the two dc motors. The final image contains the full wiring harness wired together inside the chassis. In the block diagram image located above you'll see that the system is controlled via infrared (IR), this control scheme works perfectly with the UCTRONICS motor-controller because the motor-controller contains a built in IR sensor, thus reducing the physical electronics package. The last image is the IR remote controller which can be swapped and programmed with any IR remote control you desire. This is best explained in the Arduino code sketch step.
Step 3: Arduino Sketch
The arduino sketch for the entire assembly is very simple. It uses the adafruit motor controller library to control the DC motors, the standard servo motor library to control the turret, and the infrared sensor library to control the entire tank itself. The structure of the code allows you to use any IR remote controller and find the corresponding values on the remote to program the arduino to work with any IR remote.
Step 4: Fabrication
The fabrication and assembly of the assembly is very simple the two halfs of the chassis are bolted together using 6-24 screws, any length of 6-24 screws are acceptable. the chassis is 3D printed with holes already modeled into the CAD file. the motors also come with M3 machine screws that bolt into the frame of the assembly. I only use one screw per motor to provide enough clearance to the wheel when they stick into the motors. The 65 mm wheels slide into the shaft on the motors (see pic 3) and the heads of the screws stick out a little, hence only one screw is needed to assembly the structure motors the chassis. The motor's are then held in place via hot glue to provide better structure and security to the motors. The front wheels are held together via a 3D printed shaft and uses 3 #10 SAE brass washers as shims to properly space out the front wheels. The wheels are then secured together via hot glue. This does make the assembly permanent but it makes the assembly quite strong. the internal electronics are held together using double sided sticky tape holding the battery and the motor motor controller and arduino. The next step is to use hot glue to fasten the servo in the rear for the turret assembly. The second to last photo shows how that the front plate has holes drilled into it. This is a post process procedure on the forward upper armor plating of the tank. Four holes are drilled in using a 3/8" drill bit, the two wholes upfront are for the battery wires being routed from the rear of the tank to the front where the motor controller slot is. The second front hole is drilled out to create a clear line of sight for the IR sensor to come into contact with the IR remote. the turret is 3D printed and hot glued together and is then glued on top of the turret. the last step is to secure the top plates together onto the chassis. The front bumpers are then hot glued onto the front and rear of the chassis. There are many methods for this but I prefer using special colored duck tape to secure the entire assembly together. it helps hold down any loose wires and it acts as way to add livery onto the tank itself.
Step 5: Tank in Operation
These videos show what you are working toward. In your projects, this shows a demo of forwards backwards pivot turn and the turret position changes.