Vanguard UAV System to Transport Mine Sensors
Mines are a huge problem. We need a new solution to safely guide army vehicles through mine prone areas and in GPS denied environments.
In the project we need to have 5 drones flying in the formation in order to satisfy the specification given by the night vision lab. Hence, in order to do that we need 5 drones with a power consumption of 9102 watts. Now with addition of 25% safety factor power consumption reached to 11377.5 watts. This power consumption gives 512.5 A as the current requirement for 5 drones, whereas voltage consumption remains to 22.2 V. So, for one drone current and voltage consumption is 102.5A and 22.2 V respectively.
Here is the power calculation for the fleet of UAVs:-
Current consumed by 1 UAV = 82 A Current consumed by 5 UAV’s = 410 A Voltage required = 22.2 V Power Consumed by 6UAV’s = Voltage * Current
= 22.2 * 410 = 9102 Watts
Safety Factor included = 25% Therefore, new Power is 11377.5 Watts So, Voltage requirement is 22.2 V
Current requirement is 512.5 A (for 5 UAV’s)
For 1 UAV Current consumed = 102.5 A Voltage Consumed = 22.2 V
Wire and its weight calculation: We are using thinnest wire possible which came out to be 18 gauge composite shielded copper cable and we also required to have 4 fiber optical cable for communication. After going over various cable manufacturers we came across the specification of this shielded cable provided by the manufacturer:  42 lb. weight is for 1000 ft. of composite cable. 1000 ft. = 42 lb. 328 ft. or 100 m = (42/1000) * 328
= 13.77lb. or 6.24 Kg
This weight of wire will be distributed equally by the 5 UAV’s
After having the cable specification and the power requirement of the UAV, we did the following calculations for
Power transmission: High current output generator will be used with o/p of 9.44 A at 240 V Then it will be stepped up using step-up transformer to 280 V at 8.13 A of current. The reason for using step up transformer is because our shielded power cable is can control maximum current of 20 A in totals at 300 V. Hence for long transmission current will drop, so to maintain the right current value for the UAV higher voltage is required through step up transformer. On-board step down transformer on each UAV will step down the high voltage to 22.2 V and give each UAV 102.5 or 103 A of current.
Pictorial Representation of the Power Analysis for the UAV’s: -
Since, we identified that formation keeping is the main challenge, We proposed two methods to overcome the challenge. The first one is the catenary method which uses the same cable, which is providing power to the drones to measure the distance and orientation and eventually providing us with the x and y coordinates. The second method is the Trilateration method. In trilateration method, if we know the distances between all the robots and distances from each robot to the other robots then using the trilateration method; we can calculate their x and y coordinates in a local space. More info on how trilateration method works is here. To get the distances between the robots, we used the LCAS ranging sensors, which were provided to us by lofaro labs. Ranging sensor uses a radar technology to calculate the distances. Once the coordinates are calculated, we can use them to get the robots in formation. Two methods have been proposed to have redundancy in the over all system, so if one of them fails ten there's other method to back it up and it also increases our confidence to implement these methods at full scale.
Adrian and Sailesh
Parth and Raghu