7.1 Battery Sizing

Components	Quantity	Operating Voltage	Current consumed
DC Geared motor	3	12V	3x300 = 900 mA
SG 90 servo motor	1	5V	1x650 = 650 mA
IR Sensor	1	5V	1x40 = 40 mA
Arduino Mega	1	5V-12V	1x100 = 100 mA
Double Channel Relay	2	5V	2x80 = 160 mA

12V	5V
900 mA	950 mA

Factor of Safety = 1.2

12V	5V
1080 mA	1140 mA

• We can use one 12V with current rating 1A and one 5V adapter with current rating 5A.
• We need this project to run for 3 hours continuously.

Battery Required

12V	5V
1.08x3 = 3.24 Ah	1.14x3 = 3.42 Ah

Motor Sizing

We will be using three DC motor for pushing the dispensed drill bits.

Required Formulae :-

T = M x A x D/2

where; T= Torque M= Mass A= Acceleration D= Diameter

REQUIRED INFORMATION

RATED RPM AT 12 V	RATED TORQUE IN Kg - Cm AT 12 V
1000	0.12
500	0.25
300	0.35
200	0.5
150	0.8
100	1.2
60	2
30	4
15	8
10	12
3.5	30

CALCULATIONS

F = mg Mass of the rotating plate = 50 gm = 0.05 Kg

Diameter of the disc = 100 mm = 0.1 m

force = 0.05 x 9.81 = 0.491 N

Torque= FD/2= 0.491 x 0.1 = 0.0491 Nm

Safety factor= 1.2

Final Torque = 1.2 x 0.0491 = 0.05892 Nm

As we know ; 1 Nm = 10.1971 kg-cm

Therefore, Torque in Kg-cm = 10.1971 x 0.05892 = 0.6008 Kg-cm

Now, by looking at the table,

• We'll need 3 DC motors of 150 RPM