scholarly journals Research on Flexible Joint Stiffness Test and Trajectory Planning of Space Manipulator

2013 ◽  
Vol 5 ◽  
pp. 280453 ◽  
Author(s):  
Yongtai Yang ◽  
Jili Rong ◽  
Jian Li ◽  
Ling Tang
Keyword(s):  
Trajectory Planning ◽  
Joint Stiffness ◽  
Space Manipulator ◽  
Flexible Joint

Flexible Joint Stiffness Modelling Improving Ultra Deep Water Rigid Risers Fatigue Damage

2019 ◽  
Author(s):  
Germain Venero ◽  
Victor Gomes ◽  
Hugues Corrignan ◽  
Daniel Carneiro
Keyword(s):  
Fatigue Damage ◽  
Deep Water ◽  
Joint Stiffness ◽  
Flexible Joint

Effect of Flexible Joint Modelling Method on Deep Water Catenary Riser Hang-Off Fatigue Response

2019 ◽  
Author(s):  
Guanyu Hu ◽  
Chaojun Huang ◽  
Fengjie Yin ◽  
Mark Cerkovnik ◽  
Guangqiang Yang
Keyword(s):  
Deep Water ◽  
Joint Stiffness ◽  
Fatigue Performance ◽  
Fatigue Load ◽  
Flexible Joint ◽  
Cyclic Bending ◽  
Modelling Method ◽  
The Impact ◽  
Nonlinear Curve ◽  
Modelling Methods

Abstract The Flexible joint is one of the most widely used hang-off systems for deep water catenary riser for its large rotation and load bearing capacity. The fatigue performance of riser hang-off region and fatigue load on the flexible joint highly depend on the rotational stiffness of the flexible joint. Thus, modelling the flexible joint stiffness to accurately simulate the behavior under cyclic bending cycles is critical in global riser fatigue analysis. The load-displacement relationship of a flexible joint typically follows a nonlinear curve, and it shows hysteresis behavior when subject to cyclic bending cycles. However, in current industry practice, the flexible joint stiffness is modelled either as a nonlinear curve or simplified as a fixed value. These simplified methods sometimes can lead to unconservative or over conservative results in riser design. Modelling the flexible joint stiffness in an accurate approach becomes more important especially when the riser fatigue is critical at the hang-off region. In addition, the design of flexible joint will also be impacted by the fatigue load extracted from global fatigue analysis, which is also largely affected by the flexible joint stiffness modelling method. Thus, modelling a flexible joint by accounting for the nonlinear hysteretic stiffness is recommended. This paper compares the different modelling methodologies of the flexible joint for catenary riser hang-off and presents the impact on fatigue performance considering hysteretic behavior. This study considers the effects of wave amplitude and hosting vessel offset. A case study is also presented on the application of all the modelling methods on fatigue performance of an SCR in the Gulf of Mexico. The fatigue behavior is compared for the different modelling methods considering long term wave motion and platform offsets. The impact on the results from different types of hosting platform is also discussed.

scholarly journals Cascaded Control of Flexible-Joint Robots Based on Sliding-Mode Estimator Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Genliang Xiong ◽  
Jingxin Shi ◽  
Haichu Chen
Keyword(s):  
Controller Design ◽  
Sliding Mode ◽  
Joint Stiffness ◽  
Perturbation Approach ◽  
Regular Form ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Highly Nonlinear ◽  
Position Controller ◽  
High Bandwidth

The inherent highly nonlinear coupling and system uncertainties make the controller design for a flexible-joint robot extremely difficult. The goal of the control of any robotic system is to achieve high bandwidth, high accuracy of trajectory tracking, and high robustness, whereby the high bandwidth for flexible-joint robot is the most challenging issue. This paper is dedicated to design such a link position controller with high bandwidth based on sliding-mode technique. Then, two control approaches ((1) extended-regular-form approach and (2) the cascaded control structure based on the sliding-mode estimator approach) are presented for the link position tracking control of flexible-joint robot, considering the dynamics of AC-motors in robot joints, and compared with the singular perturbation approach. These two-link position controllers are tested and verified by the simulation studies with different reference trajectories and under different joint stiffness.

A Precision Compensation Method for Space Manipulator Trajectory Planning Based on Particle Filter

2015 ◽  
Vol 742 ◽  
pp. 485-490
Author(s):  
Yi Fan Wang ◽  
Han Xu Sun ◽  
Gang Chen ◽  
Qing Xuan Jia
Keyword(s):  
Particle Filter ◽  
State Space ◽  
Real Time ◽  
Process Parameters ◽  
Trajectory Planning ◽  
Control Variable ◽  
Compensation Method ◽  
Statistical Process ◽  
Space Manipulator ◽  
Space Equation

A precision compensation method for space manipulator trajectory planning is presented for improving the accuracy during the execution of a task. First, the control process is described by using a state space equation. Second, process parameters are estimated in real-time using particle filter. Then, the system’s real time operational reliability is calculated based on the state space equation and process parameters. Finally, a control variable compensation strategy is given based on the theory of Statistical Process Control. Simulations show that this method effectively improves the accuracy and stability of space manipulator control system.

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