This paper proposes a method that uses an aircraft with a single-antenna GPS receiver and Pitot tube to estimate wind speed and direction and to calibrate the airspeed. This sensor combination alone does not determine the true attitude of the aircraft, so the wind parameters cannot be obtained directly from the measurements. However, if the aircraft flies at different headings, such as in banking turns or circle maneuvers, the wind magnitude and direction can be estimated from the geometrical relation between the wind and the measurements. An extended Kalman filter (EKF) is applied to estimate wind parameters. The EKF can also estimate the scaling factor used to convert dynamic pressure to airspeed. This is useful for the operation of small unmanned aerial vehicles (UAVs) because of difficulty in determining the airspeed scaling factor of a low-cost UAV. Simulations are performed for a constant 2-D wind. To test the effectiveness of the proposed method, flight tests of a small UAV are conducted. Simulations and flight test results show that the proposed method is effective.

Wind Estimation and Airspeed Calibration using a UAV with a Single-Antenna GPS Receiver and Pitot Tube

A problem is dealt with concerning a practical design scheme for a multi-input/multi-output simple adaptive control (SAC) system. The SAC method which was first derived as a sort of the direct model following adaptive control based on the command generator tracker (CGT) technique was fundamentally applicable to plants satisfying the so-called almost strictly positive real (ASPR) condition. However, the method can be applied to non-ASPR plants by using a parallel feedforward compensator (PFC), which makes the augmented plant including PFC be ASPR. Such a technique was proposed by Bar-Kana for plants satisfying the output feedback stabilizable condition. As an extension, the authors have proposed a simple and concrete PFC design procedure for SISO non-ASPR plants. The special feature of this proposal is that the method can be applicable to non-ASPR plants as the minimum phase system. The main aim of the paper is to give a practical design procedure of PFC for MIMO plants as a natural extension of the SISO c...

Realization of simple adaptive control by using parallel feedforward compensator

We have built an anatomically correct testbed (ACT) hand with the purpose of understanding the intrinsic biomechanical and control features in human hands that are critical for achieving robust, versatile, and dexterous movements, as well as rich object and world exploration. By mimicking the underlying mechanics and controls of the human hand in a hardware platform, our goal is to achieve previously unmatched grasping and manipulation skills. In this paper, the novel constituting mechanisms, unique muscle to joint relationships, and movement demonstrations of the thumb, index finger, middle finger, and wrist of the ACT Hand are presented. The grasping and manipulation abilities of the ACT Hand are also illustrated. The fully functional ACT Hand platform allows for the possibility to design and experiment with novel control algorithms leading to a deeper understanding of human dexterity.

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Mechanisms of the Anatomically Correct Testbed Hand

This paper presents an approach for a quadrocoper-based micro unmanned aerial vehicle (UAV) that estimates the wind vector (speed and direction) in real-time based on measurement data of its on-board sensors only. This method does not need any additional airspeed sensor or dedicated anemometer, and thus the micro UAV's valuable payload remains free for other sensors. Wind tunnel and field tests were used to evaluate the performance of the approach. In order to quantify its accuracy, experiments are presented where data was collected with an anemometer placed in an open field with the micro UAV in flight following a predefined trajectory around the anemometer and hovering at a defined position close to it.

Real-time wind estimation on a micro unmanned aerial vehicle using its inertial measurement unit

Ar ecent publication uses a difficult design example to show that fuzzy logic might have advantages when compared with classical compensators. Although in this particular case the application was shown to be successful, convergence of the fuzzy-logic algorithm, as well as other time-varying controllers, cannot not be guaranteed unless some preliminary conditions are satisfied. It will be shown that further exploitation of the classical design can improve robust performance. This result is then used to create sufficient conditions that guarantee convergence with time-varying controllers, and it is then shown that simple adaptive control methods can further improve performance and maintain it in changing environments. I. Introduction A RECENT publication 1 has presented successful applications of fuzzy-logic control design in a nonminimum phase autopilot with uncertainty of parameters. The authors use this difficult design case to show that fuzzy logic has advantages when compared with a classical compensator or with the ubiquitous proportional‐ integral‐derivative (PID) design when uncertainty is concerned. Although this particular fuzzy-logic application was successful, it is well known that convergence with nonstationary controllers, including adaptive and fuzzy-logic algorithms, is not inherently guaranteed. This paper intends to show that further exploitation of the basic knowledge of the plant and the uncertainty can be used to improve the performance of a classical control design and also to create sufficient conditions that guarantee convergence of time-varying controllers. The results are presented here in connection with simple adaptive control that is shown to achieve improved performance along with the guarantee of stability. Successful implementations of simple direct adaptive control techniques in various domains of application have been presented over the past two decades in the technical literature. This simpleadaptive-control (SAC) methodology has been introduced by Sobel et al. 2 and further developed by Barkana et al. 3 and Barkana and Kaufman. 4,5 These techniques have also been extended by Wenn and Balas 6 and Balas 7 to infinite-dimensional systems. Those successful applications of low-order adaptive controllers to large-scale examples have led to successful implementations of SAC in such diverse applications as flexible structures, 8−15 flight control, 16,17

Classical and Simple Adaptive Control for Nonminimum Phase Autopilot Design

This paper deals with two problems for the improvement of the control performance of simple adaptive control (SAC) techniques. First, it is discussed that the introduction of a robust adaptive control term much robustifies the SAC system concerning plant uncertainties such as state dependent disturbance. Second, a practical procedure is described for designing the parallel feedforward compensator, which is necessary for the actual realization of the SAC system, given prior information concerning the plant such that: (1) the plant is minimum phase; (2) an upper bound on the relative degree exists; and (3) approximate values of high and low frequency gains are known. The effectiveness of the proposed methods is confirmed through the simulation of typical examples of adaptive control systems.

Robust and simple adaptive control systems

Deals with the design problem of a parallel feedforward compensator which virtually realizes an almost strictly positive real (ASPR) plant It is well-known that several output feedback based control techniques can easily be applied to the plants having ASPR characteristics Unfortunately, most real plants do not satisfy this condition To improve such a situation, the implementation of a parallel feedforward compensator (PFC) which causes a non-ASPR plant to become virtually ASPR has been discussed Here, a simple and systematic method of composing such a PFC, which can be applied to a broader class of SISO plants, is considered The effectiveness of the result obtained is examined by applying them to an example of simple adaptive control >

A parallel feedforward compensator virtually realizing almost strictly positive real plant

In this paper, an algorithm to estimate wind direction by using a small and light Unmanned Air Vehicle(UAV) called KITEPLANE was proposed. KITEPLANE had a big main wing which is a kite-like delta shape and, therefore, it was easy to be disturbed by wind. However, this disadvantage implies that the KITEPLANE has an ability to sense wind and that it is expected to use the KITEPLANE as a sensor for wind estimation. In order to achieve this feature, dynamics of the KITEPLANE under wind disturbance were derived and a numerical estimation method was proposed. Devices equipped on board were also developed and the proposed method was implemented. Results of an experiment showed the effectiveness of the proposed method.

Wind Estimation by Unmanned Air Vehicle with Delta Wing

Recently, the simple adaptive control (SAC) method has attracted considerable interest because of the simple structure of its adaptive controller. The method can only be applied to plants with so-called almost strictly positive real (ASPR) characteristics. Unfortunately, most real plants do not satisfy this condition. Furthermore, real plants contain disturbances such as uncertain elements. This paper deals with such problems and proves that the implementation of a parallel feedforward compensator makes it possible to apply the SAC method to non-ASPR SISO plants with plant uncertainties. Furthermore, a robust SAC algorithm in the presence of a class of external disturbances is also considered. The effectiveness of the parallel feedforward compensator and robust adaptive controller designed in this way is examined through several numerical simulations.

Ikurou Mizumoto

Papers

Realization of simple adaptive control by using parallel feedforward compensator

Robust and simple adaptive control systems

A parallel feedforward compensator virtually realizing almost strictly positive real plant

Wind Estimation by Unmanned Air Vehicle with Delta Wing

Robust and simple adaptive control system design