Man-machine interaction-based motion control of a robotic walker

BACKGROUND: The aging population brings the problem of healthcare and dyskinesia. The lack of mobility extremely affects stroke patient’s activities of daily living (ADL) and decreases their quality of life. To assist these mobility-limited people, a robotic walker is designed to facilitate gait rehabilitation training. OBJECTIVE: The aim of this paper is to present the implementation of a novel motion control method to assist disabled people based on their motion intention. METHODS: The kinematic framework of the robotic walker is outlined. We propose an intention recognition algorithm based on the interactive force signal. A novel motion control method combined with T-S fuzzy controller and PD controller is proposed. The motion controller can recognize the intention of the user through the interactive force, which allows the user to move or turn around as usual, instead of using their hands to control the walker. RESULTS: Preliminary experiments with healthy individuals and simulated patients are carried out to verify the effectiveness of the algorithm. The results show that the proposed motion control approach can recognize the user’s intention, is easy to control and has a higher precision than the traditional proportional–integral–derivative controller. CONCLUSION: The results show that users could achieve the task with acceptable error, which indicates the potential of the proposed control method for gait training.

Download Full-text

DUTY-CYCLED SPINNING BASED 3D MOTION CONTROL APPROACH FOR BEVEL-TIPPED FLEXIBLE NEEDLE INSERTION

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519418400171 ◽

2018 ◽

Vol 18 (07) ◽

pp. 1840017 ◽

Cited By ~ 1

Author(s):

QIN YAO ◽

XUMING ZHANG

Keyword(s):

Motion Control ◽

Control Method ◽

Tracking Error ◽

Open Loop ◽

Loop Control ◽

3D Motion ◽

Control Approach ◽

Target Error ◽

The Mean ◽

Simulation Results

Flexible needle has been widely used in the therapy delivery because it can advance along the curved lines to avoid the obstacles like important organs and bones. However, most control algorithms for the flexible needle are still limited to address its motion along a set of arcs in the two-dimensional (2D) plane. To resolve this problem, this paper has proposed an improved duty-cycled spinning based three-dimensional (3D) motion control approach to ensure that the beveled-tip flexible needle can track a desired trajectory to reach the target within the tissue. Compared with the existing open-loop duty-cycled spinning method which is limited to tracking 2D trajectory comprised of few arcs, the proposed closed-loop control method can be used for tracking any 3D trajectory comprised of numerous arcs. Distinctively, the proposed method is independent of the tissue parameters and robust to such disturbances as tissue deformation. In the trajectory tracking simulation, the designed controller is tested on the helical trajectory, the trajectory generated by rapidly-exploring random tree (RRT) algorithm and the helical trajectory. The simulation results show that the mean tracking error and the target error are less than 0.02[Formula: see text]mm for the former two kinds of trajectories. In the case of tracking the helical trajectory, the mean tracking error target error is less than 0.5[Formula: see text]mm and 1.5[Formula: see text]mm, respectively. The simulation results prove the effectiveness of the proposed method.

Download Full-text

A compliant control method for robust trot motion of hydraulic actuated quadruped robot

International Journal of Advanced Robotic Systems ◽

10.1177/1729881418813235 ◽

2018 ◽

Vol 15 (6) ◽

pp. 172988141881323 ◽

Cited By ~ 9

Author(s):

Teng Chen ◽

Xuewen Rong ◽

Yibin Li ◽

Chao Ding ◽

Hui Chai ◽

...

Keyword(s):

Motion Control ◽

Control Method ◽

Middle Layer ◽

Bottom Layer ◽

Hydraulic Cylinder ◽

Simulation Software ◽

Lateral Impact ◽

Software Environment ◽

Control Approach ◽

Active Compliance

A motion control approach is proposed for hydraulic actuated quadruped robots, aiming to achieve active compliance and robust motion control. The approach is designed with a structure of three layers. Servo valve-controlled asymmetric hydraulic cylinder model is established to obtain the relationship between the desired torque and the control current signal, which is the bottom layer. The middle layer is based on the virtual model of the leg for active compliance. The upper layer considers the torso posture and velocity into planning the foot trajectories based on the spring loaded inverted pendulum model. Trotting gait simulations are conducted based on the proposed framework in the simulation software environment Webots. The motion control approach has been implemented on a robot prototype SCalf-II (SDU calf), where experiments have been conducted including omnidirectional trotting gait, lateral impact recovery and climbing slopes. The experiments demonstrate that the proposed approach can effectively control the hydraulic actuated robots.

Download Full-text

A Fuzzy Control Approach for the Coordinated-Level Control of the Modular-HTGR-Based Nuclear Steam Supplying System

Volume 5: Student Paper Competition ◽

10.1115/icone24-60417 ◽

2016 ◽

Author(s):

Yue Yuan ◽

Xiaojin Huang

Keyword(s):

Fuzzy Control ◽

Control Method ◽

Fuzzy Controller ◽

Fuzzy Model ◽

Energy System ◽

Inherent Safety ◽

Level Control ◽

Control Approach ◽

Basic Ideas ◽

Safety Features

As one of the most popular Generation IV nuclear energy system, High Temperature Gas Cooled Reactor (HTGR) has outstanding inherent safety features. However, the nonlinearity and complexity of the modular-HTGR-based nuclear steam supplying system (NSSS) has put higher requirements to its control system. Based on the basic ideas and theories of fuzzy system, fuzzy control method provides a powerful tool to the control of nonlinear systems. This paper built the T-S fuzzy model of the modular-HTGR-based nuclear steam supplying system (NSSS), and designed the steam temperature T-S fuzzy controller using the parallel distributed compensation (PDC) method. Simulation shows that the designed T-S fuzzy controller has a better effect than the traditional PID control method.

Download Full-text

High Bandwidth Motion Control for Multi-Axis Servohydraulic Mechanisms

Volume 4: Design, Analysis, Control and Diagnosis of Fluid Power Systems ◽

10.1115/imece2007-41240 ◽

2007 ◽

Cited By ~ 3

Author(s):

A. R. Plummer

Keyword(s):

Motion Control ◽

Degrees Of Freedom ◽

Control Method ◽

Earthquake Simulation ◽

Control Approach ◽

Six Degrees Of Freedom ◽

Modes Of Vibration ◽

High Bandwidth ◽

Rigid Mass ◽

Acceleration Tracking

A practical motion control method is presented for multiaxis parallel servohydraulic mechanisms in which the payload behaves as a rigid mass. The ability of this method to decouple the control axes is demonstrated. A modal control approach is used – i.e. the modes of vibration of the system are controlled individually. These modes are dependent on the inertial properties of the payload and the compliance of the actuators due to oil compressibility. For each mode, a partial non-linear dynamic inversion is performed in the control loop. To avoid the need to differentiate the position feedback signals, accelerometers are also used, and three-element motion state vectors are estimated using composite filtering. Command feedforward is used to increase the tracking bandwidth, and the closed-loop part of the controller can be conceived as a model-based disturbance observer. Simulation results are presented based on a detailed validated model of a large vibration table used for earthquake simulation. Just three of the six degrees-of-freedom of the table are considered, and the results for horizontal acceleration tracking response are presented, along with the ability of the controller to reject the ‘overturning moment’.

Download Full-text

A Manipulator Control Method Based on Deep Deterministic Policy Gradient with Parameter Noise

10.21203/rs.3.rs-1016003/v1 ◽

2021 ◽

Author(s):

Haifei Zhang ◽

Xu Jian ◽

Liting Lei ◽

Fang Wu ◽

Lanmei Qian ◽

...

Keyword(s):

Motion Control ◽

Control Method ◽

State Variables ◽

Control Approach ◽

Environment Model ◽

Policy Gradient ◽

The Stability ◽

Reinforcement Learning Models ◽

Policy Optimization ◽

Manipulator Control

Abstract Focusing on the motion control problem of two link manipulator, a manipulator control approach based on deep deterministic policy gradient with parameter noise is proposed. Firstly, the manipulator simulation environment is built. And then the three deep reinforcement learning models named the deep deterministic policy gradient (DDPG), asynchronous advantage actor-critical (A3C) and distributed proximal policy optimization (DPPO) are established for training according to the target setting, state variables and reward & punishment mechanism of the environment model. Finally the motion control of two link manipulator is realized. After comparing and analyzing the three models, the DDPG approach based on parameter noise is proposed for further research to improve its applicability, so as to cut down the debugging time of the manipulator model and reach the goal smoothly. The experimental results indicate that the DDPG approach based on parameter noise can control the motion of two link manipulator effectively. The convergence speed of the control model is significantly promoted and the stability after convergence is improved. In comparison with the traditional control approach, the DDPG control approach based on parameter noise has higher efficiency and stronger applicability.

Download Full-text

ICMA: AN EFFICIENT INTEGRATED CONGESTION CONTROL APPROACH

Recent Patents on Engineering ◽

10.2174/1872212114666191231150916 ◽

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.

Download Full-text

A Critical Review of Supersonic Flow Control for High-Speed Applications

Applied Sciences ◽

10.3390/app11156899 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6899

Author(s):

Abdul Aabid ◽

Sher Afghan Khan ◽

Muneer Baig

Keyword(s):

Supersonic Flow ◽

Flow Control ◽

Active Control ◽

Critical Review ◽

High Speed ◽

Passive Control ◽

Control Method ◽

Sudden Expansion ◽

Control Approach ◽

Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

Download Full-text

A Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽

10.3390/en14113222 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3222

Author(s):

Duc Nguyen Huu

Keyword(s):

Adaptive Control ◽

Voltage Stability ◽

Reactive Power ◽

Control Method ◽

Offshore Wind ◽

Voltage Source ◽

Long Distance ◽

Control Approach ◽

Hvdc System ◽

Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

Download Full-text

Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

Journal of Power Electronics ◽

10.1007/s43236-021-00297-7 ◽

2021 ◽

Author(s):

Nasiru B. Kadandani ◽

Mohamed Dahidah ◽

Salaheddine Ethni ◽

Musbahu Muhammad

Keyword(s):

Control Method ◽

Semiconductor Devices ◽

Junction Temperature ◽

Multilevel Converters ◽

Control Approach ◽

Circulating Current ◽

Inherent Feature ◽

Modular Multilevel Converters ◽

Current Loading ◽

Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

Download Full-text