Coordinated Trajectory Planning Research Articles

Spatio-Temporal Joint Optimization-Based Trajectory Planning Method for Autonomous Vehicles in Complex Urban Environments.

Providing safe, smooth, and efficient trajectories for autonomous vehicles has long been a question of great interest in the field of autopiloting. In dynamic and ever-changing urban environments, safe and efficient trajectory planning is fundamental to achieving autonomous driving. Nevertheless, the complexity of environments with multiple constraints poses challenges for trajectory planning. It is possible that behavior planners may not successfully obtain collision-free trajectories in complex urban environments. Herein, this paper introduces spatio-temporal joint optimization-based trajectory planning (SJOTP) with multi-constraints for complex urban environments. The behavior planner generates initial trajectory clusters based on the current state of the vehicle, and a topology-guided hybrid A* algorithm applied to an inflated map is utilized to address the risk of collisions between the initial trajectories and static obstacles. Taking into consideration obstacles, road surface adhesion coefficients, and vehicle dynamics constraints, multi-constraint multi-objective coordinated trajectory planning is conducted, using both differential-flatness vehicle models and point-mass vehicle models. Taking into consideration longitudinal and lateral coupling in trajectory optimization, a spatio-temporal joint optimization solver is used to obtain the optimal trajectory. The simulation verification was conducted on a multi-agent simulation platform. The results demonstrate that this methodology can obtain optimal trajectories safely and efficiently in complex urban environments.

Trajectory planning of a free-floating dual-arm space robot with minimal base disturbance in obstacle environments

This paper addresses the issue of trajectory planning for a free-floating dual-arm space robot, considering the constraints of collision avoidance while simultaneously minimizing the base position and attitude disturbance during on-orbit tasks. One arm is designated as the mission arm, tracking a prescribed path to complete specific goals, while the other serves as the balance arm, compensating for any base attitude disturbance. A collision-free path planning approach is presented for the mission arm, which utilizes a hybrid map, improved artificial potential field (IAPF) and adaptive coupling guidance method. The hybrid map in the mission arm joint space contains the coupling relationship between the deviation of the base position and the motion of the dual arms, along with obstacles transformed from Cartesian space. Then, to address the problem of the goals nonreachable with obstacles nearby (GNRON) of the artificial potential field (APF), a novel repulsive potential field is incorporated into the IAPF. To minimize the base position disturbance, a coupling guidance method is presented that enables the mission arm to move in areas with lower coupling factors on the hybrid map. Finally, simulations are conducted to demonstrate the effectiveness and superiority of the proposed hybrid map and coordinated trajectory planning approach.

Coordinated Trajectory Planning for Multiple Autonomous Underwater Vehicles: A Parallel Grey Wolf Optimizer

The utilization of unmanned systems has witnessed a steady surge in popularity owing to its tremendous potential for a wide range of applications. In particular, the coordination among multiple vehicle systems has been demonstrated to possess unparalleled efficacy in accomplishing intricate and diverse tasks. In light of this, the present paper delves into the coordinated path planning mission that is accomplished by collaborative efforts amongst multiple Autonomous Underwater Vehicles (AUVs). First, considering the potential threats, arrival time windows, space, and physical constraints for the AUVs, a sophisticated coordinated path planning model is formulated in a 3D environment, serving as a systematic and structured blueprint for the underlying mechanism. Subsequently, the optimization problem is addressed through the incorporation of a restricted initialization scheme and a multi-objective clustering strategy in the proposed methodology. The resulting approach leads to the development of the Parallel Grey Wolf Optimizer (P-GWO) which exhibits strong global searching abilities and a rapid convergence rate, rendering it a dependable and effective solution. The results demonstrate a 10–15% improvement in convergence rate and a reduction of over 60% in the average cost value compared to reliable references, thus presenting an effective solution for underwater missions with specific requirements.

Coordinated trajectory planning for lane-changing in the weaving areas of dedicated lanes for connected and automated vehicles

Connected and automated vehicle (CAV) technology is widely recognized as a promising way to improve traffic safety, fuel efficiency and network throughput. However, at the early stage of CAV adoption, there will inevitably be a long period when both CAVs and regular vehicles coexist in the traffic system. To facilitate CAV functionalities in mixed traffic, providing dedicated rights of way for CAVs is necessary. In such scenarios, traffic control requires careful design in the weaving areas that allow CAVs to transfer between dedicated roads and ordinary roads for both safety and efficiency considerations. This paper proposes a dynamic programming approach for the coordinated trajectory planning of CAVs in mandatory lane-changing scenarios, in which CAVs have to switch from a dedicated CAV lane into parallel ordinary lanes with mixed traffic. For a group of CAVs that are poised to enter the ordinary road, the proposed method aims to provide each CAV with a suggested lane-changing gap and a reference trajectory in a coordinated manner. To solve the problem, we establish a dynamic programming formulation to determine the suggested gaps for all CAVs. We formulate a nonconvex quadratic-constrained quadratic programming (QCQP) problem to characterize the trajectory determination problem, and a relaxation-based approximate algorithm is developed to solve the QCQP. Simulation results show that, compared to the benchmark methods, the proposed method offers substantial benefits both in terms of traffic efficiency and in-vehicle passengers experiences.

Coordinated trajectory planning of a dual-arm space robot with multiple avoidance constraints

This paper presents a coordinated trajectory planning method for a free-floating dual-arm space robot system. The research purpose of this paper is to enable a space robot to complete the specified goals while avoiding collision with an obstacle by planning the motion of the joints. The coordinated trajectory planning problem for a space robot is transformed into an optimization problem to find the optimal trajectory of the base and manipulators by using particle swarm optimization (PSO). Since the optimization method is used to find an optimal trajectory, it is unnecessary to calculate the position of the base and the inverse kinematics of the joints. Therefore, the kinematic singular problem in seeking the inverse solution can be avoided. The joint trajectories are parametrized by a sine function with seventh-order polynomial parameters. Multiple constraints are added to the objective function as penalty items, and a new increasing strategy for a penalty factor is proposed to balance the penalty and search ability under multiple constraints. Finally, numerical simulations are carried out to verify the effectiveness of the proposed method.

Coordinated Trajectory Planning for Lane-Changing in The Weaving Areas of Dedicated Lanes for Connected And Automated Vehicles

Coordinated Trajectory Planning for Lane-Changing in The Weaving Areas of Dedicated Lanes for Connected And Automated Vehicles

Trajectory Planning and Tracking for Carrier Aircraft-Tractor System Based on Autonomous and Cooperative Movement

The solution of how to plan out the cooperative moving trajectory autonomously and control the motion of carrier-based aircraft timely and accurately is the key to helping improve the overall deck operation efficiency. The main problem discussed in this article is coordinated trajectory planning strategy for multicarrier aircraft and cooperative control between tractor and carrier aircraft. First, the kinematic model and three-degree-of-freedom dynamics model of the towbarless traction system are established. Then, a coevolution mechanism for aircraft systems is proposed to ensure coordinated trajectory planning among multiple aircraft and a trajectory adapted to the tractor-aircraft system is generated based on the hybrid RRT∗ algorithm. Next, a double-layer closed-loop controller is designed for the trajectory tracking of the tractor-aircraft system on the deck under the constraints of incomplete constraints and various physical conditions. It includes an outer model predictive controller which effectively controls the cooperative motion between the carrier aircraft and tractor and an inner torque control strategy based on adaptive fuzzy PID control which strictly ensures the stability of the system. Simulation results demonstrate that the controller is more rapid, more accurate, and more robust in tracking line trajectory with initial deviation, sine curve with large curvature, and complex trajectories on decks compared with backstepping control and LQR algorithm.

Optimized artificial potential field algorithm to multi-unmanned aerial vehicle coordinated trajectory planning and collision avoidance in three-dimensional environment

Multi-unmanned aerial vehicle trajectory planning is one of the most complex global optimum problems in multi-unmanned aerial vehicle coordinated control. Results of recent research works on trajectory planning reveal persisting theoretical and practical problems. To mitigate them, this paper proposes a novel optimized artificial potential field algorithm for multi-unmanned aerial vehicle operations in a three-dimensional dynamic space. For all purposes, this study considers the unmanned aerial vehicles and obstacles as spheres and cylinders with negative electricity, respectively, while the targets are considered spheres with positive electricity. However, the conventional artificial potential field algorithm is restricted to a single unmanned aerial vehicle trajectory planning in two-dimensional space and usually fails to ensure collision avoidance. To deal with this challenge, we propose a method with a distance factor and jump strategy to resolve common problems such as unreachable targets and ensure that the unmanned aerial vehicle does not collide into the obstacles. The method takes companion unmanned aerial vehicles as the dynamic obstacles to realize collaborative trajectory planning. Besides, the method solves jitter problems using the dynamic step adjustment method and climb strategy. It is validated in quantitative test simulation models and reasonable results are generated for a three-dimensional simulated urban environment.

Area-oriented coordinated trajectory planning of dual-arm space robot for capturing a tumbling target

The growing amount of space debris poses a threat to operational spacecraft and the long-term sustainability of activities in outer space. According to the orbital mechanics, an uncontrolled space object will be tumbling, bringing great challenge to capture and remove it. In this paper, a dual-arm coordinated “Area-Oriented Capture” (AOC) method is proposed to capture a non-cooperative tumbling target. Firstly, the motion equation of the tumbling target is established, based on which, the dynamic properties are analyzed. Then, the “Area-Oriented Capture” concept is presented to deal with the problem of large pose (position and attitude) deviation and tumbling motion. An area rather than fixed points/devices is taken as the object to be tracked and captured. As long as the manipulators’ end-effectors move to a specified range of the objective areas (not fixed points on the target, but areas), the target satellite will be hugged by the two arms. At last, the proposed method and the traditional method (i.e. fixed-point oriented capture method) are compared and analyzed through simulation. The results show that the proposed method has larger pose tolerance and takes shorter time for capturing a tumbling target.

Virtual-base modeling and coordinated control of a dual-arm space robot for target capturing and manipulation

A dual-arm space robotic system has large potential in on-orbit servicing missions, such as satellite repairing, large space structure construction and space debris removal. However, there exist multiple dynamic couplings between the base, the manipulators and the target, bringing large challenge to the motion planning and control. In this paper, a virtual-base modeling method (VBM) and coordinated control strategy are proposed for a dual-arm space robot. One of the arms’ end-effector is considered as the virtual base, and the other bodies, including each link of the arms and the center body of the spacecraft, form a combined manipulator. Correspondingly, we derive the kinematic and dynamic equations of the combined manipulator with the virtual base, taking it as a hyper-redundant space manipulator. Furthermore, the coordinated trajectory planning and control methods are presented for capturing and manipulating a space target. For the pre-contact stage, the virtual base and end-effector are controlled simultaneously to track the desired trajectory in the inertial space. During contact, the operational force is regulated using admittance control law, by simplifying the operational forces of the two arms as the equivalent operational force of the combined manipulator. After the target is captured and fixed to the two arms, its pose is adjusted by simultaneously controlling the trajectory and the operational force of the virtual base and the combined manipulator. Finally, a co-simulation system is created based on MATLAB/Simulink and MSC.ADAMS. Simulation results verify the effectiveness and robustness of the proposed methods.

Coordinated trajectory planning of dual-arm space robot using constrained particle swarm optimization

Application of the multi-arm space robot will be more effective than single arm especially when the target is tumbling. This paper investigates the application of particle swarm optimization (PSO) strategy to coordinated trajectory planning of the dual-arm space robot in free-floating mode. In order to overcome the dynamics singularities issue, the direct kinematics equations in conjunction with constrained PSO are employed for coordinated trajectory planning of dual-arm space robot. The joint trajectories are parametrized with Bézier curve to simplify the calculation. Constrained PSO scheme with adaptive inertia weight is implemented to find the optimal solution of joint trajectories while specific objectives and imposed constraints are satisfied. The proposed method is not sensitive to the singularity issue due to the application of forward kinematic equations. Simulation results are presented for coordinated trajectory planning of two kinematically redundant manipulators mounted on a free-floating spacecraft and demonstrate the effectiveness of the proposed method.

Doublel-robot coordination workspace Analysis based on Matlab

Aiming at the requirements of dual robot collaborative operation, a dual robot cooperation system model is established in SolidWorks2012 software to study the dual robot cooperation space. The D-H parameters are established, and the kinematics positive solution equation is obtained. The dual robot cooperative kinematics model is given. Based on the Monte Carlo method, the workspace of the dual robot is solved. The extreme value theory method is used to analyze and calculate, so as to extract the precise boundary contour of the common area of the dual robot workspace, and the collaborative space boundary surface and limit position of the dual robot are determined. The optimal coordinated working space of the dual robot end effector is obtained, which lays a theoretical foundation for the coordinated trajectory planning of the dual robot.

Coordinated Trajectory Planning for Efficient Communication Relay Using Multiple UAVs

This paper investigates the use of small UAVs as communication relay nodes for expanding communications links and improving communication quality, primarily for a fleet of ground or navy vessels. An airborne relay in ground/maritime space can effectively connect to units operating over the horizon, beyond normal communication range, or under limited satellite communication environments. For efficient UAV communication relay, this paper firstly deals with the UAV deployment for stationary communication nodes, which finds the fixed optimal location of UAVs to improve the connectivity of a wireless network. Then, considering movements of vessels and constraints of the fixed-wing UAV in a dynamic environment, this paper proposes a decentralised nonlinear model predictive trajectory planning strategy. By exploiting motion estimates of vessels and states of UAVs, the trajectory planning algorithm finds a control input sequence over a certain time horizon, which optimises network connectivity. Numerical simulations are performed with different number of UAVs for both stationary and manoeuvring naval vessels to verify the feasibility and benefit of the proposed approach.

Study on Trajectory Planning of Dual-arm Space Robot Keeping the Base Stabilized

Aiming at the case that the base is required to be stabilized by a balance arm when a dual-arm space robotic system is performing on-orbit missions, we propose coordinated trajectory planning methods of two typical applications — keeping the base centroid fixed (approximately; the same below), and keeping the base attitude and centroid position fixed synchronously. Firstly, the concept of “system centroid equivalent manipulator” is presented, and its kinematic model is derived. Based on the resolution of the position-level kinematic equation, the trajectory of the balance arm for stabilizing the base centroid is planned. Secondly, by combining with the control of a reaction flywheel, the base attitude and centroid can be kept fixed at the same time. The desired angular speed of the flywheel is determined according to the angular momentum conservation law. Finally, a multi-body dynamic model of a dual-arm space robotic system is developed and simulation study is carried out. The proposed methods can overcome the singularity problem which is un-avoidable for previous approaches based on differential kinematics. Furthermore, there are not special requirements on the mass properties and installation position of the balance arm. Simulation results have verified the proposed methods.

Realization of a ball passing strategy for a robot soccer game: a case study of integrated planning and control

Ball passing is an elementary and frequently employed human soccer skill. This paper examines the realization and visualization of ball passing, a low level move-to-ball behavior of a soccer robot, in a robot soccer game. A case study of three mechanically identical mobile robots with a formation ready to pass a ball cyclically in a zigzag pattern is examined. We build a control command driven mobile robot motion simulator with a controller and dynamics of mobile robots, not only nonholonomic kinematic constraints to simulate the motion of a soccer robot driven by wheels torques to generate wheels accelerations, to update the robot position and orientation at successive time instants. Kick motion follows a physical law, and a simplified collision check and response model is utilized for the efficient detection of the hitting a robot with the ball or other robots. The realization of specific ball passing strategy to drive each soccer robot in a position to receive a pass includes three levels of organization, coordination, and execution: careful integrated design of a dynamic formation and role change scheme, ball position estimation, and coordinated trajectory (i.e. path and velocity) planning and tracking control. Simulations are performed to illustrate the feasibility of the realization of ball passing among three robots, implemented by a software program for coordinated trajectory planning and tracking control in the developed simulator.