Adaptive Robust Control via a Nonlinear Disturbance Observer for Cable-driven Aerial Manipulators

Li Ding,Kailei Liu,Guibing Zhu,Yaoyao Wang,Yangmin Li 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

This article proposes a novel robust control scheme for the trajectory tracking control of a cabledriven aerial manipulator in joint space, combining an adaptive fractional-order nonsingular terminal sliding mode (FONTSM) manifold and a nonlinear disturbance observer (NDOB). The proposed control scheme mainly consists of three aspects, i.e., an NDOB used to estimate the unmodeled dynamics and external disturbances, a FONTSM applied to guarantee the control accuracy of the tracking performance, and an adaptive reaching law applied to improve the robustness. The proposed scheme is based on the model-free idea that can reduce the difficulty of controller design without knowing the precise dynamics of the plant. The experimental results show that the proposed controller can ensure better transient performance and stronger robustness against lumped disturbances than two other existing controllers.

Attitude Control for Astronaut Assisted Robot in the Space Station

Yangmin Li,Jinguo Liu,Qing Gao,Zhiwei Liu 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

Because of the limited working hours of astronauts in the space station, the in-cabin robot has high valuein the technological validation and scientific research. Based on this requirement, we proposed and designed an AstronautAssisted Robot(AAR) working in the space station. It can float in the space station cabin, fly autonomously,and hold a fixed position and/or posture. In addition, it also possesses environmental awareness capabilities andintelligence. Thus the AAR can assist astronauts to complete some special scientific experiments or technical tests. In this paper, the system architecture and experimental equipment of the AAR are designed firstly depending on thecharacteristics of space microgravity environment and the requirements of assisting astronauts missions. And then,the motion principles of the AAR are analyzed and the robot’s dynamic model is established by using the Newton- Euler algorithm. Since the attitude control of the robot is the basis for its free movement, the PID Neural Network(PIDNN) algorithm, which is a kind of intelligent control algorithm, is used to design the attitude controller ofthe AAR. Finally, the reasonability of the robot’s structural design and the availability of its attitude controllers areverified through the simulation experiments.

Design, Modeling, Control and Experiment for a 2-DOF Compliant Micro-Motion Stage

Yangmin Li,Shunli Xiao,Longquan Xi,Zhigang Wu 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

A new XY micro-motion stage is proposed with the double four-bar prismatic joints to transfer linear motions and mechanicaldisplacement amplifier. The compliance models of the amplifier, the prismatic joints, and the whole stage are established based onthe flexibility matrix method. The simulation is made by using finite element analysis ANSYS software. The output cross-talk is about2% and the parasitic motions of the input points in the other limbs are less than 1.8%, which shows a good decoupling property. Themechanical prototype is fabricated, the experimental results show that the input/output of the stage has a very good linearity, the ratioof output displacement to input displacement is 5.06 and the working range is 156 μm × 156 μm. To tackle for the serious hysteresisnonlinear problems of the stage, model reference adaptive PID controller is designed, the final resolution can reach ±0.2 μm.

Disturbance Compensation based Discrete-time Sliding Mode Control with a Reference Trajectory Generator

Chao Liu,Yangmin Li,Sukun Tian,Haifeng Ma 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.12

A novel disturbance compensation based sliding mode reaching law with a reference trajectory generator is presented in this work. Unlike existing similar researches, a reference trajectory generator is added to the reachinglaw to obtain the target evolution of the switching function. Meanwhile, a high order disturbance estimator is utilized to achieve accurate disturbance rejection. Additionally, by using the nonlinear functions, the controllerparameters can be adaptively adjusted in a wise manner. The main merit of the presented method is that it is capable of ensuring a much smaller ultimate bound of the switching function, i.e., O(Tn+1) order accuracy and n is a positiveinteger, better system robustness, and improved control accuracy. Moreover, system dynamics, including the system states, are theoretically analyzed. The performance improvement of the presented method is verified through a realsimulation study.

On Convergence and Parameter Selection of an Improved Particle Swarm Optimization

Xin Chen,Yangmin Li 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.4

This paper proposes an improved particle swarm optimization named PSO with Controllable Random Exploration Velocity (PSO-CREV) behaving an additional exploration behavior. Different from other improvements on PSO, the updating principle of PSO-CREV is constructed in terms of stochastic approximation diagram. Hence a stochastic velocity independent on cognitive and social components of PSO can be added to the updating principle, so that particles have strong exploration ability than those of conventional PSO. The conditions and main behaviors of PSO-CREV are described. Two properties in terms of "divergence before convergence" and "controllable exploration behavior" are presented, which promote the performance of PSO-CREV An experimental method based on a complex test function is proposed by which the proper parameters of PSO-CREV used in practice are figured out, which guarantees the high exploration ability, as well as the convergence rate is concerned. The benchmarks and applications on FCRNN training verify the improvements brought by PSO-CREV.

Smooth Formation Navigation of Multiple Mobile Robots for Avoiding Moving Obstacles

Xin Chen,Yangmin Li 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.4

This paper addresses a formation navigation issue for a group of mobile robots passing through an environment with either static or moving obstacles meanwhile keeping a fixed formation shape. Based on Lyapunov function and graph theory, a NN formation control is proposed, which guarantees to maintain a formation if the formation pattern is C<SUP>κ</SUP>, κ≥1. In the process of navigation, the leader can generate a proper trajectory to lead formation and avoid moving obstacles according to the obtained information. An evolutionary computational technique using particle swarm optimization (PSG) is proposed for motion planning so that the formation is kept as C¹ function. The simulation results demonstrate that this algorithm is effective and the experimental studies validate the formation ability of the multiple mobile robots system.

A Generalized Input-output-based Digital Sliding-mode Control for Piezoelectric Actuators with Non-minimum Phase Property

Haifeng Ma,Yangmin Li,Zhenhua Xiong 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.3

In this paper, a generalized input-output-based digital sliding-mode control (GIODSMC) is developedfor piezoelectric actuators (PEA) with non-minimum phase (NMP) property. First, the instability mechanism ofthe traditional input-output-based digital sliding-mode control (IODSMC) for NMP systems is analyzed. Then, ageneralized approximate input-output model is established to cancel the effect of unstable zeros in NMP systems. The generalized model can be transformed into different forms, which represents a class of approximate modelssuitable for this situation. Based on this model, a controller, called the GIODSMC, is presented. Unlike existingworks, the developed controller ensures precision motion control for PEA with NMP property. Moreover, additionalcontrol parameters are not required to stabilize the NMP systems, and neither a hysteresis model nor a stateobserver is needed for the developed method. Stability of the closed-loop system is theoretically analyzed. At last,the presented method is tested through numerical simulations and experimental investigations on a piezoelectricactuator device.

Kinematics and dynamics analysis of the 3PUS-PRU parallel mechanism module designed for a novel 6-DOF gantry hybrid machine tool

Song Lu,Yangmin Li,Bingxiao Ding 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

A hybrid kinematic machine (HKM) tool with the respective advantages of serial and parallel mechanism is a significant direction for the innovation and development of current advanced sophisticated manufacturing equipment. This paper considers the configuration design, kinematics analysis and dynamics analysis of a 1-translational-3-rotational (1T3R) parallel manipulator, which acts as the main movement module of a novel 6-DOF reconfigurable HKM. The key parallel manipulator with 4 DOFs is composed of one middle PRU kinematic chain and three identical PUS kinematic chains. First, complete kinematics characteristics, including position, velocity, acceleration and jerk, are deeply analyzed by a vector analysis approach. Reachable position workspace and orientation workspace were derived through the workspace boundary search method. Furthermore, complete inverse dynamics model of the 3PUS-PRU parallel manipulator was formulated by virtue of the virtual work principle with considering the inertial and gravitational properties of struts. Finally, a driving power and energy consumption model of each actuated motor under the prescribed trajectory were obtained, resulting in the decouple contribution of each motion part correspondingly. This systematic and rigorous methodology aims at laying a solid theoretical and technical foundation for configuration design and performance analysis of this homologous type HKM.

Dual-layer Fuzzy Control Architecture for the CAS Rover Arm

Hongwei Gao,Yangmin Li,Jinguo Liu,Kun Hong,Yang Zhang 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

Since the conventional impedance control method for a rover arm is not suitable for unconstructed environment with uncertainties, a fuzzy inference method which improves the impedance model dynamically is introduced to realize high-precision control. The fuzzy PD control algorithm which applies to the joint control of a rover arm is analyzed in this paper. With the two level control algorithms, a novel dual-layer fuzzy control framework is proposed, which can enhance the control performance significantly. In order to verify the validity and reliability of the designed algorithms, the robotic arm of the CAS rover is considered as an experimental platform. Kinematics and dynamics models of robotic arm are derived at first. Moreover, the fuzzy inference mechanism and implementation process of impedance model parameters are illustrated. Extensive simulations and experimental results show that the control accuracy and the force control of the system have been significantly improved with the proposed dual-layer fuzzy control architecture.

Dynamic Modeling and Adaptive Neural-Fuzzy Control for Nonholonomic Mobile Manipulators Moving on a Slope

Yugang Liu,Yangmin Li 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.2

This paper addresses dynamic modeling and task-space trajectory following issues for nonholonornic mobile manipulators moving on a slope. An integrated dynamic modeling method is proposed considering nonholonomic constraints and interactive motions. An adaptive neural-fuzzy controller is presented for end-effector trajectory following, which does not rely on precise apriori knowledge of dynamic parameters and can suppress bounded external disturbances. Effectiveness of the proposed algorithm is verified through simulations.