Mr. Tool

“Because you’re a tool and left the garage dirty, again!”

Max Koessick IMDL Summer 2003

Mr. Tool Project Brief Autonomous vehicle that will

detect and collect ferrous tools from a garage floor in a random pattern Based on 1/16th scale R/C tank

chassis (Originally >$300) Behaviors implemented

include: metal detection, obstacle avoidance, target acquisition, target collection

Mr. Tool Processor Overview Originally used ATMega 128 with Atmel

STK500/501 ($79/$79) ATMega323 (Included) Uses:

4 PWM’s (8 Bit) 3 External IRQ’s I2C (Two Wire Interface) 12V (10 1.2V/1800mAH NiMH AA’s)

Mr. Tool Mechanical Overview Powered by single Marubuchi RS-540S 6V, 1A,

11,000 RPM motor and stout gearbox

Metal track and 28 wheel independent torsion bar suspension; 4 fixed wheels 2 front wheels control track tension 2 rear drive sprockets

Dual clutch for track control (one motor = no turn in place)

Mr. Tool Mechanical Overview Servos move mechanical arm for clutch and

switch for speed control Direction control (clutch)

Slip turn Pivot turn

3 Forward and 3 Reverse Speeds Only use lower two in both F/R Third speed only effective in O’Dome or for

chasing cars

Mr. Tool Mechanical Overview Carbon fiber/aluminum lifting arm (Free!!)

Original direct drive ineffective New winch style much more effective

Tamiya Planetary Gearbox ($11) 400:1 Reduction at 18,000 RPM Advertised 15Kg lifting force

Mr. Tool Mechanical Overview Tamiya Planetary Gearbox (Continued)

Required 3V input is supplied by PWM 7.2V H-Bridge .5A Stall Current Draw 1A Texas Instruments SN754410 Quadruple H-Bridge (Free!!)

Electromagnet ($35) 30 lbs of lifting force Control by TTL Power FET Fairchild H76107P (Free!!) Shares main 7.2V Battery

Mr. Tool Mechanical Overview Power Supply

(24) 1.2V 1800 mAH NiMH 10 required, others for backup Fabricated 10 cell battery holder

(2) 7.2V 3000 mAH 1 required, 1 backup

Provisions for ‘Shore Power’

Mr. Tool Sensor Overview Daventech SRF08 Sonar ($54)

I2C (TWI) at 100kHz Pings every 65ms Read low byte of closest object No platform interference (parallel

surfaces) Mounted on servo

Mr. Tool Sensor Overview Bump Switches (¢65)

Front Collision – Replaced by Sonar Rear Collision – Replaced by digital IR—now used to start

code (bump to start) Target Acquisition

Determines possible target (2) located on front collector Selectable negative or positive logic through 10k pullup In series, normally closed Port protection through 150Ω series resistor

Mr. Tool Sensor Overview Hall Effect Geartooth Sensor—Cherry Sensors

GS100701 ($32) Metal Detection, no external magnet needed Negative logic External IRQ

Mr. Tool Sensor Overview Sharp GP2D12 IR Sensor

Originally used digital GP2D15—toasted with reverse battery

Devised digital conversion instead of using ‘Next Day Air’ to buy new one (@ $43)

Digital conversion uses LM311 Comparator and a reference voltage set by a potentiometer

Distance (in) Output (V)

15 .4

14 1.1

13 5.32 (Vcc)

Mr. Tool Sensor Overview Sharp GP2D12 digital output conversion--Protel

Mr. Tool Daughter Board 2 Layer Protel design, intermediate between sensors

and development board (4.9”x2.8”)

National LM1085 5V, 3A regulator on large copper heatsink

Power supplied by 7.2V motor battery

Noise suppressed by 100uF input capacitor

Mr. Tool Daughter Board Houses Power FET, H-Bridge, pull-ups, and

sensor jumpers Large board mounted copper heatsink planes for H-

Bridge and TO-220 Packages

To prevent unwanted shorts, rubbed out entire board by hand with Dremel

60 mil traces—handles large amounts of power, not susceptible to board flex

Mr. Tool Daughter Board

Mr. Tool Daughter Board

Mr. Tool LED Board Constructed on protoboard

+5V→Anode Cathode→330Ω→Port Pin

Mr. Tool Concluding Remarks Will it be done by Thursday?

Will I sleep? Maybe and maybe

Behavioral code complete-mostly tested 1 day to add winch assembly, front bump switches

(circuitry in place), and basket 1 day left for Murphy Painted by Media Day (Orange and Blue splinter

camo)