Measuring Moment Arms Using Closed-Loop Force Control With an Elbow Simulator

2007 ◽  
Author(s):  
Laurel Kuxhaus ◽  
Patrick J. Schimoler ◽  
Jeffrey S. Vipperman ◽  
Angela M. Flamm ◽  
Daniel Budny ◽  
...  
Keyword(s):  
Force Control ◽  
Elbow Joint ◽  
Closed Loop ◽  
Neuromuscular Control ◽  
Joint Control ◽  
Joint Mechanics ◽  
Loop Control ◽  
Modeling And Control ◽  
Moment Arms ◽  
And Function

In search of a complete understanding of a joint’s function, one must understand both the anatomic parameters and how the brain controls the joint’s actuation. Accurate measurements of anatomical parameters are critical to non-linear biomechanical modeling and control and also to a clinical understanding of orthopaedic reconstruction. Likewise, new frontiers in the study of neuromuscular control contribute to our understanding of joint structure and function. One approach to study joint function is to use a joint simulator to actuate cadaver limbs. Towards the goals of understanding and improving human elbow joint control, a physiologic elbow joint simulator was previously constructed in our laboratory. It is the first elbow simulator to operate completely under closed-loop control. The closed-loop force control used to study joint mechanics permits measurement of moment arms in cadaveric elbow specimens. We hypothesized that the approach yields comparable results to previously-reported moment arm values.[1]

Combined Temperature and Force Control for Robotic Friction Stir Welding

2013 ◽  
Author(s):  
Axel Fehrenbacher ◽  
Christopher B. Smith ◽  
Neil A. Duffie ◽  
Nicola J. Ferrier ◽  
Frank E. Pfefferkorn ◽  
...  
Keyword(s):  
Control System ◽  
Force Control ◽  
Closed Loop ◽  
Interface Temperature ◽  
Closed Loop Control ◽  
Weld Quality ◽  
Loop Control ◽  
Friction Stir ◽  
Tool Position ◽  
Robotic Friction Stir Welding

The objective of this research is to develop a closed-loop control system for robotic friction stir welding (FSW) that simultaneously controls force and temperature in order to maintain weld quality under various process disturbances. FSW is a solid-state joining process enabling welds with excellent metallurgical and mechanical properties, as well as significant energy consumption and cost savings compared to traditional fusion welding processes. During FSW, several process parameter and condition variations (thermal constraints, material properties, geometry, etc.) are present. The FSW process can be sensitive to these variations, which are commonly present in a production environment; hence, there is a significant need to control the process to assure high weld quality. Reliable FSW for a wide range of applications will require closed-loop control of certain process parameters. A linear multi-input-multi-output process model has been developed that captures the dynamic relations between two process inputs (commanded spindle speed and commanded vertical tool position) and two process outputs (interface temperature and axial force). A closed-loop controller was implemented that combines temperature and force control on an industrial robotic FSW system. The performance of the combined control system was demonstrated with successful command tracking and disturbance rejection. Within a certain range, desired axial forces and interface temperatures are achieved by automatically adjusting the spindle speed and the vertical tool position at the same time. The axial force and interface temperature is maintained during both thermal and geometric disturbances and thus weld quality can be maintained for a variety of conditions in which each control strategy applied independently could fail.

scholarly journals Recovery of dynamics and function in spiking neural networks by closed-loop control

2015 ◽  
Author(s):  
Ioannis Vlachos ◽  
Taskin Deniz ◽  
Ad Aertsen ◽  
Arvind Kumar
Keyword(s):  
Neural Networks ◽  
Closed Loop ◽  
Brain Activity ◽  
Open Loop ◽  
Spiking Neural Networks ◽  
Delayed Feedback Control ◽  
Loop Control ◽  
Wide Range ◽  
Underlying Network ◽  
And Function

There is a growing interest in developing novel brain stimulation methods to control disease-related aberrant neural activity and to address basic neuroscience questions. Conventional methods for manipulating brain activity rely on open-loop approaches that usually lead to excessive stimulation and, crucially, do not restore the original computations performed by the network. Thus, they are often accompanied by undesired side-effects. Here, we introduce delayed feedback control (DFC), a conceptually simple but effective method, to control pathological oscillations in spiking neural networks. Using mathematical analysis and numerical simulations we show that DFC can restore a wide range of aberrant network dynamics either by suppressing or enhancing synchronous irregular activity. Importantly, DFC besides steering the system back to a healthy state, it also recovers the computations performed by the underlying network. Finally, using our theory we isolate the role of single neuron and synapse properties in determining the stability of the closed-loop system.

Robotic force control for deburring using an active end effector

Robotica ◽  
1989 ◽  
Vol 7 (4) ◽  
pp. 303-308 ◽  
Author(s):  
G. M. Bone ◽  
M. A. Elbestawi
Keyword(s):  
Control System ◽  
Force Control ◽  
Pid Controller ◽  
Closed Loop ◽  
Least Squares Method ◽  
Closed Loop Control ◽  
End Effector ◽  
Loop Control ◽  
Positioning Errors ◽  
Force Control System

SUMMARYAn active force control system for robotic deburring based on an active end effector is developed. The system utilizes a PUMA-560 six axis robot. The robot's structural dynamics, positioning errors, and the deburring cutting process are examined in detail. Based on ARMAX plant models identified using the least squares method, a discrete PID controller is designed and tested in real-time. The control system is shown to maintain the force within l N of the reference, and reduce chamfer depth errors to 0.12 mm from the 1 mm possible without closed-loop control.

scholarly journals Recovery of Dynamics and Function in Spiking Neural Networks with Closed-Loop Control

2016 ◽  
Vol 12 (2) ◽  
pp. e1004720 ◽  
Author(s):  
Ioannis Vlachos ◽  
Taşkin Deniz ◽  
Ad Aertsen ◽  
Arvind Kumar
Keyword(s):  
Neural Networks ◽  
Closed Loop ◽  
Spiking Neural Networks ◽  
Closed Loop Control ◽  
Loop Control ◽  
Dynamics And Function ◽  
And Function

Development of Hardware Simulator and Controller for Web Transport Process

2005 ◽  
Vol 128 (1) ◽  
pp. 378-381 ◽  
Author(s):  
Jeetae Kim
Keyword(s):  
Force Control ◽  
Transport Process ◽  
Closed Loop ◽  
Controller Design ◽  
Transport Model ◽  
Tension Force ◽  
Closed Loop Control ◽  
Measuring Device ◽  
Loop Control ◽  
Process Simulator

In this study a hardware simulator and controller for web transport process are developed. First the dynamics of web transport process is analyzed for simulator and controller design. An example Polypropylene transport process is investigated and its simplified transport model is derived. Then the web transport process simulator and its controller are developed. Accurate tension force control is needed to produce high quality web formed materials. The process controller uses the loadcell as a tension measuring device and closed-loop control is used for tension force regulation. The response of the system is tested under the disturbances in tension and the experimental results show that the system regulates tension disturbances properly.

Modeling and Control of the In-Situ Thermoplastic Composite Tape-Laying Process

1998 ◽  
Vol 120 (4) ◽  
pp. 507-515 ◽  
Author(s):  
Wei-Ching Sun ◽  
Susan C. Mantell ◽  
Kim A. Stelson
Keyword(s):  
Process Model ◽  
Closed Loop ◽  
Thermoplastic Composite ◽  
Closed Loop Control ◽  
Loop Control ◽  
Modeling And Control ◽  
Composite Tape ◽  
Temperature Feedback ◽  
And Control

In thermoplastic tape-laying with in-situ consolidation, a laminated composite is constructed by the local application of heat and pressure. A moving head, applying heat and pressure, lays down and bonds a new layer to the previously bonded layers (substrate). The temperature at the interface between the top ply and the substrate is critical to achieving interlaminar bonding. Recent research on the in-situ thermoplastic composite tape-laying process has focused on modeling, numerical analysis and experimental analysis, but little research has considered the control of this process. In this work, a method is proposed for modeling and control of in-situ thermoplastic composite tape-laying. The key to the control algorithm is predicting the temperature at the interface between the top ply and the substrate. Based on a process model, a state feedback controller and a state estimator for temperature are designed for closed-loop control using the linear quadratic method. Two different approaches are used to develop the process model for real-time closed-loop control through temperature feedback. In the first approach, a low-order lumped parameter model is constructed from a finite difference scheme. The second approach constructs an empirical model through system identification. The structures of the two models are identical, but the parameters differ. The experimental results have shown that the developed estimator and controller can accurately estimate and control the bonding temperature using temperature feedback indicating that the proposed modeling and control methodology can produce a high quality thermoplastic composite laminate.

scholarly journals Neuromuscular control: introduction and overview

1999 ◽  
Vol 354 (1385) ◽  
pp. 841-847 ◽  
Author(s):  
Johan L. Leeuwen
Keyword(s):  
Control Systems ◽  
Closed Loop ◽  
Neuromuscular Control ◽  
Open Loop ◽  
Open Loop Control ◽  
Loop Control ◽  
Motion Trajectories ◽  
Interdisciplinary Field ◽  
Introductory Overview ◽  
Control Introduction

This paper introduces some basic concepts of the interdisciplinary field of neuromuscular control, without the intention to be complete. The complexity and multifaceted nature of neuromuscular control systems is briefly addressed. Principles of stability and planning of motion trajectories are discussed. Closed–loop and open–loop control are considered, together with the inherent stability properties of muscles and the geometrical design of animal bodies. Various modelling approaches such as inverse and forward dynamics are outlined, as used by several authors in the Philosophical Transactions of the Royal Society of London, series B, May 1999 issue. An introductory overview is presented of the other contributions in that issue.

CLOSED-LOOP CONTROL OF QUADRICEPS/HAMSTRING ACTIVATION FOR FES-INDUCED STANDING-UP MOVEMENT OF PARAPLEGICS

2001 ◽  
Vol 05 (03) ◽  
pp. 173-184 ◽  
Author(s):  
Nan-Ying Yu ◽  
Jia-Jin Jason Chen ◽  
Ming Shiang Ju
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Mechanical Energy ◽  
Open Loop ◽  
Knee Extensors ◽  
Joint Control ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Standing Up

Functional electrical stimulation (FES) standing system can enable the paraplegics to achieve the standing position for functional activities in daily living. FES standing system is usually applied by stimulating the knee extensor muscles. The hip joints are in hyperextension and the ankle joints remain free. Therefore, the knee joint control is the key point of the FES standing control system. Traditional open-loop control often induces high knee end-velocity (KEV) when the subject reaches the upright position. In this work, the reducing of KEV by closed-loop control was addressed. An on/off feedback control based on mechanical energy conservation was developed to control the knee extensors and flexors. The result was compared to the open loop controlled standing up in a mechanically simulative experiment. It is concluded that the on/off control strategy can reduce the KEV more efficiently when compared to the open-loop control. Proportional-integral-derivative (PID) position controlled standing up was also studied and compared with the on/off control system. The PID controller was found to be capable of reducing KEV to a level lower than that of the on/off control, whereas its instability for knee control was also found.

Nanometer Range Closed-Loop Control of a Stepper Micro-Motor for Data Storage

2007 ◽  
Author(s):  
Mihai Patrascu ◽  
Stefano Stramigioli ◽  
Meint de Boer ◽  
Gijs Krijnen
Keyword(s):  
Data Storage ◽  
Closed Loop ◽  
Image Data ◽  
Closed Loop Control ◽  
Nanometer Range ◽  
Loop Control ◽  
Modeling And Control ◽  
Stepper Motors ◽  
And Control ◽  
Typical Range

We present a nanometer range, closed-loop control study for MEMS stepper actuators. Although generically applicable to other types of stepper motors, the control design presented here was particularly intended for one dimensional shuffle actuators fabricated by surface micromachining technology. The stepper actuator features 50 nm or smaller step sizes. It can deliver forces up to 5 mN (measured) and has a typical range of about 20 μm. The target application is probe storage, where positioning accuracies of about 10 nm are required. The presence of inherent actuator stiction, load disturbances, and other effects make physical modeling and control studies necessary. Performed experiments include measurements with open- and closed-loop control, where a positioning accuracy in the order of tens of nm or better is obtained from image data of a conventional fire-wire camera at 30 fps.

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