ME451A: BTech Project

Modular Aerial Vehicle(ModAV)

Team Members: Rohit Gupta (14567) | Mandeep Singh (14363) | Rohit Choudhary(14565)Supervisor: Dr. Ashish DuttaDepartment of Mechanical EngineeringIndian Institute of Technology Kanpur

Motivation

Design a modular configurable aerial robot which would address following problems and is a remedy of such problems :

- Optimum resource allocation for given payload.- Different configurations of the aerial vehicle can be advantageous for different

applications.- Scalable to payload needs.- Compact packing and transportability of the aerial vehicle.

Deliverables

- Modular docking robots in controlled environment.- Aerial Vehicle capable of delivering light weight objects (payload of 10-50

gram) to a distance of around 5 m.- Flight height of more than 5 meter- Flight time of more than 1 minutes.

DESIGN CALCULATIONS

Weight CalculationsS. No. Part Name Quantity Weight (g)

1 Block 4 3.62

2 Rotor Base 8 21.33

3 Pinion 16 8.65

4 Docker Block 8 17.5

5 Docker Face 8 6.65

6 Wire Frame 8 2.7

7 Wedge 1 16 0.04

8 Central Unit Base 1 40.58

9 Central Unit Side 1 2 25.07

10 Central Unit Side 2 2 24.81

11 Central Unit Cover 1 39.24

12 Wedge 2 4 0.51

13 Lock 4 12.09

17 Motor Shaft 4 3.05

Total 780.0

(Excluding electronic components)

Selection of motor and propellers:

Setup:Total weight of the aerial vehicle (W)~= 1700g Number of motors (n) = 4Average Efficiency of motors ()=80%Now, total thrust required at full throttle assuming = 100% (using MCCORMICK METHOD)

= 2 * W = 2 * 1700 = 3400g

Taking into account efficiency of motors, we calculate thrust at 80% throttle which roughly corresponds to 80% power/efficiencyTherefore, thrust required at 80% throttle (T) = 3400gThrust required per motor = T / n

= 3400/4 = 850g

Thrust Calculations

(THRUST CALCULATIONS ECALC BY MCCORMICK METHODS-

http://www.calvin.edu/academic/engineering/2014-15-team02/content/THRUST%20Calculations%20eCalc%20by%20McCormick%20Methods.pdf)

(Performance of Propellers - http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html)

Comparison of thrust produced by given rotor & propeller combinations are shown below

Dimension of propeller are given as (Diameter in inches) X (Pitch in inches)

http://rcbazaar.com/product.aspx?productid=4746https://www.kdedirect.com/collections/uas-multi-rotor-brushless-motors/products/kde2315xf-965

Thrust Calculations

Rotor Propeller Throttle Current(A)

Voltage(V)

Thrust(g)

Cost(Rs)

1 Avionic 3506 12x3.8 83% 12.9 11.1 870g 1350

2 Avionic PRO C3536 9x3.8 100% 17 11.1 1070g 1535

3 KDE2315XF-965 10x3.3 87.5% 10.7 11.6 900g 4000

4 KDE2814XF-775 12.5x4.3 87.5% 11.0 11.6 1060g 4600

Formula for thrust (T)obtained using momentum theory

T = 2ρAω2

for the selected motor is calculated by multiplying rated KV(RPM/V) rating by rated voltage.

ω= KV (RPM/V) * V = 850 * 11.1 = 9435 RPMA = pi *(12.5/2 * 2.52 * 0.01)^2

Therefore, T = 2 * 10^-3 *pi *(12.5/2 * 2.52 * 0.01)^2 * (9435)^2 = 15.4N

Thrust Calculations using momentum theory

Control Volume for air flow

Selection of Battery:Total discharge rate required: 12.9*4 = 51.6A = 51.6C

Voltage required: 11.1

Desired Flight Time: around 5 minutes

Desired mAh of the battery > (Total Discharge Rate / Discharge Efficiency) * Desired Flight Time(in hours) * 1000 mAh

= (51.6 / 0.67 ) * (5/60) *1000

= 5160 mAh

Thrust Calculations

Battery mAh Flight Time Price(Rs)

Turnigy Graphene 2700 ~3min 3200

LiPo 4850 3S 4850 ~5 min 8100

https://hobbyking.com/en_us/graphene-2200mah-4s-65c-w-xt60.html4.https://www.maxamps.com/lipo-4850-3s-11-1v-battery-pack

Bill of MaterialsElectronic Items Quantity Weight

(g/unit)Price

(Rs/unit)Assembly

Rotor: Avionic 3506 850kv 4 80 1350 Rotor Unit

Propellor: APC 12 x 6 E1 4 5 150 Rotor Unit

Servo Motor2 12 9 195 Platform

Big Battery: LiPo 4850 3S4 1 355 8100 Central Unit

Arduino Mini3 4 10 250 Platform

Wifi Module5 5 5 300 Platform+ Central Unit

Small Battery: 500mah 7.4V6 4 36 415 Platform

Pixhawk Controller7 1 38 12000 Central Unit

ESC8 1 50 700 Central Unit

Raspberry Pi9 1 15 3000 Central Unit

Omni Wheels10 8 60 600 Platform

Total(weight excluding Platform) 803 41100

Electronic Items

Bill of Materials

Item Estimated Cost (Rs)

Balsa Wood 3000

Adhesive 400

Glass Fibre 400

Velcro Straps 200

Miscellaneous ItemsBalsa Wood, Adhesive, Glass Fibre, Velcro Straps to be purchased locally.

Cost Estimation

Manufacturing cost: Cost of Laser cutting : 2 hrs of cutting * Rs 800/hr = Rs1600Cost of 3D printing: 2 hrs of printing * Rs300/hr = Rs 600

Total Manufacturing Cost : Rs 2200

Total estimated cost: Rs 41100 + Rs 4000 + Rs2200 = Rs 47300

Isometric Views

ModAVNet Weight: 1700 g

Rotor Module

Material: Balsa Wood with cross frame of fibre compositeManufacturing Process: Cutting, Fitting Rapid Prototyping

Platform

Central Module

Material: Balsa WoodManufacturing Process: Cutting, Fitting

Docking Mechanism

CRITICAL DESIGNMaterial: Nylon fibre or Onyx fibreManufacturing Process: Rapid prototyping, Fitting

Stress Analysis

Stress Analysis

Concept of Modularity

Concept of Modularity

References 1.Propellor: http://rcbazaar.com/product.aspx?productid=24832.Servo Motor - https://www.amazon.in/Robodo-Electronics-Tower-Micro-Servo/dp/B00MTFFAE0/ref=sr_1_1?ie=UTF8&qid=1509749507&sr=8-1&keywords=servo+motor3.Arduino Mini: https://www.amazon.in/Arduino-Atmega-Compatible-Board-Smaller/dp/B00H8MYAGI5.Wifi Module - https://www.amazon.in/ESP8266-Serial-Wireless-Transceiver-Module/dp/B00O34AGSU/ref=sr_1_4?s=industrial&ie=UTF8&qid=1509749820&sr=1-4&keywords=wifi+module+for+arduino

6.Small Battery: http://rcbazaar.com/product.aspx?productid=4848

7. PIXHAWK flight ontroller: https://www.inf.ethz.ch/personal/pomarc/pubs/MeierICRA11.pdf

8.ESC: http://rcbazaar.com/product.aspx?productid=4792

9.Raspberry pi: https://www.amazon.in/RASPBERRY-PI-MODEL-INBULT-BLUETOOTH/dp/B01G882L3G/ref=sr_1_2?s=industrial&ie=UTF8&qid=1509750158&sr=1-2&keywords=raspberry+pi+3

10.Omni Wheels: https://robokits.co.in/robot-parts/robot-wheels/omni-wheels/omni-wheel-58mm-servo-lego-nxt-compatible