On the Comparison of the Dynamic Performance of Open-Loop and Closed-Loop Mechanisms

2014 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng
Keyword(s):  
Dynamic Response ◽  
Dynamic Systems ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Open Loop ◽  
Actuation Devices

In general, mechanical systems with closed-loop mechanisms can achieve significantly higher operating speeds as compared to open-loop mechanisms such as robots performing identical tasks. In this brief paper, the reason for the superior dynamic performance of closed-loop mechanisms as compared to open-loop mechanisms performing identical tasks is shown to be the inherent dynamic response limitations of the actuation devices in open-loop dynamic systems. Several examples are provided.

On the Dynamic Response of Actuation Devices in Open and Closed-Loop Mechanisms With Nonlinear Dynamics

2014 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Response ◽  
Closed Loop ◽  
Mechanical Systems ◽  
Open Loop ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Actuation System ◽  
Highly Nonlinear ◽  
Actuation Devices

This paper presents a study of the dynamic response of actuation devices used in mechanical systems with open and closed-loop linkage mechanisms and highly nonlinear dynamics such as robot manipulators. The study shows that the actuation forces/torques provided by actuation devices can be divided into two basic groups. The first group corresponds to the components of each actuator force/torque that is “actuator motion independent”. The dynamic response of this group is relatively high and limited only by the dynamic response limitations — for the case of electrically driven actuation systems — of the driving power amplifiers, electronics, computational and signal processing devices and components. The second group corresponds to those components of the actuator forces/torques that is “actuator motion dependent”. The dynamic response of this group is relatively low and dependent on the actuator effective inertial load and actuation speed. In all mechanical systems that are properly designed, the dynamic response of the first group is significantly higher than those of the second group. By separating the required actuating forces/torques into the above two groups, the dynamic response of such nonlinear dynamics systems may be determined for a given synthesized trajectory. The information can also be used to significantly increase the performance of mechanical systems. When a feed-forward control signal is used, the performance of the system is shown to be significantly improved by generating each one of the group of actuation components separately considering the dynamic response of the actuation system to each group of components. A method for separating the actuation forces/torques into the said “actuator motion independent” and “actuator motion dependent” groups for mechanical systems with open-loop and closed-loop linkage mechanisms is provided. Provided examples include an open-loop manipulators with feed-forward trajectory control and a closed-loop mechanism, both with highly nonlinear dynamics. Practical methods for implementing the proposed feed-forward control for nonlinear dynamics systems are discussed.

scholarly journals Hysteresis Controlled Quadratic Boost Converter Based AC Micro Grid System with Improved Dynamic Response

2019 ◽  
Vol 8 (2S11) ◽  
pp. 3327-3337
Keyword(s):  
Closed Loop ◽  
Power Grid ◽  
Dynamic Performance ◽  
Boost Converter ◽  
Open Loop ◽  
Grid System ◽  
Renewable Power ◽  
Renewable Power Generation ◽  
Hysteresis Controller ◽  
Micro Grid

Renewable power generation and enabling of AC Microgrids are fundamentally changing the traditional power grid. Microgrid has revealed its promising potential as an active subsystem of the modern power grid. This paper reviews and analyses ways to boost and regulate the voltage of the AC-Micro-Grid-System(QBCIMGS) for improving the microgrid power quality. “A QBC(Quadratic-boost-converter-inverter based AC-Micro-Grid-System(QBCIMGS) is conferred-here”. This work recommends-QBC(quadratic-boost-converter) between rectifier &inverter. This paper investigates open loop and closed loop response of Quadratic boost-converter based AC-Micro-Grid-System(MGS) with Proportional resonant(PR) & Hysteresis-controller(HC). The mat lab outcome attained illustrates a developed dynamic-performance by using Hysteresiscontrolled AC-Micro-Grid-System(MGS)

scholarly journals PI- Controlled PV Fed Fly Back Converter with Enhanced Dynamic Response

2019 ◽  
Vol 8 (2S11) ◽  
pp. 4031-4034
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Rise Time ◽  
Closed Loop ◽  
Input Voltage ◽  
Pi Controller ◽  
Open Loop ◽  
Load Variations ◽  
Simulink Model ◽  
Step Down

Fly back converter is the most popular converter because of its simplicity, low part counts and isolation. It occupies less volume and it saves cost. Fly back converter steps up and step down the voltage with the same polarity. Open loop operation remains insensitive to the input voltage and load variations. Matlab Simulink model for Fly back converter is established using PI controller. Open loop Fly back converter system and closed loop fly back converter systems are simulated and their outcomes are compared. Comparison is done in terms of Rise time ,Settling time and steady state error

Modeling and Analysis for Thermal Control of Spindles for Reconfigurable Machines

2001 ◽  
Author(s):  
Jeffrey L. Stein ◽  
John E. Harder
Keyword(s):  
High Speed ◽  
Metal Cutting ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Thermal Control ◽  
Open Loop ◽  
Limiting Factor ◽  
Process Conditions ◽  
Bearing Load ◽  
Bearing Loads

Abstract Control of thermally induced bearing loads remains an important but unsolved problem for precision, high-speed, metal cutting, machining spindles. Spindle dynamic performance, as well as spindle life, depends on bearing loads. Because these loads can change drastically with a change in process conditions, poor spindle dynamic performance, and dramatically reduced bearing life can result. The purpose of this paper is to evaluate the feasibility of controlling bearing loads by controlling the heat generated by a thermal actuator placed around the housing of the spindle. A mathematical model of the open loop response of a laboratory prototype spindle is developed and validated. The model is then used to evaluate the closed loop performance. The results show that closed loop control of the bearing load is achievable in steady state and under bandwidth limited transient conditions. The proposed system has reasonable command authority when additional heat is required, however, it is possible for the system to lose control when the heater is required to “provide” negative heat. This situation can be mitigated by proper choice of initial preload. As expected, measurement noise limits the control gain but is not a limiting factor. More open loop tests are suggested to validate the model under a broader set of conditions. In addition, closed loop validation is suggested. However, based on results obtained it appears bearing load control is achievable by controlling the thermal field around the spindle.

scholarly journals On finite-time consensus objectives in time-varying interconnected discrete linear dynamic systems under internal and external delays

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878484 ◽  
Author(s):  
Manuel De la Sen ◽  
Santiago Alonso-Quesada
Keyword(s):  
Dynamic Systems ◽  
Finite Time ◽  
Closed Loop ◽  
Discrete Systems ◽  
Open Loop ◽  
Time Varying ◽  
Common Error ◽  
Linear Dynamic Systems ◽  
External Point ◽  
Point Delays

This article formulates the properties of achievable consensus of linear interconnected discrete systems with multiple internal and external point delays. The formulation is stated in an algebraic generic context as the ability of achievement of (a non-necessarily zero) finite-time common error between the various subsystems. The consensus signals are generically defined so that they can be, in general, distinct of the output or state components. However, the consensus signals of all the interconnected subsystems have the same dimension for coherency reasons. A particular attention is paid to the case of weak interconnection couplings in both the open-loop case and the closed-loop one under, in general, linear output feedback. Some further extensions are given related to consensus over intervals and related to consensus of positive interconnected systems.

On the Dynamic Response of Actuation Devices in Nonlinear Dynamics Systems

2013 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Response ◽  
Control Systems ◽  
Mechanical Systems ◽  
Inertial Load ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Actuation System ◽  
Actuation Devices ◽  
Actuation Systems

This paper presents a study of the dynamic response of actuation devices used in mechanical systems with nonlinear dynamics such as robot manipulators. The study shows that the actuation forces/torques provided by actuation devices can be divided into two basic groups. The first group corresponds to the components of each actuator force/torque that is “actuator motion independent”. The dynamic response of this group is relatively high and limited only by the dynamic response limitations — for the case of electrically driven actuation systems — of the driving power amplifiers, electronics, computational and signal processing devices and components. The second group corresponds to those components of the actuator forces/torques that is “actuator motion dependent”. The dynamic response of this group is relatively low and dependent on the actuator effective inertial load and actuation speed. In all mechanical systems that are properly designed, the dynamic response of the first group is significantly higher than those of the second group. By separating the required actuating forces/torques into the above two groups, the dynamic response of such nonlinear dynamics systems may be determined for a given synthesized trajectory. The information can also be used to significantly increase the performance of control systems of such mechanical systems. When a feed-forward control signal is used, the performance of the system is shown to be significantly improved by generating each one of the group of components separately considering the dynamic response of the actuation system to each one of the groups of components. An example and practical methods of implementing the proposed feed-forward control for nonlinear dynamics systems are provided.

scholarly journals Positioning system for assembly and manufacturing tasks

2019 ◽  
Vol 299 ◽  
pp. 02002
Author(s):  
Radu-Eugen Breaz ◽  
Sever-Gabriel Racz
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Closed Loop Control ◽  
Positioning System ◽  
Programmable Logic ◽  
Loop Control ◽  
Asynchronous Motors ◽  
Voltage Frequency ◽  
Incremental Encoder ◽  
Actuation Devices

The paper presents a two-axis positioning system using asynchronous motors as actuation devices. Theuse of asynchronous motors reduces the overall cost of the system, while providing actuating torques superior to the ones provided by stepping motors. The system is controlled by mean of a programmable logic controller (PLC) and two voltage-frequency inverters fitted with motion control cards. In contrasts to a stepping motor system, which works in open loop mode, the proposed system uses closed loop control on each axis. The motion loop is closed by means of an incremental encoder.

An Optimization-Based Framework for Simultaneous Plant-Controller Redesign

1990 ◽  
Author(s):  
Robert Beyers ◽  
Subhas Desa
Keyword(s):  
Performance Improvement ◽  
Closed Loop ◽  
Optimization Problems ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Loop System ◽  
Closed Loop System ◽  
Central Notion ◽  
Computer Controlled

Abstract In this paper we develop a framework for the redesign of computer-controlled, closed-loop, mechanical systems for improved dynamic performance. A central notion which underlies the redesign framework is that, in order to achieve the best possible performance from a constrained closed-loop system, the plant and controller should be designed simultaneously. The framework is presented as the formulation and solution of a progression of optimization problems which enable the designer to systematically establish the various redesign possibilities. An example clearly demonstrates the underlying ideas as well as the use of the redesign framework for performance improvement.

scholarly journals A new approach to railway track switch actuation: Dynamic simulation and control of a self-adjusting switch

2019 ◽  
Vol 234 (7) ◽  
pp. 779-790
Author(s):  
Saikat Dutta ◽  
Tim Harrison ◽  
Christopher Patrick Ward ◽  
Roger Dixon ◽  
Tara Scott
Keyword(s):  
Closed Loop ◽  
Dynamic Performance ◽  
Real Data ◽  
Open Loop ◽  
Railway Track ◽  
Railway Network ◽  
Loop Control ◽  
Novel Approach ◽  
Loop Feedback ◽  
And Control

The track switch is one of the key assets in any railway network. It is essential to allow trains to change route; however, when it fails, significant delays are almost inevitable. A relatively common fault is ‘loss of detection’, which can happen when there is a gradual track movement and the switch machines (actuators) no longer close the gap between the switch rail and stock rail to within safe tolerance levels. Currently, such misalignment is mitigated by a preventative programme of inspection and manual re-adjustment. In contrast to many other industries, the actuators are exclusively operated in open loop, with sensors (often limit switches) mainly being used for detection. Hence, an opportunity exists to investigate the closed loop control concepts for improving the operation of the switch. This paper proposes two advances: first, a novel approach is taken for modelling the dynamic performance of track switch actuators and the moving permanent-way components of the switch. The model is validated against real data from an operational switch. Secondly, the resulting dynamic model is then used to examine the implementation of closed loop feedback control as an integral part of track switch actuation. The proposed controller is found to perform well and offers the potential of ‘self-adjustment’, i.e. re-adjusting itself to close any gap (within a predefined range) between the stock and switch rails, thereby completing the switching operation.

Variational integrators for open-loop and closed-loop optimal control of mechanical systems

PAMM ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 791-792 ◽  
Author(s):  
Kathrin Flaßkamp ◽  
Todd D. Murphey ◽  
Christof Büskens
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Mechanical Systems ◽  
Open Loop ◽  
Variational Integrators
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