scholarly journals Impedance Adaptive Controller for a Prototype of a Whiplash Syndrome Rehabilitation Device

2019 ◽  
Vol 2019 ◽  
pp. 1-21
Author(s):  
Isai Guzman-Victoria ◽  
Ivan Salgado-Ramos ◽  
Manuel Mera-Hernandez ◽  
Isaac Chairez ◽  
Hafiz Ahmed
Keyword(s):  
Sliding Mode ◽  
Weighting Function ◽  
Adaptive Controller ◽  
Reference Trajectory ◽  
Leading Role ◽  
Cervical Orthosis ◽  
Single Structure ◽  
The Face ◽  
On Line ◽  
Whiplash Syndrome

The objective of this study was to design of an output based impedance adaptive controller for a special class of cervical orthoses, a class of biomedical devices for the rehabilitation of neck illnesses. The controller used the adaptive sliding mode theory to enforce the tracking of the reference trajectory if the patient was not resistant to the therapy. If the patient rejects the orthosis activity, a second impedance-based controller governs the orthosis movement allowing the patient to take the leading role in the orthosis sequence of movements. The proposed controller considers a weighted controller combining the tracking and the impedance controls in a single structure. The monitoring of the external force was evaluated on a novel weighting function defining on-line the role of each controller. The proposed orthosis was motivated by the prevalence of whiplash, which is a syndrome that is produced by forced hyperextension and hyperflexion of the neck. This study included the development of a technological prototype of the orthotic type to support the recovery of patients diagnosed with whiplash. The sections that make up the orthotic device are two independent systems that move the patient’s head in the sagittal and frontal planes. For this purpose, the mechanical structure of the cervical orthosis was made up of 7 pieces printed in 3D with polylactic acid (PLA). The operation of the cervical orthosis was evaluated in two sections: (a) using a simulation system, which consists of a spring with an artificial head and the development of a graphic interface in Matlab, and (b) evaluating the controller on the proposed orthosis. With these elements, the follow-up of the trajectory proposed by the actuators was evaluated, as well as its performance in the face of the opposition that a patient generates. The superiority of the proposed controller was confirmed by comparing the tracking efficiency with proportional-integral-derivative and first-order sliding variants.

Adaptive Tracking Control without Image Velocity Measurement

2015 ◽  
Vol 734 ◽  
pp. 147-152
Author(s):  
Su Ye ◽  
Yu Tang Ye ◽  
Juan Xiu Liu ◽  
Lin Liu ◽  
Chun Lei Du
Keyword(s):  
Parameter Estimation ◽  
Measurement Errors ◽  
Visual Servoing ◽  
Sliding Mode ◽  
Adaptive Controller ◽  
Reference Trajectory ◽  
Image Velocity ◽  
Adaptive Tracking Control ◽  
Tuning Parameters ◽  
Image Position

This paper presents a adaptive controller for visual servoing systems to allow the tracking of a 2D reference trajectory without using image velocity measurements when the kinematics and dynamics parameters are uncertain. To avoid performance decaying caused by measurement errors of the image velocity, we proposed the adaptive controller, with which image velocity need not be directly measured. The first derivative of designed sliding mode vector is not affected by actual image speed. The parameter estimation of image position is used to replace the parameter estimation of image speed. We removed the filter structure in controller, which is used to predict the image velocity. The method makes the controller structure is simpler and more reliable, and reduces the difficulty of project implementation and tuning parameters. The asymptotic stability of the system is proved by using the Lyapunov’s method. Simulation results show that the SCARA robot end effector is able to converge to a desired trajectory.

A Fault-Tolerant and Anti-Disturbance Control Based on Sliding Mode Iterative Learning Law for Attitude of Satellite

2013 ◽  
Vol 339 ◽  
pp. 10-15
Author(s):  
Jian Cheng LI ◽  
Tao Xi ◽  
Bo Wang
Keyword(s):  
Fault Tolerant ◽  
Sliding Mode ◽  
External Disturbance ◽  
Tracking Error ◽  
Iterative Learning ◽  
Reference Trajectory ◽  
Control Input ◽  
Orbit Control ◽  
On Line ◽  
Learning Law

To cope with the problem of the degradation of actuation effectiveness caused by actuator deflection or fault in the attitude and orbit control system (AOCS) of spacecraft on-orbit, an attitude fault-tolerant and anti-disturbance control scheme is proposed based on a sliding mode iterative learning law, in which the pseudo control input is applied to design the sliding mode controller to ensure the AOCS tracks a reference trajectory precisely after some fault occurred; By analyzing the Lyapunov stability, a novel adaptive iterative learning law is developed, which in term of the tracking error, determine some parameters in controller on-line to address the actuator failure and external disturbance. Numerical simulation experiments show that the fault-tolerant and anti-disturbance controller can ameliorate actuation malfunction and compensate the influence of external disturbance effectively.

Robust adaptive super twisting controller: methodology and application of a human-driven knee joint orthosis

2019 ◽  
Vol 46 (4) ◽  
pp. 481-489
Author(s):  
Rihab Bkekri ◽  
Anouar Benamor ◽  
Mohamed Amine Alouane ◽  
Georges Fried ◽  
Hassani Messaoud
Keyword(s):  
Knee Joint ◽  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
Adaptive Controller ◽  
Adaptive Sliding Mode Control ◽  
Reference Trajectory ◽  
Content Type ◽  
Control Approach ◽  
Mode Control

Purpose The application of the sliding mode control has two obstacle phenomena: chattering and high activity of control action. The purpose of this paper concerns a novel super-twisting adaptive sliding mode control law of a human-driven knee joint orthosis. The proposed control approach consists of using dynamically adapted control gains that ensure the establishment, in a finite time, of a real second-order sliding mode. The efficiency of the controller is evaluated using an experimental set-up. Design/methodology/approach This study presents the synthesis of a robust super-twisting adaptive controller for the control of a lower limb–orthosis system. The developed control strategy will take into consideration the nonlinearities as well as the uncertainties resulting from the dynamics of the lower limb–orthosis system. It must also guarantee a good follow-up of the reference trajectory. Findings The authors first evaluated on a valid subject, the performances of this controller which were studied and compared to several criteria. The obtained results show that the controller using the Adaptive Super-Twisting algorithm is the one that guarantees the best performance. Validation tests involved a subject and included robustness tests against external disturbances and co-contractions of antagonistic muscles. Originality/value The main contribution of this paper is in developing the adaptation super-twisting methodology for finding the control gain resulting in the minimization of the chattering effect.

Sliding Mode Observer-Based Synthesis of State Derivative-Free Model Reference Adaptive Control of Distributed Parameter Systems

2000 ◽  
Vol 122 (4) ◽  
pp. 725-731 ◽  
Author(s):  
Y. V. Orlov
Keyword(s):  
Sliding Mode ◽  
Measurement Data ◽  
Identification Problem ◽  
Adaptive Controller ◽  
Distributed Parameter Systems ◽  
Distributed Parameter ◽  
Model Reference ◽  
Control Laws ◽  
On Line ◽  
Model Reference Adaptive

This paper presents control laws for distributed parameter systems of parabolic and hyperbolic types which, on the one hand ensure robustness with respect to small dynamic uncertainties and disturbances, and on the other hand, permit on-line plant parameter estimation. The novelty of the algorithms proposed is (a) in the construction of a sliding mode-based state derivative observer and (b) in the inclusion of this observer into a model reference adaptive controller which thereby regularizes the ill-posed identification problem itself. Apart from this, the controllers constructed do not suffer from on-line computation of spatial derivatives of the measurement data, and hence they are of reduced sensitivity with respect to the measurement noise. [S0022-0434(00)02104-3]

Plato’s Laws

2019 ◽  
pp. 358-378
Author(s):  
Susan Sauvé Meyer
Keyword(s):  
Reference Point ◽  
Highest Good ◽  
Leading Role ◽  
The Face

This chapter presents a an overview of the themes and topics of Plato’s Laws and then focusses on the grand hierarchy of divine and human goods identified in book I (631b-d) as the reference point of all proper legislation. The hierarchy rests on a conception of virtue distinct from what we find in other Platonic dialogues. It ranks courage last among the virtues and describes justice as a blend of moderation with wisdom and courage. This chapter argues that courage is ranked last because it is a natural or non-rational trait of fearlessness, analogous to the “ordinary” trait of moderation (self-restraint in the face of pleasure) that is presented as a trifling virtue in books III and IV. Justice, as conceived of in the Laws, requires combining these two traits and informing them with wisdom. The chapter concludes by noting that the leading role played by wisdom in Plato’s hierarchy of goods prefigures Aristotle’s conception of the highest good.

scholarly journals Emergency Response to Australia’s Black Summer 2019–2020: The Role of a Zoo-Based Conservation Organisation in Wildlife Triage, Rescue, and Resilience for the Future

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1515
Author(s):  
Marissa L. Parrott ◽  
Leanne V. Wicker ◽  
Amanda Lamont ◽  
Chris Banks ◽  
Michelle Lang ◽  
...  
Keyword(s):  
Emergency Response ◽  
State Government ◽  
Captive Breeding ◽  
Catastrophic Events ◽  
Breeding Programs ◽  
Leading Role ◽  
The Future ◽  
The Face ◽  
Captive Breeding Programs

Modern zoos are increasingly taking a leading role in emergency management and wildlife recovery. In the face of climate change and the predicted increase in frequency and magnitude of catastrophic events, zoos provide specialised expertise to assist wildlife welfare and endangered species recovery. In the 2019–2020 Australian bushfire season, now called Australia’s Black Summer, a state government-directed response was developed, assembling specialised individuals and organisations from government, non-government organisations, research institutions, and others. Here, we detail the role of Zoos Victoria staff in wildlife triage and welfare, threatened species evacuation and recovery, media and communications, and fundraising during and after the fires. We share strategies for future resilience, readiness, and the ability to mobilise quickly in catastrophic events. The development of triage protocols, emergency response kits, emergency enclosures, and expanded and new captive breeding programs is underway, as are programs for care of staff mental health and nature-based community healing for people directly affected by the fires. We hope this account of our response to one of the greatest recent threats to Australia’s biodiversity, and steps to prepare for the future will assist other zoos and wildlife organisations around the world in preparations to help wildlife before, during, and after catastrophic events.

Event-triggered integral sliding mode fixed time control for trajectory tracking of autonomous underwater vehicle

2021 ◽  
pp. 014233122199438
Author(s):  
Bo Su ◽  
Hongbin Wang ◽  
Ning Li
Keyword(s):  
Trajectory Tracking ◽  
Control Strategy ◽  
Autonomous Underwater Vehicle ◽  
Sliding Mode ◽  
Fixed Time ◽  
Underwater Vehicle ◽  
Reference Trajectory ◽  
Integral Sliding Mode ◽  
Time Control ◽  
Event Triggered

In this paper, an event-triggered integral sliding mode fixed-time control method for trajectory tracking problem of autonomous underwater vehicle (AUV) with disturbance is investigated. Initially, the global fixed time stability is ensured with conventional periodic sampling method for reference trajectory tracking. By introducing fixed time integral sliding mode manifold, fixed time control strategy is expressed for the AUV, which can effectively eliminate the singularity. Correspondingly, in order to reduce the damage caused by chattering phenomenon, an adaptive fixed-time method is proposed based on the designed continuous integral terminal sliding mode (ITSM) to ensure that the trajectory tracking for AUV is achieved in fixed-time with external disturbance. In order to reduce resource consumption in the process of transmission network, the event-triggered sliding mode control strategy is designed which condition is triggered by an event. Also, Zeno behavior is avoided by proof of theoretical. It is shown that the upper bounds of settling time are only dependent on the parameters of controller. Theoretical analysis and simulation experiment results show that the presented methods can realize the control object.

Controlling Chaos by Hybrid System Based on FREN and Sliding Mode Control

2005 ◽  
Vol 128 (2) ◽  
pp. 352-358 ◽  
Author(s):  
C. Treesatayapun ◽  
S. Uatrongjit
Keyword(s):  
Sliding Mode ◽  
Adaptive Controller ◽  
Descent Method ◽  
Fuzzy Rules ◽  
System Stability ◽  
Steepest Descent Method ◽  
Upper And Lower Bounds ◽  
Adaptation Algorithm ◽  
Control Effort ◽  
Fine Tune

This paper presents a direct adaptive controller for chaotic systems. The proposed adaptive controller is constructed using the network called fuzzy rules emulated network (FREN). FREN’s structure is based on human knowledge in the form of fuzzy rules. Parameter adaptation algorithm based on the steepest descent method is presented to fine tune the controller’s performance. To improve the system stability, the modified sliding mode algorithm is applied to estimate the upper and lower bounds of the control effort. The suitable control effort is generated by FREN and kept within these bounds. Some computer simulations of using the controller to control the Hénon map have been performed to demonstrate the performance of the proposed controller.

scholarly journals Friendship jealousy: One tool for maintaining friendships in the face of third-party threats?

2020 ◽  
Author(s):  
Jaimie Krems ◽  
Keelah Williams ◽  
Douglas Kenrick ◽  
Athena Aktipis
Keyword(s):  
Romantic Relationships ◽  
Real World ◽  
Reproductive Fitness ◽  
Third Parties ◽  
Third Party ◽  
Primary Reason ◽  
Developmental Research ◽  
Emotional Experiences ◽  
The Face ◽  
On Line

Friendships can foster happiness, health, and reproductive fitness. But friendships end—even when we might not want them to. A primary reason for this is interference from third parties. Yet little work has explored how people meet the challenge of maintaining friendships in the face of real or perceived threats from third parties, as when our friends inevitably make new friends or form new romantic relationships. In contrast to earlier conceptualizations from developmental research, which viewed friendship jealousy as solely maladaptive, we propose that friendship jealousy is one overlooked tool of friendship maintenance. We derive and test—via a series of 11 studies (N = 2918) using hypothetical scenarios, recalled real-world events, and manipulation of on-line emotional experiences—whether friendship jealousy possesses the features of a tool well-designed to help us retain friends in the face of third-party threats. Consistent with our proposition, findings suggest that friendship jealousy is (1) uniquely evoked by third-party threats to friendships (but not the prospective loss of the friendship alone), (2) sensitive to the value of the threatened friendship, (3) strongly calibrated to cues that one is being replaced, even over more intuitive cues (e.g., the amount of time a friend and interloper spend together), and (4) ultimately motivates behavior aimed at countering third-party threats to friendship (“friend guarding”). Even as friendship jealousy may be negative to experience, it may include features designed for beneficial—and arguably prosocial—ends: to help maintain friendships.

scholarly journals Adaptive PD Sliding Mode Control For 4 DOF SCARA Variant

2021 ◽  
Author(s):  
Manjeet Tummalapalli
Keyword(s):  
Sliding Mode Control ◽  
Trajectory Tracking ◽  
High Speed ◽  
Sliding Mode ◽  
Adaptive Controller ◽  
Degree Of Freedom ◽  
Tracking Performance ◽  
Advantages And Disadvantages ◽  
Model Free ◽  
Adaptive Law

This project proposes a new SCARA variant with 4 degree of freedom. The proposed variant is achieved by swapping joint 2 and joint 3 of the standard SCARA robots. An adaptive controller is defined based on the advantages and disadvantages of PD, and SMC controllers.The purpose of the project is to understand the dynamics of the variant and to track the performance for trajectories. Simulations for tracking performance are carried under linear and circular trajectories. The variant is studied over the three controllers; PD, PD-SMC and A-PD-SMC. The variant under the adaptive controller is most efficient in terms of tracking performance and the control inputs to the system. The system is simulated under high speed and with the influence of friction at the joints. The control gains are held constant for both the trajectories and hence the controller is able to perform good under changing trajectories. Due to the use of the adaptive law, the system is at the ease of implementation and since no priori knowledge if the system is needed, it is model free. Therefore, the proposed adaptive PD-SMC has proven to provide good, robust trajectory tracking.

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