Alternative Control Design Approach to Shaking Facilities for Re-Creating Seismic Motion

2002 ◽  
Author(s):  
Eiji Sato ◽  
Tomoyoshi Kakegawa ◽  
Taku Suzuki ◽  
Koichi Kajiwara ◽  
Yasutaka Tagawa ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Control Design ◽  
Maximum Load ◽  
Shaking Table ◽  
Three Dimensions ◽  
Test Model ◽  
Test Models ◽  
Under Construction ◽  
Three Degree Of Freedom

The 3-D Full-Scale Earthquake Testing Facility (E-Defense) is now under construction in Miki City near Kobe. When completed, the facility will have a 750-ton shaking table measuring 20m by 15m, with a maximum load mass of 1200 tons. It will be able to create vibration in three dimensions with six degrees of freedom. However, the test model considered for this facility has a mass of 1200 tons compared to the shaking table mass of 750 tons, i.e., 1.6 times as heavy as the shaking table and much larger than ordinary test models. In addition, the vibration characteristics change considerably during the experiment due to the damage done to the test weight. Therefore, a better control design is urgently needed in order to overcome these problems. This research suggests a control method that will reproduce the earthquake wave accurately on the shaking table and will consider the robustness. Moreover, we will verify its efficiency by performing a control experiment using an existing two–dimensional, three-degree-of-freedom small shaking table, to which this control method is applied.

Mechanical Design and Control Method of a Hollow Modular Joint for Minimally Invasive Spinal Surgery

2018 ◽  
Vol 15 (04) ◽  
pp. 1850017
Author(s):  
Guoli Song ◽  
Che Hou ◽  
Yiwen Zhao ◽  
Xingang Zhao ◽  
Jianda Han
Keyword(s):  
Minimally Invasive ◽  
Spinal Surgery ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Control Design ◽  
Torque Sensor ◽  
Minimally Invasive Spinal Surgery ◽  
Minimally Invasive Surgical ◽  
And Control

Design of the hollow modular joint plays an important role in modern robot layout, fixation, and wiring. In this paper, a hollow modular joint that meets the requirement of a minimally invasive surgical robot is proposed. The mechanical and control design is sequentially illustrated, and the torque sensor and its optimization are provided. Furthermore, a free-force control method is introduced. To analyze the designed module, the simulation of the redundant robot, comprised of the designed joint in seven degrees of freedom, is presented. The results of analyses showed that the designed hollow modular joint is valid and effective.

scholarly journals Discrete Motion Prediction Based on EMG Signals

2019 ◽  
Vol 37 (3) ◽  
pp. 509-514
Author(s):  
Lei Zhang ◽  
Wendong Wang ◽  
Yikai Shi ◽  
Jiahao Liu ◽  
Yang Chu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Recognition Accuracy ◽  
Robot Arm ◽  
Accuracy Rate ◽  
Exoskeleton Robot ◽  
Designed Experiment ◽  
Three Degree Of Freedom ◽  
Discrete Motion ◽  
Three Degrees Of Freedom

Most of the current rehabilitation equipment is bulky and slow to respond. Therefore, we designed a portable three-degree-of-freedom exoskeleton and discrete-mode control system for this situation. The three degrees of freedom of the exoskeleton robot arm was the wrist swing, the forearm lateral movement, and the elbow rotation. We collected the EMG signals of the biceps and triceps, then filtered the acquired EMG signals and extracted features in order to obtain effective information that reflected the activity intentions. Based on this, a discrete motion control method using the EMG signals to achieve elbow rotation was designed. Experiment suggests that the average pattern recognition accuracy rate can reach more than 90%.

A Study of an Arm Type Damper Consisting of Two Links, Two Joints and a Hinge

2002 ◽  
Author(s):  
Taichi Matsuoka ◽  
Kenichiro Omata ◽  
Yasuhisa Okano
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Experimental Results ◽  
Shaking Table ◽  
Friction Damper ◽  
Six Degrees Of Freedom ◽  
Human Arm ◽  
Three Degree Of Freedom ◽  
Ball Joints ◽  
Theoretical Results

In this paper, an arm type passive damper consisting of two links, two joints and a hinge, which is similar to a human arm, has developed. Two magnetic ball joints were used for the joints and a rotary friction damper was used for the hinge. The arm type damper has six degrees of freedom and gives damping in three translational and three rotational directions. The resisting force characteristics of the damper in three translational directions were analyzed. A trial damper was made and the load-displacement curves of the damper in three translational directions were measured. The experimental results agree with the theoretical results to some degree. Next, the damper was attached to a three-degree-of-freedom system composed of a mass, three guide rails and four coil springs, in which the mass is able to move in three translational directions along the guide rails. The seismic responses of the mass in three translational directions were measured using a two-dimensional electrohydraulic type shaking table and the experimental results were compared with the calculated results obtained by the Mathematica 3.0. The experimental results agree with the calculated results to some degree, and the effects of vibration suppression of the damper and the propriety of the calculations were substantiated.

New Development of Control Method of Shaking Table With Bi-Linear Structures

2002 ◽  
Author(s):  
Nobuyuki Shimizu ◽  
Yuichirou Shinohara ◽  
Eiji Sato
Keyword(s):  
Control Method ◽  
Earth Science ◽  
Full Scale ◽  
Lessons Learned ◽  
Shaking Table ◽  
Control Synthesis ◽  
Small Scale ◽  
Control Procedure ◽  
Test Model ◽  
And Control

The Hanshin-Awaji earthquake disaster occurred in Kobe area of Japan in 1995. Considering the lessons learned from the disaster of this earthquake, Japanese government has decided to construct a three-dimensional Full Scale Earthquake Testing Facility. It is now being constructed under the supervision of the National Research Institute for Earth Science and Disaster Prevention (NIED). The purpose of this shaking table is to conduct fracturing tests rather than elastic vibration tests for full scale structures. In the tests, the classical operation and control procedure for shaking table such as the trial excitation cannot be effectively applied to this shaking table, because dynamic property of the test structure varies with the progress of fracturing. Therefore, the development of a new operation and control method for the shaking table is the urgent research subject. In this study, firstly, we studied dynamic interaction behaviors of the shaking table with a bi-linear test model. Secondly, to reduce the interaction from the motion of the shaking table, the Minimal Control Synthesis (MCS) algorithm was newly introduced into the conventional control (CC) system. This paper deals with the efficacy of the MCS algorithm through the simulations and experiments using the two dimensional small scale shaking table with a bi-linear model structure.

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

scholarly journals Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1015
Author(s):  
Mingfei Huang ◽  
Yongting Deng ◽  
Hongwen Li ◽  
Jing Liu ◽  
Meng Shao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Torque Ripple ◽  
Current Loop ◽  
Two Degrees Of Freedom ◽  
Robust Stability Analysis ◽  
Resonant Controller ◽  
Testing Environments

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

Research on Simulation Customers Participate Type in Open Innovation

2014 ◽  
Vol 926-930 ◽  
pp. 2054-2057
Author(s):  
Jun Hui He
Keyword(s):  
Open Innovation ◽  
Degrees Of Freedom ◽  
New Products ◽  
Innovation Process ◽  
Degree Of Freedom ◽  
Three Dimensions ◽  
Dynamic Evolution ◽  
Evolution Simulation ◽  
High Degree

This paper proposed customers to participate typology based on three dimensions, which are the customers’ autonomy in the process, the nature of the firm‐customer collaboration, and the stage of the innovation process. Then proposed customers to participate in the type of open innovation framework. Through the static comparative and dynamic evolution simulation found: customers tend to be open to participate in the development of new products pre innovation, the tendency to begin to choose the low participation of degrees of freedom, and ultimately tend to opt for a high degree of freedom to participate.

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