Building Mongoose Mechatronics Robot: Part 1 with PIC18F2525

Contents hide

1 Building the Mongoose Mechatronics Robot: Part 1 Chassis & Gearbox

2 Preparing the Gearbox for the Dual Rotation Sensors

3 Adding the rotation encoders to two blue gears.

Building the Mongoose Mechatronics Robot: Part 1 Chassis & Gearbox

This is the first of a series of illustrated instructions for assembling the Mongoose Robot kit available from blueroomelectronics

Mongoose highlights:

- Powerful PIC18F2525 microcontroller (32KHz to 32MHz)
- Hardware PWM controlled SN754410 H-Bridge with thermal shutdown
- Differential drive with powerful 114.75:1 gearbox
- Low drag steel ball caster with steel rollers
- Dual optical rotation sensors (108 transitions per revolution)
- Dedicated in circuit programming / debugging connector
- Dedicated TTL Serial port (EUSART)
- Generous 400 hole solderless prototyping area
- Top mounted 20pin I/O for breadboard or LCD display
- Forward facing standoffs with 10pin I/O connector (0.1″ PCB compatible)
- 10K trimpot and high brightness LED headlight (programmable)
- Very low center of gravity for stable operation
- Small enough to take anywhere 115mm x 110mm x 60mm

Requires 4x AA NiMH batteries

Programmable in ASM, Swordfish BASIC SE & C18 SE

Part 1: Chassis & Gearbox
Part 2: Electrical, motors & battery holders
Part 3: Electronics, 18F2525 Controller & SN754410 H-Bridge
Part 4: Final assembly, Main driving wheels, solderless breadboard
Part 5: Programming & Testing using Swordfish BASIC SE (free) & the Junebug (PICkit2)
Part 6: Demo code LCD, PWM and Tachometer examples

Requires a PIC programmer, see the blueroomelectronics site for details.

Preparing the Gearbox for the Dual Rotation Sensors

The Mongoose uses a Tamiya Double Gearbox. Part T4 requires a simple modification to allow the optical rotation sensors to monitor wheel rotation.

Simply remove by sanding or cutting away 5mm of material (plastic) from the main gearbox casing as shown in the illustration below.

Adding the rotation encoders to two blue gears.

The blue gears as shown below are IR transparent, so we’re going to add IR opaque aluminum foil to a set of gears one for either side of the gearbox (the blue gears are all identical so any two will do)

The kit includes a small piece of self adhesive aluminum foil with a hole punched in the center.

You will need two of the blue gears as supplied with the kit.

Cut the foil into four pieces using the hole as the center.
Remove the adhesive backing from the foil only when you’re ready to apply it
Apply two foil pieces to each gear, each foil piece should be opposite each other.
Carefully burnish the foil onto the gear with a toothpick or soft burnishing tool (the example below use a piece of spruce from the gearbox assembly)
Carefully trim away excess foul by slowly running a sharp hobby knife through the foil as show in the pictures below.

For more detail: Building the Mongoose Mechatronics Robot: Part 1 Chassis & Gearbox using PIC18F2525

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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