A Nonlinear Observer for Minimizing Quantization Effects in Virtual Walls

1999 ◽  
Author(s):  
Daniel R. Madill ◽  
David W. L. Wang ◽  
Mennas C. Ching
Keyword(s):  
Coulomb Friction ◽  
Force Sensor ◽  
Performance Model ◽  
Nonlinear Observer ◽  
Direct Drive ◽  
Model Based ◽  
Measured Position ◽  
Three Degree Of Freedom ◽  
The Cost ◽  
Estimator Design

Abstract Quantization effects can reduce the achievable stiffness of virtual walls. Phase delays introduced by filtering are also an issue. This paper presents a non-linear model-based observer that produces smooth position and velocity estimates with very little delay based on measured position and force signals. Compensation for Coulomb friction and motor saturation is incorporated into the estimator. Use of the estimator in the implementation of a virtual wall yielded higher wall stiffnesses and better performance. Model-based estimator design was possible due to the design of the manipulator. The three degree-of-freedom manipulator employed is direct-drive, gravity-balanced, and dynamically-decoupled with nearly linear dynamics. The robot structure itself is employed as a force sensor, reducing the cost of the device.

scholarly journals A Dam Performance Model Based on Rehabilitation of the Kariba Dam

2021 ◽  
Vol 1757 (1) ◽  
pp. 012159
Author(s):  
Junxiao Zhou ◽  
Junwei Cheng ◽  
Qian Li
Keyword(s):  
Performance Model ◽  
Model Based

Nonlinear observer based sliding mode control and oxygen fraction estimation for diesel engine

2017 ◽  
Vol 40 (7) ◽  
pp. 2227-2239 ◽  
Author(s):  
Haoping Wang ◽  
Qiankun Qu ◽  
Yang Tian
Keyword(s):  
Diesel Engine ◽  
Sliding Mode Control ◽  
Oxygen Concentration ◽  
Control Method ◽  
Sliding Mode ◽  
Observer Design ◽  
Nonlinear Observer ◽  
Linear Matrix ◽  
Model Based ◽  
Mode Control

In this paper, a nonlinear observer based sliding mode control (NOSMC) approach for air-path and a model-based observer for oxygen concentration in the diesel engine equipped with a variable geometry turbocharger and exhaust gas recirculation is introduced. We propose a less conservative observer design technique for Lipschitz nonlinear systems using Ricatti equations. The observer gains are obtained by solving the linear matrix inequality (LMI). Then a robust nonlinear control method, sliding mode control is applied for the states of intake and exhaust manifold pressure and compressor mass flow rate for the sake of the minimization of emissions. The proposed NOSMC controller is applied on a mean value model of turbocharged diesel engine. Besides this, a model-based observer is developed to estimate the oxygen concentration in the intake and exhaust manifolds owing to its significance in reducing emissions of diesel engines. The validation and efficiency of the proposed method are demonstrated by AMESim and Matlab/Simulink co-simulation results.

Analysis of Effect of Advanced Technique Configurations on Overall Performance of High Bypass Turbofan Engine

2014 ◽  
Author(s):  
Liu Jian Jun
Keyword(s):  
Air Flow ◽  
Engine Performance ◽  
Performance Model ◽  
Direct Drive ◽  
Nozzle Throat ◽  
Advanced Technique ◽  
Turbofan Engine ◽  
Overall Performance ◽  
Cooling Air Flow ◽  
Cooling Air

An analytical study was undertaken using the performance model of a two spool direct drive high BPR 300kN thrust turbofan engine, to investigate the effects of advanced configurations on overall engine performance. These include variable bypass nozzle, variable cooling air flow and more electric technique. For variable bypass nozzle, analysis on performance of outer fan at different conditions indicates that different operating points cannot meet optimal performance at the same time if the bypass nozzle area kept a constant. By changing bypass nozzle throat area at different states, outer fan operating point moves to the location where airflow and efficiency are more appropriate, and have enough margin away from surge line. As a result, the range of variable area of bypass nozzle throat is determined which ensures engine having a low SFC and adequate stability. For variable cooling airflow, configuration of turbine cooling air flow extraction and methodology for obtaining change of cooling airflow are investigated. Then, base on temperature analysis of turbine vane and blade and resistance of cooling airflow, reduction of cooling airflow is determined. Finally, using performance model which considering effect of cooling air flow on work and efficiency of turbine, variable cooling airflow effect on overall performance is analyzed. For more electric technique, the main characteristic is to use power off-take instead of overboard air extraction. Power off-take and air extraction effect on overall performance of high bypass turbofan engine is compared. Investigation demonstrates that power offtake will have less SFC.

Model-Based Analysis of Friction-Induced Sub-Synchronous Whirl for a Rotor Contacting With Clearance Bearings Under Axial Load

2015 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Lawrence Hawkins
Keyword(s):  
Axial Load ◽  
Coulomb Friction ◽  
Friction Forces ◽  
Root Finding ◽  
Model Based ◽  
Simple Physical Interpretation ◽  
Level Of Agreement ◽  
Model Based Analysis

For rotors supported by active magnetic bearings (AMBs), clearance bearings are commonly used to provide backup support under loss of AMB functionality. Test data from real machines shows that rotor vibration during touchdown on backup bearings may involve steady forward whirling at a sub-synchronous frequency. This excitation is believed to be due to friction forces transmitted between the rotor and a bearing end-face under axial load. This paper proposes a new analytical approach to model and predict such friction-driven forward whirl behaviors. A set of constraint equations are derived that relate a circular whirl motion of arbitrary orbital speed to the frequency response functions of the rotor-housing structure. This model is coupled with an evaluation of Coulomb friction associated with slip between the rotor and the supporting end-face of a thrust bearing. The resulting equations can be used to compute a set of possible whirl motions via a root-finding procedure. A case study is undertaken for a 140 kW energy storage flywheel. Model-based predictions are compared with measured data from spin-down tests and show a good level of agreement. The study confirms the role of friction-related forces in driving forward-whirl response behaviors. It also highlights the key role of housing and machine support characteristics in response behavior. This influence is shown to be complex and not open to simple physical interpretation. Therefore, the proposed analytical method is seen as a useful tool to investigate this influence while avoiding the need for time consuming numerical simulations.

Force Sensor Model Based on FEA for the Electromagnetic Levitation System

2019 ◽  
Vol 21 (6) ◽  
pp. 20-25 ◽  
Author(s):  
Qilong Jiang ◽  
Da Liang ◽  
Feng Yan ◽  
Dong Liu
Keyword(s):  
Electromagnetic Levitation ◽  
Force Sensor ◽  
Model Based ◽  
Sensor Model ◽  
Levitation System
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