Adaptive robust control of soft bending actuators: an empirical nonlinear model-based approach

2021 ◽  
Vol 22 (9) ◽  
pp. 681-694
Author(s):  
Cong Chen ◽  
Jun Zou
Keyword(s):  
Robust Control ◽  
Nonlinear Model ◽  
Adaptive Robust Control ◽  
Model Based

Nonlinear Model Based Coordinated Adaptive Robust Control of Electro-Hydraulic Robotic Manipulators: Methods and Comparative Studies

2001 ◽  
Author(s):  
Fanping Bu ◽  
Bin Yao
Keyword(s):  
Robust Control ◽  
Comparative Studies ◽  
Adaptive Robust Control ◽  
Robot Arm ◽  
Tracking Accuracy ◽  
Output Tracking ◽  
Model Based ◽  
Acceleration Feedback ◽  
Hydraulic Cylinders ◽  
Electrical Motors

Abstract Compared to conventional robot manipulators driven by electrical motors, hydraulic robot arms have richer nonlinear dynamics and stronger couplings among various joints (or hydraulic cylinders). This paper focuses on the physical model based coordinated adaptive robust control (ARC) strategies that explicitly take into account the strong coupling among various hydraulic cylinders (or joints). In our recent studies, two such methods were proposed to avoid the need of acceleration feedback in doing ARC backstepping designs. The first method uses an observer to recover the state needed for the ARC backstepping design. The second method utilizes the property that the adjoint matrix and the determinant of the inertial matrix can be linearly parametrized by certain suitably selected parameters and employ certain over-parametrizing techniques. Theoretically, both the resulting ARC controllers guarantee a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties only. This paper focuses on the comparative studies of these two methods under various practical constraints. Extensive simulation results which are based on a three degree-of-freedom (DOF) hydraulic robot arm are presented to illustrate the advantages and drawbacks of each method.

Constraint-oriented integrated longitudinal and lateral robust control for connected and automated vehicle platoons

2021 ◽  
pp. 107754632110026
Author(s):  
Zeyu Yang ◽  
Jin Huang ◽  
Zhanyi Hu ◽  
Diange Yang ◽  
Zhihua Zhong
Keyword(s):  
Robust Control ◽  
Estimation Error ◽  
Uniform Boundedness ◽  
Path Tracking ◽  
Adaptive Robust Control ◽  
Connected Vehicle ◽  
Vehicle Platoon ◽  
Tracking Model ◽  
Vehicle Platoons ◽  
Following Error

The coupling, nonlinearity, and uncertainty characteristics of vehicle dynamics make the accurate longitudinal and lateral control of an automated and connected vehicle platoon a tough task. Little research has been conducted to fully address the characteristics. By using the ideology of constraint-following control this article proposes an integrated longitudinal and lateral adaptive robust control methodology for a vehicle platoon with a bidirectional communication topology. The platoon control objectives contain the path tracking stability, the platoon internal stability, and the string stability. First, we establish the nonlinear kinematics path tracking model and the coupled vehicle longitudinal and lateral dynamical model that contains time-varying uncertainties. Second, we design a series of nonlinear equality constraints that directly guarantee the control objectives based on the kinematic relations. On this basis, an adaptive robust constraint-following control is proposed. It is shown that the control guarantees the uniform boundedness and the uniform ultimate boundedness of the constraint-following error and the uncertainty estimation error. Finally, simulation results are provided to validate the effectiveness of the proposed methodology.

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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