The United States Marine Corps (USMC) wants to develop a miniature radar-based collision avoidance sensor suite (RCASS) for small unmanned air vehciles (UAVs) operating autonomously in civil airspace alongside other aircraft types.
The proposed RCASS system would be developed under the US small business technology transfer (STTR) programme, with formal solicitations for the requirement opening 20 February.
Technology briefs for the requirement released 22 January identify a target weight range of around 1.1kg (2.42lb) and volume of less than 200cm3 (12.2cu. in.) in a nominal small UAV payload bay. Small UAVs are defined by the brief as platforms with a span of less than 3.3m (11ft), with the Advanced Ceramic Silver Fox cited as an indicative UAV type for the class.
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The USMC's proposed miniature radar sense and avoid system would be capable of being carried by a platform in the class of the Advanced Ceramics Silver Fox |
“ONR is interested in any intelligent autonomous systems that would be able to perform the sense and avoid function while adhering to the size, weight and power constraints of small UAVs. The Navy will only fund proposals that are innovative and involve technical risk” says the brief.
It says RCASS should be “effective against all air traffic, with or without transponder-based collision avoidance systems such as TCAS [traffic alert/collision avoidance system] or ADS-B [automatic dependent surveillance-broadcast]. One component of the RCASS may include omni-directional radar. The RCASS system design must provide an energy density per unit solid angle supporting detection at ranges compatible with collision avoidance”.
Where a wholly autonomous UAV is being operated in heavy air traffic environments, “the UAV must sense or be aware of the coarse 3-D trajectories of neighbouring air traffic relative to its own flight trajectory. The RCASS processor will update and maintain its own internal map of the neighbourhood air picture, as well as optimising its actual 3-D trajectory path with its pre-planned 3-D trajectory as a constraint”.
However, the system is also intended to operate on a stand-alone basis, rather than as a component of an integrated air traffic management system. “The RCASS is a point solution and does not require modifications to the external air traffic control system in CONUS [Continental USA] or worldwide.”
Nominal radar power requirements for the radar are capped at 40W. The brief says the proposed system “must also be electromagnetically compatible with traditional UAV sensors including electro-optical/infra-red, magnetic detectors, as well as on-board avionics (including global positioning system) and wireless communication systems”.
The Office of Naval Research and the US Marine Corps PMA-263 programme office are to jointly manage the development effort.
Initial project activity would see the selected contractors develop an “initial system design that demonstrates scientific merit and capabilities of the proposed radar based RCASS system for small UAVs. This includes a calculation of the RCASS awareness volume surrounding the UAV. The volume is to be determined in part by the limited detection ranges of the sensors. It must support the slower response time of UAVs relative to nearby higher speed military and civilian aircraft kinematics”.
The initial phase would also see high level design of the proposed radar sensors and system hardware, and development of a software simulation of the collision avoidance function in a heavy civilian traffic environment.
If approved for STTR phase two development, the contractors would then build a prototype and conduct field testing using a surrogate manned aircraft. Second phase activities would also see initial liaison with the US Federal Aviation Administration on requirements for a potential UAV based demonstration in US airspace.
The proposed third project phase would see the US national airspace small UAV demonstration proceed and the development of production plans aimed at both the military and civil UAV markets.
Source: FlightGlobal.com
