Two Degree of Freedom Control Synthesis With Applications to Agricultural Systems

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Yangmin Xie ◽  
Andrew Alleyne
Keyword(s):  
Disturbance Rejection ◽  
Feedforward Control ◽  
Mechanical Design ◽  
System Modeling ◽  
Degree Of Freedom ◽  
Control Synthesis ◽  
Height Control ◽  
Performance Improvements ◽  
Elevation Changes ◽  
Two Degree Of Freedom

This paper presents a two degree of freedom (DOF) controller for combine harvester header height control (HHC). Fundamental limitations to the tracking and disturbance rejection bandwidth for feedback control designs exist in the HHC system due to the considerable actuator delay and underactuated and noncollocated mechanical design. In this work, we utilize H∞ optimal control design to ensure closed-loop stability and robust performance, and augment the feedback loop with a feedforward control structure based on readily available global positioning system (GPS) information. The GPS provides anticipatory information of the field map elevation; albeit with noise, resolution limits, and latency. The elevation changes result in disturbances to the header height control problem and the feedforward controller uses the knowledge of the field to increase the overall disturbance rejection bandwidth. Simulation and experimental results illustrate the performance improvements resulting from the 2-DOF design over the stand alone feedback controller, which removes a long standing obstacle in increasing the harvesting productivity. Additionally, an error analysis examines the effect of uncertainties from system modeling and field map measurements on the system performance.

Two-degree-of-freedom Controller Design for Uncertain Processes Using Input/output Linearization Control Technique

2011 ◽  
Vol 11 (1) ◽  
pp. 16 ◽  
Author(s):  
Pisit Sukkarnkha ◽  
Chanin Panjapornpon
Keyword(s):  
Disturbance Rejection ◽  
Control Structure ◽  
Control Method ◽  
Random Noise ◽  
Degree Of Freedom ◽  
Control Technique ◽  
Input Output ◽  
Tracking Controller ◽  
Two Degree Of Freedom ◽  
Input Output Linearization

In this work, a new control method for uncertain processes is developed based on two-degree-of-freedom control structure. The setpoint tracking controller designed by input/output linearization technique is used to regulate the disturbance-free output and the disturbance rejection controller designed is designed by high-gain technique. The advantage of two-degree-of-freedom control structure is that setpoint tracking and load disturbance rejection controllers can be designed separately. Open-loop observer is applied to provide disturbance-free response for setpoint tracking controller. The process/disturbance-free model mismatches are fed to the disturbance rejection controller for reducing effect of disturbance. To evaluate the control performance, the proposed control method is applied through the example of a continuous stirred tank reactor with unmeasured input disturbances and random noise kinetic parametric uncertainties. The simulation results show that both types of disturbances can be effectively compensated by the proposed control method.

Error Dynamics Design via a Repetitive Loop for UDE-Based Robust Control to Reject Periodic Disturbances

2020 ◽  
Author(s):  
Yeqin Wang ◽  
Yiting Dong ◽  
Jiguo Dai ◽  
Beibei Ren ◽  
Qing-Chang Zhong
Keyword(s):  
Robust Control ◽  
Disturbance Rejection ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Reference Tracking ◽  
Charging System ◽  
Internal Model Principle ◽  
Periodic Disturbances ◽  
Error Dynamics ◽  
Two Degree Of Freedom

Abstract The uncertainty and disturbance estimator (UDE)-based robust control has a two-degree-of-freedom nature through the design of the error dynamics and the design of the UDE filters. In the conventional design to handle periodic disturbances or mixed sinusoidal disturbances, high-order UDE filters incorporated with the internal model principle (IMP) or time-delay filters (TDF) are adopted to achieve the asymptotic reference tracking and the asymptotic disturbance rejection. In this paper, a new error dynamics design combined with a repetitive loop is proposed for the UDE-based robust control to achieve the asymptotic rejection of both step disturbances and periodic disturbances. The disturbance rejection performance is investigated through the two-degree-of-freedom nature, and the practical implementation of the proposed design is illustrated to eliminate the infinite bandwidth of the repetitive loop. The proposed design is validated through the simulation studies of a battery charging system with comparison to different reported designs of the conventional UDE-based robust control.

A Complete Model of a Two Degree of Freedom Platform Actuated by Three Pneumatic Muscles Elaborated for Control Synthesis

2016 ◽  
Author(s):  
David Bou Saba ◽  
Eric Bideaux ◽  
Xavier Brun ◽  
Paolo Massioni
Keyword(s):  
Volume Ratio ◽  
Degree Of Freedom ◽  
Control Synthesis ◽  
Complete Model ◽  
Pneumatic Muscles ◽  
Wide Range ◽  
Mechanical Study ◽  
Industrial Use ◽  
Two Degree Of Freedom ◽  
Nonlinear Control Synthesis

Pneumatic muscles have a high potential in industrial use, as they provide safety, high power over volume ratio, low price and wide range of pulling effort. Nevertheless, their control is quite hard to achieve due to the non linearity and hysteresis phenomena, plus the uncertainties in their behavior. This paper presents the modeling of a two degree of freedom platform actuated by three pneumatic muscles for control purposes. Three servovalves are used to supply airflow inside the muscles. The innovative concept is the modeling of each component including the static and dynamic muscle behavior. The model of the servovalve consists of a look-up table gathering the three variables: airflow, pressure and voltage applied to the servovalve. In addition, a thermodynamic and a mechanical study of the system complete the model. The result is a complete model design having as input the voltage applied to the three servovalves, and as outputs, the two angles of rotation. Simulated and experimental results permit to validate the complete model for high variation in static and dynamic conditions. These results will be helpful for nonlinear control synthesis.

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