Published December 30, 2018 © MIT

Robot Car Base - Raspberry Pi - IoT Core

Heavy duty robot car base operating at 12V DC. Using speed controllers and a Raspberry Pi to handle communication and control.

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Robot Car Base - Raspberry Pi - IoT Core

Things used in this project

Hardware components

CIM Motor

Specifications Free Current: 2.7 AMPs Free Speed: 5,310 RPM Maximum Power: 337 Watts Stall Current: 133 AMPs Stall Torque: 343.4 in-oz Voltage: 12 Volts

120 A Breaker

Specifications Manufacturer Part #: CB185-120 / CB3-SM-120 Size: 2.9 x 1.9 x 1.5 in. Style: Manual Reset Thread: 1/4-28 threaded studs Weight: 0.24 lbs

ATC/ATO 8 Gang Fuse Block with Ground Terminal

Specifications Maximum Current: for all circuits is 100 Amps Size: 3-3/8" x 4-3/8" x 7/8"

Raspberry Pi 3 Model B

Running IoT Core

12V Battery

Larger 12 V 18 Ah Battery. I'm using a smaller old power drill battery. Specifications AMP Hours: 18 Life Expectancy: 100% Depth of Discharge: 200 Cycles,80% Depth of Discharge: 225 Cycles,50% Depth of Discharge: 500 Cycles Life Span: 3-5 years in float service application,1-2 years in competition robotics at peak performance,but longer as a practice or demo battery Manufacturer: Interstate Batteries Manufacturer Part #: SLA1116 Material: ABS plastic Size: 7.1" long x 3.0" wide x 6.58" tall Style: Sealed Lead Acid Voltage: 12 Weight: 12.5 lbs each battery

Sabertooth 2x25A Motor Controller

Product features Combat robots up to 100lb. Normal and hobby robots up to 300lb. Input modes: Analog, R/C, simplified serial, packetized serial. Sabertooth 2X25: 25A continuous, 50A peak per channel. Size: 65 x 80 x 20 mm / 2.6" x 3.2" x .8". Weight: 96g / 3.5oz. Uses: Differential drive robots. Electric vehicles, ride-on toys, scooters, and more!

Lexan

CIMple Box - Single Stage Gearbox

Specifications Gear Type: spur gears, 20 dp, 14.5 degree pressure angle Material: 4140 steel,Nylon 6/6 with long fiberglass fill Output Shaft: 1/2 in. diameter, with 1/8" keyway, 4140 steel Weight: 1.40 lbs

Jumper wires (generic)

PWM Cables

.25 x 20 TPI Bolts

Standard Quarter-20 Bolts of required sizes.

Wheels- 8in Pneumatic

Requires : Sprocket - Mounting Kit - and Bearings - https://www.andymark.com/products/3-8-in-id-flanged-shielded-ball-bearing-fr6zz?via=Z2lkOi8vYW5keW1hcmsvV29ya2FyZWE6OkNhdGFsb2c6OkNhdGVnb3J5LzViNmEwMjc4YmM2ZjZkMTNlYWE1NDQ5YQ Specifications Bolt Pattern: 6 holes, 0.20 diameter on 1.875 in. diameter bolt circle Bore: 1.00 in. thru hole, with 1.125 in. x 0.375 in. deep bearing pockets Diameter: 7.65 in. Load Capacity: 120 lbs Material: black polycarbonate,gray rubber Maximum Pressure: 35 psi Tread Width: 2 in. Valve Stem: The valve stem may stick out up to 0.375" from hub Weight: 1.13 lbs Width Across Middle: 1.8 in.

Pneumatic Wheel Mounting Kit

Bearings

Software apps and online services

Microsoft Windows 10 IoT Core

Hand tools and fabrication machines

Hand Drill

Wrench

Wire Crimper, Cutter, Stripper

Story

As a FIRST Robotics Mentor, I'd like to create a base platform to help teach kids all kinds of programming and design techniques. Particularly how to use.net to write IoT / robotics programs. This foundation will have enough processing power on the robot to add other attached functionality, wireless connectivity, and enable a simple control architecture with a simple analog input from mobile devices.

The base drive system is powered by 2 of the FIRST standard CIM workhorse DC motors. Power is handled with a simple transmission attached to each CIM driving a chain attached to a pneumatic drive wheel. The other wheels allow for easy rotation.

Energy is provided by 12 DC batteries through a fuse base and provided to speed controllers. A separate battery pack will be provided to ensure that the Pi isn't exposed to current supply fluctuations under heavy load from the motors.

Control signals are produced by the Pi as PWM signals and relayed to the speed controllers. The signals are created based analog inputs coming from the mobile app.