Suresh K. Kannan

2008 Aerial Robotics

June 25, 2008

This is a video of the GTMax during the recent International Aerial Robotics Competition. It is seen deploying a 90-ft slung load carrying a small rover.

Hornet at McKenna

June 22, 2007

The Hornet is a very small form-factor helicopter UAV. The airframe and avionics is developed by a spin-off company, Adaptive Flight. Here it is seen in flight at the McKenna MOUT site, Fort Benning, Georgia.

First sustained vision-only formation flight

June 15, 2006

This is a video of vision-only formation flight. Both aicraft use the inner-outer loop adaptive system to fly. A video camera onboard the helicopter is used to perform image processing (by Jin Cheol Ha) and estimation (by Yoko Watanabe) in order to generate trajectory commands to track the lead aicraft.

Autonomous transition to and from hover of a high-thrust to weight ratio aircraft

November 5, 2005

The GTEdge unmanned aircraft was a prototype used to test the adaptive control system in vertical and forward flight modes. The full scale version is the Air Force SkyTote. This is probably the first time a fully autonomous foward-flight->hover->forward-flight has been accomplished. The figures and video show the vehicle in forward flight at 80ft/s performing a circular orbit. At t = 26s a transition to hover is initiated by supplying external trajectory commands that lower the vehicle’s speed. Transition is completed at t = 35s with a low residual speed of approximately 5ft/s. At t = 55s a transition back to forward flight at 80ft/s is initiated and completed at t = 65s. During hover, t=[35, 55], the control deflections are seen to be significantly higher due to the lower dynamic pressure. The ailerons are saturated for significant intervals in a particular direction in order to counteract engine torque.

Release of a 11-inch Ducted Fan from the GTMax unmanned helicopter, both autonomous

November 24, 2004

The videos show the launch of a small ducted-fan (GTSpy) from the GTMax autonomous helicopter. The GTSpy was mounted on the GTMax with its engine on and then deployed from a safe altitude. The GTSpy was able to recover from the initial deployment transient and maintain attitude and position within 5 seconds of launch. Both aircraft are flying the same inner-outer loop adaptive flight control system and under automatic control. This is the first known deployment of one autonomous rotorcraft from another autonomous rotorcraft.

Some videos from the Software Enabled Control Demo at Fort Benning, GA.

August 25, 2004

Trajectory tracking adaptive control of a 11-inch ducted-fan

August 7, 2004

The videos show the first autonomous takeoff and landing of the GTSpy ducted-fan. At 11-inches in diameter, in 2004, it was the smallest ducted-fan in the world capable of fully-autonomous flight. As of 2008, it is probably still the smallest fully automatic ducted-fan UAV. The GTSpy has a maximum take-off weight of 5.5lbs and is driven by a two-bladed fixed-pitch propeller. The propeller is enclosed in an annular wing duct with an outer diameter of 11 inches. Vanes located directly beneath the propeller move in order to provide yaw control about the propeller axis. Two sets of control surfaces located further below the propeller move in order to provide pitch and roll moments. Maneuvering is accomplished by tilting the thrust vector with the control surfaces relying primarily on inflow for dynamic pressure during hover.

The tracking response during a small 50ft box maneuver shown below. The large deviation on the eastern side of the box is most likely due to a wind gust.

Envelope Expansion to 95 fps

February 7, 2003

To evaluate controller performance at different points of the envelope, the vehicle was commanded to track a trajectory that accelerated up to a speed of 100ft/s. To account for wind, an upwind and downwind leg were flown. In the upwind leg the vehicle accelerated up to 80ft/s and during the downwind leg the vehicle accelerated up to a speed of 97ft/s as shown in the figures. Collective and longitudinal control deflections are also shown. In the upwind leg, the collective is saturated and the vehicle is unable to accelerate further. The longitudinal control deflections behave nominally as the vehicle accelerates and decelerates through a wide range of the envelope. The NN is able to adapt to rapidly changing flight conditions, from the baseline inverting design at hover through to the maximum speed of the aircraft. A conventional proportional-integral-derivative design would have required scheduling of gains throughout the speed range. More significantly, classical design would require accurate models at each point, unlike this design, which does not.

Pirouette Manuever

October 31, 2003

Many maneuvers such as high-speed flight are quasi-steady, in the sense that once in the maneuver, control deflection changes are only necessary for disturbance rejection. To evaluate performance where the controls have to vary significantly in order to track the commanded trajectory, the helicopter was commanded to perform a circular maneuver in the north-east plane with constant altitude and a constantly changing heading. The figures and video show the response to a trajectory command with speed 10 ft/s, and one anticlock-wise rotation per revolution. After the initial transition into the circular maneuver, the tracking is seen to be within 5 ft.

Aggressive turn (e-turn)

November 2, 2002

A tactically useful maneuver was flown to test controller performance at high speeds and pitch attitudes. The objective of the maneuver is to make a 180-degree velocity change from a forward flight condition of 70ft/s north to a 70ft/s forward flight going south. The trajectory command and response in the north-altitude plane are shown in the figures along with the pitch angle and collective control deflections. During the maneuver the helicopter is commanded to increase altitude by up to 50ft in order to minimize saturation of the down collective. In the deceleration phase the vehicle is able to track the command trajectory well; however in accelerating to 70ft/s going south, tracking performance suffers. In both the acceleration and deceleration phases, poor tracking corresponds with saturation of the collective control. The oscillations in altitude are expected and are due to control saturation which limits the vehicle’s descent rate. The large pitch attitudes experienced are what the outer-loop inversion evaluates as being required to perform such rapid decelerations and accelerations.

This experiment is an example of maneuvering where the commanded trajectory is more aggressive than the capability of the vehicle and is reflected by the extended periods of saturation. It is possible to operate at the limits of the vehicle primarily due to PCH which protects the adaptation process.

First Hover

April 10, 2002

This is video of the first fully automatic hover using the inner-outer loop adaptive control system performed on the GTMax Unmanned helicopter.