Adaptive nonlinear guidance law considering control loop dynamics

2003 ◽  
Vol 39 (4) ◽  
pp. 1134-1143 ◽  
Author(s):  
Dongkyoung Chwa ◽  
Jin Young Choi
Keyword(s):  
Control Loop ◽  
Guidance Law ◽  
Loop Dynamics

How to design externally positive feedback loops – an open problem of control theory

2020 ◽  
Vol 68 (5) ◽  
pp. 301-311
Author(s):  
Alexander Schwab ◽  
Jan Lunze
Keyword(s):  
Open Problem ◽  
Closed Loop ◽  
Design Procedure ◽  
Positive Control ◽  
Feedback Loops ◽  
Positive Systems ◽  
Control Loop ◽  
Output Variable ◽  
Control Loops ◽  
Loop Dynamics

AbstractThis paper addresses the properties of externally positive systems and summarises existing conditions and design approaches that achieve externally positive closed-loop dynamics. The output variable of such systems is always nonnegative for any nonnegative input which is a very useful property in various control tasks. This paper investigates the problem of rendering control loops externally positive by an appropriate choice of a feedback. It shows that there is currently no general design procedure for that purpose and the question of when such a controller exists has not been clarified yet. It is also shown that there are plants for which there is no controller that leads to an externally positive control loop.

scholarly journals CONTROL SYNTHESIS FOR TWO LOOPS DISCRET SYSTEM

2018 ◽  
pp. 22-26
Author(s):  
O. F. Opeiko
Keyword(s):  
Stability Domain ◽  
Pi Controller ◽  
Numerical Control ◽  
Control Synthesis ◽  
Control Loop ◽  
Time Period ◽  
Parameters Uncertainty ◽  
Loop Dynamics ◽  
The Stability ◽  
Siso Systems

The aim of this paper is the linear synthesis of two loops SISO systems with discreet time proportional integral (PI) controllers. This linear synthesis is dedicated for the systems with plant parameters uncertainty. The synthesis is based on the time scale method, providing the separate slow and fast components of the control low. The PI- controller parameters calculation is based on the modal control and plant model reduction. The conditions carried out for the each control loop dynamics still similar to the second order one. The discrete time microcontroller based numerical control restricts the stability domain of the system and each control loop in it. The stability domain of each loop is the round on the complex plane with radius, depending on the time period. Each inner loop must be more fast, then each outer one. Hence, in the outer loop the time period, required for the PI controller reaction computation, can be more then in the inner loop. This PI- controller parameter calculation method is approximate, and it is efficient for the systems, whose dynamics contains the slow and fast components. In particular, the electrical drives control systems contain the fast electromagnetic component and the slow mechanical part. The effectiveness of this method is illustrated by the example and simulation.

scholarly journals Rope-Hook Recovery Controller Designed for a Flying-Wing UAV

Aerospace ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 384
Author(s):  
Zhao Deng ◽  
Fuqiang Bing ◽  
Zhiming Guo ◽  
Liaoni Wu
Keyword(s):  
Attitude Control ◽  
Tracking Error ◽  
Recovery Process ◽  
Flight Test ◽  
Control Loop ◽  
Proportional Navigation ◽  
Outer Loop ◽  
Guidance Law ◽  
Disturbance Rejection Control ◽  
And Control

Due to the complexity of landing environments, precision guidance and high-precision control technology have become key to the rope-hook recovery of shipborne unmanned aerial vehicles (UAVs). The recovery process was divided into three stages and a reasonable guidance strategy had been designed for them, respectively. This study separated the guidance and control issues into an outer guidance loop and an inner control loop. The inner loop (attitude control loop) controled the UAV to follow the acceleration commands generated by the outer loop (trajectory tracking loop). The inner loop of the longitudinal controller and the lateral controller were designed based on active disturbance rejection control (ADRC), which has strong anti-interference ability. In the last phase, the outer loop of the longitudinal controller switched from a total energy control system (TECS), which greatly decoupled the altitude channel and speed channel, to the proportional navigation (PN) guidance law, while the outer loop of lateral controller switches from the proportional control law based on the L1 guidance law, which can reduce the tracking error and deviation, to the PN guidance law, which considerably enhances the tracking precision. Finally, the simulation data and flight test data show that the controller has strong robustness and good tracking precision, which ensures safe rope-hook recovery.

Modeling and Stability of Milling Processes With Active Damping

2019 ◽  
Author(s):  
David Lehotzky ◽  
Zoltan Dombovari
Keyword(s):  
High Speed ◽  
Finite Impulse Response ◽  
Low Frequency ◽  
Recent Decade ◽  
Control Loop ◽  
Measuring Device ◽  
Stability Lobe ◽  
Loop Dynamics ◽  
Real Behavior ◽  
Tuning Strategy

Abstract In the recent decade, active dampers have been introduced to machining for the avoidance of machine tool chatter in milling processes. The tuning strategy for most of these devices is based on models which do not account for the dynamics of control loop within the active dampers, hence neglect the dynamics of actuator and measuring device, and do not consider filtering. However, these simplified models might lead to inaccurate stability predictions which can deteriorate the performance of active dampers. In order to better approximate the real behavior of milling processes controlled by active dampers, this paper develops a new mathematical model which incorporates the dynamics of control loop within these devices. In particular, the inertial actuator is modeled as an electromagnetic proof-mass transducer, while the dynamics of piezoelectric accelerometer and finite-impulse-response filtering are also taken into account. By the computation of stability lobe diagrams, it is shown that, at low-frequency actuation and at high-speed milling, the consideration of control loop dynamics in active dampers can be essential.

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