Michael Ruderman

Bio: Michael Ruderman is an academic researcher from University of Agder. The author has contributed to research in topics: Hysteresis & Motion control. The author has an hindex of 19, co-authored 121 publications receiving 1352 citations. Previous affiliations of Michael Ruderman include Nagaoka University of Technology & Nagoya Institute of Technology.

Modeling and Identification of Elastic Robot Joints With Hysteresis and Backlash

Abstract: This paper presents a novel approach to the modeling and identification of elastic robot joints with hysteresis and backlash. The model captures the dynamic behavior of a rigid robotic manipulator with elastic joints. The model includes electromechanical submodels of the motor and gear from which the relationship between the applied torque and the joint torsion is identified. The friction behavior in both presliding and sliding regimes is captured by generalized Maxwell-slip model. The hysteresis is described by a Preisach operator. The distributed model parameters are identified from experimental data obtained from internal system signals and external angular encoder mounted to the second joint of a 6-DOF industrial robot. The validity of the identified model is confirmed by the agreement of its prediction with independent experimental data not previously used for model identification. The obtained models open an avenue for future advanced high-precision control of robotic manipulator dynamics.

Observer of Nonlinear Friction Dynamics for Motion Control

Abstract: Kinetic friction in motion control systems is subject to large uncertainties due to the multiple, and often weakly known, internal and external factors such as roughness, thermal and lubricant state of contacting surfaces, varying normal loads, dwell time, wear, and others. The single modeling of friction behavior, even if comprehensive and accurate enough, appears to be insufficient for accurately compensating the friction disturbances, due to their time- and state-varying nature. In this paper, we propose a novel nonlinear friction observer aimed at the motion control. We analyze the uncertainties of viscous and Coulomb friction and derive an asymptotic observer for two-state friction dynamics without assuming a particular dynamic friction model. The linear observer gains prove to be sufficient for achieving an accurate friction estimate with a controllable eigenbehavior. Furthermore, we analyze the friction observer within the linear feedback loop and describe the required system identification and design of controller. An experimental case study accomplished on a rotary actuator system is provided for evaluating both the friction observer and its use for precise positioning.

Sensorless Torsion Control of Elastic-Joint Robots With Hysteresis and Friction

Abstract: Sensorless torsion control is proposed for elastic-joint robots, with the geared drives subject to hysteresis and friction nonlinearities. The concept of the so-called “virtual torsion sensor” uses the motor torque and velocity, inherently available in most industrial robots, for estimating the reactive joint torque and predicting, based thereupon, the nonlinear joint torsion. The dynamics of the elastic-joint robot is described and augmented by a rate-independent torsion–torque hysteresis and nonlinear friction assumed on the side of motor drives. The classical two-degrees-of-freedom robot control, which includes the centralized torque feedforward control and proportional-derivative feedback control, is extended by the virtual torsion sensor in the loop. In particular, we show that the computed joint torsion can be injected in the feedback loop upon the motor position, thus making the control operating in a “virtual” joint output (link) space. The proposed control is experimentally evaluated on a single-joint setup consisting of an actuator with harmonic-drive gear and inertial load under additional impact of gravity.

Tracking Control of Motor Drives Using Feedforward Friction Observer

Abstract: In motor drives, just as in other mechanical actuators, the friction compensation is extremely important as friction can have adverse impact on the overall control performance. In this paper, a feedforward friction observer (FFFO) is proposed as formulating an explicit analytical expression for the applied observation function. This ensures the cancelation of friction disturbances and time variances at steady state. The proposed observation scheme utilizes the two-state dynamic friction model with elastoplasticity (abbreviated as 2SEP), which is compact in parameterization and captures both the presliding and sliding phases of kinetic friction. The method to identify a motor drive plant with nonlinear friction in the frequency domain has been applied using only few frequency-response-function measurements. The feedback control design is performed with respect to the time delay detectable in the system, thus under additional constraints when determining the control gains. The optimal proportional-integral (PI) control designed this way is compared with the proportional control combined with the observer (P-FFFO). The simulation results show that P-FFFO control compensates faster for frictional disturbances at suddenly changing frictional conditions than PI control. In addition, an extensive experimental evaluation of velocity tracking control discloses P-FFFO as superior in terms of a faster steady-state convergence after various transient phases.

Modelling and Control of Robot Manipulators

Abstract: Feel lonely? What about reading books? Book is one of the greatest friends to accompany while in your lonely time. When you have no friends and activities somewhere and sometimes, reading book can be a great choice. This is not only for spending the time, it will increase the knowledge. Of course the b=benefits to take will relate to what kind of book that you are reading. And now, we will concern you to try reading modelling and control of robot manipulators as one of the reading material to finish quickly.

Modeling and Control of Piezo-Actuated Nanopositioning Stages: A Survey

Abstract: Piezo-actuated stages have become more and more promising in nanopositioning applications due to the excellent advantages of the fast response time, large mechanical force, and extremely fine resolution. Modeling and control are critical to achieve objectives for high-precision motion. However, piezo-actuated stages themselves suffer from the inherent drawbacks produced by the inherent creep and hysteresis nonlinearities and vibration caused by the lightly damped resonant dynamics, which make modeling and control of such systems challenging. To address these challenges, various techniques have been reported in the literature. This paper surveys and discusses the progresses of different modeling and control approaches for piezo-actuated nanopositioning stages and highlights new opportunities for the extended studies.

Hydraulic Control Systems

Abstract: Thank you for downloading hydraulic control systems. As you may know, people have look numerous times for their chosen readings like this hydraulic control systems, but end up in infectious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they are facing with some infectious bugs inside their laptop. hydraulic control systems is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the hydraulic control systems is universally compatible with any devices to read.

Introduction To Stochastic Control Theory

Abstract: Thank you for downloading introduction to stochastic control theory. Maybe you have knowledge that, people have look hundreds times for their chosen novels like this introduction to stochastic control theory, but end up in infectious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they juggled with some infectious bugs inside their laptop. introduction to stochastic control theory is available in our digital library an online access to it is set as public so you can get it instantly. Our book servers saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the introduction to stochastic control theory is universally compatible with any devices to read.