Torque-Dependent Compliance Control in the Joint Space for Robot-Mediated Motor Therapy

2005 ◽  
Vol 128 (1) ◽  
pp. 152-158 ◽  
Author(s):  
Domenico Formica ◽  
Loredana Zollo ◽  
Eugenio Guglielmelli
Keyword(s):  
Experimental Tests ◽  
Joint Space ◽  
Loop Control ◽  
Control Approach ◽  
Safety Requirements ◽  
Interaction Control ◽  
Adaptive Capabilities ◽  
Human Arm ◽  
Control Scheme ◽  
Control Schemes

This paper is focused on the design of interaction control of robotic machines for rehabilitative motor therapy of the upper limb. The control approach tries to address requirements deriving from the application field and adopts a bioinspired approach for regulating robot behavior in the interaction with the patient. An inner-outer loop control scheme is proposed. In order to tune the level of force and improve robot adaptability in the interaction with the patient, a classical outer force control loop is used. For the inner loop, a novel control law for low-level tuning of robot compliance is introduced, that is borrowed from studies on the biological mechanisms for regulating the elastic properties of the human arm. A dedicated simulation tool, which models the dynamics of an operational robotic machine interacting with a human subject, has been developed. Validation of basic adaptability and safety requirements of the control scheme is carried out in simple tasks, e.g., reaching and contact/noncontact transitions, as well as in simulated situations of typical motor exercises. In particular, the simulation tests demonstrate the adaptive capabilities of the proposed control schemes, e.g., in counterbalancing patient incorrect movements related to the various levels of disability. Moreover, preliminar experimental tests carried out on a real robotic system demonstrated the possibility of using the proposed approach for guaranteeing safe interaction with the patient.

A novel nonsingular integral terminal sliding mode control scheme in epilepsy treatment

2021 ◽  
pp. 014233122110507
Author(s):  
Moshu Qian ◽  
Zhen Zhang ◽  
Guanghua Zhong ◽  
Cuimei Bo
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Sliding Mode ◽  
Tracking Error ◽  
Lyapunov Theory ◽  
Terminal Sliding Mode ◽  
Loop Control ◽  
Control Approach ◽  
Control Scheme ◽  
Loop Control System

In this paper, a closed-loop brain stimulation control problem is investigated using the nonsingular integral terminal sliding mode (NITSM) control approach. First, the thalamocortical model of epilepsy seizure is given, which is composed of the cortical PY-IN subnetwork and the subcortical RE-TC subsystem. Then, a nonsingular integral terminal sliding mode surface is designed utilizing the derived output tracking error, and the stability of the sliding mode dynamics is proved by Lyapunov approach. Furthermore, a disturbance observer (DOB) based NITSM controller design approach is proposed for the established thalamocortical model, and the reachability of the closed-loop control system under the designed controller is analyzed using Lyapunov theory. Finally, simulation results are given to illustrate the effectiveness and superiority of the designed control scheme.

A dual-loop robust controller for DC electro-mechanical servo system

2015 ◽  
Vol 06 (03) ◽  
pp. 1550026
Author(s):  
Tianpeng He ◽  
Shu Li ◽  
Xiaodong Liu
Keyword(s):  
Sliding Mode ◽  
Servo System ◽  
Differential Method ◽  
Control Input ◽  
Tracking Accuracy ◽  
Loop Control ◽  
Control Scheme ◽  
Control Schemes ◽  
Parameter Perturbations ◽  
System Robustness

In order to further improve the tracking performances of the conventional disturbance observer (DOB)-based control schemes, a dual-loop robust control scheme is proposed for DC electro-mechanical servo system. The outer-loop sliding mode controller (SMC) is designed in order to deal with the impacts from the remainder equivalent disturbances, which is due to the inadequate estimation of the inner-loop DOB. Meanwhile, the existence of DOB can reduce the switching gain of SMC law, which can suppress the high-frequency chattering of control input to a certain extent. Moreover, an approximate differential method is employed in order to reliably acquire the differential information in a noisy environment. From the experiment results on a DC motor servo system, it is presented that the proposed dual-loop control scheme can effectively improve the tracking performances with respect to higher tracking accuracy and stronger system robustness against external disturbances and parameter perturbations, compared with the traditional DOB+PD control scheme.

Adaptive underslung beam using shape-memory alloys for frequency-tuning

2016 ◽  
Vol 28 (10) ◽  
pp. 1260-1271 ◽  
Author(s):  
Filipe Amarante dos Santos ◽  
Corneliu Cismaşiu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Natural Frequency ◽  
Frequency Tuning ◽  
Control Process ◽  
Experimental Tests ◽  
Small Scale ◽  
Temperature Modulation ◽  
Loop Control ◽  
Control Approach

The present article addresses the study of an adaptive-passive beam structure with a shape-memory alloy based actuator. In order to mitigate adverse dynamic effects resulting from externally induced vibrations, the structure is able to automatically tune its natural frequency to avoid resonance. The adaptive-passive beam configuration is based on an underslung cable-stayed girder concept. Its frequency tuning is achieved by temperature modulation of the shape-memory alloy elements through a closed-loop control process based on a proportional-integral-derivative algorithm. The effectiveness of the proposed control solution is substantiated by numerical simulations and experimental tests on a small-scale prototype. The validated numerical model enables the simulation of the proposed control approach in a real-scale footbridge, subjected to a prescribed pedestrian loading. The results are very encouraging and show that, by activating the shape-memory alloy elements, the system is able to successfully shift its natural frequency and to mitigate the effects of induced vibrations.

Research on Intelligent Synchronization Control of Erecting System Driven by Two Hydraulic Cylinders

2011 ◽  
Vol 422 ◽  
pp. 167-171 ◽  
Author(s):  
Qin He Gao ◽  
Wen Liang Guan
Keyword(s):  
Pid Control ◽  
Control Algorithm ◽  
Control Valve ◽  
Synchronization Control ◽  
Loop Control ◽  
Control Approach ◽  
Control Scheme ◽  
Hydraulic Cylinders ◽  
Intelligent Pid ◽  
System Synchronization

The synchronization control problem of a large equipment erecting system driven by two oil cylinders side-by-side is analyzed. A closed loop control scheme of hydraulically driven erecting system based on electro-hydraulic proportion control valve is given. Considering the existence of time-varying parameters of hydraulic system, intelligent PID control algorithm is implemented by adding neurotic adaptive element control approach to improve the adaptive control capacity of the controller. Simulation results show that the intelligent PID control algorithm is more effective than conventional method for the erecting system synchronization control.

Gap control for a proportional floating vacuum pad

2008 ◽  
Vol 222 (11) ◽  
pp. 2069-2076
Author(s):  
J-C Renn ◽  
C-Y Chen ◽  
C-H Lu
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Control Mode ◽  
Work Piece ◽  
Force Output ◽  
Suction Force ◽  
Loop Control ◽  
Control Approach ◽  
Control Schemes ◽  
Gap Control

In this article, a new proportional pneumatic floating vacuum pad is developed and constructed. There are two features concerning this new vacuum pad. The first is the inclusion of a proportional solenoid, which enables the continuously variable control of the suction force output. The floating mechanism design between the vacuum pad and the work-piece is the second feature, which is more preferable in real industries because it can protect the surface of the work-piece from scratches or other damage. Moreover, in addition to the open-loop gap control mode, two closed-loop gap control schemes are proposed in this paper. The first is the constant gap control. A preset gap is input to the controller as the command input that further drives the proportional solenoid to maintain a steady-state gap between the vacuum pad and the work-piece. In the second control approach, the gap between the vacuum pad and the work-piece is kept as large as possible to minimize the energy consumption. Both closed-loop control schemes are successfully implemented in this study.

scholarly journals Adaline-Based Control Schemes for Non-Sinusoidal Multiphase Drives—Part II: Torque Optimization for Faulty Mode

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 249
Author(s):  
Duc Tan Vu ◽  
Ngac Ky Nguyen ◽  
Eric Semail ◽  
Hailong Wu
Keyword(s):  
Harmonic Distortion ◽  
Experimental Tests ◽  
Open Circuit ◽  
Permanent Magnet Synchronous Machine ◽  
Torque Density ◽  
Control Scheme ◽  
Control Schemes ◽  
Demonstration Video ◽  
Torque Ripples ◽  
Copper Losses

Fault tolerance has been known as one of the main advantages of multiphase drives. When an open-circuit fault happens, smooth torque can be obtained without any additional hardware. However, a reconfiguration strategy is required to determine new reference currents. Despite advantages of non-sinusoidal electromotive forces (NS-EMFs) such as high torque density, multi-harmonics existing in NS-EMFs cause more challenges for control, especially under faulty conditions. Therefore, to guarantee high-quality vector control of multiphase drives with multi-harmonic NS-EMFs, this two-part study proposes control schemes using adaptive linear neurons (Adalines) to adaptively eliminate torque ripples. The proposed simple Adalines are efficient because of taking advantage of the knowledge of rotor position and of torque harmonic rank induced by the NS-EMFs. The control scheme using an Adaline for healthy mode was described in part I of this study. In this second part, the control scheme using another Adaline for an open-circuit operation, under the impacts of multi-harmonics in NS-EMFs, is proposed. Notably, smooth torque and similar copper losses in the remaining healthy phases can be obtained. Experimental tests are carried out on a seven-phase permanent magnet synchronous machine (PMSM) with a high total harmonic distortion (THD = 38%) of NS-EMFs. A demonstration video is provided with this paper.

ICMA: AN EFFICIENT INTEGRATED CONGESTION CONTROL APPROACH

2019 ◽  
Vol 14 ◽  
Author(s):  
Tayyab Khan ◽  
Karan Singh ◽  
Kamlesh C. Purohit
Keyword(s):  
Congestion Control ◽  
Packet Loss ◽  
Control Method ◽  
Multicast Communication ◽  
Bandwidth Utilization ◽  
File Transfer ◽  
Control Approach ◽  
Communication Technique ◽  
Control Scheme ◽  
Multiparty Video Conferencing

Background: With the growing popularity of various group communication applications such as file transfer, multimedia events, distance learning, email distribution, multiparty video conferencing and teleconferencing, multicasting seems to be a useful tool for efficient multipoint data distribution. An efficient communication technique depends on the various parameters like processing speed, buffer storage, and amount of data flow between the nodes. If data exceeds beyond the capacity of a link or node, then it introduces congestion in the network. A series of multicast congestion control algorithms have been developed, but due to the heterogeneous network environment, these approaches do not respond nor reduce congestion quickly whenever network behavior changes. Objective: Multicasting is a robust and efficient one-to-many (1: M) group transmission (communication) technique to reduced communication cost, bandwidth consumption, processing time and delays with similar reliability (dependability) as of regular unicast. This patent presents a novel and comprehensive congestion control method known as integrated multicast congestion control approach (ICMA) to reduce packet loss. Methods: The proposed mechanism is based on leave-join and flow control mechanism along with proportional integrated and derivate (PID) controller to reduce packet loss, depending on the congestion status. In the proposed approach, Proportional integrated and derivate controller computes expected incoming rate at each router and feedback this rate to upstream routers of the multicast network to stabilize their local buffer occupancy. Results: Simulation results on NS-2 exhibit the immense performance of the proposed approach in terms of delay, throughput, bandwidth utilization, and packet loss than other existing methods. Conclusion: The proposed congestion control scheme provides better bandwidth utilization and throughput than other existing approaches. Moreover, we have discussed existing congestion control schemes with their research gaps. In the future, we are planning to explore the fairness and quality of service issue in multicast communication.

scholarly journals Nonlinear Current-Mode Control of SCIG Wind Turbines

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 55
Author(s):  
Nicholas Hawkins ◽  
Bhagyashri Bhagwat ◽  
Michael L. McIntyre
Keyword(s):  
Current Mode ◽  
Nonlinear Controller ◽  
Flux Observer ◽  
Current Mode Control ◽  
Mode Control ◽  
Squirrel Cage ◽  
Control Scheme ◽  
Control Schemes ◽  
Rotor Flux ◽  
Squirrel Cage Induction Generator

In this paper, a nonlinear controller is proposed to manage the rotational speed of a full-variable Squirrel Cage Induction Generator wind turbine. This control scheme improves upon tractional vector controllers by removing the need for a rotor flux observer. Additionally, the proposed controller manages the performance through turbulent wind conditions by accounting for unmeasurable wind torque dynamics. This model-based approach utilizes a current-based control in place of traditional voltage-mode control and is validated using a Lyapunov-based stability analysis. The proposed scheme is compared to a linear vector controller through simulation results. These results demonstrate that the proposed controller is far more robust to wind turbulence than traditional control schemes.

scholarly journals Constant Transmission Efficiency Dimming Control Scheme for VLC Systems

Photonics ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 7
Author(s):  
Jia-Ning Guo ◽  
Jian Zhang ◽  
Gang Xin ◽  
Lin Li
Keyword(s):  
Visible Light Communication ◽  
Transmission Efficiency ◽  
Error Performance ◽  
Constant Weight ◽  
Block Coding ◽  
Control Scheme ◽  
Control Schemes ◽  
Indoor Wireless ◽  
Communication Function ◽  
Dimming Control

As a novel mode of indoor wireless communication, visible light communication (VLC) should consider the illumination functions besides the primary communication function. Dimming control is one of the most crucial illumination functions for VLC systems. However, the transmission efficiency of most proposed dimming control schemes changes as the dimming factor changes. A block coding-based dimming control scheme has been proposed for constant transmission efficiency VLC systems, but there is still room for improvement in dimming range and error performance. In this paper, we propose a dimming control scheme based on extensional constant weight codeword sets to achieve constant transmission efficiency. Meanwhile, we also provide a low implementation complexity decoding algorithm for the scheme. Finally, comparisons show that the proposed scheme can provide a wider dimming range and better error performance.

A computationally efficient adaptive robust control scheme for a quad-rotor transporting cable-suspended payloads

2021 ◽  
pp. 095441002110136
Author(s):  
Nasim Ullah ◽  
Irfan Sami ◽  
Wang Shaoping ◽  
Hamid Mukhtar ◽  
Xingjian Wang ◽  
...  
Keyword(s):  
Robust Control ◽  
Fractional Order ◽  
Sliding Mode ◽  
Adaptive Robust Control ◽  
Computationally Efficient ◽  
Control Scheme ◽  
Control Schemes ◽  
Adaptive Laws ◽  
Unknown Disturbances ◽  
The Stability

This article proposes a computationally efficient adaptive robust control scheme for a quad-rotor with cable-suspended payloads. Motion of payload introduces unknown disturbances that affect the performance of the quad-rotor controlled with conventional schemes, thus novel adaptive robust controllers with both integer- and fractional-order dynamics are proposed for the trajectory tracking of quad-rotor with cable-suspended payload. The disturbances acting on quad-rotor due to the payload motion are estimated by utilizing adaptive laws derived from integer- and fractional-order Lyapunov functions. The stability of the proposed control systems is guaranteed using integer- and fractional-order Lyapunov theorems. Overall, three variants of the control schemes, namely adaptive fractional-order sliding mode (AFSMC), adaptive sliding mode (ASMC), and classical Sliding mode controllers (SMC)s) are tested using processor in the loop experiments, and based on the two performance indicators, namely robustness and computational resource utilization, the best control scheme is evaluated. From the results presented, it is verified that ASMC scheme exhibits comparable robustness as of SMC and AFSMC, while it utilizes less sources as compared to AFSMC.

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