Fall 2015 Power Budget

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FINALIZED POWER BUDGET

By Brian Walton (Manufacturing Engineer)
Approved by Paul Oo (Project Manager)
Approved by Railly Mateo (Systems Engineer)

 

Item Quantity Max Consumption Average Consumption Total Average Consumption Total Max Consumption
MG92B (servos) 6 0.7488170658 0.02 0.12 4.492902395
Arduino Micro (microcontoller) 1 0.85 0.37 0.37 0.85
Ultrasonic Sensor
 1 0.015 0.015 0.015 0.015
Gyroscope 1 0.0065 0.0065 0.0065 0.0065
HC-06 (Bluetooth) 1 0.04 0.008 0.008 0.04
Total 0.5195 0.9115
Regular Amps Available: 2 Surge Amps Available: 10
Margin%: 284.985563 Margin%: 85.0343344

The above table presents the electronics subsystem that comprises of this year’s µBiPed project. The subsystem consists of both the main (Arduino Micro) and sub-components (*servos, ultrasonic sensor, gyroscope, and Bluetooth communication). These components were then spec’d for quantity, max, average, total average, and total max current consumption. From this data, we used the specs from our chosen battery to find marginal current ratings.

Note: The servo specifications did not provide maximum current consumption. The following calculations were made to find the maximum current consumption.

Servo Calculations:
Power = 2*pi*torque*rotational speed
Torque = 3.5 kg/cm = .34323275 newton meters
Rotational Speed = revolutions/sec = .08sec/60 degree = .48 sec/360 degrees = 2.08333333 rev/sec
Power per Servo = 4.492902395 Watts
I= W/V = 0.7488170658 max current consumption

Conclusion:
As you might notice, the marginal percentages are very high. The battery blog post explains why we chose the Dynamite Lipo battery, but the power budget (in correlation with mass budget, system-load testing, and contingencies) verifies why higher marginal ratings are good.  Considering that the design innovations have high contingencies, (total mass, incline/decline walking, additional servos, and general walking motion) it is important we leave room for error.