A Multi-Directional Single-Proof-Mass Accelerometer Contact Microphone (Accelophone) with 10Khz Open-Loop Bandwidth

2021 ◽  
Author(s):  
Pranav Gupta ◽  
Anosh Daruwalla ◽  
Haoran Wen ◽  
Farrokh Ayazi
Keyword(s):  
Proof Mass ◽  
Open Loop ◽  
Loop Bandwidth

Study of Dominant Performance Characteristics in Robot Transmissions

1993 ◽  
Vol 115 (3) ◽  
pp. 472-482 ◽  
Author(s):  
H. Schempf ◽  
D. R. Yoerger
Keyword(s):  
Force Control ◽  
Closed Loop ◽  
Stability Margin ◽  
Viscous Friction ◽  
Open Loop ◽  
Phase Lag ◽  
Stability Margins ◽  
Loop Bandwidth ◽  
Hard Contact ◽  
Following Error

Six different transmission types suitable for robotic manipulators were compared in an experimental and theoretical study. Single-degree-of-freedom mechanisms based on the different transmissions were evaluated in terms of force control performance, achievable bandwidth, and stability properties in hard contact tasks. Transmission types considered were (1) cable reducer, (2) harmonic drive, (3) cycloidal disk reducer, (4) cycloidal cam reducer, (5) ball reducer, and (6) planetary/cycloidal gear head. Open loop torque following error, attenuation and phase lag, and closed loop bandwidth and stability margin were found to be severely dominated by levels of inertia, stiffness distribution and variability, stiction, coulomb and viscous friction, and ripple torque. These aspects were quantified and shown to vary widely among all transmissions tested. The degree of nonlinearity inherent in each transmission affected its open and closed loop behavior directly, and limited the effectiveness of controller compensation schemes. Simple transmission models based on carefully measured transmission characteristics are shown to predict stability margins and achievable force-control bandwidths in hard contact to within a 5 to 15 percent error margin.

Design of a High-Bandwidth XY Nanopositioning Stage for High-Throughput Micro/Nano Manufacturing

2010 ◽  
Author(s):  
Sebastian Polit ◽  
Jingyan Dong
Keyword(s):  
Mechanism Design ◽  
High Throughput ◽  
Closed Loop ◽  
Open Loop ◽  
Dynamic Responses ◽  
Element Analysis ◽  
Loop Bandwidth ◽  
Decoupled Motion ◽  
High Bandwidth ◽  
Critical Requirement

A high natural frequency (open-loop bandwidth) is a critical requirement for nanopositioners in high-throughput nanomanufacturing and nano-metrology applications. This paper presents the design and analysis of a high-bandwidth nanopositioning XY stage. The monolithic stage design has two axes and each axis is comprised of a doubly-clamped beam and a parallelogram hybrid flexure with complaint beams and circular flexure hinges. The doubly-clamped beam that is actuated by a piezoelectric actuator acts as a linear prismatic axis. The parallelogram hybrid flexures are used to decouple the actuation effect from the other axis. The mechanism design decouples the motion in the X and Y directions and restricts parasitic rotations in the XY plane while allowing for an increased bandwidth with linear kinematics in the operating region (or workspace). Kinematic and dynamic analysis shows that the mechanical structure of the stage has decoupled motion in XY direction, while achieving high bandwidth and good linearity. Finite element analysis is adapted to verify the dynamic responses from theoretical analysis. The stage is actuated by piezoelectric stack actuators, and two capacitive gauges were added to the system to build a closed-loop positioning system. The results from frequency test show that the resonation frequencies of the two vibrational modes are over 8K Hz. The stage is capable of about 15 microns of motion along each axis with a resolution of about 1 nanometer. Due to parallel kinematic mechanism design, a uniform performance is achieved across the workspace. A PI controller is implemented for the stage and a high closed-loop bandwidth is obtained.

scholarly journals Fundamental Limits in Combine Harvester Header Height Control

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Yangmin Xie ◽  
Andrew G. Alleyne ◽  
Ashley Greer ◽  
Dustin Deneault
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
The Other ◽  
Specific System ◽  
Fundamental Limits ◽  
Height Control ◽  
Sensor Actuator ◽  
Loop Transfer Function ◽  
Loop Bandwidth ◽  
Combine Harvester

This paper investigates fundamental performance limitations in the control of a combine harvester's header height control system. There are two primary subsystem characteristics that influence the achievable bandwidth by affecting the open loop transfer function. The first subsystem is the mechanical configuration of the combine and header while the second subsystem is the electrohydraulic actuation for the header. The mechanical combine + header subsystem results in an input–output representation that is underactuated and has a noncollocated sensor/actuator pair. The electrohydraulic subsystem introduces a significant time delay. In combination, they each reinforce the effect of the other thereby exacerbating the overall system limitation of the closed loop bandwidth. Experimental results are provided to validate the model and existence of the closed loop bandwidth limitations that stem from specific system design configurations.

Active and passive Damping of Euler-Bernoulli Beams and Their Interactions

1993 ◽  
Vol 115 (3) ◽  
pp. 379-384 ◽  
Author(s):  
S. T. Pang ◽  
T.-C. Tsao ◽  
L. A. Bergman
Keyword(s):  
Imaginary Axis ◽  
Proof Mass ◽  
Open Loop ◽  
Reaction Mass ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Passive Damping ◽  
Negative Real Axis ◽  
Poles And Zeros ◽  
Mode Truncation

Active and Passive damping of Euler-Bernoulli beams and their interactions have been studied using the beam’s exact transfer function model without mode truncation or finite element or finite difference approximation. The combination of viscous and Voigt damping is shown to map the open-loop poles and zeros from the imaginary axis in the undamped case into a circle in the left half plane and into the negative real axis. While active PD collocated control using sky-hooked actuators is known to stabilize the beam, it is shown that the derivative action using proof-mass (reaction-mass) actuators can destabilize the beam.

Integrated Plant and Controller Design of a Combine Harvester System

2011 ◽  
Author(s):  
Yangmin Xie ◽  
Andrew Alleyne
Keyword(s):  
Controller Design ◽  
Design Method ◽  
Open Loop ◽  
System Response ◽  
Height Control ◽  
Loop Bandwidth ◽  
Original Plant ◽  
Bandwidth Limitation ◽  
Combine Harvester ◽  
And Control

This article proposes a plant and controller design method based on performance analysis of a header height control problem on a combine harvester. The achievable bandwidth was found to be limited by the under-actuated and non-collocated features of the mechanical structure, and a parameter optimization is then applied to solve this problem by improving the property of open loop zeros and poles. H∞ controller design is used to achieve the best performance with the considerations of tracking bandwidth, disturbance rejection and control energy. The simulation results show that this approach can obtain relatively high closed loop bandwidth which surpasses the bandwidth limitation of the original plant. The simulation of tracking comparison also shows that the integrated plant and controller design generate a superior system response.

Electromagnetic Coupling in a dc Motor and Tachometer Assembly

2004 ◽  
Vol 126 (3) ◽  
pp. 684-691 ◽  
Author(s):  
Shorya Awtar ◽  
Kevin C. Craig
Keyword(s):  
Disturbance Rejection ◽  
Closed Loop ◽  
Electromagnetic Coupling ◽  
Dc Motor ◽  
Open Loop ◽  
Conventional Model ◽  
Open Loop System ◽  
Nonminimum Phase ◽  
Motion System ◽  
Loop Bandwidth

This paper presents an enhanced tachometer model that takes into account the effect of electromagnetic coupling that can exist between the actuator and sensor in an integrated dc motor-tachometer assembly, where the conventional model is found to be inadequate. The tachometer dynamics identified in this paper is experimentally verified, and incorporated in the modeling and parameter identification of a motion system that has multiple flexible elements. It is shown that the tachometer dynamics contributes additional nonminimum phase zeros that degrade the servo system performance in terms of closed-loop bandwidth, disturbance rejection and sensitivity to modeling uncertainty. The zeros of the open loop system are found to vary with the geometric parameters of the motor-tachometer assembly. Based on the insight gained by modeling the electromagnetic coupling, methods for eliminating it and its resulting detrimental effects are also suggested.

Set of open-loop block-diagonalizers of transfer matrices

1989 ◽  
Vol 49 (1) ◽  
pp. 161-168
Author(s):  
A. Bülent Özgü Ler ◽  
Vasfi Eldem
Keyword(s):  
Open Loop ◽  
Transfer Matrices

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

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