Active Artificial Hair Cells Using Nonlinear Feedback Control

2014 ◽  
Author(s):  
Bryan S. Joyce ◽  
Pablo A. Tarazaga
Keyword(s):  
Feedback Control ◽  
Hair Cell ◽  
Hair Cells ◽  
Dynamic Range ◽  
Control Law ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Cochlear Hair Cells ◽  
Amplitude Compression ◽  
Bimorph Beam

There is interest in developing devices that mimic the sound transduction of the cochlear hair cells. Current artificial hair cell (AHC) designs have focused on passive transduction of sound into electrical signals. However, measurements inside living cochleae have revealed that a nonlinear amplification is at work in mammalian hearing. This amplification lowers the threshold for sound detection allowing mammals to hear faint sounds. The nonlinearity results in an amplitude compression whereby a large range of sound pressure levels produces a smaller range of displacements. This compressive nonlinearity gives the ear a large dynamic range. This work seeks to develop and analyze active artificial hair cells which employ a bio-inspired amplification to improve performance. This paper examines two artificial hair cell designs. The first is an 18.5 in long aluminum cantilever beam which is excited and controlled using piezoelectric actuators along the length of the beam. The second design is a one inch piezoelectric bimorph beam subject to a base excitation. In both cases a nonlinear feedback control law is implemented which reduces the beam’s linear viscous damping and introduces a cubic damping term. Model and experimental results show the control law amplified the response of the artificial hair cell to low excitation levels near the resonance frequency. Increasing input levels produced a compressive nonlinearity at resonance similar to that observed in measurements from mammalian cochleae. This work could lead to the development of new bio-inspired sensors with a lower threshold of detection, improved frequency sensitivity, and larger dynamic range.

Semi-global output regulation for discrete-time singular linear systems with input saturation via composite nonlinear feedback control

2016 ◽  
Vol 39 (3) ◽  
pp. 352-360 ◽  
Author(s):  
Xiaoyan Lin ◽  
Dongyun Lin ◽  
Weiyao Lan
Keyword(s):  
Feedback Control ◽  
Linear Systems ◽  
Discrete Time ◽  
Input Saturation ◽  
Output Regulation ◽  
Control Law ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Composite Nonlinear Feedback ◽  
Singular Linear Systems

The semi-global output regulation problem of multi-variable discrete-time singular linear systems with input saturation is investigated in this paper. A composite nonlinear feedback control law is constructed by using a low gain feedback technique for semi-global stabilisation of discrete-time singular linear systems with input saturation. The sufficient solvability conditions of the semi-global output regulation problem by composite nonlinear feedback control are established. When the composite nonlinear feedback control law is reduced to a linear control law, the solvability conditions are an exact discrete-time counterpart of the semi-global output regulation problem of continuous-time singular linear systems. With the extra control freedom of the nonlinear part in the composite nonlinear feedback control law, the transient performance of the closed-loop system can be improved by carefully choosing the linear feedback gain and the nonlinear feedback gain. The design procedure of the composite nonlinear feedback control law and the improvement of the transient performance are illustrated by a numerical example.

Compound control for autonomous docking to a three-axis tumbling target

2018 ◽  
Vol 41 (4) ◽  
pp. 911-924
Author(s):  
Dong Ye ◽  
Wei Lu ◽  
Zhongcheng Mu
Keyword(s):  
Feedback Control ◽  
Attitude Control ◽  
Sliding Mode ◽  
Control Law ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Integral Sliding Mode ◽  
Compound Control ◽  
Tumbling Target ◽  
Autonomous Docking

This paper investigates the coupled position and attitude control problem of an on-orbit servicing spacecraft autonomous docking to a three-axis freely tumbling target in space. A compound control law is presented to guarantee that the docking port of servicing spacecraft is always directing towards the docking port of tumbling target, which is accomplished through the combination of the coupled relative position tracking and relative attitude control. For the purpose of avoiding collision between the two spacecraft, a two-phased approach for the terminal approaching the tumbling target is proposed. Also, the compound control is composed of a nonlinear feedback control law and an integral sliding mode control law. The nonlinear feedback control law is mainly used to track the system command and the integral sliding mode control law is mainly used to deal with the external disturbances and system uncertainties to enhance the robustness of the control system. Furthermore, the control saturation problem is considered. In addition, the characteristic of integral sliding mode under the control constraint and measurement noise is also analyzed. Finally, several numerical simulations are performed to verify the effectiveness and robustness of the compound control law for autonomous docking to a three-axis freely tumbling target.

Compound Control of Attitude Synchronization for Autonomous Docking to a Tumbling Satellite

2013 ◽  
Vol 394 ◽  
pp. 470-476 ◽  
Author(s):  
Xue Yan An ◽  
Wei Lu ◽  
Zhang Ren
Keyword(s):  
Feedback Control ◽  
Control Law ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
External Disturbances ◽  
Compound Control ◽  
Bounded Disturbances ◽  
System Uncertainties ◽  
Attitude Synchronization ◽  
Autonomous Docking

In order to solve the attitude synchronization control problem for an on-orbit servicing spacecraft autonomous docking to a tumbling satellite in the presence of unknown bounded disturbances and system uncertainties, a compound control law is presented in this paper. The compound control law is composed of a nonlinear feedback control law and a compensate control law. The nonlinear feedback control law is mainly used to track the system command and the compensate control law is mainly used to deal with the external disturbances and system uncertainties to enhance the robustness of the control system. Simulation results verified the effectiveness of the designed compound control law, and the robustness to the unknown bounded disturbances, system uncertainties is also demonstrated.

Active Compressor Surge Control Using Piston Actuation

2011 ◽  
Author(s):  
Nur Uddin ◽  
Jan Tommy Gravdahl
Keyword(s):  
Feedback Control ◽  
Closed Loop ◽  
Linear Feedback ◽  
Control Law ◽  
Asymptotically Stable ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Closed Loop System ◽  
Linear Feedback Control ◽  
Surge Control

A novel approach to active surge control in compressors using piston actuation is presented. Two control laws are compared in order to evaluate the feasibility of implementing the concept. The first control law is a nonlinear feedback control derived by using backstepping and the second one is a linear feedback control derived by analyzing the eigenvalues of the linearized system around the operating point. The nonlinear feedback control law makes the closed loop system globally asymptotically stable (GAS) and uses full states feedback. The linear feedback control is only using feedback from plenum pressure and piston velocity and the removal of the mass flow feedback is advantageous for implementation. The closed loop system with the linear feedback control is locally asymptotically stable around the operating point. Simulations show that both controllers are capable of stabilizing surge.

Active Artificial Hair Cells for Use in Fluid Environments

2015 ◽  
Author(s):  
Bryan S. Joyce ◽  
Pablo A. Tarazaga
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Dynamic Range ◽  
Fluid Simulation ◽  
Fluid Loading ◽  
Fluid Inertia ◽  
Nonlinear Feedback ◽  
Flow Sensing ◽  
Nonlinear Amplifier ◽  
Nonlinear Control Law

Artificial hair cells (AHCs) are sensors inspired by biological hair cells. These devices often have lower sensitivities and poorer frequency resolutions than their biological counterparts. This is especially true when AHCs are placed in fluid. In the authors’ previous work, active AHCs were developed which used nonlinear feedback control to mimic the cochlea’s nonlinear amplifier. Incorporating this nonlinear control law can improve the AHC’s sensitivity, frequency selectivity, and dynamic range. This work examines an active artificial hair cell partially submerged in water. The fluid loading on the sensor adds inertia and significantly increases damping. A model of the sensor in air is developed and then modified to incorporate the added inertia and damping from the fluid. Simulation and experimental results show that the active artificial hair cell can overcome the added fluid inertia and damping to amplify oscillations due to low input levels and create a sharper frequency response. The resulting sensor is better suited to operate in fluid environments for flow sensing than an otherwise passive device. These sensors could potentially develop into replacements for damaged hair cells in the fluid-filled cochlea.

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