http://www.ifac-papersonline.net/ en Copyright 07:58 PM Wednesday 22, 2012 IFAC-PapersOnline http://www.ifacpapersonline.com 07:58 PM Wednesday 22, 2012 07:58 PM Wednesday 22, 2012 ET webmaster@ifac-papersonline.net webmaster@ifac-papersonline.net http://www.ifac-papersonline.net/Detailed/47339.html 04:00 PM Wednesday 31, 1969 A nonlinear optimal guidance and control scheme for the atmospheric reentry of an RLV using pitch plane maneuver is presented. The guidance law generates an angle of attack control command that satisfies the terminal constraints (considered as hard constraints) and the path constraints (considered as soft minimizable constraints). The guidance update process is done rapidly and in closed form using model predictive static programming (MPSP), a technique that provides a finite time nonlinear suboptimal guidance law. A nonlinear optimal controller for the reaction control system (RCS) and aerodynamic controls has been designed using dynamic inversion (DI) and optimal dynamic inversion (ODI) respectively. A fusion logic for the RCS and aerodynamic control combination provides the total control action required. After each guidance cycle, the guidance command updates the trajectory using the actual states obtained from the control design. The control design is found to track the guidance commands well for perturbations in the initial reentry conditions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47359.html 04:00 PM Wednesday 31, 1969 This paper reports results of an on-orbit experiment using Engineering Test Satellite VIII (ETS-VIII) spacecraft. The ETS-VIII was launched into geostationary orbit by the Japan Aerospace Exploration Agency in December 18 2006. The main mission is to support next-generation mobile digital communications, and for this purpose it is equipped with two large deployable antenna reflectors and a pair of large solar paddles that rotate around the pitch axis. For the spacecraft, the authors have proposed several control methods by applying advanced control theories for the linear parameter varying multi-input multi-output system. Among them, this paper describes the results using two degrees-of-freedom control system based on symmetric feedback control. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47369.html 04:00 PM Wednesday 31, 1969 Developing higher level 3-axis attitude control mechanics is desired in recent satellite attitude control systems, so that we propose an innovative 3-axis attitude control for recent and future satellites by using Reflectivity Control Device, RCD, which is capable of changing its reflectance according to applied voltage. This paper shows some examples of the high accuracy and stability 3-axis attitude control method using RCD, and indicates usefulness of this method with the 3-axis attitude control simulation including the torques generated by solar radiation pressure. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47429.html 04:00 PM Wednesday 31, 1969 The general context of this paper is the design of active Fault Tolerant Control (FTC) strategies for Linear Time Invariant (LTI) uncertain systems. Active FTC systems work in such a way that when a fault is diagnosed by a Fault Detection and Isolation (FDI) unit, the control law is reconfigured to compensate the effect of fault. FDI and FTC performances are thus highly connected. In this paper, a procedure based on the structured singular value µ and its generalization µg is proposed to manage, for a given application, the interaction between the set of FDI and FTC units. It is shown that asymptotic stability is guaranteed and that global performance can be reached by means of the used µ/µg criteria. The HiMAT aircraft benchmark is used to illustrate the main steps of the method. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47473.html 04:00 PM Wednesday 31, 1969 This paper introduces the dynamic inversion with the Lyapunov function method. This is for a guidance and control system of a chase UAV with the velocity controller which is designed based on a dynamic inversion approach. The guidance and control system employs the pure pursuit guidance to determine the UAV's orientation, and a two-time scale dynamic inversion technique to control the attitude. All together, they enable the UAV to keep formation flight. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47345.html 04:00 PM Wednesday 31, 1969 A newly developed nonlinear continuous-time model predictive static programming (MPSP) technique with input inequality constraints is presented in this paper for a carrier launch vehicle in a hypersonic mission, which leads to a closed form solution of the necessary guidance command. The proposed optimal guidance algorithm can be implemented online and leads to computational efficient. In this paper, the trajectory of the launch vehicle from launch point to terminal injection point is divided into two segments. In the first segment, a nonlinear feedback guidance loop using dynamic inversion is incorporated to assure vertical raise in presence of wind disturbance, thrust misalignment etc for launch clearance. In the second segment, the proposed guidance algorithm is incorporated to ensure the desired terminal conditions within a tight error bound with minimum control effort and to satisfy the others path constraints like desired control (angle of attack) effort in the transonic zone and high dynamics pressure region. The promising simulation results suggest that the proposed guidance algorithm with input inequality constraints is quite successful in obtaining the performance of the carrier launch vehicle. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47433.html 04:00 PM Wednesday 31, 1969 This paper focuses on the problem of nonlinear fault detection, diagnosis, and fault tolerant control for a satellite model through the construction of disturbance decoupled adaptive filters designed via the nonlinear geometric approach. Each filter of the bank is sensitive to all but one fault, and decoupled from aerodynamic disturbances. In order to fulfil the requirements of the proposed mission, the disturbance decoupling represents the key point, since the aerodynamic model is often uncertain. To the authors' knowledge, this is the first work presenting the solution of the aerodynamic disturbance decoupling problem. The controller reconfiguration logic exploits a further control loop depending on the on-line estimate of the fault signals. Simulations results for the case of a nonlinear satellite model with aerodynamic, gravitational, magnetic, and solar pressure disturbances are presented with reference to a pointing mission. The suggested approach allows to achieve better performances with respect to control schemes simply designed to be robust with respect to the considered disturbance contributions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47413.html 04:00 PM Wednesday 31, 1969 In this paper, a formation problem of a spacecraft with a leader in an elliptic orbit is considered, where the follower is required to track asymptotically a given periodic relative orbit. The linearized equations of relative motion along an eccentric orbit are known as Tschauner-Hempel equations. The Tschauner-Hempel equations are transformed into simpler ones by the change of variables. For the transformed system, the active formation problem is formulated, and feedback controllers are designed by the regulator equations associated with the Hill-Clohessy-Wiltshire equations. Feedback controllers are also designed using a DRE associated with the TH equations, and the L1-norms of designed controllers are compared. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47347.html 04:00 PM Wednesday 31, 1969 Spacecraft motion control system is very important for safely landing on the moon surface. To reduce complexity and increase performance in landing system motivates to develop a new idea for lunar lander descent scheme. Moreover, precise landing capability with high robustness against parameter uncertainties and optimality in fuel consumption with the ability to be landed vertically are essential for future lunar or planetary landing missions. This research qualitatively represents an advanced gravity-turn descent issue to allow an accurate depiction of descent from orbital condition. In fact, this idea expands the sphere of legitimacy of the gravity-turn illumination from low velocity terminal descent to a complete descent starting at parking orbit. It can readily be used to develop real-time guidance algorithm for future lunar landing mission reducing the computational burden. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47417.html 04:00 PM Wednesday 31, 1969 Swarms of multiple, autonomous mobile agents have been shown to have advantages over single agent systems such as scalability, robustness and flexibility. This papers considers swarm pattern control using a generic artificial potential field and a range of dissipation control terms. An investigation of a number of dissipation terms to induce different swarm behaviours is undertaken. In addition, a novel dissipation control term is introduced based on time-delay feedback control. It is shown that a delayed dissipation term can induce vortex formations without knowledge of relative velocities. Finally, a stability analysis is undertaken that verifies swarm behaviour in a subset of these cases. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47435.html 04:00 PM Wednesday 31, 1969 In this paper a fault accommodation approach especially suitable for nonlinear dynamic inversion controllers is presented and applied to an atmospheric re-entry vehicle. The approach is based on the nominal/robustness decoupling principle used in recent high-performance architectures, reminiscent of anti-windup compensator approaches, and is well connected to the Youla-Kucera controller parameterizations used in the field of fault tolerant systems. The applicability of the approach is exemplified through its application to a high-fidelity nonlinear simulator of a reusable launch vehicle during re-entry which includes a nonlinear dynamic controller and an H-infinity based fault detection and isolation filter. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47465.html 04:00 PM Wednesday 31, 1969 As is well known, in Low Earth Orbit, besides gravitational force, a number of perturbing factors influence a spacecraft's trajectory. It is possible to divide these perturbations into two basic groups: gravitational-due to Earth's non-sphericity, other celestial bodies attraction (The Sun, the Moon) and non-gravitational-due to mainly atmosphere drag and direct/indirect solar radiation pressure. In this paper attention will be paid to method of assessment and measurement on the spacecraft board, especially accelerations rising by virtue of non-gravitational perturbing forces. The development of a special measurement instrument-the microaccelerometer-its block diagram, control concept and its application in space research projects are presented in this paper also. New developed electrostatic accelerometer is considered and analyzed as a smart sensor. The areas of aerospace application and advantages are described. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47377.html 04:00 PM Wednesday 31, 1969 Nano-JASMINE (Nano-Japan Astrometry Satellite Mission for INfrared Exploration) is a nano astrometry satellite developed at the ISSL, University of Tokyo. The mission objective is to measure the positions of stars to accuracy of 1.8 milli-arcsecond (mas). In order to obtain accurate astrometry data, the satellite should be stabilized to better than 4 × 10-7 rad/s, which is difficult to achieve using only conventional sensors. In Nano-JASMINE mission, the attitude will be determined by assessing the quality of the star image observed with the mission telescope. In this research, sequence of each attitude control mode and how to estimate angular velocity in observation phase is focused on. Based on simulation results, the research concludes that the use of star blurred image data to estimate attitude information is a feasible method for use on the Nano-JASMINE mission. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47293.html 04:00 PM Wednesday 31, 1969 In this paper we have designed and implemented a predictive automatic flight controller for an airplane that takes as input the estimated pose obtained from the visual data and provides control outputs for an inner-loop augmented aircraft. In order to make the predictive controller suitable for flight control, it had to be modified. The most important modification was the introduction of the short term reference trajectories, linking the time-based and the position-based control strategy. Furthermore a controller switching mechanism was introduced to enable the aircraft to fly at different flight conditions. The parameters of the controller have been derived by experimental optimization. The tests have shown good overall tracking and disturbance rejection properties; the aircraft is able to perform various maneuvers and the touchdown in all the tested weather (wind, turbulence) conditions. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47317.html 04:00 PM Wednesday 31, 1969 This paper examines the closed-loop stability characteristics of the Synthetic Waypoint Guidance (SWG) algorithm. Following the development of the underlying guidance laws, an analysis into the effect of guidance parameter variations on aircraft performance was conducted. The dynamics of the synthetic waypoint was integrated with the dynamics of the aircraft to develop an augmented state space model incorporating aircraft and guidance states. A linear stability analysis was performed and showed that guidance parameter variations had a significant effect on the overall stability of the system with the introduction of a new guidance mode. The properties of the guidance mode and its influence on the state response of the aircraft are illustrated by simulation. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47475.html 04:00 PM Wednesday 31, 1969 A control moment gyro (CMG) is a device used as an actuator for a attitude control of spacecrafts and provides high agility. This study focuses on the control law that is especially efficient for periodic maneuvering satellites with SGCMGs arranged like a pyramid. This kind of maneuvers can be utilized for observation satellites to widen the swath and observe multiple targets. The control law for periodic maneuvering satellites is formulated. In addition, this paper discusses the stability and optimality of the proposed control law. The problem for using the control law has the potential to occur the undesirable convergence near, or at a singularity. The modification of the control law using the diagonal matrix is proposed to solve the singularity problem. Simulation results show the useful merits that the proposed control law can converge the gimbal angles from initial gimbal angle combination to the desired optimal gimbal state even if a singularity exists while converging the gimbal angles and the satellite can perform commanded periodic maneuver with minimum energy consumption. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47333.html 04:00 PM Wednesday 31, 1969 In this paper, we proposed a cooperative guidance strategy to consider many on many engagements for maritime area air defence. The main idea is that a cooperative missile guidance law can defend the area as long as it guarantees that the keep out zone is always within the defended area defined by Earliest Intercept Geometry (EIG) or a No Escape Zone (NEZ). Since one of the most important issues for the cooperative guidance is to allocate attacking missiles to defending missiles, we focused on developing an allocation plan. The cooperative guidance algorithm proposed in this paper consists of two main parts: a pre allocation algorithm designed by using the EIG guidance law and Differential Geometry Guidance Law (DGGL); in flight target allocation proposed based on the differential game theory. Whilst the pre allocation plan is activated during the mid course and deactivated after the mid course, the in flight target allocation is activated during all in flight phases to refine the initial allocation. Mathematical analysis for the allocation algorithms is carried out to check their characteristics and the performance of the proposed strategy is verified by some numerical examples. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47297.html 04:00 PM Wednesday 31, 1969 This paper proposes a design method of a model-following PID controller which is an extension of the design method of a proportional and derivative preceded integral (I-PD) controller based on integral-type optimal servomechanism (IOS) and the ν-gap metric. This original method is simple, compared with conventional ones and consists of two stages. First, a given high-order plant is reduced to a second-order system in terms of the ν-gap metric, and next, the state feedback gains of the IOS for the second-order system are computed to obtain PID control gains. The I-PD controller is extended to a model-following type by adding a reference model and a feedforward compensator for a desirable output response. This design method has been applied to Mini Aerial Vehicle (MAV) flight controllers to demonstrate that the proposed design method has sufficient effectiveness. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47375.html 04:00 PM Wednesday 31, 1969 A 50-kg-class microsatellite "MAIDO-1 (SOHLA-1)" was launched, along with six other piggyback subsatellites, by a Japanese H-2A rocket on January 23, 2009. The fundamental and detailed designs of the satellite were developed by university students under the technical guidance of the Japan Aerospace Exploration Agency (JAXA). A string-type sun sensor (Fudai Sun Sensor; FSS) was also developed by the students with the technical assistance of JAXA and Advanced Engineering Services (AES) Co. Ltd. The FSS was mounted on the satellite as an experimental component. This paper reports the development of MAIDO-1 and FSS as well as the satellite operation by the students and the results of on-orbit experiments. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47453.html 04:00 PM Wednesday 31, 1969 This paper studied the dynamic model of Variable Speed Control Moment Gyros (VSCMG) with uncertainty. The configuration uncertainty and the rotator's inertia uncertainty are introduced into the dynamic model; the effect of uncertainties is also discussed. A new Jacobian matrix is defined to describe the effect of uncertainties. Compared with the traditional definition, this new definition includes the information of installation angle and rotator's inertia. A new steering law is designed based on singularity value decomposition theory. The linearization of dynamic model is discussed and an adaptive parameter estimation method is then proposed to deal with the parameter uncertainty. Monte Carlo approach is used for the simulation. The results show that the proposed parameter estimation method could reduce the output torque error effectively. In the same time, the estimation value can reach to its actual value quickly. It means that the proposed method could counteract the effect of uncertainties, which makes the system dynamics and output torque character dissatisfied, and the system performance is guaranteed. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47405.html 04:00 PM Wednesday 31, 1969 An essential subtask for performing autonomous on-orbit servicing is the relative navigation between the approaching spacecraft and the target spacecraft. Camera based solutions can be cheap and lightweight and have low power consumption, but they need adequate estimation algorithms. In mobile robotics many approaches for camera based autonomous navigation have been developed so far. We present an approach for vision based autonomous relative spacecraft rendezvous navigation between a chaser and an uncooperative and unknown target based on simultaneous localization and mapping algorithms (SLAM) concepts. The paper outlines the general concept and details the mathematical formulation for stereo image observables. Performance results are shown based on simulation experiments. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47403.html 04:00 PM Wednesday 31, 1969 We consider the safety of a V-bar hopping manoeuvre which forms part of the final stage in autonomous space rendezvous. This manoeuvre is controlled by thrusters: we assume these inputs are perfect impulses and model the system in a hybrid automaton framework. We consider the operation of the system under bounded parametric uncertainties, e.g. thruster misalignment, and use the concept of Barrier function certificates to assess system safety. This methodology provides an efficient tool for the systematic investigation of the safety property and does not rely on Monte-Carlo simulations. In particular, the existence of a Barrier function certificate guarantees that all trajectories of the system starting from a given initial set do not enter a predefined unsafe region under any possible combination of parameter deviations. Such a Barrier function certificate can be constructed efficiently using the Sum of Squares (SOS) decomposition and semi-definite programming (SDP). http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47361.html 04:00 PM Wednesday 31, 1969 Satellite control is facing up new requirements in terms of high precision. Actuators satisfying these demands appear to be sensitive to the saturation. This can induce negative effects (i.e. oscillations, instability). To modify this situation an anti-windup strategy can be applied. The idea consists in introducing control modifications to keep the response close to the linear one. Two main architectures are used. The first one is based on a computation of a saturating feedback law. The second one is based on selecting an anti-windup incorporating a model of the plant. This work combines both approaches to compute a dynamic anti-windup. Simulations compare this anti-windup with other existing architectures. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47425.html 04:00 PM Wednesday 31, 1969 This paper describes an application of a new fault detection and isolation (FDI) technique based on set-valued observers (SVOs) to a linear parameter varying (LPV) longitudinal aircraft dynamic model. The FDI strategy adopted herein computes and uses the set-valued estimates of the SVOs to eliminate models of the plant that are not compatible with the set of observations provided by the aircraft sensor suite and actuation data. The design of the SVOs takes into account model uncertainty and disturbances, thus avoiding false alarms due to such perturbations. The behavior of the proposed solution is assessed in simulation, by deliberately generating hard and soft sensor/actuator faults. The results show that the faults take, in general, only a few iterations to be detected and isolated, therefore paving the way for the use of the proposed methodology in practical applications. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif http://www.ifac-papersonline.net/Detailed/47431.html 04:00 PM Wednesday 31, 1969 In this paper, a Fault Tolerant Control (FTC) strategy using a virtual actuator for non-linear systems represented as Linear Parameter Varying (LPV) models is proposed. The main idea of this FTC method is to adapt the faulty plant to the nominal controller instead of adapting the controller to the faulty plant. That is, the faulty plant together with the virtual actuator block allows the controller to see the same plant as before the fault. This virtual actuator is designed using polytopic LPV techniques and LMIs. To assess the performance of the proposed approach a two degree of freedom helicopter is used. http://www.ifac-papersonline.net/static/luna/images/ifac/icon-download.gif