Plans and The Structure of Target Acquisition Behavior

1981 ◽  
Vol 25 (1) ◽  
pp. 571-575
Author(s):  
R. A. Miller ◽  
R. J. Jagacinski ◽  
R. B. Nalavade ◽  
W. W. Johnson
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
General Strategy ◽  
Velocity Control ◽  
Additional Time ◽  
First Order ◽  
Oscilloscope Screen ◽  
Activity Sequence ◽  
Event Based

Subjects manipulated a position control stick with one hand and a velocity control stick with the other hand in order to capture a moving target displayed on an oscilloscope screen. The two control sticks were additively coupled. In order to understand the coordination of the two control sticks, event-based first-order markov “activity sequence generators” were constructed for individual subjects. These discrete probabilistic structures are closely related to each subject's overall plan or general strategy for the capture task. Striking individual differences and strategic errors in performance were revealed. When combined with additional time-conditioned (open-loop) and error-conditioned (closed-loop) details, the activity sequence generators provide a basis for a hierarchic description of this perceptual-motor skill.

Experimental investigation and propulsion control for a bio-inspired robotic undulatory fin

Robotica ◽  
2015 ◽  
Vol 33 (5) ◽  
pp. 1062-1084 ◽  
Author(s):  
Michael Sfakiotakis ◽  
John Fasoulas ◽  
Manolis M. Kavoussanos ◽  
Manolis Arapis
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Control Strategies ◽  
Underwater Vehicles ◽  
Open Loop ◽  
Water Tank ◽  
Velocity Control ◽  
Wave Kinematics ◽  
Propulsion Control ◽  
Simultaneous Adjustment

SUMMARYUndulatory fin propulsion, inspired by the locomotion of aquatic species such as electric eels and cuttlefish, holds considerable potential for endowing underwater vehicles with enhanced propulsion and maneuvering abilities, to address the needs of a growing number of applications. However, there are still gaps in our understanding of the effect of the fin undulations' characteristics on the generated thrust, particularly within the context of developing propulsion control strategies for such robotic systems. Towards this end, we present the design and experimental evaluation of a robotic fin prototype, comprised of eight individually-actuated fin rays. An artificial central pattern generator (CPG) is used to produce the rays' undulatory motion pattern. Experiments are performed inside a water tank, with the robotic fin suspended from a carriage, whose motion is constrained via a linear guide. The results from a series of detailed parametric investigations reveal several important findings regarding the effect of the undulatory wave kinematics on the propulsion speed and efficiency. Based on these findings, two alternative strategies for propulsion control of the robotic fin are proposed. In the first one, the speed is varied through changes in the undulation amplitude, while the second one involves simultaneous adjustment of the undulation frequency and number of waves. These two strategies are evaluated via experiments demonstrating open-loop velocity control, as well as closed-loop position control of the prototype.

scholarly journals Control-Oriented High-Frequency Turbomachinery Modeling: Single-Stage Compression System 1D Model

1993 ◽  
Author(s):  
O. O. Badmus ◽  
S. Chowdhury ◽  
K. M. Eveker ◽  
C. N. Nett
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Closed Loop ◽  
Open Loop ◽  
Rotating Stall ◽  
Single Stage ◽  
Model Parameters ◽  
Compression System ◽  
First Order ◽  
Direct Model

In this paper, a 1D unsteady compressible viscous flow model of a generic compression system previously developed by the authors is applied to a multi-stage axial compressor experimental rig configured for single–stage operation. The required model parameters and maps are identified from experimental data. The resulting model is an explicit system of 9 first order ODE’s. The model inputs are compressor speed, nozzle area, compressor discharge bleed area, plenum bleed area, inlet total pressure and entropy, and nozzle and bleed exit static pressures. The model and experimental data are compared with respect to both open–loop uncontrolled and closed–loop controlled behaviors. These comparisons focus on i) forced transients and ii) global nonlinear dynamics and bifurcations. In all cases the comparison between the model and experimental data is excellent. Of particular interest is the ability of the model, which does not include any hysteretic maps, to predict experimentally observed hysteresis with respect to the onset and cessation of surge. This predictive capability of the model manifests itself as the coexistence of a stable equilibrium (rotating stall) and a stable periodic solution (surge) in the model at a single fixed set of system input values. Also of interest is the fact that the controllers used for closed–loop comparisons were designed directly from the model with no a posteriori tuning of controller parameters. Thus, the excellent closed–loop comparisons between the model and experimental data provide strong evidence in support of the validity of the model for use in direct model based controller design. The excellent agreement between the model and experimental data summarized above is attributed in large part to the use of effective lengths within the model, as functions of axial Mach number and nondimensional compressor rotational speed, as prescribed by the modeling technique. The use of these effective lengths proved to be far superior to the use of physical lengths. The use of these effective lengths also provided substantial improvement over the use of physical lengths coupled with fixed first order empirical lags, as proposed by other authors for the modeling of observed compressor dynamic lag. The overall success of this model is believed to represent a positive first step toward a complete experimental validation of the approach to control–oriented high–frequency turbomachinery modeling being developed by the authors.

Analysis of Barriers to Control of Manipulators Within Accessible Output Sets

1995 ◽  
Author(s):  
Edward J. Haug ◽  
Frederick A. Adkins ◽  
Chaoxin Charles Qiu ◽  
Jeng Yen
Keyword(s):  
Quadratic Forms ◽  
Closed Loop ◽  
Position Control ◽  
Quantitative Information ◽  
Second Order ◽  
Velocity Control ◽  
Unilateral Constraints ◽  
Open Chain ◽  
Output Control ◽  
Curves And Surfaces

Abstract Barriers to output control of manipulators, both in the interior and at the boundary of accessible output sets, are analyzed using first and second order Taylor approximations of the output in selected directions as functions of manipulator input. The formulation is valid for both planar and spatial manipulators, with open chain and closed loop structures, and accounts for the effects of unilateral constraints on the range of admissible control inputs. Criteria defining curves and surfaces associated with singular output control of manipulators are extended to define normals to such curves and surfaces. It is shown that output velocity in the direction normal to such curves and surfaces must be zero, so they arc barriers to velocity control in the associated manipulator configuration. Second order Taylor expansion of normal output with respect to input parameters yields quantitative information regarding barriers to output position control. Definiteness properties of the resulting quadratic approximation define directions of admissible and inadmissible outputs. Algorithms for automatically computing the associated quadratic forms and eigenvalues that determine their definiteness properties are presented and illustrated using planar examples.

scholarly journals A dual-loop tracking control approach to precise nanopositioning

2018 ◽  
Vol 25 (3) ◽  
pp. 666-674 ◽  
Author(s):  
Mohammed Altaher ◽  
Douglas Russell ◽  
Sumeet S. Aphale
Keyword(s):  
Closed Loop ◽  
Reference Signal ◽  
Open Loop ◽  
Performance Criteria ◽  
Control Technique ◽  
Loop Control ◽  
Control Approach ◽  
First Order ◽  
Integral Controller ◽  
Double Integrator

Nanopositioners are mechanical devices that can accurately move with a resolution in the nanometer scale. Due to their mechanical construction and the piezoelectric actuators popularly employed in nanopositioners, these devices have severe performance limitations due to resonance, hysteresis and creep. A number of techniques to control nanopositioners, both in open-loop and closed-loop, have been reported in the literature. Closed-loop techniques clearly outperform open-loop techniques due to several desirable characteristics, such as robustness, high-bandwidth, absence of the need for tuning and high stability, along with others. The most popular closed-loop control technique reported is one where a damping controller is first employed in an inner loop to damp the mechanical resonance of the nanopositioner, thereby increasing achievable bandwidth. Consequently, a tracking controller, typically an Integral controller or a proportional–integral controller, is implemented in the outer loop to enforce tracking of the reference signal, thereby reducing the positioning errors due to hysteresis and creep dynamics of the employed actuator. The most popular trajectory a nanopositioner is forced to track is a raster scan, which is generated by making one axis of the nanopositioner follow a triangular trajectory and the other follow a slow ramp or staircase. It is quite clear that a triangle wave (a finite velocity, zero acceleration signal) cannot be perfectly tracked by a first-order integrator and a double integrator is necessary to deliver error-free tracking. However, due to the phase profile of the damped closed-loop system, implementing a double integrator is difficult. This paper proposes a method by which to implement two integrators focused on the tracking performance. Criteria for gain selection, stability analysis, error analysis, simulations, and experimental results are provided. These demonstrate a reduction in positioning error by 50%, when compared to the traditional damping plus first-order integral tracking approach.

Experiments on Point-to-Point Control of a Flexible Beam Using Laplace Transform Technique: Part II—Closed-Loop

1991 ◽  
Vol 113 (3) ◽  
pp. 438-443 ◽  
Author(s):  
S. P. Bhat ◽  
D. K. Miu
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
Flexible Beam ◽  
Laplace Domain ◽  
Loop Control ◽  
Feed Forward Control ◽  
Laplace Transform Technique ◽  
Point Control ◽  
Point To Point

Using the Laplace domain synthesis technique documented in earlier publications, experiments on the closed-loop point-to-point position control of a flexible beam are presented. Two different approaches are described, a feed-forward control and an iterative open-loop control. Solution to the robustness problems encountered during actual implementation is also demonstrated.

A Digital Compensator Design for Electrohydraulic Single-Rod Cylinder Position Control Systems

1990 ◽  
Vol 112 (3) ◽  
pp. 403-409 ◽  
Author(s):  
J. Watton
Keyword(s):  
Control Systems ◽  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
Closed Loop System ◽  
Forward Algorithm ◽  
Loop Transfer Function ◽  
Compensator Design ◽  
Feedback Algorithm ◽  
Position Control System

A digital compensator using a forward algorithm, F(z−1), and a feedback algorithm, H(z−1), is developed for an electrohydraulic position control system incorporating an underlapped servovalve and a single-rod cylinder. The main problems encountered with designing such a closed-loop system are discussed, and it is shown how the filter coefficients may be easily determined for a particular class of open-loop transfer function. An excellent comparison between theory and experiment is obtained and it is deduced that one coefficient only need be changed in the forward algorithm for such gain-change dominant systems.

Design and Modelling of a Novel Servovalve Actuated by a Piezoelectric Ring Bender

2015 ◽  
Author(s):  
L. Johan Persson ◽  
Andrew R. Plummer ◽  
Christopher R. Bowen ◽  
Ian Brooks
Keyword(s):  
Mathematical Model ◽  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
Closed Loop Control ◽  
Hydraulic Fluid ◽  
Loop Control ◽  
Frequency Responses ◽  
Spool Valve ◽  
The Mathematical Model

This paper describes the design, simulation and testing of a piezoelectric spool valve. An actuator has been connected to the valve and tested under closed loop control. A mathematical model of the valve was produced and a prototype of the valve was tested. The mathematical model is validated against the experimental data. Step and frequency responses for both the valve and actuator are presented. It was found that displacement of the hydraulic fluid by the ring bender had an impact on the valve performance. To reduce the effect of the piezoelectric hysteresis, closed loop spool position control was evaluated. A noticeable difference can be observed between open loop and closed loop performance.

scholarly journals Research on a High-Speed and Heavy-Duty Closed-Loop Drive System of a Two-Phase Hybrid Stepping Motor Based on a Hybrid Controller

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhou Yansuo ◽  
Leng Yonggang ◽  
Lu Wenqi ◽  
Li Yu ◽  
Li Qingmian ◽  
...  
Keyword(s):  
High Speed ◽  
Closed Loop ◽  
Position Control ◽  
Load Capacity ◽  
Open Loop ◽  
Drive System ◽  
Heavy Duty ◽  
Two Phase ◽  
Hybrid Controller ◽  
State Process

Low load capacity and poor positioning accuracy of stepper motors in high-speed operation are currently two of the bottlenecks that limit their application in high-speed and heavy-duty drive applications. To solve this problem, a hybrid controller is proposed for the high-speed heavy-duty closed-loop stepper motor driving system, which includes two core contents. First, for the position control, a hybrid controller based on position error for open-loop/closed-loop automatic switching-combined spatial current given amplitude and angle automatic adjustment is proposed. Secondly, an advanced angle compensation strategy based on error-integrated feedforward is adopted to compensate for the electrical angle of the combined space current vector. To verify the effectiveness of the proposed method, theoretical analysis and system development as well as testing are carried out. Compared with the traditional open-loop drive system, results show that the maximum operating speed and maximum torque of the newly developed drive system based on the proposed method are improved by 50% and 81.25%, respectively. And at the same set speed and position, the response speed is faster and the accuracy of the steady-state process is higher. In the case of setting higher running speed and load torque, the drive system also maintains high-precision operation.

scholarly journals Hamilton’s rule, gradual evolution, and the optimal (feedback) control of phenotypically plastic traits

2020 ◽  
Author(s):  
Piret Avila ◽  
Tadeas Priklopil ◽  
Laurent Lehmann
Keyword(s):  
Closed Loop ◽  
Expression Profiles ◽  
Open Loop ◽  
Order Conditions ◽  
Optimal Feedback Control ◽  
State Variables ◽  
First Order ◽  
Hamilton’S Rule ◽  
Gradual Evolution ◽  
Hamilton's Rule

AbstractMost traits expressed by organisms, such as gene expression profiles, developmental trajectories, behavioural sequences and reaction norms are function-valued traits (colloquially “phenotypically plastic traits”), since they vary across an individual’s age and in response to various internal and/or external factors (state variables). Furthermore, most organisms live in populations subject to limited genetic mixing and are thus likely to interact with their relatives. We here formalise selection on genetically determined function-valued traits of individuals interacting in a group-structured population, by deriving the marginal version of Hamilton’s rule for function-valued traits. This rule simultaneously gives a condition for the invasion of an initially rare mutant function-valued trait and its ultimate fixation in the population (invasion thus implies substitution). Hamilton’s rule thus underlies the gradual evolution of function-valued traits and gives rise to necessary first-order conditions for their uninvadability (evolutionary stability). We develop a novel analysis using optimal control theory and differential game theory, to simultaneously characterise and compare the first-order conditions of (i) open-loop traits - functions of time (or age) only, and (ii) closed-loop (state-feedback) traits - functions of both time and state variables. We show that closed-loop traits can be represented as the simpler open-loop traits when individuals do no interact or when they interact with clonal relatives. Our analysis delineates the role of state-dependence and interdependence between individuals for trait evolution, which has implications to both life-history theory and social evolution.

scholarly journals Taking Sensors Out of Motors

1998 ◽  
Vol 120 (01) ◽  
pp. 74-75
Author(s):  
Greg Paula
Keyword(s):  
Motor Control ◽  
Closed Loop ◽  
Position Control ◽  
Great Accuracy ◽  
Open Loop ◽  
Torque Control ◽  
Disk Drives ◽  
Precise Position ◽  
Speed Regulation ◽  
Signal Processors

This article discusses that advanced signal processors are replacing the feedback sensors that had been required for motor control in applications ranging from disk drives to appliance motors. The traditional method of closed-loop motor control has been to use one or more sensors to provide feedback. A growing number of applications, however, are now eliminating the sensor through one of several methods, such as back electromotive force (EMF) or inductance measurement. Sensorless motors are best suited for applications where speed control is needed, but precise position control is not critical. Sensorless motors are proving to be most appropriate for applications where the position of the rotor does not have to be pinpointed with great accuracy and all that is needed is speed and torque control. Prime candidates for sensorless motors are applications where open-loop scalar control had been used but better speed regulation and more torque at low speed are needed.

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