Actuators

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19 pages, 2823 KiB

Open AccessArticle

Dynamic Control of a Novel Planar Cable-Driven Parallel Robot with a Large Wrench Feasible Workspace

by Sergio Juárez-Pérez, Andrea Martín-Parra, Andrea Arena, Erika Ottaviano, Vincenzo Gattulli and Fernando J. Castillo-García

Actuators 2022, 11(12), 367; https://doi.org/10.3390/act11120367 - 7 Dec 2022

Cited by 6 | Viewed by 3153

Abstract

Cable-Driven Parallel Robots (CDPRs) are special manipulators where rigid links are replaced with cables. The use of cables offers several advantages over the conventional rigid manipulators, one of the most interesting being their ability to cover large workspaces since cables are easily winded. [...] Read more.

Cable-Driven Parallel Robots (CDPRs) are special manipulators where rigid links are replaced with cables. The use of cables offers several advantages over the conventional rigid manipulators, one of the most interesting being their ability to cover large workspaces since cables are easily winded. However, this workspace coverage has its limitations due to the maximum permissible cable tensions, i.e., tension limitations cause a decrease in the Wrench Feasible Workspace (WFW) of these robots. To solve this issue, a novel design based in the addition of passive carriages to the robot frame of three degrees-of-freedom (3DOF) fully-constrained CDPRs is used. The novelty of the design allows reducing the variation in the cable directions and forces increasing the robot WFW; nevertheless, it presents a low stiffness along the x direction. This paper presents the dynamic model of the novel proposal together with a new dynamic control technique, which rejects the vibrations caused by the stiffness loss while ensuring an accurate trajectory tracking. The simulation results show that the controlled system presents a larger WFW than the conventional scheme of the CDPR, maintaining a good performance in the trajectory tracking of the end-effector. The novel proposal presented here can be applied in multiple planar applications. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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15 pages, 2643 KiB

Open AccessCommunication

Adaptive Terminal Sliding Mode Control of Picking Manipulator Based on Uncertainty Estimation

by Caizhang Wu and Shijie Zhang

Actuators 2022, 11(12), 347; https://doi.org/10.3390/act11120347 - 25 Nov 2022

Cited by 1 | Viewed by 1703

Abstract

In this paper, a robust nonsingular fast terminal sliding mode control scheme for the picking manipulator under the condition of load change and nonlinear friction disturbance is presented. Firstly, the dynamic equation of the picking manipulator under the condition of load change and [...] Read more.

In this paper, a robust nonsingular fast terminal sliding mode control scheme for the picking manipulator under the condition of load change and nonlinear friction disturbance is presented. Firstly, the dynamic equation of the picking manipulator under the condition of load change and nonlinear friction disturbance is established. Then, in order to avoid the singularity problem existing in the terminal sliding mode and improve the convergence time, a new nonsingular fast terminal sliding mode control strategy is adopted to design the control law of the picking manipulator, which can guarantee the finite time convergence. The adaptive law is used to estimate the uncertainties of the system, and the finite time convergence of the system state is proved by the Lyapunov criterion. In addition, the genetic algorithm is used to identify the friction parameters to realize the nonlinear friction compensation control of the system. Finally, the simulation results of the picking manipulator under different load conditions show that the controller designed in this paper realizes the fast and accurate positioning of the picking manipulator under load change and nonlinear friction, and the control strategy is reasonable and effective. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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13 pages, 4912 KiB

Open AccessEditor’s ChoiceArticle

Cable-Driven Parallel Robot Actuators: State of the Art and Novel Servo-Winch Concept

by Edoardo Idà and Valentina Mattioni

Actuators 2022, 11(10), 290; https://doi.org/10.3390/act11100290 - 11 Oct 2022

Cited by 17 | Viewed by 6400

Abstract

Cable-Driven Parallel Robots (CDPRs) use cables arranged in a parallel fashion to manipulate an end-effector (EE). They are functionally similar to several cranes that automatically collaborate in handling a shared payload. Thus, CDPRs share several types of equipment with [...] Read more.

Cable-Driven Parallel Robots (CDPRs) use cables arranged in a parallel fashion to manipulate an end-effector (EE). They are functionally similar to several cranes that automatically collaborate in handling a shared payload. Thus, CDPRs share several types of equipment with cranes, such as winches, hoists, and pulleys. On the other hand, since CDPRs rely on model-based automatic controllers for their operations, standard crane equipment may severely limit their performance. In particular, to achieve reasonably accurate feedback control of the EE pose during the process, the length of the cable inside the workspace of the robot should be known. Cable length is usually inferred by measuring winch angular displacement, but this operation is simple and accurate only if the winch transmission ratio is constant. This problem called for the design of novel actuation schemes for CDPRs; in this paper, we analyze the existing architectures of so-called servo-winches (i.e., servo-actuators which employ a rotational motor and have a constant transmission ratio), and we propose a novel servo-winch concept and compare the state-of-the-art architectures with our design in terms of pros and cons, design requirements, and applications. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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15 pages, 2025 KiB

Open AccessArticle

Optimal Design of a Novel Leg-Based Stair-Climbing Wheelchair Based on the Kinematic Analysis of the Stair Climbing States

by Diego Delgado-Mena, Emiliano Pereira, Cristina Alén-Cordero, Saturnino Maldonado-Bascón and Pedro Gil-Jiménez

Actuators 2022, 11(10), 289; https://doi.org/10.3390/act11100289 - 9 Oct 2022

Viewed by 2867

Abstract

This work presents a method to find the optimal configuration of a leg-based stair-climbing wheelchair. This optimization begins with the definition of a high-level control architecture, in which the kinematics restrictions related to the specific obstacles are considered. Then, the reference trajectories for [...] Read more.

This work presents a method to find the optimal configuration of a leg-based stair-climbing wheelchair. This optimization begins with the definition of a high-level control architecture, in which the kinematics restrictions related to the specific obstacles are considered. Then, the reference trajectories for all the actuators are generated as a function of the physical parameters of the mechanism, the dynamic restrictions of the actuators (velocity and acceleration) and the sensor errors. This work illustrates, based on a set of configurations, how the total time to climb up and climb down a defined stair depends on all these parameters, also reporting the best set of parameters that reduces the time and makes the mechanism more stable for a given scenario. The optimization in this work is performed with a brute-force search within a grid of parameters with a resolution of 1 mm. Thus, as the local minima is located, the complexity of the problem is revealed. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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17 pages, 6707 KiB

Open AccessArticle

An Active Fault-Tolerant Control Based on Synchronous Fast Terminal Sliding Mode for a Robot Manipulator

by Quang Dan Le and Hee-Jun Kang

Actuators 2022, 11(7), 195; https://doi.org/10.3390/act11070195 - 17 Jul 2022

Cited by 10 | Viewed by 2231

Abstract

To maintain the safe operation and acceptable performance of robot manipulators when faults occur inside the system, fault-tolerant control must deal differently uncertainties and disturbances, especially with the occurrence of loss-effective faults. Therefore, in this paper, an active fault-tolerant control for robot manipulators [...] Read more.

To maintain the safe operation and acceptable performance of robot manipulators when faults occur inside the system, fault-tolerant control must deal differently uncertainties and disturbances, especially with the occurrence of loss-effective faults. Therefore, in this paper, an active fault-tolerant control for robot manipulators based on the combination of a novel finite-time synchronous fast terminal sliding mode control and extended state observer is proposed. Due to the internal constraints of the synchronization technique, the position error at each actuator simultaneously approaches zero and tends to be equal. Therefore, the proposed controller can suppress the effects of faults and guarantee the acceptable performance of robot manipulators when faults occur. First, an extended state observer is designed to estimate the lumped uncertainties, disturbance and faults. Then, the information from the observer is used to combine with the main novel synchronous fast terminal sliding mode controller as a compensator. By combining the merits of the observer compensation, sliding mode and synchronization technique, the proposed fault-tolerant controller is able to deal with uncertainties and disturbances in normal operation mode and reduce the effects of faults in case faults occur, especially in the occurrence of loss-effective faults. Finally, the enhanced safety, reality and effectiveness of the proposed fault-tolerant control are evaluated through the control of a 3-DOF robot manipulator in both a simulated environment and experiment. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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13 pages, 1811 KiB

Open AccessCommunication

A Finite-Time Trajectory-Tracking Method for State-Constrained Flexible Manipulators Based on Improved Back-Stepping Control

by Yiwei Zhang, Min Zhang, Caixia Fan and Fuqiang Li

Actuators 2022, 11(5), 139; https://doi.org/10.3390/act11050139 - 19 May 2022

Cited by 5 | Viewed by 2190

Abstract

In order to solve the trajectory-tracking-control problem of the state-constrained flexible manipulator systems, a finite-time back-stepping control method based on command filtering is presented in this paper. Considering that the virtual signal requires integration in each step, which will lead to high computational [...] Read more.

In order to solve the trajectory-tracking-control problem of the state-constrained flexible manipulator systems, a finite-time back-stepping control method based on command filtering is presented in this paper. Considering that the virtual signal requires integration in each step, which will lead to high computational complexity in the traditional back-stepping, the finite-time command filter is used to filter the virtual signal and to obtain the intermediate signal in finite time, to thus reduce the computational complexity. The compensation mechanism is used to eliminate the error generated by the command filter. Furthermore, the adaptive estimation method is introduced to approach the uncertainty of the state-constrained flexible manipulator system. Then, the Lyapunov function is used to prove that the tracking error of the system can be stabilized in a sufficiently small origin neighborhood within a finite time. The simulation of a single rod flexible manipulator system demonstrates the effect of the proposed approach. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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18 pages, 23079 KiB

Open AccessArticle

Structural Design and Experiments of a Dynamically Balanced Inverted Four-Bar Linkage as Manipulator Arm for High Acceleration Applications

by Matthijs J. J. Zomerdijk and Volkert van der Wijk

Actuators 2022, 11(5), 131; https://doi.org/10.3390/act11050131 - 5 May 2022

Cited by 1 | Viewed by 2961

Abstract

Industrial robotic manipulators in pick-and-place applications require short settling times to achieve high productivity. The fluctuating reaction forces and moments on the base of a dynamically unbalanced manipulator, however, cause base vibrations, leading to increased settling times. These base vibrations can be eliminated [...] Read more.

Industrial robotic manipulators in pick-and-place applications require short settling times to achieve high productivity. The fluctuating reaction forces and moments on the base of a dynamically unbalanced manipulator, however, cause base vibrations, leading to increased settling times. These base vibrations can be eliminated with dynamic balancing, which is achieved, in general, with the addition of counter-masses and counter-inertias. Adding these elements, however, comes at the cost of increased moving mass and inertia, resulting in lower natural frequencies and again higher settling times. For a minimal settling time it is therefore essential that a balanced mechanism has high natural frequencies with an optimal mass distribution. A dynamically balanced inverted four-bar linkage architecture is therefore favoured over architectures which depend on counter-masses and counter-rotating flywheels. The goal of this paper is to present and experimentally verify a structural design of a manipulator arm with high natural frequencies that is based on a dynamically balanced inverted four-bar linkage. The dynamical properties and the robustness to manufacturing tolerances are both verified with simulations and experiments. Experiments for 5.2 G tip accelerations show, when fully balanced, a reduction of 99.3% in reaction forces and 97.8% in reaction moments as compared to the unbalanced mechanism. The manipulator reached 21 G tip accelerations and a first natural frequency of 212 Hz was measured, which is significantly high and more than adequate for implementation in high acceleration applications. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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19 pages, 4038 KiB

Open AccessArticle

Smooth-Switching Gain Based Adaptive Neural Network Control of n-Joint Manipulator with Multiple Constraints

by Qing Yang, Haisheng Yu, Xiangxiang Meng, Wenqian Yu and Huan Yang

Actuators 2022, 11(5), 127; https://doi.org/10.3390/act11050127 - 29 Apr 2022

Viewed by 2103

Abstract

Modeling errors, external loads and output constraints will affect the tracking control of the n-joint manipulator driven by the permanent magnet synchronous motor. To solve the above problems, the smooth-switching for backstepping gain control strategy based on the Barrier Lyapunov Function and adaptive [...] Read more.

Modeling errors, external loads and output constraints will affect the tracking control of the n-joint manipulator driven by the permanent magnet synchronous motor. To solve the above problems, the smooth-switching for backstepping gain control strategy based on the Barrier Lyapunov Function and adaptive neural network (BLF-ANBG) is proposed. First, the adaptive neural network method is established to approximate modeling errors, unknown loads and unenforced inputs. Then, the gain functions based on the error and error rate of change are designed, respectively. The two gain functions can respectively provide faster response speed and better tracking stability. The smooth-switching for backstepping gain strategy based on the Barrier Lyapunov Function is proposed to combine the advantages of both gain functions. According to the above strategy, the BLF-ANBG strategy is proposed, which not only solves the influence of multiple constraints, unknown loads and modeling errors, but also enables the manipulator system to have better dynamic and steady-state performances at the same time. Finally, the proposed controller is applied to a 2-DOF manipulator and compared with other commonly used methods. The simulation results show that the BLF-ANBG strategy has good tracking performance under multiple constraints and model errors. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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13 pages, 3673 KiB

Open AccessArticle

Control Design for CABLEankle, a Cable Driven Manipulator for Ankle Motion Assistance

by Idumudi Venkata Sai Prathyush, Marco Ceccarelli and Matteo Russo

Actuators 2022, 11(2), 63; https://doi.org/10.3390/act11020063 - 21 Feb 2022

Cited by 9 | Viewed by 3311

Abstract

A control design is presented for a cable driven parallel manipulator for performing a controlled motion assistance of a human ankle. Requirements are discussed for a portable, comfortable, and light-weight solution of a wearable device with an overall design with low-cost features and [...] Read more.

A control design is presented for a cable driven parallel manipulator for performing a controlled motion assistance of a human ankle. Requirements are discussed for a portable, comfortable, and light-weight solution of a wearable device with an overall design with low-cost features and user-oriented operation. The control system utilizes various operational and monitoring sensors to drive the system and also obtain continuous feedback during motion to ensure an effective recovery. This control system for CABLEankle device is designed for both active and passive rehabilitation to facilitate the improvement in both joint mobility and surrounding muscle strength. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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17 pages, 17044 KiB

Open AccessArticle

Robotic Sponge and Watercolor Painting Based on Image-Processing and Contour-Filling Algorithms

by Lorenzo Scalera, Giona Canever, Stefano Seriani, Alessandro Gasparetto and Paolo Gallina

Actuators 2022, 11(2), 62; https://doi.org/10.3390/act11020062 - 19 Feb 2022

Cited by 5 | Viewed by 3088

Abstract

In this paper, the implementation of a robotic painting system using a sponge and the watercolor painting technique is presented. A collection of tools for calibration and sponge support operations was designed and built. A contour-filling algorithm was developed, which defines the sponge [...] Read more.

In this paper, the implementation of a robotic painting system using a sponge and the watercolor painting technique is presented. A collection of tools for calibration and sponge support operations was designed and built. A contour-filling algorithm was developed, which defines the sponge positions and orientations in order to color the contour of a generic image. Finally, the proposed robotic system was employed to realize a painting combining etching and watercolor techniques. To the best of our knowledge, this is the first example of robotic painting that uses the watercolor technique and a sponge as the painting media. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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17 pages, 2589 KiB

Open AccessArticle

Simulation and Model-Based Verification of an Emergency Strategy for Cable Failure in Cable Robots

by Roland Boumann and Tobias Bruckmann

Actuators 2022, 11(2), 56; https://doi.org/10.3390/act11020056 - 14 Feb 2022

Cited by 8 | Viewed by 2528

Abstract

Cable failure is an extremely critical situation in the operation of cable-driven parallel robots (CDPR), as the robot might be instantly outside of its predefined workspace. Therefore, the calculation of a cable force distribution might fail and, thus, the controller might not be [...] Read more.

Cable failure is an extremely critical situation in the operation of cable-driven parallel robots (CDPR), as the robot might be instantly outside of its predefined workspace. Therefore, the calculation of a cable force distribution might fail and, thus, the controller might not be able to master the guidance of the system anymore. However, as long as there is a remaining set of cables, the dynamic behavior of the system can be influenced to prevent further damage, such as collisions with the ground. The paper presents a feasible algorithm, introduces the models for dynamical multi-body simulation and verifies the algorithm within control loop closure. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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13 pages, 7207 KiB

Open AccessArticle

Influence of the Dynamic Effects and Grasping Location on the Performance of an Adaptive Vacuum Gripper

by Matteo Maggi, Giacomo Mantriota and Giulio Reina

Actuators 2022, 11(2), 55; https://doi.org/10.3390/act11020055 - 12 Feb 2022

Cited by 8 | Viewed by 2538

Abstract

A rigid in-plane matrix of suction cups is widely used in robotic end-effectors to grasp objects with flat surfaces. However, this grasping strategy fails with objects having different geometry e.g., spherical and cylindrical. Articulated rigid grippers equipped with suction cups are an underinvestigated [...] Read more.

A rigid in-plane matrix of suction cups is widely used in robotic end-effectors to grasp objects with flat surfaces. However, this grasping strategy fails with objects having different geometry e.g., spherical and cylindrical. Articulated rigid grippers equipped with suction cups are an underinvestigated solution to extend the ability of vacuum grippers to grasp heavy objects with various shapes. This paper extends previous work by the authors in the development of a novel underactuated vacuum gripper named Polypus by analyzing the impact of dynamic effects and grasping location on the vacuum force required during a manipulation cycle. An articulated gripper with suction cups, such as Polypus, can grasp objects by adhering to two adjacent faces, resulting in a decrease of the required suction action. Moreover, in the case of irregular objects, many possible grasping locations exist. The model explained in this work contributes to the choice of the most convenient grasping location that ensures the minimum vacuum force required to manipulate the object. Results obtained from an extensive set of simulations are included to support the validity of the proposed analytical approach. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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15 pages, 25738 KiB

Open AccessArticle

Application of the Half-Order Derivative to Impedance Control of the 3-PUU Parallel Robot

by Luca Bruzzone, Pietro Fanghella and Davide Basso

Actuators 2022, 11(2), 45; https://doi.org/10.3390/act11020045 - 1 Feb 2022

Cited by 6 | Viewed by 2520

Abstract

This paper presents an extension of impedance control of robots based on fractional calculus. In classical impedance control, the end-effector reactions are proportional to the end-effector position errors through the stiffness matrix K, while damping is proportional to the first-order time-derivative of the [...] Read more.

This paper presents an extension of impedance control of robots based on fractional calculus. In classical impedance control, the end-effector reactions are proportional to the end-effector position errors through the stiffness matrix K, while damping is proportional to the first-order time-derivative of the end-effector coordinate errors through the damping matrix D. In the proposed approach, a half-derivative damping is added, proportional to the half-order time-derivative of the end-effector coordinate errors through the half-derivative damping matrix HD. The discrete-time digital implementation of the half-order derivative alters the steady-state behavior, in which only the stiffness term should be present. Consequently, a compensation method is proposed, and its effectiveness is validated by multibody simulation on a 3-PUU parallel robot. The proposed approach can be considered the extension to MIMO robotic systems of the PDD^1/2 control scheme for SISO mechatronic systems, with potential benefits in the transient response performance. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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20 pages, 5658 KiB

Open AccessArticle

Redundancy Exploitation of an 8-DoF Robotic Assistant for Doppler Sonography

by Elie Gautreau, Juan Sandoval, Aurélien Thomas, Jean-Michel Guilhem, Giuseppe Carbone, Saïd Zeghloul and Med Amine Laribi

Actuators 2022, 11(2), 33; https://doi.org/10.3390/act11020033 - 24 Jan 2022

Cited by 2 | Viewed by 3386

Abstract

The design of a teleoperated 8-DoF redundant robot for Doppler sonography is detailed in this paper. The proposed robot is composed of a 7-DoF robotic arm mounted on a 1-DoF linear axis. This solution has been conceived to allow Doppler ultrasound examination of [...] Read more.

The design of a teleoperated 8-DoF redundant robot for Doppler sonography is detailed in this paper. The proposed robot is composed of a 7-DoF robotic arm mounted on a 1-DoF linear axis. This solution has been conceived to allow Doppler ultrasound examination of the entire patient’s body. This paper details the design of the platform and proposes two alternative control modes to deal with its redundancy at the torque level. The first control mode considers the robot as a full 8-DoF kinematics chain, synchronizing the action of the eight joints and improving the global robot manipulability. The second control mode decouples the 7-DoF arm and the linear axis controllers and proposes a switching strategy to activate the linear axis motion when the robot arm approaches the workspace limits. Moreover, a new adaptive Joint-Limit Avoidance (JLA) strategy is proposed with the aim of exploiting the redundancy of the 7-DoF anthropomorphic arm. Unlike classical JLA approaches, a weighting matrix is actively adapted to prioritize those joints that are approaching the mechanical limits. Simulations and experimental results are presented to verify the effectiveness of the proposed control modes. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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15 pages, 3170 KiB

Open AccessArticle

Development of a Mechatronic System for the Mirror Therapy

by Maurizio Ruggiu and Pierluigi Rea

Actuators 2022, 11(1), 14; https://doi.org/10.3390/act11010014 - 5 Jan 2022

Cited by 5 | Viewed by 2952

Abstract

This paper fits into the field of research concerning robotic systems for rehabilitation. Robotic systems are going to be increasingly used to assist fragile persons and to perform rehabilitation tasks for persons affected by motion injuries. Among the recovery therapies, the mirror therapy [...] Read more.

This paper fits into the field of research concerning robotic systems for rehabilitation. Robotic systems are going to be increasingly used to assist fragile persons and to perform rehabilitation tasks for persons affected by motion injuries. Among the recovery therapies, the mirror therapy was shown to be effective for the functional recovery of an arm after stroke. In this paper we present a master/slave robotic device based on the mirror therapy paradigm for wrist rehabilitation. The device is designed to orient the affected wrist in real time according to the imposed motion of the healthy wrist. The paper shows the kinematic analysis of the system, the numerical simulations, an experimental mechatronic set-up, and a built 3D-printed prototype. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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13 pages, 2383 KiB

Open AccessArticle

A New Method for Identifying Kinetic Parameters of Industrial Robots

by Bin Kou, Shijie Guo and Dongcheng Ren

Actuators 2022, 11(1), 2; https://doi.org/10.3390/act11010002 - 23 Dec 2021

Cited by 3 | Viewed by 3869

Abstract

Identifying the kinetic parameters of an industrial robot is the basis for designing a controller for it. To solve the problems of the poor accuracy and easy premature convergence of common bionic algorithms for identifying the dynamic parameters of such robots, this study [...] Read more.

Identifying the kinetic parameters of an industrial robot is the basis for designing a controller for it. To solve the problems of the poor accuracy and easy premature convergence of common bionic algorithms for identifying the dynamic parameters of such robots, this study proposed simulated annealing with similar exponential changes based on the beetle swarm optimization (SEDSABSO) algorithm. Expressions for the dynamics of the industrial robot were first obtained through the SymPyBotics toolkit in Python, and the required trajectories of excitation were then designed to identify its dynamic parameters. Following this, the search pattern of the global optimal solution for the beetle swarm optimization algorithm was improved in the context of solving for these parameters. The global convergence of the algorithm was improved by improving the iterative form of the number N of skinks in it by considering random perturbations and the simulated annealing algorithm, whereas its accuracy of convergence was improved through the class exponential change model. The improved beetle swarm optimization algorithm was used to identify the kinetic parameters of the Zhichang Kawasaki RS010N industrial robot. The results of experiments showed that the proposed algorithm was fast and highly accurate in identifying the kinetic parameters of the industrial robot. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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20 pages, 932 KiB

Open AccessArticle

Pattern-Moving-Based Partial Form Dynamic Linearization Model Free Adaptive Control for a Class of Nonlinear Systems

by Xiangquan Li and Zhengguang Xu

Actuators 2021, 10(9), 223; https://doi.org/10.3390/act10090223 - 5 Sep 2021

Cited by 5 | Viewed by 2162

Abstract

This work addresses a pattern-moving-based partial form dynamic linearization model free adaptive control (P-PFDL-MFAC) scheme and illustrates the bounded convergence of its tracking error for a class of unknown nonaffine nonlinear discrete-time systems. The concept of pattern moving is to take the pattern [...] Read more.

This work addresses a pattern-moving-based partial form dynamic linearization model free adaptive control (P-PFDL-MFAC) scheme and illustrates the bounded convergence of its tracking error for a class of unknown nonaffine nonlinear discrete-time systems. The concept of pattern moving is to take the pattern class of the system output condition as a dynamic operation variable, and the control purpose is to ensure that the system outputs belong to a certain pattern class or some desired pattern classes. The P-PFDL-MFAC scheme mainly includes a modified tracking control law, a deviation estimation algorithm and a pseudo-gradient (PG) vector estimation algorithm. The classification-metric deviation is considered as an external disturbance, which is caused by the process of establishing the pattern-moving-based system dynamics description, and an improved cost function is proposed from the perspective of a two-player zero-sum game (TP-ZSG). The bounded convergence of the tracking error is rigorously proven by the contraction mapping principle, and the validity of the theoretical results is verified by simulation examples. Full article

(This article belongs to the Special Issue Dynamics and Control of Robot Manipulators)

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