Lion UAV Systems



HeLion is the first generation of the UAV helicopter family built at the National University of Singapore. Its baseline is a high-quality radio-controlled (RC) Raptor 90 helicopter. Its sophisticated avionic system is constructed based on a systematic design methodology, and consists of the following five parts: (1) PC-104 computer processor boards; (2) avionic sensors including INS/GPS, ultrasonic sonar and RPM sensor; (3) servo controllers; (4) wireless modem; and (5) Li-Po batteries. Special attention has been paid to the anti-vibration and anti-pollution during the construction procedure. HeLion is an ideal platform for advanced control law implementation and evaluation. It can perform reliable automatic flight in the full flight envelope including automatic taking-off and landing. It is also a key member of the multiple UAV formation control project, which is currently one main focus of our team.


SheLion is the second member of the UAV helicopter family. Its design and construction is very similar to those for HeLion. The main difference resides on the extra equipped onboard image-processing system, which consists of (1) a high-speed image-processing computer board; (2) an image frame-grabber; and (3) a high-resolution but micro-size digital camera. Besides all of the functions which can be completed by HeLion, SheLion can also perform precise ground target searching and tracking, which is another main focus of our research. SheLion is also cooperating with HeLion and serving for the multiple UAV formation control project.


HengLion and HaLion are the biggest in size in our UAV family. The bare helicopter selected for integrating HengLion and HaLion is an AF25B from Copterworks Inc. This helicopter has 1.8 m in length and 2.2 m in its rotor-span, and is powered by a twin-cylinder gasoline engine. With around 10 kg payload, AF25B could achieve up to 55 minutes flight endurance, which makes it much more suitable for practical missions such as emergence rescue and traffic surveillance. The avionic system equipped is also constructed following our proposed systematic design methodology. The fully autonomous control has been realized and the design and construction of a more advanced vision system is in process. HengLion and HaLion will take the lead in the ongoing Multiple Agent System (MAS) project.


BabyLion is a miniature UAV helicopter suitable for both indoor and outdoor flight environments. It is built up based on a mini-size single-rotor helicopter named Trex-450 from ALIGN Inc. Due to its limited payload and space, it is very challenging to integrate its avionic system. We have managed to build up a fully functional avionic system with the weight of 210 g, by integrating (1) Stargate single-board-computer; (2) MNAV100 INS/GPS; and (3) AmbiCom wireless CF module. Compared with HeLion and SheLion, BabyLion is with much smaller size and lower cost, but can provide equivalent automatic control performance in the full flight envelope. BabyLion is a good starting point for our research extension to indoor navigation and surveillance.


PetiteLion is the smallest member in our UAV helicopter family. The original intention for constructing PetiteLion is to build up a micro-size and reliable VTOL UAV prototype for indoor surveillance. PetiteLion adopts the Eflite coaxial helicopter as its baseline. This helicopter is equipped with two main rotors for both thrust generation and torque balance. As such, it does not require the tail rotor and the overall size shrinks greatly, compared with the classical single rotor helicopter with similar payload. Its avionic system is ultra-light weighting about 170 g. Its main components include (1) Gumstix single-board-computer; (2) MNAV100 INS/GPS; (3) XBee-Pro wireless modem; and (4) SRF08 ultrasonic sonar. PetiteLion can perform reliable automatic hovering and low-speed cruise in the indoor environment without GPS. It is the best-theory winner of the 2009 Singapore Amazing Flying Machine Competition (SAFMC).


KingLion is developed based on the PetiteLion’s platform. It was originally intended to tackle the Singapore Amazing Flying Machine Competition (SAFMC) 2010. Compared to the PetiteLion, KingLion has included more sensors and components. It is embedded with two Gumstix computers, an IMU, a sonar sensor, wireless modems, and a camera. Due to the additional components, a bigger co-axial helicopter platform is used. The best improvement of the system is that the vision processing for navigation has been carried on-board. In order to achieve this, an image processing system with high successful rate while maintaining low computational cost is built within the Gumstix computer. KingLion has won the Best Performance Award in the SAFMC 2010.


FeiLion is a miniature coaxial platform used for complicated 3D indoor navigation purposes. By equipping with sensors including IMU, laser scanner and mono-camera, it is designed for tasks like indoor exploration, 3D reconstruction, and search and rescue. Efficient machine vision, simultaneous localization and mapping (SLAM), obstacle detection and avoidance, and data fusion algorithms are being tested on this platform


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. GremLion took part and appeared as one of the top 9 finalists in the DARPA UAVForge competition in 2012.


ULion is an unconventional reconfigurable hybrid UAV, designed by National University of Singapore. The UAV is mainly implemented with carbon fiber and EPO form, the main advantage of U-Lion is as follows.

Flying mode

The design adopt reconfigurable wing and tail sitter structure, which combines the advantage of fixed wing plane and rotor helicopter effectively. U-Lion has a vertical take-off and landing (VTOL) ability and could also fly in cruise mode such to realize long duration and long distance fly.

Vectoring thrust

The propulsion of U-Lion comes from a self-fabricated contra rotating motor. The maximum thrust provided by the motor can be as high as 40N. The motor is fixed on a gimbal mechanism which can change the direction of the motor, or the thrust. The vectoring thrust controls the six degree of motion in VTOL mode and also acts as additional control in cruise fly mode.

Internal mechanism design

U-Lion has a few special internal designs: (1) Reconfigurable wings: the wings are reconfigurable to adapt to different flying mode. (2) Adaptive center of gravity (CG): The battery can be moved through a pulley system thus to fulfill the different requirement of CG for VTOL mode and cruise fly mode. (3) Canard system: Two rotating canard wings are designed in the down flow areas of propellers to assist the yaw control in the VTOL mode.


NUS²TLion is a rotor wing helicopter, which is designed for the 2nd AVIC Cup International UAV Grand Prix. It is fully autonomous when performing a list of tasks, like navigating to a moving ship and transferring the buckets on its side to another moving ship. Instead of using sophisticated differential GPS, NUS²TLion has incorporated multiple sensors such as camera and laser scanner for more accurate position estimation.The UAV won the first place in the final round of the competition and overall 2nd place.