Review of snake robots in constrained environments

Unmanned aerial vehicles (UAVs) are being increasingly used in different applications in both military and civilian domains [...]

https://www.mdpi.com/2079-9292/8/4/452/pdf

Autonomous Control of Unmanned Aerial Vehicles

In this paper, a fuzzy adaptive linear active disturbance rejection control (Fuzzy-LADRC) is proposed for strong coupling and nonlinear quadrotor unmanned aerial vehicle (UAV). At present, UAV conveys new opportunities in the industry, such as power line inspection, petroleum conduit patrolling, and defects detection for the wind turbine, because of its advantages in flexibility, high efficiency, and economy. Usually, the scene of the UAV mission has a high risk, and there are internal sensor noise and unknown external disturbance. Thus, the attitude stability and anti-interference ability of UAV are especially essential. To solve the strong coupling problem of UAV, the dynamics model of UAV is established via the Newton-Euler method, and the coupling part of dynamics is modeled as an internal disturbance. According to the function of linear active disturbance rejection control (LADRC) parameters, a Fuzzy-LADRC is proposed to improve the dynamic performance of the system. The proposed control method makes full use of the adaptive ability of the fuzzy controller and the anti-interference ability of LADRC to the nonlinear and strong coupling systems. As we know, this is the first time that Fuzzy-LADRC has been used in UAV control. In the simulation, the performance indicators of four controllers, including Fuzzy-LADRC, LADRC, PID, and Fuzzy-PID are compared and analyzed. The results indicate that the average response speed of Fuzzy-LADRC is 12.65% faster than LADRC, and it is 29.25% faster than PID. The average overshoot of Fuzzy-LADRC is 17% less than LADRC and 77.75% less than PID. The proposed control method can significantly improve the response speed and anti-interference ability of UAV.

An Industrial Quadrotor UAV Control Method Based on Fuzzy Adaptive Linear Active Disturbance Rejection Control

In this paper, a radial basis neural network adaptive sliding mode controller (RBF-NN ASMC) for nonlinear electromechanical actuator systems is proposed. The radial basis function neural network (RBF-NN) control algorithm is used to compensate for the friction disturbance torque in the electromechanical actuator system. An adaptive law was used to adjust the weights of the neural network to achieve real-time compensation of friction. The sliding mode controller is designed to suppress the model uncertainty and external disturbance effects of the electromechanical actuator system. The stability of the RBF-NN ASMC is analyzed by Lyapunov's stability theory, and the effectiveness of this method is verified by simulation. The results show that the control strategy not only has a better compensation effect on friction but also has better anti-interference ability, which makes the electromechanical actuator system have better steady-state and dynamic performance.

https://www.mdpi.com/1424-8220/21/4/1508/pdf

Friction Compensation Control of Electromechanical Actuator Based on Neural Network Adaptive Sliding Mode.

Research in robotics is one of the promising areas in mobile robot development, which is planned to be implemented in extreme dangerous conditions of areas explored by humans. This article aims at developing and improving a prototype of zoomorphic mobile robots that are designed to repeat the existing biological objects in nature. The authors performed a detailed analysis on the structure and dynamics of the geometrical family caterpillar movement, which is passed on a practical design implemented to perform the dynamic movement on uneven vertical surfaces. Based on the obtained analysis, the design and kinematic scheme of the movement is developed. Also, the structural control scheme via the Internet technologies that allow carrying out remote control is presented in this paper, considering the dangerous mobile robot work zones. To test the recommended solutions, the authors developed detailed 3D printed models of the mobile robot constructions for the implemented hardware. The model of the mobile robot is constructed, and the control system with examples of the user program code implementations is performed. Several experiments were performed, which showed the efficiency of the achieved mobile robot for solving problems of vertical movement on uneven metal surfaces. Moreover, the obtained slow motion of the designed robot proves that the simulated robot behaves similarly to the natural behavior of caterpillar movement.

https://downloads.hindawi.com/journals/cin/2022/3046116.pdf

Zoomorphic Mobile Robot Development for Vertical Movement Based on the Geometrical Family Caterpillar

In order to study the winding motion of a multi-joint snake-like robot with multi-degree of redundancy in plane, a motion planning algorithm of a multi-joint snake-like robot based on improved Serpenoid curve equation is proposed in this paper. Firstly, the kinematics and dynamics models of a multi-joint snake-like robot are established, and the joint angle curve equation and the thrust expression of each joint of the robot relative to time are obtained. Next, the existing Serpenoid curve equation is improved to calculate the axial bending moment function with joint angle amplitude adjustment factor and turn angle adjustment factor. By analyzing the relationship between the forward thrust of the robot and the improved Serpenoid curve equation, a simple, efficient and reliable closed-loop control system was designed. Then, MATLAB and SimWise4D were used for simulation to obtain the motion trajectory of the robot based on the improved Serpenoid curve motion planning algorithm, and the influence of different parameters on the forward velocity of the multi-joint snake robot was analyzed. Finally, the validity of the motion planning algorithm of a multi-joint snake-like robot based on improved Serpenoid curve equation is verified by the actual experiment.

/pdf/motion-planning-algorithm-of-a-multi-joint-snake-like-robot-3bzhzxg4wf.pdf

Motion Planning Algorithm of a Multi-Joint Snake-Like Robot Based on Improved Serpenoid Curve

A longitudinal attitude decoupling algorithm based on the fuzzy sliding mode control for a small coaxial rotor unmanned aerial vehicle (UAV) is presented in this paper. The attitude system of a small coaxial rotor UAV is characterized by nonlinearity, strong coupling and uncertainty, which causes difficulties pertaining to its flight control. According to its six-degree-of-freedom model and structural characteristics, the dynamic model was established, and a longitudinal attitude decoupling algorithm was proposed. A fuzzy sliding mode control was used to design the controller to adapt to the underactuated system. Compared with the uncoupled fuzzy sliding mode control, simulation results indicated that the proposed method could improve the stability of the system, presented with a better adapting ability, and could effectively suppress the modeling error and external interference of the coaxial rotor aircraft attitude system. The proposed method also has the advantages of high accuracy, good stability, and the ease of implementation.

https://www.mdpi.com/2079-9292/8/1/107/pdf

Longitudinal Attitude Control Decoupling Algorithm Based on the Fuzzy Sliding Mode of a Coaxial-Rotor UAV

The invention relates to a small-sized coaxial dual-rotor aircraft, which belongs to the field of aircrafts. The small-sized coaxial dual-rotor aircraft is novel in structure and reasonable in design;a steering engine swinging arm and a long connecting rod are driven by a steering engine to rotate so as to change an inclination direction of an inclining disc, and the inclining disc can rotate intwo perpendicular directions along a central spherical hinge bulb, so that the free control of an inclining disc plane can be realized, the change of the inclining disc plane leads to the change of the inclination direction of a rotor frame, the direction of a lifting surface of a lower rotor is changed, and the flight of the aircraft in different directions can be realized. The manipulation mechanism is not complicated, the manipulation for a coaxial dual-rotor structure can be realized; the inclining disc plane is controlled by two steering engines to move in two perpendicular directions, sothat a control system of the aircraft is easier to design compared with other similar aircrafts.

Small-sized coaxial dual-rotor aircraft

Aiming at the problem that the electromechanical actuator system needs to track the target without error within a finite time, fuzzy sliding mode control has been studied Aiming at the problems of conventional fuzzy sliding mode control, such as: low precision, low dynamic quality of system, obvious chattering phenomenon and so on, the disturbance observer is introduced to estimate the uncertainty of electromechanical actuator and combine it with conventional fuzzy sliding mode control, then a fuzzy sliding mode control method based on disturbance observer is proposed Firstly, we build the model of the sliding mode control system of the electromechanical actuator, then design the controller and verify the stability of the system Finally, we carried out some experiments by MATLAB& Simulink, the results indicate that the fuzzy sliding mode controller based on disturbance observer can decrease the tracking error and the response time, movement accuracy and the resistance to disturbance of the system can be improved, the system has a good performance in tracking, which has a great value to the control of electromechanical actuator

Yiran Wei

Papers

Motion Planning Algorithm of a Multi-Joint Snake-Like Robot Based on Improved Serpenoid Curve

Longitudinal Attitude Control Decoupling Algorithm Based on the Fuzzy Sliding Mode of a Coaxial-Rotor UAV

Small-sized coaxial dual-rotor aircraft

Fuzzy sliding mode control based on disturbance observer for electromechanical actuator on guided projectile

Research on a combinatorial control method for coaxial rotor aircraft based on sliding mode