Monday, July 18, 2016

ASCI 530 Module 7 Research: Wilderness SAR UAS Design


Incident commanders are the personnel responsible for coordinating responses to disasters or searches. Access to a UAS that can search a large area and return data for both tactical decisions and detailed analysis can greatly aid the success of a search/response mission. This UAS is designed for use by a quick response team in a rural or wilderness setting.

Given the high-level baseline requirements for the air vehicle element, the datalink, and total cost, the following derived requirements and testing requirements have been developed. Following the derived requirements and testing procedures, a small fixed-wing tactical UAS specific to search and rescue operations could be developed in about one year.

Proposed Requirements
A.    Air vehicle element
1.     Shall be capable of flight up to 500 feet altitude above ground level (AGL)
1.1.  Aircraft design shall facilitate steady climb to assigned altitude, up to and including 500 feet AGL
1.1.1.              Verify aircraft reaches 500 feet AGL in manual control mode
1.1.2.              Verify aircraft maintains assigned altitudes in autonomous flight control mode
1.1.3.              Record aircraft speeds:
1.1.3.1.                  Determine Vx
1.1.3.2.                  Determine Vy
1.1.3.3.                  Determine Vmc
1.1.3.4.                  Determine Vs1
1.1.3.5.                  Determine Vso
1.1.3.6.                  Determine Vne
1.1.4.              Verify minimum aircraft speeds for each phase of flight
1.2.  Aircraft flight weight and balance envelope shall include scenarios for all phases of flight
1.2.1.              Verify aircraft forward CG does not negatively impact climb performance
1.2.2.              Verify aft CG does not negatively impact stall recovery
1.2.3.              Verify nominal CG does not negatively impact performance in high wing loading conditions
1.3.  Payload performance shall meet minimum visual standards at 500 feet AGL
1.3.1.              Verify visual detection test with payload imagery from 500 feet AGL
2.     Shall be capable of sustained flight (at loiter speed) in excess of one hour
2.1.  Battery capacity shall meet system electrical load analysis plus powerplant load for 1 hour plus 20% endurance
2.1.1.              Perform powerplant electrical load analysis for all phases of flight
2.1.2.              Perform airframe electrical load analysis for all phases of flight
2.1.3.              Verify battery discharge rate meets manufacturer specification for calculated electrical load analysis
2.1.4.              Verify battery capacity meets manufacturer specification for discharge time (measured in mAh)
3.     Shall be capable of covering an operational radius of one mile
3.1.  Datalink shall be capable of communication range exceeding two miles (per B.1.1)
3.1.1.              Perform primary datalink range test
3.1.2.              Perform secondary datalink range test
3.2.  Payload signal transmission power shall reach two miles (per B.1.4)
3.2.1.              Perform full-motion video range test
4.     Shall be deployable and on station (i.e., in air over mission area) in less than 15 minutes
4.1.  Aircraft speed must be greater than speed that reaches 2 mile range while permitting deployment of system within 15 minutes
4.1.1.              Determine system assembly/emplacement time
4.1.1.1.                  Verify accuracy of system emplacement checklist to determine time-saving procedures
4.1.1.2.                  Verify accuracy of aircraft launch checklist to determine time-saving procedures
4.1.2.              Verify aircraft dash speed at nominal mission weight
5.     Shall be capable of manual and autonomous operation
5.1.  Control system shall include teleoperation control mode
5.1.1.              Verify aircraft control surface movement with remote controller
5.2.  Control system shall include GPS waypoint navigation mode
5.2.1.              Verify aircraft control surface movement with programmed waypoint navigation
5.3.  Control system shall include semi-autonomous stabilized teleoperation mode
5.3.1.              Verify opposite aircraft control surface movement while aircraft is moved about axis
5.4.  Autonomous control mode shall permit dynamic re-tasking
5.4.1.              Verify mission control software features point/click waypoint assignment in flight modes
5.4.2.              Verify aircraft flight performance when active waypoint is moved or changed
5.5.  Autonomous control mode shall permit manual GPS waypoint entry
5.5.1.              Verify mission control software features manual waypoint latitude/longitude entry
5.6.  Autonomous control mode shall include return-to-home mode in case of control link loss
5.6.1.              Verify proper aircraft performance with induced link loss
5.7.  Autonomous control mode shall include dead reckoning mode in case of GPS signal loss
5.7.1.              Verify proper aircraft performance with simulated loss of GPS signal
6.     Shall provide capture of telemetry, including altitude, magnetic heading, latitude/longitude position, and orientation (i.e., pitch, roll, and yaw)
6.1.  Ground control system display shall include primary flight display
6.1.1.              Verify status of PFD reports during all phases of flight
6.2.  Ground control system display shall include moving map display with position of aircraft and programmed waypoints
6.2.1.              Verify aircraft position during all phases of flight
6.3.  Ground control system shall record telemetry to local hard drive
6.3.1.              Verify list of recorded parameters for accuracy
6.4.  Autopilot shall record telemetry to local storage
6.4.1.              Verify recorded parameters match recorded ground control station telemetry
7.     Shall provide power to payload, telemetry sensors, and data-link
7.1.  Payload, telemetry sensors, and communication transceivers shall be connected to the same power source
7.1.1.              Verify electrical system continuity
7.2.  Power source load analysis shall provide capacity for payload, sensors, and transceivers
7.2.1.              Verify payload operation with power applied
7.2.2.              Verify telemetry sensor operation with power applied
7.2.3.              Verify datalink transceiver operation with power applied
7.2.4.              Verify all electrical equipment operation with full system load
8.     Shall provide capability to orbit (i.e., fly in circular pattern around) or hover over an object of interest
8.1.  Autonomous control modes shall include option to loiter around fixed point
8.1.1.              Verify aircraft performance in loiter mode, turns to left
8.1.2.              Verify aircraft performance in loiter mode, turns to right
8.2.  Autonomous control modes shall include option to alter loiter radius
8.2.1.              Verify aircraft performance when loiter radius is changed
8.3.  Loiter position over POI should be able to be manually entered via latitude/longitude
8.3.1.              Verify proper aircraft response when new POI loiter is assigned

B.    Data-link (communications)
1.     Shall be capable of communication range exceeding two miles visual line of sight (VLOS)
1.1.  See A.3.1
1.2.  Airborne datalink transceivers shall transmit sufficient power
1.2.1.              Bench test transceiver transmitted power
1.2.2.              Bench test transceiver system impedance
1.2.3.              Bench test antenna gain
1.2.4.              Bench test antenna impedance
1.2.5.              Verify installed system VSWR values
1.3.  Ground-based datalink transceivers shall transmit sufficient power
1.3.1.              Bench test transceiver transmitted power
1.3.2.              Bench test transceiver system impedance
1.3.3.              Bench test antenna gain
1.3.4.              Bench test antenna impedance
1.3.5.              Verify installed system VSWR values
1.4.  Ground support equipment shall include a high-gain tracking antenna based on aircraft GPS position
1.4.1.              Verify operation of antenna tracking with aircraft movement
1.5.  Full motion video signal shall be visible at two miles VLOS
1.5.1.              Bench test video transmitter power
1.5.2.              See A.3.2.1
2.     Shall provide redundant communication capability (backup) for C2
2.1.  COTS transceivers shall be re-certified for reliability
2.1.1.              Verify primary datalink reliability in nominal operating environment
2.1.2.              Verify secondary datalink reliability in nominal operation environment
2.2.  Primary datalink transceiver shall transmit in FCC ISM band
2.2.1.              Verify transceiver channel selectivity
2.2.2.              Verify transceiver bandwidth at nominal data transmission baud rate
2.3.  Secondary datalink transceiver shall transmit in FCC amateur band
2.3.1.              Verify transceiver channel selectivity
2.3.2.              Verify transceiver bandwidth at nominal data transmission baud rate
2.4.  Datalink transceiver signal shall not degrade telemetry sensor accuracy
2.4.1.              Bench test telemetry sensor accuracy with all transceivers transmitting full power
3.     Shall use power provided by air vehicle element
3.1.   (Same as A.7.1)

C.     Cost
1.     Shall be less than $100,000 (equipment cost only)
1.1.  System deliverable shall include bill of materials (BOM) detailing COTS pricing
1.1.1.              Verify complete price list of all deliverables
1.2.  BOM shall include cost of raw materials
1.2.1.              Capture specific market price reflected in BOM

Development Process

Phases:
1.     System Development: 12 weeks
a.     Concept Design
                                      i.     4 weeks
b.     Concept Research
                                      i.     4 weeks
c.     Preliminary Design
                                      i.     4 weeks
d.     Detail Design
                                      i.     Timeline
2.     Ground testing: 6 weeks
a.     Specimen Test
                                      i.     6 weeks
                                    ii.     Verification of selected COTS components
                                   iii.     Subsystem testing
                                   iv.     Flight test site selection
3.     Flight testing: 32 weeks
a.     Prototype Build & Test
                                      i.     8 weeks
                                    ii.     System integration testing - ground
                                   iii.     Flight testing
1.     Test preparation
2.     Flight test
                                   iv.     Begin tracking MTBF
b.     Development & Modification
                                      i.     8 weeks
                                    ii.     Continue prototype iteration test flights
                                   iii.     Capture MTBF data for production and sustainment
                                   iv.     Environmental tests
c.     Certification
                                      i.     16 weeks+
                                    ii.     Certification deliverables
                                   iii.     Demonstration of baseline requirements
4.     Production
a.     Initiate maintenance tracking system
5.     Sustainment


Justification

A fixed-wing system was selected for the task because it provides greater range and endurance, and can therefore cover a greater area. The faster images can be collected and analyzed, the greater the Probability of Detection for a missing object or individual (US SAR Task Force, n.d.). Full-motion video and recorded still images are desirable because the video can provide perspective and context clues to the detailed image analysis, even if at a lower resolution (Murphy, 2014, p. 128).

To reduce cost and development lead time, either a currently available airframe with modifications or a new airframe built with COTS sub-systems would be suitable. The development schedule reflects built-in time for integration and verification of COTS component standards.

References:
Murphy, R.R. (2014). Disaster Robotics. Cambridge, MA: The MIT Press.
U.S. Search and Rescue Task Force. (n.d.). Search & rescue and disaster glossary and acronyms.     Retrieved from http://www.ussartf.org/glossary_acronyms.htm





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