scholarly journals Nonlinear energy-based control of soft continuum pneumatic manipulators

2021 ◽  
Author(s):  
Enrico Franco ◽  
Tutla Ayatullah ◽  
Arif Sugiharto ◽  
Arnau Garriga-Casanovas ◽  
Vani Virdyawan
Keyword(s):  
Nonlinear Control ◽  
Hamiltonian Formulation ◽  
Design Procedure ◽  
Needle Valve ◽  
Control Laws ◽  
Pid Algorithm ◽  
Digital Pressure ◽  
Unknown Disturbances ◽  
Pressure Dynamics ◽  
Improved Performance

AbstractThis paper investigates the model-based nonlinear control of a class of soft continuum pneumatic manipulators that bend due to pressurization of their internal chambers and that operate in the presence of disturbances. A port-Hamiltonian formulation is employed to describe the closed loop system dynamics, which includes the pressure dynamics of the pneumatic actuation, and new nonlinear control laws are constructed with an energy-based approach. In particular, a multi-step design procedure is outlined for soft continuum manipulators operating on a plane and in 3D space. The resulting nonlinear control laws are combined with adaptive observers to compensate the effect of unknown disturbances and model uncertainties. Stability conditions are investigated with a Lyapunov approach, and the effect of the tuning parameters is discussed. For comparison purposes, a different control law constructed with a backstepping procedure is also presented. The effectiveness of the control strategy is demonstrated with simulations and with experiments on a prototype. To this end, a needle valve operated by a servo motor is employed instead of more sophisticated digital pressure regulators. The proposed controllers effectively regulate the tip rotation of the prototype, while preventing vibrations and compensating the effects of disturbances, and demonstrate improved performance compared to the backstepping alternative and to a PID algorithm.

Computationally Efficient Nonlinear H∞ Control Designs for a Rigid Body Spacecraft

2008 ◽  
Author(s):  
Qian Zheng ◽  
Fen Wu
Keyword(s):  
Nonlinear Control ◽  
Design Procedure ◽  
Computationally Efficient ◽  
Control Laws ◽  
Spacecraft Control ◽  
Control Approach ◽  
Programming Techniques ◽  
Axis Of Symmetry ◽  
Control Designs ◽  
Better Than

In this paper, we consider nonlinear control of a symmetric spacecraft about its axis of symmetry with two control torques. Using a computationally efficient ℋ∞ control design procedure, attitude regulation and trajectory tracking problems of the axi-symmetric spacecraft were solved. Resorting to higher order Lyapunov functions, the employed nonlinear ℋ∞ control approach reformulates the difficult Hamilton-Jacobian-Isaacs (HJI) inequalities as semi-definite optimization conditions. Sum-of-squares (SOS) programming techniques are then applied to obtain computationally tractable solutions, from which nonlinear control laws will be constructed. The proposed nonlinear ℋ∞ designs will be able to exploit the most suitable forms of Lyapunov function for spacecraft control and the resulting controllers will perform better than existing nonlinear control laws.

Improved Tracking Control of Hydraulic Systems

1999 ◽  
Vol 123 (3) ◽  
pp. 457-462 ◽  
Author(s):  
Bora Eryilmaz ◽  
Bruce H. Wilson
Keyword(s):  
Bulk Modulus ◽  
Tracking Control ◽  
Design Procedure ◽  
Singular Perturbation Theory ◽  
Hydraulic Systems ◽  
Control Laws ◽  
Lyapunov Techniques ◽  
Sinusoidal Input ◽  
Nonlinear Tracking ◽  
Improved Performance

Tracking control for hydraulic systems is a key system requirement, as these devices must often follow prescribed motions. Tracking control of hydraulic systems has been approached using both linear and nonlinear control laws. The latter provides improved performance, but at the expense of additional sensors. Further, the control laws often employ hydraulic fluid bulk modulus—a difficult-to-characterize quantity—as a parameter. To overcome these difficulties, we have developed a control design procedure that requires no additional sensors and is robust to variations in the bulk modulus. A dual approach of singular perturbation theory and Lyapunov techniques form the basis for the procedure. For the cases of a small-amplitude sinusoidal input and large-amplitude polynomial input, a candidate system achieved good tracking performance and exhibited outstanding robustness. The ability to accomplish good tracking in a robust manner with no additional sensors provides advantages over other nonlinear tracking algorithms.

scholarly journals Aero-Thermal Design and Testing of Advanced Turbine Blades

1997 ◽  
Author(s):  
M. Haendler ◽  
D. Raake ◽  
M. Scheurlen
Keyword(s):  
Gas Turbines ◽  
Full Range ◽  
Turbine Blades ◽  
Design Procedure ◽  
Thermal Design ◽  
Test Facility ◽  
Optical Pyrometer ◽  
Electrical Systems ◽  
Operation Conditions ◽  
Improved Performance

Based on the experience gained with more than 80 machines operating worldwide in 50 and 60 Hz electrical systems respectively, Siemens has developed a new generation of advanced gas turbines which yield substantially improved performance at a higher output level. This “3A-Series” comprises three gas turbine models ranging from 70 MW to 240 MW for 50 Hz and 60 Hz power generation applications. The first of the new advanced gas turbines with 170 MW and 3600 rpm was tested in the Berlin factory test facility under the full range of operation conditions. It was equipped with various measurement systems to monitor pressures, gas and metal temperatures, clearances, strains, vibrations and exhaust emissions. This paper presents the aero-thermal design procedure of the highly thermal loaded film cooled first stage blading. The predictions are compared with the extensive optical pyrometer measurements taken at the Siemens test facility on the V84.3A machine under full load conditions. The pyrometer was inserted at several locations in the turbine and radially moved giving a complete surface temperature information of the first stage vanes and blades.

scholarly journals Analysis of the stability of multi-mode systems with approximating nonlinear control laws

2021 ◽  
Vol 872 (1) ◽  
pp. 012010
Author(s):  
E A Shakhray ◽  
E V Lubentsova ◽  
V F Lubentsov ◽  
M V Meflekh
Keyword(s):  
Nonlinear Control ◽  
Control Laws ◽  
The Stability ◽  
Multi Mode

Nonlinear Control for Missile Terminal Guidance

2000 ◽  
Vol 122 (4) ◽  
pp. 663-668 ◽  
Author(s):  
Der-Cherng Liaw ◽  
Yew-Wen Liang ◽  
Chiz-Chung Cheng
Keyword(s):  
Nonlinear Control ◽  
Design Procedure ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Missile Guidance ◽  
Proportional Navigation ◽  
Structure Control ◽  
Guidance Laws ◽  
Terminal Guidance

Variable Structure Control (VSC) technique is applied to the design of robust homing missile guidance laws. In the design procedure, the target’s maneuver is assumed to be unpredictable and is considered as disturbances. Guidance laws are then proposed to achieve the interception performance for both cases of longitude-axis control being available and unavailable. The proposed guidance laws are continuous which alleviate chattering drawback by classic VSC design. Results are obtained and compared with those by realistic true proportional navigation design to illustrate the benefits of the proposed design. [S0022-0434(00)00604-3]

scholarly journals Target Tracking in 3-D Using Estimation Based Nonlinear Control Laws for UAVs

Aerospace ◽  
2016 ◽  
Vol 3 (1) ◽  
pp. 5 ◽  
Author(s):  
Mousumi Ahmed ◽  
Kamesh Subbarao
Keyword(s):  
Nonlinear Control ◽  
Target Tracking ◽  
Control Laws

The Application of Reconfigurable Logic to Active Magnetic Bearing Controller

2009 ◽  
Author(s):  
Zbigniew Kulesza
Keyword(s):  
Integrated Circuit ◽  
Dynamic Performance ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Experimental Investigations ◽  
Control Law ◽  
Reconfigurable Logic ◽  
Control Laws ◽  
Pid Algorithm ◽  
Point Representation

The article presents the main problems of implementing the PID control law in the reconfigurable logic, namely FPGA integrated circuit. The consecutive steps of discretizing and choosing the fixed-point representation of the continuous, floating-point PID algorithm are described. The FPGA controller is going to be used in the active hetero-polar magnetic bearings system consisting of two radial and one axial bearings. The results of the experimental investigations of the controller are presented. The dynamic performance of the controller is better when compared with the dSPACE controller, that was used so far. The designed hardware and software, the developed implementation procedure and the experience acquired during this stage of the whole project are going to be used during the implementation of more sophisticated control laws (e.g. H∞ robust) in the FPGA for AMB controllers.

On the Design of Magnetic Suspension Systems

1990 ◽  
Author(s):  
A. Sinha
Keyword(s):  
Nonlinear Control ◽  
Initial Conditions ◽  
Dynamic Performance ◽  
Magnetic Suspension ◽  
Linear Feedback ◽  
Control Laws ◽  
Suspension Systems ◽  
Mass Damper ◽  
Linear Spring ◽  
Feedback Laws

First, the dynamic performance of magnetic suspension systems (Figures 1–3), which are designed on the basis of linear feedback laws, are examined. Then, nonlinear control laws are developed to make the dynamics of a suspension system to be exactly that of a linear spring-mass-damper system. It is found that such control laws are not defined for all initial conditions of the supported mass. Lastly, it is shown that it is possible to achieve a true spring-mass-damper behavior for all initial conditions by using two electromagnets, but operating only one at a time.

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