[1] Robust Digital Control System Design using a Discrete Sliding Mode Control, Jung Soon Jang, Claire J. Tomlin, in preparation of Journal of Guidance, Navigation, and Control.
This paper presents a new discrete sliding mode controller for a
nonlinear input-output system. For digital implementation, the proposed
controller uses a discrete output feedback linearization for which the control
law is derived from an equivalent sampled form of nonlinear dynamics obtained
from the Adams-Bashforth method. To take into account
the model uncertainty, coming from actual uncertainty about the plant or from
the purposeful choice of a simplified representation of dynamics, we add a
non-switching type discrete sliding mode term by which the chattering is highly
attenuated, and a smooth control signal is generated. The resulting control law
is augmented with a flight envelope protection algorithm, which re-plans the
reference trajectory when an aircraft encounters inherent constraints such as
thrust and angle of attack limitations. The control law is implemented on a
Hardware-in-the-Loop Simulation, which is a testbed
platform that provides faithful laboratory representation of the DragonFly UAV
in flight. We evaluate the control law under aileron surface damages and different
maneuver types and present our results.
[2] Multivariable Output Tracking of Nonlinear Systems under
Input Constraints with Application to the Stanford DragonFly UAVs, Jung Soon Jang, Claire J. Tomlin, in preparation
of Journal of Conference on Decision
and Control.
Nonlinear dynamic inversion with a cascaded structure is
exhibited for aircraft lateral dynamics control under actuator saturations. The
control input limiting algorithm is developed to keep the control input within
a given control authority by computing the maximum acceleration envelope and
then reducing the bandwidth of the reference acceleration dynamics in
real-time. Then, sufficient condition for Lyapunov
stability is presented.
[3] Flight Demonstration of Provably Safe Closely Spaced
Parallel Approaches, Rodney Teo, Jung Soon Jang, and
Claire J. Tomlin, in preparation of
Journal of Guidance, Navigation, and Control.
[1] The Stanford Testbed of Autonomous Aircraft for Multi-Agent Control, Steven L. Waslander, Gabe Hoffmann, Dev Gorur Rajnarnayan, Jung Soon Jang, and Claire J. Tomlin, submitted in 23th IEEE Digital Avionics Conference, 2004.
[2] Automated Multiple UAV Flight–the Stanford DragonFly UAV Program, Rodney Teo, Jung Soon Jang, and Claire J. Tomlin, will appear in the IEEE Conference on Decision and Control, 2004.
[3] Nonlinear Sliding Mode Control Using Angular Acceleration Measurement, Jung Soon Jang and Claire J. Tomlin, will appear in the AIAA GNC Conference, 2004.
[4] Inference Methods for Autonomous Stochastic Linear Hybrid Systems, Hamsa Balakrishnan, Inseok Hwang, Jung Soon Jang, and Claire J. Tomlin, will appear in HSCC 2004.
[5] Longitudinal Stability Augmentation System Design
of the Stanford DragonFly UAV using a Single GPS Receiver, Jung Soon Jang, Claire
J. Tomlin, in the proceedings of the AIAA GNC Conference,
This paper presents the design of a longitudinal stability
augmentation system (SAS) to investigate practical methods of autonomous
control for the Stanford DragonFly UAV when only a single GPS receiver is used.
Unlike algorithms requiring GPS differential carrier phase measurements, and
multiple GPS receivers in order to determine aircraft attitudes, the problem of
attitude determination is posed as state estimation by introducing a
formulation of aircraft longitudinal dynamics in which only kinematic
measurements (position and velocity) from GPS are required. Then the
longitudinal SAS, which consists of control laws for automating
climb-rate/airspeed hold and altitude/airspeed command, is designed using the
LQR method, and a switching logic is added to capture a desired cruise
altitude. The stability of this switching control system is analyzed using Lyapunov methods. With a detailed modeling of GPS,
simulated scenarios are used to validate proposed algorithms, and the
efficiency of the algorithm is discussed.
[6] Design and Implementation
of a Low Cost, Hierarchical and Modular Avionics Architecture for the DragonFly
UAVs, Jung Soon Jang, Claire J. Tomlin, in
the proceedings of the AIAA GNC Conference, Monterey, CA, Aug. 2002.
We present the design and implementation of the safety critical avionics
for the Stanford DragonFly Unmanned Aerial Vehicles (UAVs).
The software architecture of the avionics is based on the Server-Client architecture
of QNX Neutrino, the real-time operating system used. Our architecture
is hierarchical and modular: it isolates user-defined applications from
underlying low-level system services for implementing inter-process
communication, data-acquisition, and associated hardware management. Also, we
employ a new run-time scheduling algorithm to maximize the execution of tasks
within a given deadline. The integrated hardware architecture is based on
standard PC/104 and RS232 technology, making it possible to use Commercial
Off-The-Shelf (COTS) components and provide an efficient means of communication
between components. We have developed this architecture in parallel (and in
conjunction) with Boeing’s Open Control Platform (OCP) architecture, which is a
new software infrastructure based on real-time CORBA technology, and we use the
OCP to implement ground station functionalities. We present the design
principles and choices, the resulting avionics architecture, and the
implementation in a robust and compact avionics package. We then present
initial results of the avionics in car tests, and discuss the results.
[7] Dragonfly:
A Versatile UAV Platform for the Advancement of Aircraft Navigation and Control,
J. Evans, G. Inalhan, J.S. Jang, R. Teo, and C. Tomlin, In the Proceedings of the 20th IEEE
Digital Avionics Systems Conference, Oct. 2001.
This paper gives an overview of the DragonFly experimental test bed and the
specific research goals that it currently supports.
[8] Autopilot
Design for the Stanford DragonFly UAV: Validation through Hardware-in-the-Loop
Simulation, Jung Soon Jang, Claire J. Tomlin, in the proceedings
of the AIAA GNC Conference,
We present an embedded autopilot design for the Stanford DragonFly Unmanned
Aerial Vehicle (UAV) of which the digital computer in the avionics is only
capable of processing sampled data and executing discrete-time control
policies. We demonstrate that linear control design is not sufficient to
satisfy performance requirements for specified high performance maneuvers at
slow sample rates. We design a new nonlinear digital controller using an
approximate feedback linearization. The sampled nonlinear dynamics for the
feedback linearization is obtained using the Adams-Bashforth
method, and the resulting control law is augmented with the discrete
disturbance accommodation control to improve the performance and stability of
the controlled system. The control law is implemented on a Hardware-in-the-Loop
Simulation, which is a testbed platform that provides
a faithful laboratory representation of the DragonFly UAV in flight: sensor and
actuator packet delay and communication constraints in control, are included in
this testbed. We evaluate the control law using
different sample rates and present our results.
[9] Nonlinear Dynamic Inversion Control for Bank-to-Turn
Missile, Jinho Kim, Jung Soon Jang, in the
proceedings of the AIAA GNC Conference,
This paper presents the nonlinear dynamic inversion control for
a bank-to-turn missile. The control is used to linearize
the highly nonlinear terms such as gyroscopic and coriolis
cross-coupling products. The attitude control algorithm is designed for missile
to track the desired attitude so that the missile may produce the commanded
acceleration. The conventional guidance and tracking method is adapted to
generate the desired acceleration for the target maneuver. Finally, the
simulation is conducted to demonstrate the effectiveness of the proposed
nonlinear control.
[10] Lateral Stability Augmentation using Decentralized
Control, Jung Soon Jang, Jinho Kim,
Conference Papers (Korean)
[1] The Autopilot System Design of BTT missile using Decentralized Control, Jung Soon Jang, Jinho Kim, in the proceedings of the KSAS Sping Annual Meeting, 1994, pp. 410-414.
For missile control, a linear
quadratic regulator and a pole placement are studied. A decentralized control
method is also applied to the LQR system to improve the damping characteristics
of the lateral modes. The proposed method can place eigenvalues
selectively on desired locations while retaining a given cost function and
maintaining remaining eigenvalues.
[2] The study on Autopilot System with Pre-designed Gain
Schedule, Jung Soon Jang, Choonbae Park, in the
proceedings of Korean Control Association, 1993, pp. 613-618.
A linear control system operating over the full flight envelope
is designed using a gain scheduling method. For each design point selected from
the flight envelope, the classic PID controller is designed to satisfy a given
performance specification such as a rising time and a overshoot. Then the gain
matrix is interpolated and extrapolated as the function of a dynamic pressure
at the off-design points.
[3] The Parameter Estimation Method for Tail Rotor Design,
Jung Soon Jang, Choonbae Park, in the proceedings
of the KSAS Autumn Annual Meeting, 1992, pp. 263-269.
The tail rotor configuration has a critical impact on the
specific performance of a helicopter (maximum side velocity). The tail rotor
performance is analyzed using a finite difference method.
[4] The Turbulence Simulation on Research Flight Simulator,
Jung Soon Jang, Choonbae Park, in the proceedings
of the KSAS Spring Annual Meeting, 1992, pp. 139-144.
[1] Embedded Software Design for the Stanford DragonFly UAVs,
Jung Soon Jang, Rodney Teo,
Claire J. Tomlin, Department of Aeronautics and Astronautics,
Reports (Korean)
[1] The Study on Hang-glider Motion for Simulator Development,
Jung Soon Jang, Choonbae
Park, Aviation Management Research Institute,
[2] The Calculation of Aerodynamic Variables for 6 DOF Flight Simulator,
Sanghee Ko, Hyunho Na, Byungmoon Kim, Jung Soon Jang, Choonbae Park, Daewoo Heavy Industrial Inc., 1994.
[3] The Study on the Characteristics of Fly-by-Wire Servo System,
Younghyun Shin, Jung Soon Jang,
Nonlinear Control Using Discrete-Time Dynamic
Inversion Under Input Saturation: Theory and
Experiment on the Stanford DragonFly UAVs. Jung Soon Jang, Department of Aeronautics and Astronautics,
Computing Danger Zones For Probably Safe Closely
Spaced Parallel Approaches: Theory and Experiment. Rodney Teo,
Department of Aeronautics and
Astronautics,