Open Loop Force Control of Piezo-Actuated Stick-Slip Drives

2011 ◽  
Vol 1 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Christoph Edeler ◽  
Sergej Fatikow
Keyword(s):  
Force Control ◽  
State Of The Art ◽  
Open Loop ◽  
Force Generation ◽  
New Method ◽  
Stick Slip ◽  
Micro Actuator ◽  
Friction Models ◽  
Application Fields

In this paper a new method to generate forces with stick-slip micro drives is described. The forces are generated if the runner of the stick-slip drive operates against an obstacle. It is shown that the generated force can be varied selectively without additional sensors and that virtually any force between zero and a limiting force given by certain parameters can be generated. For the investigated micro actuator this force is typically in the range up to hundreds of mN. For this reason, the method has the potential to expand the application fields of stick-slip positioners. After the presentation of the testbed containing the measured linear axis, measurements showing the principle and important parameters are discussed. Furthermore, it is shown that the force generation can be qualitatively simulated using state-of-the-art friction models. Finally, the results are discussed and an outlook is given.

Open Loop Force Control of Piezo-Actuated Stick-Slip Drives

2013 ◽  
pp. 1-18 ◽  
Author(s):  
Christoph Edeler ◽  
Sergej Fatikow
Keyword(s):  
Force Control ◽  
State Of The Art ◽  
Open Loop ◽  
Force Generation ◽  
New Method ◽  
Stick Slip ◽  
Micro Actuator ◽  
Friction Models ◽  
Application Fields

In this paper a new method to generate forces with stick-slip micro drives is described. The forces are generated if the runner of the stick-slip drive operates against an obstacle. It is shown that the generated force can be varied selectively without additional sensors and that virtually any force between zero and a limiting force given by certain parameters can be generated. For the investigated micro actuator this force is typically in the range up to hundreds of mN. For this reason, the method has the potential to expand the application fields of stick-slip positioners. After the presentation of the testbed containing the measured linear axis, measurements showing the principle and important parameters are discussed. Furthermore, it is shown that the force generation can be qualitatively simulated using state-of-the-art friction models. Finally, the results are discussed and an outlook is given.

Friction compensation control of an electropneumatic servovalve by using an evolutionary algorithm

2000 ◽  
Vol 214 (3) ◽  
pp. 173-184 ◽  
Author(s):  
S H Choi ◽  
C O Lee ◽  
H S Cho
Keyword(s):  
Search Algorithm ◽  
Static Friction ◽  
Open Loop ◽  
Friction Model ◽  
Experimental Results ◽  
Friction Compensation ◽  
Stick Slip ◽  
Air Contamination ◽  
Compensation Control ◽  
Friction Models

A poppet-type electropneumatic servovalve developed in this study utilizes a poppet directly operated by a moving-coil actuator in the metering stage and is controlled by a digital controller. This servovalve is insensitive to air contamination and has no problem of air leakage at null, but it has relatively large friction between the O-rings installed in the peripheral grooves of the balance pistons and the valve sleeve. For friction compensation control, a static friction model that enables simulation of the stick-slip phenomena and a dynamic model that captures the friction behaviour such as presliding displacement and varying break-away force are presented. The parameters for the friction models are identified by utilizing an evolution strategy, one of the evolutionary algorithms, which is a probabilistic global search algorithm based on the model of natural evolution. These friction models are then used in designing a non-linear friction compensation controller. It is found in the experiment that the electropneumatic servovalve has almost no hysteresis and that the friction compensation control significantly improves valve performance. The experimental results of the open loop test on poppet positioning agree well with simulation results of the valve model with identified friction parameters. It is also shown that the experimental results of friction compensation control using a static friction model show a small steady state error but those using a dynamic friction model show almost no such error.

Measurements and Potential Applications of Force-Control Method for Stick-Slip-Driven Nanohandling Robots

2011 ◽  
Vol 467-469 ◽  
pp. 1556-1561 ◽  
Author(s):  
Christoph Edeler
Keyword(s):  
Mobile Robots ◽  
Force Control ◽  
Control Method ◽  
The Other ◽  
Force Generation ◽  
Stick Slip ◽  
The Real ◽  
Other Hand ◽  
Potential Applications ◽  
Application Potential

This paper describes the transition of a recently invented force-generation method to mobile nanohandling robots and outlines future applications. The presented mobile nanohandling robot makes use of miniaturized, piezo-driven Stick-Slip actuators. This allows for very accurate and fast positioning. The drives are fully developed and have proven their performance in fast pickand- place applications. On the other hand, the mentioned force-generation method allows a Stick- Slip axis to exert a dedicated force to any object, which could be useful in many micro- and nanohandling scenarios. However, the method was tested yet only in a testbed similar to the conditions in the robot. Therefore this paper deals with the extrapolation of the results to the real conditions in the robots and discusses benefits and drawbacks. After an introduction of the robot and the force-generation method, measurements are presented and discussed. The paper ends with a sketch of a possible application, which could boost the application potential not only of such mobile robots, but of Stick-Slip-based setups in general.

Modeling of Piezo-Actuated Stick-Slip Micro-Drives: An Overview

2012 ◽  
Vol 81 ◽  
pp. 39-48 ◽  
Author(s):  
Ha Xuan Nguyen ◽  
Christoph Edeler ◽  
Sergej Fatikow
Keyword(s):  
Mechanical Model ◽  
Integrated Model ◽  
Friction Model ◽  
Fundamental Importance ◽  
Future Research ◽  
Stick Slip ◽  
Research Activities ◽  
Model Combining ◽  
Friction Models

This paper gives an overview about problems of modeling of piezo-actuated stick-slip micro-drives. It has been found that existing prototypes of such devices have been investigated empirically. There is only few research dealing with the theory behind this kind of drives. By analyzing the current research activities in this field, it is believed that the model of the drive depends strongly on the friction models, but in most cases neglecting any influences of the guilding system.These analyses are of fundamental importance for an integrated model combining friction model and mechanical model offering promising possibilities for future research.

Static Friction Models for Vehicle Simulation Study

2006 ◽  
Author(s):  
Xubin Song ◽  
Daniel G. Smedley
Keyword(s):  
Simulation Study ◽  
Static Friction ◽  
Friction Modeling ◽  
Stick Slip ◽  
Vehicle Simulation ◽  
Engineering Software ◽  
Variable Step ◽  
History Of ◽  
Friction Models ◽  
Smooth Dynamics

The history of the challenge of friction modeling is briefly reviewed. Then this paper focuses on the modeling and simulation study of the friction related dynamics in the Simulink® environment, because Matlab®/Simulink® are popular engineering software tools for both industry and academia. Matlab® and Simulink® are the proprietary products of MathWorks, Inc. In this paper, the static friction models are studied through Simulink® by applying fixed and variable step sizes. The comparison shows that the static Karnopp model is not only numerically tractable but also can be inclusive of the fundamental friction characteristics of both stick slip and correct friction predictions. Finally this paper presents an improved Karnopp model for clutch modeling with the use of Simulink®, and the simulation shows that this model is computationally tractable with smooth dynamics.

Sensorless Force Control Interface for DEAP Stack-Actuators

2015 ◽  
Author(s):  
Thorben Hoffstadt ◽  
Jürgen Maas
Keyword(s):  
Force Control ◽  
Electromechanical Coupling ◽  
Force Measurement ◽  
Scale Up ◽  
Electroactive Polymers ◽  
Open Loop ◽  
Control Interface ◽  
Electromechanical Drive ◽  
Electrostatic Pressure ◽  
Drive Systems

Transducers based on dielectric electroactive polymers (DEAP) offer an attractive balance of work density and electromechanical efficiency. For example in automation and haptic applications, especially multilayer transducers are used to scale up their absolute deformation and force. Depending on the application different transducer controls have to be realized to match the specifications of the particular application. However, analogous to conventional electromechanical drive systems an inner sensor-less force control can be realized for DEAP transducers, too. For this force control the nonlinear relations between voltage and electrostatic pressure as well as the electromechanical coupling have to be considered. The resulting open-loop force control can be used for superimposed motion controls, such as position, vibration and impedance controls. Therefore, within this contribution the authors propose a model-based feedforward force control based on an overall model of the transducer that does not require any force measurement. Finally, the derived open-loop force control interface is experimentally validated using in-house developed DEAP stack-transducers and driving power electronics.

AN INFORMATION-THEORETIC FILTER METHOD FOR FEATURE WEIGHTING IN NAIVE BAYES

2014 ◽  
Vol 28 (05) ◽  
pp. 1451007 ◽  
Author(s):  
CHANG-HWAN LEE
Keyword(s):  
Data Mining ◽  
Bayesian Learning ◽  
State Of The Art ◽  
Feature Weighting ◽  
New Method ◽  
Filter Method ◽  
Information Theoretic ◽  
Naive Bayesian ◽  
Naïve Bayesian ◽  
Unrealistic Assumption

In spite of its simplicity, naive Bayesian learning has been widely used in many data mining applications. However, the unrealistic assumption that all features are equally important negatively impacts the performance of naive Bayesian learning. In this paper, we propose a new method that uses a Kullback–Leibler measure to calculate the weights of the features analyzed in naive Bayesian learning. Its performance is compared to that of other state-of-the-art methods over a number of datasets.

scholarly journals Using control charts for on-line video summarisation

2019 ◽  
Vol 277 ◽  
pp. 01012 ◽  
Author(s):  
Clare E. Matthews ◽  
Paria Yousefi ◽  
Ludmila I. Kuncheva
Keyword(s):  
Feature Extraction ◽  
Control Chart ◽  
Control Charts ◽  
State Of The Art ◽  
Synthetic Data ◽  
New Method ◽  
Data Sets ◽  
On Line ◽  
Memory Constraints ◽  
Video Summarisation

Many existing methods for video summarisation are not suitable for on-line applications, where computational and memory constraints mean that feature extraction and frame selection must be simple and efficient. Our proposed method uses RGB moments to represent frames, and a control-chart procedure to identify shots from which keyframes are then selected. The new method produces summaries of higher quality than two state-of-the-art on-line video summarisation methods identified as the best among nine such methods in our previous study. The summary quality is measured against an objective ideal for synthetic data sets, and compared to user-generated summaries of real videos.

Variational Formulation for Frictional Interface Dynamics

2012 ◽  
Author(s):  
Timothy Truster ◽  
Arif Masud ◽  
Lawrence A. Bergman
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Coulomb Friction ◽  
Bolted Joints ◽  
Lap Joint ◽  
Stick Slip ◽  
Element Simulation ◽  
Friction Models ◽  
Frictional Interface ◽  
Current Emphasis

The dynamic response of component bolted joints often plays a significant role in the overall behavior of a structural system. Accurate finite element simulation of these problems requires proper treatment of the interface conditions. We present a formulation carefully suited to these problems that incorporates discontinuous Galerkin (DG) treatment locally at the interface. The present work is an extension of our previous investigations of friction models within a finite element method for quasi-static problems. The current emphasis is on the treatment of the inertial term and ensuring that artificial resonance is not induced by the discrete interface. The weak imposition of continuity constraints allows the stick-slip behavior at the jointed surface to proceed smoothly, reducing the numerical instability compared to node-to-node contact techniques. As a model problem, we simulate the dynamic response of a lap joint subjected to an impulse axial force assuming Coulomb friction at the interface.

Development of a 3-DOF Tripedal Stick-Slip Microrobotic Mobile Platform for Unconstrained, Omnidirectional Sample Positioning

2018 ◽  
Author(s):  
Iman Adibnazari ◽  
William S. Nagel ◽  
Kam K. Leang
Keyword(s):  
Visual Servoing ◽  
Feedforward Control ◽  
Low Cost ◽  
Tracking Error ◽  
Kinematic Model ◽  
Open Loop ◽  
Step Cycle ◽  
Stick Slip ◽  
Slip Step ◽  
Forward Kinematic

This paper presents the development of a piezo-based three-degree-of-freedom (3-DOF), tripedal microrobotic platform that allows for unlimited travel with sub-micron precision over a planar surface. Compliant mechanical amplifiers are incorporated with each piezoelectric stack actuator to improve both the stroke and load-bearing capability of the platform. A forward kinematic model of the stage based on its tripedal leg architecture is derived for each stick-slip step cycle and inverted for feedforward control of the platform. A prototype is constructed using low-cost 3D-printing techniques. Experimental results demonstrate actuator stroke of 29.4 μm on average with a dominant resonance of approximately 860 Hz. Results demonstrate the stage tracks a 3 mm by 3 mm square trajectory in open loop. Feedback control through visual servoing is then simulated on a model that includes flexure dynamics, observed surface interactions, and camera sampling times, reducing the root-mean-square (RMS) tracking error by 90%. This control scheme is then implemented experimentally, resulting in 99% RMS position error reduction relative to when only feedforward control is used.

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