scholarly journals Time Coordination and Collision Avoidance Using Leader-Follower Strategies in Multi-Vehicle Missions

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 34
Author(s):  
Camilla Tabasso ◽  
Venanzio Cichella ◽  
Syed Bilal Mehdi ◽  
Thiago Marinho ◽  
Naira Hovakimyan
Keyword(s):  
Collision Avoidance ◽  
Time Delays ◽  
Control Strategies ◽  
Vehicle Safety ◽  
Performance Bounds ◽  
Coordination Problem ◽  
Control Framework ◽  
Cooperative Vehicles ◽  
Speed Adjustment ◽  
Avoidance Problem

In recent years, the increasing popularity of multi-vehicle missions has been accompanied by a growing interest in the development of control strategies to ensure safety in these scenarios. In this work, we propose a control framework for coordination and collision avoidance in cooperative multi-vehicle missions based on a speed adjustment approach. The overall problem is decoupled in a coordination problem, in order to ensure coordination and inter-vehicle safety among the agents, and a collision-avoidance problem to guarantee the avoidance of non-cooperative moving obstacles. We model the network over which the cooperative vehicles communicate using tools from graph theory, and take communication losses and time delays into account. Finally, through a rigorous Lyapunov analysis, we provide performance bounds and demonstrate the efficacy of the algorithms with numerical and experimental results.

Automatic Control of Underway Replenishment Maneuvers in a Random Sea

1978 ◽  
Vol 22 (01) ◽  
pp. 20-28
Author(s):  
Reidar Alvestad
Keyword(s):  
Computer Simulation ◽  
Automatic Control ◽  
Collision Avoidance ◽  
Nonlinear Interaction ◽  
Interaction Forces ◽  
Random Seas ◽  
Close Proximity ◽  
Controller Performance ◽  
Hybrid Computer ◽  
Avoidance Problem

This paper describes a hybrid computer simulation of two ships performing replenishment operations in random seas. Such operations present collision hazards due to the nonlinear interaction forces and moments which result from close proximity maneuvering while underway. Maneuvers are simulated to demonstrate automatic controller performance during station-keeping, station-changing, and the approach and breakaway phases of typical underway replenishment (UNREP) operations. Results indicate that automatic control should be considered as a possible solution to the UNREP collision avoidance problem.

scholarly journals Velocity Obstacle Approaches for Multi-Agent Collision Avoidance

2019 ◽  
Vol 07 (01) ◽  
pp. 55-64 ◽  
Author(s):  
James A. Douthwaite ◽  
Shiyu Zhao ◽  
Lyudmila S. Mihaylova
Keyword(s):  
Collision Avoidance ◽  
Critical Analysis ◽  
Monte Carlo Analysis ◽  
The Other ◽  
Multi Agent Systems ◽  
Agent Systems ◽  
Multi Agent ◽  
Velocity Obstacle ◽  
Scalable Computation ◽  
Avoidance Problem

This paper presents a critical analysis of some of the most promising approaches to geometric collision avoidance in multi-agent systems, namely, the velocity obstacle (VO), reciprocal velocity obstacle (RVO), hybrid-reciprocal velocity obstacle (HRVO) and optimal reciprocal collision avoidance (ORCA) approaches. Each approach is evaluated with respect to increasing agent populations and variable sensing assumptions. In implementing the localized avoidance problem, the author notes a problem of symmetry not considered in the literature. An intensive 1000-cycle Monte Carlo analysis is used to assess the performance of the selected algorithms in the presented conditions. The ORCA method is shown to yield the most scalable computation times and collision likelihood in the presented cases. The HRVO method is shown to be superior than the other methods in dealing with obstacle trajectory uncertainty for the purposes of collision avoidance. The respective features and limitations of each algorithm are discussed and presented through examples.

Guaranteed Collision Avoidance in Multivehicle Cooperative Missions Using Speed Adjustment

2020 ◽  
Vol 17 (8) ◽  
pp. 436-453
Author(s):  
Camilla Tabasso ◽  
Venanzio Cichella ◽  
Syed Bilal Mehdi ◽  
Thiago Marinho ◽  
Naira Hovakimyan
Keyword(s):  
Collision Avoidance ◽  
Speed Adjustment

A comparison of NH4/NO3 control strategies for alternating activated sludge processes

1999 ◽  
Vol 39 (4) ◽  
pp. 93-102 ◽  
Author(s):  
L. J. S. Lukasse ◽  
K. J. Keesman ◽  
A. Klapwijk ◽  
G. van Straten
Keyword(s):  
Activated Sludge ◽  
Time Delays ◽  
Control Strategies ◽  
Treatment Plant ◽  
Biological Processes ◽  
Effluent Quality ◽  
N Removal ◽  
Activated Sludge Reactor ◽  
The Difference ◽  
Activated Sludge Processes

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.

A multi-delay model for pest control with awareness induced interventions — Hopf bifurcation and optimal control analysis

2020 ◽  
Vol 13 (06) ◽  
pp. 2050047
Author(s):  
Fahad Al Basir
Keyword(s):  
Optimal Control ◽  
Hopf Bifurcation ◽  
Time Delay ◽  
Time Delays ◽  
Control Strategies ◽  
Control Analysis ◽  
Agricultural Practice ◽  
Delay Model ◽  
Awareness Campaigns ◽  
Farming Awareness

Farming awareness is an important measure for pest controlling in agricultural practice. Time delay in controlling pest may affect the system. Time delay occurs in organizing awareness campaigns, also time delay may takes place in becoming aware of the control strategies or implementing suitable controlling methods informed through social media. Thus we have derived a mathematical model incorporating two time delays into the system and Holling type-II functional response. The existence and the stability criteria of the equilibria are obtained in terms of the basic reproduction number and time delays. Stability changes occur through Hopf-bifurcation when time delays cross the critical values. Optimal control theory has been applied for cost-effectiveness of the delayed system. Numerical simulations are carried out to justify the analytical results. This study shows that optimal farming awareness through radio, TV etc. can control the delay induced bifurcation in a cost-effective way.

In-space structural assembly using predefined performance based method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xianliang Zhang ◽  
Weibing Zhu ◽  
Xiande Wu ◽  
Ting Song ◽  
Yaen Xie ◽  
...  
Keyword(s):  
Robust Control ◽  
Collision Avoidance ◽  
Dynamic Models ◽  
Control Method ◽  
Transient State ◽  
Transportation Systems ◽  
Performance Bounds ◽  
Tracking Errors ◽  
Performance Control ◽  
Content Type

Purpose The purpose of this paper is to propose a pre-defined performance robust control method for pre-assembly configuration establishment of in-space assembly missions, and collision avoidance is considered during the configuration establishment process. Design/methodology/approach First, six-degrees-of-freedom error kinematic and dynamic models of relative translational and rotational motion between transportation systems are developed. Second, the prescribed transient-state performance bounds of tracking errors are designed. In addition, based on the backstepping, combining the pre-defined performance control method with a robust control method, a pre-defined performance robust controller is designed. Findings By designing prescribed transient-state performance bounds of tracking errors to guarantee that there is no overshoot, collision-avoidance can be achieved. Combining the pre-defined performance control method with a robust control method, robustness to disturbance is guaranteed. Originality/value This paper proposed a pre-defined performance robust control method. Simulation results demonstrate that the proposed controller can achieve a pre-assembly configuration establishment with collision avoidance in the existence of external disturbances.

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