Modeling and Analyses of the N-link PenduBot
As the foundation of the multi-link PenduBot control, the mathematical model should be established first. Based on the method of kinematics and dynamics, the N-link PenduBot mathematical models are established in this paper, including the nonlinear model, the linear model and the generalized model which considers the motor characteristic. The natural characteristic of the system is analyzed. By using the condition number of the controllability matrix, the control difficulty for the higher order systems is compared. From the comparison result, the control law of the different links PenduBot is obtained. Increasing with the count of PenduBot links, the control difficulty is growing dramatically. Only a strong control measure can make it stable. So, further study on multi-link PenduBot can be carried on.
Design of control system with limited feedback gain based on CPSO algorithm
To solve the problem that the feedback gain is too high during high-order control system design, we propose the design idea of limited feedback gain. Using the chaos particle swarm algorithm (CPSO), we realized the process of limited feedback gain control system design. Taking the three-link PenduBot controller as an example, the design process is illustrated in detail. Simulation and physical control results indicate that the design method is effective, the gain we get is relatively low, and could be easily implemented. The design idea provides a new and effective method for high-order control system design.
FORTE observations of lightning radio‐frequency signatures: Capabilities and basic results
The FORTE satellite, launched on August 29, 1997, carries both radio‐frequency‐receiver and optical (imaging and photometric) payloads for the study of lightning. The radio‐frequency (RF) data for the first 7 months of operation are described, both to illustrate the satellite's capabilities and to explain the basic statistical findings so far. FORTE's multichannel RF trigger system represents a significant advance in space‐based monitoring of lightning emissions. We are able to observe even rather weak and diffuse RF emissions from lightning and are no longer limited to the brightest known events, “transionospheric pulse pairs,” or TIPPs. We do see TIPPs, and we show that the FORTE observations of TIPPs are consistent only with the second pulse's being due to a ground reflection. We find that TIPPs are basically bimodal in character, one type having a steep roll‐off of power from 38 to 130 MHz and the other being essentially flat‐spectrum in that range. The steep‐spectrum TIPPs cluster together in the manner of most RF emissions from lightning, while the flat‐spectrum events tend to maintain a wider spacing (>0.1 s) between recurrent emissions.