A method for measuring mechanical response of a plant stem against small impact force is proposed. In this method, the mechanical characteristics of the plant stem against small force are determined by means of the "Levitation Mass Method" (LMM). The LMM is a method for accurately measuring varying force without the use of force transducers. Mechanical characteristics of a plant stem were measured with high accuracy by means of an instrument developed base on the LMM. In the measurement, a mass that is levitated with a pneumatic linear bearing, and hence encounters negligible fiction, is made to collide with a plant stem under test. During the collision, the Doppler frequency shift of a laser beam reflecting from the mass is highly accurately measured using an optical interferometer. The velocity, position, acceleration and inertial force of the mass are calculated from the measured time-varying Doppler shift. The mechanical response of a plant stem against small impact loading is also characterized from the measured data.

Characterization of Impact Response of a Plant Stem

A collection of simple robots can replace a complex robot via cooperation. In the process of cooperation, forming a specific formation pattern will enhance the efficiency of work and data transmission between robots. In order to form a specific formation pattern, interaction between robots should be well studied. The interaction can be divided into two groups: motion interaction and information interaction. Motion interaction means the relative movement between robots and information interaction means the exchange of sensor readings or communication data of robots. In this study, graph theory is used to model the physical relationship and information exchanging topology among robots. Artificial potential field based high-level controllers are designed for the motion interaction of robots to form stable formations. Considering effects of different information topologies, two scenarios with six robots in formation control problem are presented and discussed. Simulation studies of the two scenarios show that motion interaction of robots in formation control is affected by information interaction. Factors such as robustness, convergence speed, power consuming, sensitivity, and system efficiencies are compared for different information topologies.

Analysis of Formation Control and Communication Pattern in Multi-Robot Systems

Hybrid systems are usually consisted of states described partially by continuous variables and partially by discrete variables. In this work, we propose an LMI-based control design for hybrid systems by using fuzzy model-based approach and averaging method. We start with the control-oriented presentation to define the hybrid automata. Then, it is described by a fuzzy model. In light of the concept of pulse-width modulation (PWM) scheme, the crisp fuzzy set is with the value of the duration in an interval. Instead of directly designing the switching sequence for our hybrid systems, the values of the duration are the control signals which need to be designed. Then, the switching sequence for the hybrid systems can be realized by using PWM method.

Fuzzy Model and Control for Hybrid Systems Using Averaging Techniques

Hybrid systems areusually consisted ofstates described partially bycontinuous variables andpartially by discrete variables. Inthis work, wepropose anLMI-based control design forhybrid systems byusing fuzzy model-based approach andaveraging method. We start withthecontrol-oriented presentation todefine thehybrid automata. Then, it isdescribed byafuzzy model. Inlight oftheconcept ofpulse-width modulation (PWM)scheme, thecrisp fuzzy setis withthevalue oftheduration inaninterval. Instead ofdirectly designing theswitching sequence forourhybrid systems, thevalues oftheduration arethecontrol signals whichneedtobedesigned. Then, theswitching sequence forthehybrid systems canberealized byusing PWM method.

http://ieeexplore.ieee.org/iel5/4108013/4108014/04108907.pdf

FuzzyModelandControl forHybrid Systems Using Averaging Techniques

In this paper, the development of a two-vehicle coordinated control system to push an object is presented. Starting from the mechanical design, two unmanned vehicles (mobile robots) were built up, each consisting of a platform moving with four wheels. Carrier phase differential GPS algorithm is used to determine the positions of the vehicles up to centimeter accuracy. A fuzzy controller is designed on the vehicle to perform the tracking of a desired trajectory. Another fuzzy controller is installed in the control station to fulfill the coordination process. Experimental results show that the proposed methodology is feasible and effective. The object can be pushed along a pre-specified trajectory smoothly.

Coordinated Control and Experiments of Pushing an Object by Using Two Unmanned Vehicles

In this paper, a control and design consideration of PV/ diesel hybrid distributed generation system using dual inverter for weak grid is presented. The dual inverter employs a combination of a voltage controlled voltage source inverter (VCVSI) and a current controlled voltage source inverter (CCVSI), connected in series on the DC side and in parallel on the AC side. This system is able provide an uninterruptible power supply (UPS), load voltage stabilization, unity power factor correction, maximum power point tracking (MPPT), and demand side management (DSM). To verify the proposed system, a comprehensive evaluation with theoretical analysis and experimental results is presented.

S.h. Ko

Papers

A Control Approach and Design Consideration of PV/Diesel Hybrid Distributed Generation System Using Dual Voltage Source Inverter for Weak Grid