DARPA UAVForge 2012

 

GremLion


The NUS UAV Team from the National University of Singapore (NUS), Singapore has participated in 2012 UAVForge Challenge. In order to compete in the challenge along with competitors from the rest of the world, a rotorcraft UAV codenamed GremLion is designed and constructed specially to tackle the given tasks in this competition.

The GremLion is a unique unmanned coaxial rotorcraft, constructed based on sophisticated mechanical design. It realizes robust and efficient flight behavior with an optimized structure. With its ability to retreat the pairs of blades while not in flight, its dimensions can be reduced to the size of a backpack.

Most of the required tasks mentioned in the UAVForge Challenge has already been realized in GremLion. More specific details are listed below.



Launch Starting Point (Task 1) & Transition to Altitude (Task 2)

Several flight tests have been conducted on the GremLion from taking-off from ground to hovering at a designated altitude. The GremLion has demonstrated its capabilities to complete Task 1 and Task 2 in a stable condition.

Maneuver to Avoid Obstacles (Task 3 & Task 7)

A decent algorithm has been developed to automatically detect the trunk-like obstacles and dangerous objects in near distance. It will be employed to the GremLion to realize path planning around the obstacles.

Waypoint to Landing Area (Task 4)

The aircraft is required to navigate to the top of the building and land on the roof top. Our GremLion has demonstrated its ability to land on the roof top of a multi-storey building.

Landing Area & Transmit Video (Task 5)

Upon landed on the roof top, it is required to transmit the video images to the ground control station two miles away. A long range video transmission test has been conducted, realizing the video transmission of at least two miles through the use of the video transmitter. With the receiver on the ground two miles away, the continuous video has been recorded on the ground control station.

Performs 'Follow-Me' Task (Task 10)

To realize vision target tracking, a sophisticated vision based target tracking scheme is proposed and tested in flight tests. It employed robust feature extractor and the vision image tracking technique integrated with the flight control systems. It will guide GremLion in following the target on the ground in Task 10.

 

Video Milestones

1. GremLion Stage 1 & Stage 2

2. GremLion Stage 3

 

Lion Hub

LionHub is a comprehensive electronic board that connects all the essential avionic components of UAV system. LionHub connects the main processor, inertial measurement unit (IMU), servo controller, multiplexer and provides ports for power supply, serial communication and servo output. It reduces the weight and simplifies the avionic system since the wiring among components is removed. This can also improve the robustness of the system against vibration during flight. Figure 1 is one compact design with a size of 51 mm × 97 mm × 35 mm. This design, featuring a low cost IMU (ArduIMU), is applicable in small fix-wing UAVs and small scale rotorcraft UAVs where area and cost is of concern. Figure 2 is another LionHub for GremLion where the height is constrained. This version incorporates a high performance IMU (IG-500N) and a servo control board (UAV100) that is capable of logging the manual control signal and switching between manual and autonomous mode.





Figure 1: Compact Version of LionHub




Figure 2: Flat Version of LionHub