Motor sizing:-

DC motor:

Approximate Weight of drawer, rack and pinion= 0.5 kg

Number of DC motors = 1

The radius of the pinion =0.05m

Weight acting on DC motor = M = 0.5 kg

Co-efficient of friction = 0.45

g = 9.8 m/s^2

Force = F = Co-efficient of friction x M x g = 0.450.59.8=2.205N

Torque = T = F x R = 2.205*0.05= 0.11025 N-m = 1.1025 kg-cm

Total Torque = T x Factor of safety (FOS) = T x 1.5 = 1.1025= 1.65375 kg-cm

Therefore, we require 1 20 rpm DC motor for the opening of the drawer.

Servo motor:

Approximate Weight of hook= 0.1 kg

Number of servo motor = 1

The radius of the angular hook =0.03m

Weight acting on servo motor = M = 0.1 kg

Co-efficient of friction = 0.45

g = 9.8 m/s^2

Force = F = Co-efficient of friction x M x g = 0.450.19.8=0.441N

Torque = T = F x R = 0.441*0.05= 0.02205N-m = 0.2205 kg-cm

Total Torque = T x Factor of safety (FOS) = T x 1.5 = 0.2205 *1.5= 0.33075 kg-cm

Battery Sizing:

Sr No	Components	Quantity	Voltage Required	Current Drawn
1.	DC motor	1		12V
2.	SG 90 Servo motor	1	5V	100mA
3.	Aurdino UNO R3	1	5V	100mA

• So, for 12V current drawn (C1) = 600 mA
• For 5V currents drawn (C2) = 100+100=200mA

Now considering the factor of safety FOS = 1.2

C1= 600*1.2 C1= 720 mA = 0.720 A

C2= 200*1.2 C2= 240 mA = 0.24 A

For time(T)=3 hrs

For 12 V

Battery required = 0.720*3 = 2.16 Ah

For 5V

Battery required = 0.24*3 = 0.72 Ah

Therefore 1 battery is required.