Automatic heat source finding laptop cooling pad By Team 26 ECE 445 Automatic heat source finding laptop cooling pad By Team 26

Introduction Objectives Design review Block diagrams and schematics Success and challenges Future improvements

Objectives Features: Automatic heat finding system Fan speed changes according to the temperature LCD display panel

Basic Design A skeleton case (including tracks) 4 IR sensors Circuit board Bumper system

OUR DESIGN

Block diagram

Grove IR sensor This sensor outputs an analog voltage (0 ~ 1.1V) according to target’s temperature Measure accuracy:  ±2℃ Temperature measure range:  -10~100 ℃ Nominal measure distance: 9cm Cut on wavelength: Min 4.7 um, Max 5.3 um

Sensors in our design

Feature of the IR sensors This sensor outputs an analog voltage (0 ~ 1.1V) according to target’s temperature Measure accuracy:  ±2℃ Temperature measure range:  -10~100 ℃ Nominal measure distance: 9cm Cut on wavelength: Min 4.7 um, Max 5.3 um

Circuits

H-Bridge SN754410 There are basically three states for the H-bridge we use Function table:

H-bridge (continue) What we have for H-bridge Output current range <1A Supply voltage range 4.5V to 36V What we need 0.6A current for fan 12V voltage for both fan and motor

Voltage regulator Formula: ( 𝑅 𝑓 𝑅 𝑔 )=( 𝑉 𝑜𝑢𝑡 𝑉 𝑖𝑛 −1)

Micro-controller Atmega328 PU Max Op Frequency : 20 MHz Flash (Kbytes) : 32 Kbytes 14 digital pins 6 analog pins Output maximum voltage: 5V Output maximum current : 40mA

PID control and the fan Both P and D value are set high for quick reaction to rising or falling temperature (Kp=15 Ki=0.01 Kd=2) We programmed the fan to have it follow the hottest spot on your laptop

Reset button Four reset buttons attached on each side When the fan hit the wall it would stop moving toward it’s previous direction

Several changes we made Switch from TMP006 to Grove IR sensors Use a H bridge to drive the motors instead of a voltage amplifier Change from PCB board to vector board

Tmp006

The temp006 circuit we built The temperature we measured using this circuit is unstable (from 10°C to 40°C) It took a whole afternoon to solder this and we need 4

PCB

Problem with this PCB We did not left enough Vcc and ground pins when we design this PCB We did not left pins for the input from our bumper The output for the motors changed as we insert our h bridge into the board (we still cannot figure out why) As a result we changed to a vector board

Accomplishments Fan spins according to the temperature Correct tracing of the hotspot LCD works perfectly Programs runs flawlessly Reset bumper detects boundary conditions

Difficulties Spend way too much time on soldering Program at start was way too buggy Spend a lot time on finding the correct IR sensor Burned at least 3 chips and a LCD Gluing everything together

Future improvements Cut down the cost for IR sensor Make the cooling pad more mobile Have everything powered by the USB Have the desired temperature set by user Make the fan more quite Make the motor more quite

Thank you! Questions? Comments? Flowers?