scholarly journals Mapping a Space Manipulator to a Dynamically Equivalent Manipulator

1998 ◽  
Vol 120 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Bin Liang ◽  
Yangsheng Xu ◽  
Marcel Bergerman
Keyword(s):  
Control Strategies ◽  
Dynamic Performance ◽  
Open Loop ◽  
Space Environment ◽  
Theoretical Development ◽  
Space Manipulator ◽  
Loop Control ◽  
Fixed Base ◽  
Kinematic Equivalence ◽  
Kinematic Properties

In this paper, we discuss the problem of how a free-floating space manipulator can be mapped to a conventional, fixed-base manipulator which preserves both its dynamic and kinematic properties. This manipulator is called Dynamically Equivalent Manipulator (DEM). The DEM concept not only allows us to model a free-floating space manipulator system with simple, well-understood methods, but also to build a conventional manipulator system to experimentally study the dynamic performance and task execution of a space manipulator system, without having to resort to complicated experimental set-ups to simulate the space environment. This paper presents the theoretical development of the DEM concept, demonstrates the dynamic and kinematic equivalence, and presents simulation results to illustrate the equivalence under open-loop and closed-loop control strategies.

Small Scale Wind Generation System: Part II – A Novel Quasi-Z-Source Inverter and FRG-QZSI-Micro Grid Interface

2017 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
M. Ramkumar ◽  
K. N. Srinivas
Keyword(s):  
Control Strategies ◽  
Research Work ◽  
Open Loop ◽  
Small Scale ◽  
Loop Control ◽  
Power Injection ◽  
System Part ◽  
Micro Grid ◽  
Wind Generation System ◽  
And Control

<p>This paper proposes modelling, analysis and control of a small scale wind energy conversion system employing a direct driven Flux Reversal Generator (FRG) connected to the micro grid through a quasi-Z-source inverter (QZSI). This entire research is made up of two major parts viz., FRG and QZSI. In the part I report of this research work, the role of FRG has been thoroughly modelled and verified. In this part II, the modelling and analysis of QZSI for this purpose is presented. In addition, the modified space vector PWM (SVPWM) technique is proposed in this paper to satisfy the shoot-through characteristic of QZSI, which is a novel. The interface of FRG and QZSI to inject power in to micro grid has been finally presented. The simulation results are validated with the analytical results. Section I discusses the open loop control of QZSI. The mathematical modelling of QZSI for this purpose is given and analytically validated. This flowed by section II in which the proposed SVPWM is presented. The procedure to obtain triggering pulses using this proposed modulation technique is discussed. Section III presents closed loop control strategies for QZSI. Section IV presents the micro grid<br />inte face and power injection.</p>

Point Control of a One-Link Flexible Manipulator

1986 ◽  
Vol 53 (1) ◽  
pp. 23-27 ◽  
Author(s):  
S. B. Skaar ◽  
D. Tucker
Keyword(s):  
Transfer Functions ◽  
Control Strategies ◽  
Open Loop ◽  
Flexible Manipulator ◽  
Distributed Parameter ◽  
Loop Control ◽  
Control Approach ◽  
Alternative Approach ◽  
Single Link ◽  
Point Control

An alternative approach to the control of nonrigid, distributed parameter systems is presented. Transfer functions that relate the response of points on the system to a controlling force or torque are used in place of ordinary differential equations, which represent an approximation to the system dynamics. The implications of this “point control” approach are discussed with regard to plant modeling accuracy, uncontrolled regions, open-loop and closed-loop control strategies, system identification, and feedback estimation. Sample optimal control histories are illustrated for a single-link manipulator member with end load.

scholarly journals Control of Flexible Manipulator Systems

1996 ◽  
Vol 210 (2) ◽  
pp. 113-130 ◽  
Author(s):  
M O Tokhi ◽  
A K M Azad
Keyword(s):  
Closed Loop ◽  
Control Strategies ◽  
Open Loop ◽  
Flexible Manipulator ◽  
Closed Loop Control ◽  
Loop Control ◽  
Acceleration Feedback ◽  
Low Pass ◽  
Input Torque ◽  
Collocated Control

This paper presents an investigation into the development of open-loop and closed-loop control strategies for flexible manipulator systems. Shaped torque inputs, including Gaussian-shaped and low-pass (Butter-worth and elliptic) filtered input torque functions, are developed and used in an open-loop configuration and their performance studied in comparison to a bang-bang input torque through experimentation on a single-link flexible manipulator system. Closed-loop control strategies that use both collocated (hub angle and hub velocity) and non-collocated (end-point acceleration) feedback are then proposed. A collocated proportional and derivative (PD) control is first developed and its performance studied through experimentation. The collocated control is then extended to incorporate, additionally, non-collocated feedback through a proportional integral derivative (PID) configuration. The performance of the hybrid collocated and non-collocated control strategy thus developed is studied through experimentation. Experimental results verifying the performance of the developed control strategies are presented and discussed.

scholarly journals Practical Design Considerations for Performance and Robustness in the Face of Uncertain Flexible Dynamics in Space Manipulators

2021 ◽  
Vol 8 ◽  
Author(s):  
Connor Holmes
Keyword(s):  
Control Strategies ◽  
Low Frequency ◽  
Open Loop ◽  
Unmodeled Dynamics ◽  
Loop Control ◽  
Stability Margins ◽  
Flexible Mode ◽  
Space Manipulators ◽  
The Face ◽  
And Performance

Low frequency dynamics introduced by structural flexibility can result in considerable performance degradation and even instability in on-orbit, robotic manipulators. Although there is a wealth of literature that addresses this problem, the author has found that many advanced solutions are often precluded by practical considerations. On the other hand, classical, robust control methods are tractable for these systems if the design problem is properly constrained. This paper investigates a pragmatic engineering approach that evaluates the system’s stability margins in the face of uncertain, flexible perturbation dynamics with frequencies that lie close to or within the bandwidth of the nominal closed-loop system. The robustness of classical control strategies is studied in the context of both collocated (joint rate) and non-collocated (force/torque and vision-based) feedback. It is shown that robust stability and performance depend on the open-loop control bandwidth of the nominal control law (as designed for a simplified, rigid plant). Namely, the designed bandwidth must be constrained to be lower than the minimum flexible mode frequency of the unmodeled dynamics by a given factor. This strategy gives credence to popular heuristic methods commonly used to reduce the effect of unmodeled dynamics in complex manipulator systems.

A Method for Teaching Feedback Control Using the Enhanced Mass-Spring-Damper System

2011 ◽  
Author(s):  
Dean H. Kim
Keyword(s):  
Feedback Control ◽  
Control Strategies ◽  
Open Loop ◽  
Open Loop Control ◽  
Improve Performance ◽  
Loop Control ◽  
System Input ◽  
Advanced Controls ◽  
Mass Spring ◽  
Force Generator

This paper presents a method that the author has developed to teach students about the need for feedback control and to facilitate the understanding of controller implementation. The initial discussion focuses on the limitations of open-loop control to improve performance of the traditional mass-spring-damper system. The key contribution is the introduction of an enhanced mass-spring-damper system with a position sensor and force generator, resulting in voltages as system input and output. This enhanced system provides a foundation for discussion of basic feedback control strategies such as PID-Control in addition to advanced controls concepts. The analysis is provided in time-domain to facilitate the understanding of these important controls concepts.

scholarly journals Turbulent boundary layer under the control of different schemes

2017 ◽  
Vol 473 (2202) ◽  
pp. 20170038 ◽  
Author(s):  
Z. X. Qiao ◽  
Y. Zhou ◽  
Z. Wu
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
High Speed ◽  
Control Strategies ◽  
Local Maximum ◽  
Open Loop ◽  
Open Loop Control ◽  
Feed Forward ◽  
Loop Control ◽  
Combined Feed

This work explores experimentally the control of a turbulent boundary layer over a flat plate based on wall perturbation generated by piezo-ceramic actuators. Different schemes are investigated, including the feed-forward, the feedback, and the combined feed-forward and feedback strategies, with a view to suppressing the near-wall high-speed events and hence reducing skin friction drag. While the strategies may achieve a local maximum drag reduction slightly less than their counterpart of the open-loop control, the corresponding duty cycles are substantially reduced when compared with that of the open-loop control. The results suggest a good potential to cut down the input energy under these control strategies. The fluctuating velocity, spectra, Taylor microscale and mean energy dissipation are measured across the boundary layer with and without control and, based on the measurements, the flow mechanism behind the control is proposed.

scholarly journals Model-based Control Strategies for Anaerobic Digestion Processes

BIOMATH ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 1907127 ◽  
Author(s):  
Neli Dimitrova ◽  
Mikhail Krastanov
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Methane Production ◽  
Control Strategies ◽  
A Priori ◽  
Open Loop ◽  
Open Loop Control ◽  
Loop Control ◽  
Model Based Control ◽  
Anaerobic Wastewater Treatment

In this paper we consider a four-dimensional bioreactor model, describing an anaerobic wastewater treatment with methane production. Different control strategies for stabilizing the dynamics are presented and discussed. A general and practice-oriented bounded open-loop control is proposed, aimed to steer the model solutions towards an a priori given set in thephase plane.

Microassembly via Coordinated Manipulation of Objects Using a Multifingered Micromanipulator

2011 ◽  
Author(s):  
Christopher Pelzmann ◽  
Laxman Saggere
Keyword(s):  
Closed Loop ◽  
State Of The Art ◽  
Control Strategies ◽  
Open Loop ◽  
Open Loop Control ◽  
Multiple Objects ◽  
Loop Control ◽  
Micro Scale ◽  
Novel Approach ◽  
On Chip

This paper presents a novel approach to manipulation and assembly of micro-scale objects using a chip-scale multi-fingered micromanipulator, in which multiple, independently controlled compliant fingers coordinate with each other to grasp and manipulate multiple objects simultaneously on-chip. The structural and functional advantages of this multi-fingered micromanipulator in achieving high dexterity in a compact form as compared to other state-of-the-art manipulation tools are discussed. A formulation of the kinematics of the manipulator’s compliant fingers along with two different control strategies including an operator-driven closed-loop control and a semi-autonomous open-loop control for coordinated manipulation and on-chip assembly of micro-scale objects are introduced. Finally, the details of implementation of both control strategies and successful experimental demonstration of manipulations and assembly of two interlocking micro-scale parts with sub-micron mating clearance using the multifingered manipulator are presented.

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