Mass Report
By: Mesfer Aldosari
| Devices | Mass (g) | Quantity | Total Mass (g) |
| Arduino Micro Atmega 32u4 | 13 | 1 | 13 |
| Micro Servos (MG905) | 13.4 | 12 | 160.8 |
| Sain Smart HC-SR04 Ultrasonic Sensor | 8.5 | 1 | 8.5 |
| MPU 6050 | 13 | 1 | 13 |
| HC-06 | 1 | 1 | 1 |
| Battery | 28 | 2 | 56 |
| Plastic | 10 | 1 | 10 |
| Total Mass | 262.3 |
* Values given have been weighed by a scale.
The table above explains what the mass of each device being used, there are seven devices in total. Which are: Arduino Micro, MG92B, Ultrasonic sensor, HC-06, MPU-6050, batteries, and 3-D PLAplastic. The above table helps the group infer how much the robot may weigh and if they are near the mass limit.
Battery and Regulators
By: Mesfer Aldosari
Micro biped will use two batteries LIPO 2S 350mAh to supply power to the robot.
So after calculating the total current that is required to operate all of the component, the project needed 5 v minimum to run our project and 1500 mAh if the project was going to be ran for one hour. However, since the goal is to simply complete a track the mAh of the battery can be lowered.
So that means the project needs a battery that can provide at least 5 volts and provide enough current to power the device. In addition to providing enough power the batteries need to light enough to allow the servos to move.
2S Lipo battery
*Click on the link above to see the specifications at Hobby People, the following information was taken from there.
Features:
- It has light weight which is about 28g
- Maximum discharge rate at 10 Amps
- Maximum pack voltage at 8.4V, Minimum pack voltage at 6V
- Its dimension: 8 x 31 x 2
- 7.4 volt
Capacity: 350mah
Voltage: 2S/2Cell/ 7.4V
Weight: 28g
Lifetime of the battery:
Battery Life = Battery Capacity in Milli amps per hour / Load Current in Mill amps * 0.70
[Battery capacity(mAh)/device consuption(mA)]*0.7
(350/1500)x0.7 = 0.1633
0.1633x60x2= 19 minutes is our battery last long
The factor of 0.7 makes allowances for external factors, which can affect battery life.
19 minutes without the power lost it is going to be 28 minutes
The formula used was taken from Digi-Key.com, at this link.
Regulators:
Micro biped will need to use at least one voltage regulator to drop the voltage down to 5 volts from the 7.4 volts a LiPO battery provides. To do this two LM 7805s, made by Fairchild, were chosen. The LM7805 will take in 7V – 30V and has an output of 1.5A, so theoretically the LM7805s should be able to give out enough current to power the devices.
Power Budget
By: Ameen Alattas
| Devices | Quintity | Operating
DC volt.(v) |
Max Current
(mA) |
Operating
Current (mA) |
Total Current
(mA) |
Power
(mA) |
Margin of error |
| Micro
Arduino |
1 | 5 | 50 | 45 | 45 | 225 | 0% |
| Servos
MG92B |
12 | 5 | 448
(Stall) |
200 | 2400 | 12000 | 15% |
| HC-SR04 | 1 | 5 | 15 | 15 | 15 | 75 | 0% |
| MPU6050 | 1 | 5 | 7 | 5.1 | 5.1 | 25.5 | 0% |
| HC-06 | 1 | 5 | 45 | 40 | 40 | 200 | 0% |
| TLC5940 | 1 | 5 | 120 | 95 | 95 | 475 | 5% |
| Total | 2600.1 | 13000.5 |
* All values are measured
As shown on the table, there are have six devices (Micro Arduino, Servos, HC-SR04, MPU6050, HC-06, TLC5940) that are operating on 5 volts. It was chosen to use 5 volts instead of 3.3 volts for the HC-06 because the module being used has a built in voltage regulator for 5 volts to 3.3 volts. The provided operating current and power are the actual values for all devices except for TLC5940 and servos. The TLC5940 uses current from 60-12 depending in how many servos attached to it. Since the group is using 12 servos it is assumed that it will draw about 95 mA. That’s why the 5% margin of error still present. The servos, it depends on the weight that it will be carrying. Which will result in a current draw from 100mA-230mA. It was decided to go with 200mA for a 15% margin of error.
