In the field of mobile robotics, the study of multi-robot systems (MRSs) has grown significantly in size and importance in recent years. Having made great progress in the development of the basic problems concerning single-robot control, many researchers shifted their focus to the study of multi-robot coordination. This paper presents a systematic survey and analysis of the existing literature on coordination, especially in multiple mobile robot systems (MMRSs). A series of related problems have been reviewed, which include a communication mechanism, a planning strategy and a decision-making structure. A brief conclusion and further research perspectives are given at the end of the paper.

https://journals.sagepub.com/doi/pdf/10.5772/57313

A Survey and Analysis of Multi-Robot Coordination

Recent advances in technology are delivering robots of reduced size and cost. A natural outgrowth of these advances are systems comprised of large numbers of robots that collaborate autonomously in diverse applications. Research on effective autonomous control of such systems, commonly called swarms, has increased dramatically in recent years and received attention from many domains, such as bioinspired robotics and control theory. These kinds of distributed systems present novel challenges for the effective integration of human supervisors, operators, and teammates that are only beginning to be addressed. This paper is the first survey of human–swarm interaction (HSI) and identifies the core concepts needed to design a human–swarm system. We first present the basics of swarm robotics. Then, we introduce HSI from the perspective of a human operator by discussing the cognitive complexity of solving tasks with swarm systems. Next, we introduce the interface between swarm and operator and identify challenges and solutions relating to human–swarm communication, state estimation and visualization, and human control of swarms. For the latter, we develop a taxonomy of control methods that enable operators to control swarms effectively. Finally, we synthesize the results to highlight remaining challenges, unanswered questions, and open problems for HSI, as well as how to address them in future works.

/pdf/human-interaction-with-robot-swarms-a-survey-2rxowb3zn9.pdf

Human Interaction With Robot Swarms: A Survey

This article presents an agent-based computational model of civil violence. Two variants of the civil violence model are presented. In the first a central authority seeks to suppress decentralized rebellion. In the second a central authority seeks to suppress communal violence between two warring ethnic groups.

Chapter 11. MODELING CIVIL VIOLENCE: AN AGENT-BASED COMPUTATIONAL APPROACH

A taxonomy for task allocation problems with temporal and ordering constraints

Automated guided vehicle systems, state-of-the-art control algorithms and techniques

We present distributed algorithms for multirobot task assignment where the tasks have to be completed within given deadlines. Each robot has a limited battery life and thus there is an upper limit on the amount of time that it has to perform tasks. Performing each task requires certain amount of time (called the task duration) and each robot can have different payoffs for the tasks. Our problem is to assign the tasks to the robots such that the total payoff is maximized while respecting the task deadline constraints and the robot’s battery life constraints. Our problem is NP-hard since a special case of our problem is the classical generalized assignment problem (which is NP-hard). There are no known algorithms (distributed or centralized) for this problem with provably good guarantees of performance. We present a distributed algorithm for solving this problem and prove that our algorithm has an approximation ratio of 2. For the special case of constant task duration we present a distributed algorithm that is provably almost optimal. Our distributed algorithms are polynomial in the number of robots and the number of tasks. We also present simulation results to depict the performance of our algorithms.

Distributed Algorithms for Multirobot Task Assignment With Task Deadline Constraints

In this paper, we present provably-good distributed task assignment algorithms for a heterogeneous multi-robot system, in which the tasks form disjoint groups and there are constraints on the number of tasks a robot can do (both within the overall mission and within each task group). Each robot obtains a payoff (or incurs a cost) for each task and the overall objective for task allocation is to maximize (minimize) the total payoff (cost) of the robots. In general, existing algorithms for task allocation either assume that tasks are independent or do not provide performance guarantee for the situation, in which task constraints exist. We present a distributed algorithm to provide an almost optimal solution for our problem. The key aspect of our distributed algorithm is that the overall objective is (almost) maximized by each robot maximizing its own objective iteratively (using a modified payoff function based on an auxiliary variable, called price of a task) . Our distributed algorithm is polynomial in the number of tasks, as well as the number of robots.

Provably-Good Distributed Algorithm for Constrained Multi-Robot Task Assignment for Grouped Tasks

In this paper, we present provably-good algorithms for multi-robot task assignment, where each task has to be completed within its deadline. Each robot has a upper limit on the maximum number of tasks that it can perform due to its limited battery life, and each task takes the same amount of time to complete. Each robot has a different payoff (or cost) for the tasks and the objective is to assign the tasks to the robots such that the total payoff (cost) is maximized (minimized) while respecting the task deadline constraints. This problem is an extension of a special generalized assignment problem (where each task consumes the same time resource and must be finished), with additional deadline constraints for the time resource assignment. We show that the problem can be reduced to a problem of assigning tasks to robots, where the tasks are organized in overlapping sets, and each robot has a limit on the number of tasks it can perform from each set, which is a variant of multi-robot assignment problem with set precedence constraint (SPC-MAP) discussed in [1].We present a distributed auction-based algorithm for this problem and prove that the solution is almost-optimal. We also present simulation results to depict the performance of our algorithm.

/pdf/distributed-algorithm-design-for-multi-robot-task-assignment-5e01hefkhq.pdf

Distributed algorithm design for multi-robot task assignment with deadlines for tasks

In this paper, we present task allocation (assignment) algorithms for a multi-robot system where the tasks are divided into disjoint groups and there are precedence constraints between the task groups. Existing auction-based algorithms assume the task independence and hence can not be used directly to solve the class of multi-robot task assignment problems that we consider. In our model, each robot can do a fixed number of tasks and obtains a benefit (or incurs a cost) for each task. The tasks are divided into groups and each robot can do only one task from each group. These constraints arise when the robots have to do a set of tasks that have precedence constraints and each task takes the same time to be completed. We extend the auction algorithm to provide an almost optimal solution to the task assignment problem with set precedence constraints (the theoretical guarantees are the same as that of the original auction algorithm for unconstrained tasks). In other words, we guarantee that we will get a solution within a factor of O(n t e) of the optimal solution, where n t is the total number of tasks and e is a parameter that we choose. We first present our algorithm using a shared memory model and then indicate how consensus algorithms can be used to make the algorithm totally distributed.

/pdf/multi-robot-assignment-algorithm-for-tasks-with-set-3zrqg98hq0.pdf

Multi-robot assignment algorithm for tasks with set precedence constraints

Digital microfluidic systems (DMFS) are an emerging class of lab-on-a-chip systems that manipulate individual droplets of chemicals on a planar array of electrodes. The biochemical analyses are performed by repeatedly moving, mixing, and splitting droplets on the electrodes. Mixers and storage units, composed of electrodes, are two important functional resources. Mixers perform droplet mixing and splitting operations, while storage units store droplets that have been produced for subsequent mixings. In this paper, we focus on minimizing the completion time of biochemical analyses by exploiting the binary tree representation of analyses to schedule mixing operations. Using pipelining, we overlap mixing operations with input and transportation operations. We find the lower bound of the mixing completion time based on the tree structure of input analyses, and calculate the minimum number of mixers Mlb required to achieve the lower bound. We present a scheduling algorithm for the case with a specified number of mixers M , and prove it is optimal to minimize the mixing completion time. We also analyze resource constraint issues for two extreme cases. For the case with just one mixer, we prove that all schedules that keep the mixer busy at all times result in the same mixing completion time and then design algorithms for scheduling and to minimize the number of storage units. For the case with zero storage units, we find the minimum number of mixers required. We extend our analyses and algorithms assuming identical mixing durations to the case of different mixing durations. Finally, we illustrate the benefits of our scheduling methods on an example of DNA polymerase chain reaction (PCR) analysis.

Lingzhi Luo

Papers

Distributed Algorithms for Multirobot Task Assignment With Task Deadline Constraints

Provably-Good Distributed Algorithm for Constrained Multi-Robot Task Assignment for Grouped Tasks

Distributed algorithm design for multi-robot task assignment with deadlines for tasks

Multi-robot assignment algorithm for tasks with set precedence constraints

Optimal Scheduling of Biochemical Analyses on Digital Microfluidic Systems