This document discusses power sources and motor control for robotics competitions. It recommends using lithium polymer (Lipo) batteries due to their high energy density, rechargeability, and low self-discharge rate. Factors for choosing a Lipo like voltage, capacity, weight, and discharge rate are outlined. Radio control is recommended for its high controlling range, with 4-6 channel receivers typically used. Reversing a brushless DC motor's direction can be done autonomously using a microcontroller like Arduino and relays, with the schematics and sample code provided.

1. MSPC 2018
POWER AND CONTROL
Prepared By
Fahim Ahmed Irfan
1412015
Department Representative
BUET Robotics Society

2. Choosing a battery:
The main part of hardware is to select a good power source.
In this case Lipo Battery is very reliable.
Lipo Battery means Lithium Polymer battery.

3. Why Lipo Battery???
There are several reasons for choosing Lipo Battery as power source. Such as:
● It has high energy density meaning highly powerful.
● It is rechargeable.
● The rate of self-discharging is very low.
● Lipo battery does not need any maintenance for its better performance.

4. How to choose a Lipo???
One can not choose a battery randomly. There are some things to consider before
choosing a Lipo battery. Such as :
● Voltage
● Capacity
● Weight
● Physical size
● Connector
● Discharge
● Charging rate

5. Calculations of Lipo:
The capacity of a Lipo Battery is defined as mAh. MAh means milliampere per
hour. We need to know the discharge rate and the duty time of a Lio Battery.
Example:
Discharging:
A 3S 2200 mAh 40C Lipo battery discharging rate needs to be calculated:
Here, S = number of cell
mAh = capacity
C = rating

6. Calculations of Lipo(continued):
Discharging = 2200 mAh * 40 C =88,000 mAh = 88,000/1000 = 88 ampere.
So, this battery can handle an ampere draw of 88 ampere maximum.
Duty Time:
If a constant current draw of 20 ampere from the battery, its duty time is need to
be calculated:
Duty time = 2200 mAh / 20 = 0.11 hr = 0.11 * 60 = 6.6 minutes
Considering discharging and duty time, a battery should be selected.

7. Controlling System:
There are various types of wireless communication available such as :
● Bluetooth Communication
● Wifi Communication
● Radio Frequency Communication(RF)
● Radio Control Communication(RC)
In this competition, it is recommended to use RC controller for its high
controlling range.

8. RC Controller:
RC controller has several types of channel. But 4 - channel and 6 - channel are
the common used.

9. RC Controller(continued):
Pinout of the receiver(6-channel):

10. RC Bind :
● Short the Bind OR Bat pins (if Bind pins are not indicated ) of receiver then
push the bind button of controller :

11. Reversing BLDC:
If we want to reverse the direction of BLDC manually, we can alter any two of
three wires connecting ESC.
But we can not alter manually at the time of race. The alternation should be
autonomous. For this we need two components.
1. Microcontroller as arduino
2. Relay

12. Reversing BLDC using relay:
Relay will be used for altering the pole of the BLDC and arduino will be used for
the connection between relay and RC controller.

13. Working procedure of relay:

14. Motor Control Directional:

15. Reversing BLDC using relay(continued):
Schematic of relay connections:

16. Reversing BLDC using relay(continued):
Schematic of arduino connections:

17. Reversing BLDC using relay(continued):
GND , VCC Pins of Arduino & Relay are connected to Receivers (ch 6) GND , VCC pins

18. Reversing BLDC using relay(continued):
Arduino relay code:

19. DON’T FORGET TO ASK ANY QUESTION….