scholarly journals Wearable Biofeedback System to Induce Desired Walking Speed in Overground Gait Training

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 4002
Author(s):  
Huanghe Zhang ◽  
Yefei Yin ◽  
Zhuo Chen ◽  
Yufeng Zhang ◽  
Ashwini K. Rao ◽  
...  
Keyword(s):  
Closed Loop ◽  
Walking Speed ◽  
New Technology ◽  
Past Research ◽  
Gait Training ◽  
Open Loop ◽  
Vibrotactile Stimulation ◽  
Loop Control ◽  
Biofeedback System ◽  
Walking Speeds

Biofeedback systems have been extensively used in walking exercises for gait improvement. Past research has focused on modulating the wearer’s cadence, gait variability, or symmetry, but none of the previous works has addressed the problem of inducing a desired walking speed in the wearer. In this paper, we present a new, minimally obtrusive wearable biofeedback system (WBS) that uses closed-loop vibrotactile control to elicit desired changes in the wearer’s walking speed, based on the predicted user response to anticipatory and delayed feedback. The performance of the proposed control was compared to conventional open-loop rhythmic vibrotactile stimulation with N = 10 healthy individuals who were asked to complete a set of walking tasks along an oval path. The closed-loop vibrotactile control consistently demonstrated better performance than the open-loop control in inducing desired changes in the wearer’s walking speed, both with constant and with time-varying target walking speeds. Neither open-loop nor closed-loop stimuli affected natural gait significantly, when the target walking speed was set to the individual’s preferred walking speed. Given the importance of walking speed as a summary indicator of health and physical performance, the closed-loop vibrotactile control can pave the way for new technology-enhanced protocols for gait rehabilitation.

Active Control of Combustion Instability Using Symmetric and Asymmetric Premix Fuel Modulation

2007 ◽  
Author(s):  
Daniel Guyot ◽  
Christian Oliver Paschereit
Keyword(s):  
Heat Release ◽  
Closed Loop ◽  
Modulation Frequency ◽  
Combustion Instability ◽  
Open Loop ◽  
Closed Loop Control ◽  
Nox Emissions ◽  
Loop Control ◽  
Asymmetric Modulation ◽  
Control Schemes

Active instability control was applied to an atmospheric swirl-stabilized premixed combustor using open loop and closed loop control schemes. Actuation was realised by two on-off valves allowing for symmetric and asymmetric modulation of the premix fuel flow while maintaining constant time averaged overall fuel mass flow. Pressure and heat release fluctuations in the combustor as well as NOx, CO and CO2 emissions in the exhaust were recorded. In the open loop circuit the heat release response of the flame was first investigated during stable combustion. For symmetric fuel modulation the dominant frequency in the heat release response was the modulation frequency, while for asymmetric modulation it was its first harmonic. In stable open loop control a reduction of NOx emissions due to fuel modulation of up to 19% was recorded. In the closed loop mode phase-shift control was applied while triggering the valves at the dominant oscillation frequency as well as at its second subharmonic. Both, open and closed loop control schemes were able to successfully control a low-frequency combustion instability, while showing only a small increase in NOx emissions compared to, for example, secondary fuel modulation. Using premixed open loop fuel modulation, attenuation was best when modulating the fuel at frequencies different from the dominant instability frequency and its subharmonic. The performance of asymmetric fuel modulation was generally slightly better than for symmetric modulation in terms of suppression levels as well as emissions. Suppression of the instability’s pressure rms level of up to 15.7 dB was recorded.

Multi-Stage System Identification of a Gas Turbine

2017 ◽  
Author(s):  
Amit Pandey ◽  
Maurício de Oliveira ◽  
Chad M. Holcomb
Keyword(s):  
Gas Turbine ◽  
Closed Loop ◽  
Open Loop ◽  
Loop System ◽  
Closed Loop Control ◽  
Input Output ◽  
Open Loop System ◽  
Loop Control ◽  
Multi Stage ◽  
Identification Techniques

Several techniques have recently been proposed to identify open-loop system models from input-output data obtained while the plant is operating under closed-loop control. So called multi-stage identification techniques are particularly useful in industrial applications where obtaining input-output information in the absence of closed-loop control is often difficult. These open-loop system models can then be employed in the design of more sophisticated closed-loop controllers. This paper introduces a methodology to identify linear open-loop models of gas turbine engines using a multi-stage identification procedure. The procedure utilizes closed-loop data to identify a closed-loop sensitivity function in the first stage and extracts the open-loop plant model in the second stage. The closed-loop data can be obtained by any sufficiently informative experiment from a plant in operation or simulation. We present simulation results here. This is the logical process to follow since using experimentation is often prohibitively expensive and unpractical. Both identification stages use standard open-loop identification techniques. We then propose a series of techniques to validate the accuracy of the identified models against first principles simulations in both the time and frequency domains. Finally, the potential to use these models for control design is discussed.

scholarly journals The Modelling, Simulation and FPGA-Based Implementation for Stepper Motor Wide Range Speed Closed-Loop Drive System Design

Machines ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 56 ◽  
Author(s):  
Chiu-Keng Lai ◽  
Jhang-Shan Ciou ◽  
Chia-Che Tsai
Keyword(s):  
Embedded System ◽  
High Speed ◽  
Closed Loop ◽  
Open Loop ◽  
Drive System ◽  
Stepper Motor ◽  
Motor Drive ◽  
Digital Controllers ◽  
Loop Control ◽  
Wide Range

Owing to the benefits of programmable and parallel processing of field programmable gate arrays (FPGAs), they have been widely used for the realization of digital controllers and motor drive systems. Furthermore, they can be used to integrate several functions as an embedded system. In this paper, based on Matrix Laboratory (Matlab)/Simulink and the FPGA chip, we design and implement a stepper motor drive. Generally, motion control systems driven by a stepper motor can be in open-loop or closed-loop form, and pulse generators are used to generate a series of pulse commands, according to the desired acceleration/run/deceleration, in order to the drive system to rotate the motor. In this paper, the speed and position are designed in closed-loop control, and a vector control strategy is applied to the obtained rotor angle to regulate the phase current of the stepper motor to achieve the performance of operating it in low, medium, and high speed situations. The results of simulations and practical experiments based on the FPGA implemented control system are given to show the performances for wide range speed control.

Outlook of the Dynamic Behavior of Closed-Loop Control through Open-Loop Analysis for Intensified Separation Processes

2018 ◽  
Vol 57 (49) ◽  
pp. 16795-16808
Author(s):  
Julián Cabrera-Ruiz ◽  
César Ramírez-Márquez ◽  
Shinji Hasebe ◽  
Salvador Hernández ◽  
J. Rafael Alcántara Avila
Keyword(s):  
Dynamic Behavior ◽  
Closed Loop ◽  
Open Loop ◽  
Closed Loop Control ◽  
Loop Analysis ◽  
Separation Processes ◽  
Loop Control

scholarly journals Design and Analysis of Multi-Device Interleaved Boost Converter Driving an Induction Motor

2021 ◽  
Vol 850 (1) ◽  
pp. 012036
Author(s):  
R Latha ◽  
S Adharsh Babu ◽  
M Vivek Kumar
Keyword(s):  
Induction Motor ◽  
Electric Vehicles ◽  
Closed Loop ◽  
Boost Converter ◽  
Open Loop ◽  
Power Electronic ◽  
Loop Control ◽  
Interleaved Boost Converter ◽  
Control Methodology ◽  
Electronic Interface

Abstract Electric vehicles are the future of mobility solutions. The electric vehicles are driven by an electric motor with the help of a power electronic interface. The power electronic interface needs to be designed in an efficient way both in mechanical and electrical aspects. This paper proposes the concept of design, simulation and analysis of a 10 kW Multi-Device Interleaved DC-DC Boost Converter (MDIBC) to drive a 4 kW Induction Motor. The motor is driven from the MDIBC through an inverter with SPWM technique. The variation in DC link voltage due to motor is controlled and stabilized to give a constant DC of 400 V. MDIBC consists of semi-controlled switches topology excited by Phase Shifted PWM technique to reduce the ripple current in interleaving inductors. The dual loop control methodology using PI controller is adopted to reduce the ripple in input inductor current and DC link voltage. The open loop simulation and closed loop simulation are done in MATLAB Simulink environment. The simulation results show that the overshoots and steady state error in inductor currents and output voltage are reduced in addition with reduction in current and voltage ripples.

scholarly journals Automatic locking of a parametrically resonating, base-excited, nonlinear beam

2021 ◽  
Author(s):  
Nir Ben Shaya ◽  
Izhak Bucher ◽  
Amit Dolev
Keyword(s):  
Relative Phase ◽  
Closed Loop ◽  
Dynamical Behavior ◽  
Open Loop ◽  
Vibration Modes ◽  
Nonlinear Structure ◽  
Nonlinear Beam ◽  
Loop Control ◽  
Control Scheme ◽  
Slender Beams

AbstractDescribed is a closed-loop control scheme capable of stabilizing a parametrically excited nonlinear structure in several vibration modes. By setting the relative phase between the spatially filtered response and the excitation, the open-loop unstable solution branches are stabilized under a 2:1 parametric excitation of a chosen mode of vibration. For a given phase, the closed-loop automatically locks on a limit cycle, through an Autoresonance scheme, at any desired point on the solution branches. Axially driven slender beams and nanowires develop large transverse vibration under suitable amplitudes and frequency base-excitation that are sensitive to small potential coupled field. To utilize such a structure as a sensor, stable and robust operation are made possible by the control scheme. In addition, an optimal operating point with large sensitivity to the sensed potential field can be set using phase as a tunable parameter. Detailed analysis of the dynamical behavior, experimental verifications, and demonstrations sheds light on some features of the system dynamics.

Tangible Programming for Basic Control System New Frameworks to Engineering Education for Children

2014 ◽  
Vol 931-932 ◽  
pp. 1298-1302
Author(s):  
Thiang Meadthaisong ◽  
Siwaporn Meadthaisong ◽  
Sarawut Chaowaskoo
Keyword(s):  
Control System ◽  
Engineering Education ◽  
Control Systems ◽  
Primary Schools ◽  
Closed Loop ◽  
Open Loop ◽  
Closed Loop Control ◽  
College Level ◽  
Loop Control ◽  
Tangible Programming

Programming control in industrial design is by its nature expert upon an example being Programmable Logic Controller (PLC). Such programmes are unsuitable for children or novices as they cannot understand how to use the programme. This research seeks to present tangible programming for a basic control system in new frameworks in engineering education for children. Such programmes could be for use in kindergartens, primary schools or general teaching where knowledge about basic control is required. Normally open-loop and closed-loop control system programming is taught at university and college level. This may be late as far as acquiring knowledge of basic control systems is concerned. Using tangible programming without a computer but instructions and interface, relay and motor could result in children in kindergartens and primary schools being able to programme open-looped control systems which mix chemicals or closed-loop control systems which control conveyor belts. However, the children would not be able to undertake programming using programmable control in a similar scenario.

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.

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