QUADROTOR

PURPOSE• Agro Studies

DESIGN REQUIREMENTS• Can remain static in air

• Moderately stable

WHY QUADROTORS• Fixed winged can’t remain static

• Helicopters are very useful –but fragileLots of moving parts, lots to go wrong

• Quad-rotors can have only four moving parts!

Simple, robust, reliable, low maintenance

DESIGN CHECKLIST

• Rotor Design

• Drive System

• Attitude Control

• Control Feedback

PROPELLERS

• 10kgf total thrust

• 2.5kgf per rotor

• 30% margin gives 3.25kgf per rotor

• 3.25kgf = 31.85N

PROPELLERS• Lift produced is as evenly spread as possible from hub to

tip.

• High quality carbon fiber, they are stiff, yet extremely light in weight (14.5 grams).

• Specifications:Diameter: 17 inchesPitch: 5.5 inchesRotation: Left and Right pair Shaft Hole diameter: 5mmDrive Hole diameter: 3mm

PROPELLERS• To avoid blade tip interference, set rotor

separation R

• R = 215.6 mm

• Momentum theory gives power as P = / (A)

Expected 425.1 W per rotor

DRIVE SYSTEM• Need 425.1 W in air per rotor

• Rotors are % efficient

• Expect motors to be % efficient

• Battery supplies W to each rotor

MOTORSSpecifications:

• Model: NTM Prop Drive Series 50-50 580kv• Kv: 580rpm/v• Max current: 90A• Max Power: 2000W at 22.2v (6S) • Shaft: 8mm• Weight: 347g• ESC: 100A• Cell count: 4s~6s Lipoly• Bolt holes: 30mm• Bolt thread: M4• Connection: 4mm Bullet-connector

BATTERYSpecifications

• Minimum Capacity: 5000mAh• Configuration: 6S1P / 22.2v / 6Cell• Constant Discharge: 30C• Peak Discharge (10sec): 40C• Pack Weight: 805g• Pack Size: 145 x 50 x 50mm• Charge Plug: JST-XH• Discharge plug: 5.5mm Bullet-connector

ESCSpecifications

• Output: Continuous 120A, burst 180A up to 10 seconds.

• Input Voltage: 5-12 cells lithium battery or 15-36 cells NIMH battery.   

• BEC:  None.• Control Signal Transmission: Optically coupled

system.• Max Speed

  2 Pole: 210,000rpm    6 Pole: 70,000rpm  12 pole: 35,000rpm

• Size: 88mm (L) * 55mm (W) * 15mm (H).• Weight: 125g

STABILIZATION BOARD Specifications• Operating voltage: 3.7~22.2V (no UBEC is required) • Dimensions

MC: 92x61x18mmMU: 48.5x40.5x22mmGPS/Compass:55x11mm  2.4ghz WiFi unit: 65x40x14.5mm

• Weight (w/all components): approximately 212grams• Way points: 4 Programmable as standard (Upgradeable)• Included in box:

1x Main Controller1x IMU1x GPS/Compass1x 2.4ghz WiFi1x Damper PadWires/CableSerial 9 cable

DYNAMICS

HOVER

All rotors have same angular velocity

YAW

Two rotors rotating in one direction have more thrust

PITCH / ROLL

One rotor have higher speed than its diametrically opposite rotor

PID CONTROL

• The ESCs are powered by the Li-Poly cells–Large speed changes can instantaneously

draw very high current (up to 100 A per motor)–Causes bus voltage to sag–ESC microprocessor resets (very bad!)

• Use software slew rate saturation to prevent dangerously large steps

–But then what about our speed response?!• Control to the rescue

–We can use proportional control with a feed forward term to anticipate and reduce instantaneous demand

PID CONTROL

PID CONTROL

 : Proportional gain, a tuning parameter: Integral gain, a tuning parameter: Derivative gain, a tuning parametere( )t : Error 

Proportional term• Process Error value proportional to current

error value• = * e( )t

PV vs time, for three values of Kp (Ki and Kd held constant)

Integral term• Process Error proportional to both

magnitude of error and duration of the error

•  Sum of the instantaneous error over time• Gives the accumulated offset that should

have been corrected previously• = ) t dt

Derivative term• Process error by determining the slope of

the error over time and multiplying this rate of change by the derivative gain 

•  Predicts system behaviour and thus improves settling time

• =

Thank you