Roderich Groß

The University of Sheffield | Sheffield · Department of Automatic Control and Systems Engineering

This paper studies how groups of robots can effectively navigate through a crowd of agents. It quantifies the performance of platooning and less constrained, greedy strategies, and the extent to which these strategies disrupt the crowd agents. Three scenarios are considered: (i) passive crowds, (ii) counter-flow crowds, and (iii) perpendicular-flow...

This paper provides a data-driven analysis of the trends of research on multi-robot systems (MRS). First, it reports the findings of an exhaustive search of the MRS studies published from 2010 to 2020 in 27 leading robotics journals, including a quantitative analysis of trends. Second, it reports the findings of a survey capturing the views of 68 l...

How each individual selects others within a group to interact with based on visual perception is a fundamental process underlying various collective motion behaviors. This process, however, remains poorly understood theoretically so far, partially due to the challenges of modeling neurological perception systems. Here, the classic zoom-lens visual...

Purpose of Review This review studies recent developments towards the physical design and control of self-assembling multi-robot systems. Recent Findings A wide range of novel robotic systems have been developed lately, for potential applications in terrestrial, aquatic, and aerospace environments. They increasingly make use of connectors which en...

We investigate how reliable movement can emerge in aggregates of highly error-prone individuals. The individuals—robotic modules—move stochastically using vibration motors. By coupling them via elastic links, soft-bodied aggregates can be created. We present distributed algorithms that enable the aggregates to move and deform reliably. The concept...

The fascinating collective behaviors of biological systems have inspired extensive studies on shape assembly of robot swarms. Here, we propose a strategy for shape assembly of robot swarms based on the idea of mean-shift exploration: when a robot is surrounded by neighboring robots and unoccupied locations, it would actively give up its current loc...

A single sheepdog can bring together and manoeuvre hundreds of sheep from one location to another. Engineers and ecologists are fascinated by this sheepdog herding because of the potential it provides for ‘bio‐herding’: a biologically inspired herding of animal groups by robots. Although many herding algorithms have been proposed, most are studied...

This paper addresses the multi-robot barrier coverage problem. It presents a group of memory-less robots that encircle a group of herd agents, by moving along a polygonal barrier. The results, produced from simulations in CoppeliaSim, demonstrate high retention of herd agents, and robust performance across a range of simulated scenarios.

This paper investigates the problem of moving a mixture of active and passive elements to a desired location using a swarm of wheeled robots that require only two bits of sensory input. It examines memory-less control strategies that map a robot’s sensory input to the respective wheel velocities. Results from embodied simulations show that the prob...

Multi-robot systems are often made of physically small robots, meaning obstacles that could be overcome by larger robots pose a greater challenge to them. This paper considers how a group of such robots could self-assemble into bridges to cross large gaps in their environment. We build on previous work demonstrating construction of cantilevers to s...

This paper investigates the problem of moving a mixture of active and passive elements to a desired location using a swarm of wheeled robots that require only two bits of sensory input. It examines memory-less control strategies that map a robot's sensory input to the respective wheel velocities. Results from embodied simulations show that the prob...

This paper proposes a novel aggregation strategy for a network of mobile wheeled robots with constrained dynamics. The strategy assumes a centralized control architecture, which collects all the robot positions and generates the control signals sent to the robots in the network. To do this a control Lyapunov function (CLF) based approach is designe...

Involving human operators to support swarms of robots can be beneficial to address increasingly complex scenarios. However, the shared control between multiple operators remains a challenge, especially where communication between the operators is not available. This paper studies the problem of forming a dynamic chain of robots connecting two opera...

This paper studies aerobatic tic-toc control of quadcopters. Tic-toc control enables rotorcraft to fly almost in the vertical plane rather than the horizontal plane. It is one of the most challenging manoeuvrers to achieve autonomously. The problem has to our knowledge not yet been studied for quadcopters. Studying it could expand their flight enve...

Research into variable pitch propeller (VPP) quadcopters has seen a marked increase in recent years which is due to their enhanced dynamic capabilities compared to conventional fixed pitch propeller quadcopters. Adding actuators to control the pitch angles of the propellers increases the mechanical complexity and hence may increase the risk of faul...

This paper addresses the multi-robot barrier coverage problem. It presents a group of memory-less robots that encircle a group of herd agents, by moving along a polygonal barrier. The results, produced from simulations in CoppeliaSim, demonstrate high retention of herd agents, and robust performance across a range of simulated scenarios.

This work proposes a novel solution to the problem of covering a bounded grid world using a swarm of robotic agents. The controller requires no run-time memory and only few, discrete sensory inputs. Two variants of the solution to the problem are studied, one effectively modulating the sensing range based on the agent’s context. It is found that du...

Inspired by how ants construct bridges out of their bodies, this paper investigates how a swarm of autonomous robotic agents could self-assemble into cantilevers as a first step towards constructing bridges. Two distributed self-assembly algorithms are presented that consider local force information to ensure links between agents do not break: one...

Modular Fluidic Propulsion (MFP) is a novel concept for modular reconfigurable robots that promises to combine effective propulsion, a large reconfiguration space, and a scalable design. MFP robots are modular fluid networks. To propel, they route fluid through themselves. Both hydraulic and pneumatic implementations are considered. The robots are...

Searching for a lost teammate is an important task for multirobot systems. We present a variant of rapidly expanding random trees (RRT) for generating search paths based on a probabilistic belief of the target teammate’s position. The belief is updated using a hidden Markov model built from knowledge of the target’s planned or historic behavior. Fo...

Modular robotic systems comprise groups of physically connected modules which can be reconfigured to create morphologies that suit an environment or task. One method of reconfiguration is via subtraction, where extraneous modules disconnect from an initial configuration, before being removed by external intervention. In this paper, we consider an a...

We propose a hybrid formulation of Turing Learning and study its application in mobile robotics. Instead of using a single type of discriminator, in the hybrid formulation, both active and passive discriminators are used. Active discriminators come to their judgments while interacting with the system under investigation, which helps improve model a...

Robot swarms are groups of robots that each act autonomously based on only local perception and coordination with neighbouring robots. While current swarm implementations can be large in size (e.g. 1000 robots), they are typically constrained to working in highly controlled indoor environments. Moreover, a common property of swarms is the underlyin...

Supervisory Control Theory (SCT) provides a formal framework for controlling discrete event systems. It has recently been used to generate correct-by-construction controllers for swarm robotics systems. Current SCT frameworks are limited, as they support only (private) events that are observable within the same robot. In this paper, we propose an e...

This article studies a relatively new type of aerial platform: variable‐pitch propeller (VPP) quadcopters. Unlike conventional fixed‐pitch propellers that can only generate upward thrust forces, a VPP can adjust its pitch angle to generate either upward or downward thrust forces. This provides VPP quadcopter with high agility and strong maneuverabi...

Supervisory Control Theory (SCT) provides a formal framework for controlling discrete event systems. It has recently been used to generate correct-byconstruction controllers for swarm robotics systems. Current SCT frameworks are limited, as they support only (private) events that are observable within the same robot. In this paper, we propose an ex...

Swarm robotics investigates groups of relatively simple robots that use decentralized control to achieve a common goal. While the robots of many swarm systems communicate via optical links, the underlying channels and their impact on swarm performance are poorly understood. This paper models the optical channel of a widely used robotic platform, th...

Modular reconfigurable robots are touted for their flexibility, as their bodies can assume a wide range of shapes. A particular challenge is to make them move efficiently in 3D without compromising the scalability of the system. This paper proposes decentralized and fully reactive controllers for pose control of 3D modular reconfigurable robots. Th...

Save for some special cases, current training methods for Generative Adversarial Networks (GANs) are at best guaranteed to converge to a ‘local Nash equilibrium’ (LNE). Such LNEs, however, can be arbitrarily far from an actual Nash equilibrium (NE), which implies that there are no guarantees on the quality of the found generator or classifier. This...

2019 IEEE. We propose stochastic control policies for gathering a group of embodied agents in a two-dimensional square tile environment. The policies are fully decentralized and can be executed on anonymous, oblivious agents with chirality, but no sense of orientation. The agents require only 4 ternary digits of information. We prove that a group o...

Swarm robotics is an emerging technology that has the potential to revolutionise precision agriculture by coordinating fleets of small autonomous vehicles to minimise soil damage, increase farming resolution, lower the cost of automation, and provide solutions that are intrinsically safer and more sustainable than large monolithic systems. Here, we...

This paper presents a distributed boundary detection method for a swarm of robots. It employs the cyclic-shape algorithm together with a local coordinate identification, thereby allowing boundary detection without bearing measurements. Each robot can communicate with, and estimate the distance to, its neighbouring robots. The method is validated us...

We present a distributed boundary detection method for a swarm of robots. It employs the cyclic-shape algorithm together with a local coordinate identification, thereby allowing boundary detection without bearing measurements. Each robot can communicate with, and estimate the distance to, its neighbouring robots. The method is validated using swarm...

Multirobot coverage is the problem of planning paths for several identical robots such that the combined regions traced out by the robots completely cover their environment. We consider the problem of multirobot coverage with the objective of minimizing the mission time, which depends on the number of turns taken by the robots. To solve this proble...

We study the problem of controlling a swarm of anonymous, mobile robots to cooperatively cover an unknown two-dimensional space. The novelty of our proposed solution is that it is applicable to extremely simple robots that lack run-time computation or storage. The solution requires only a single bit of information per robot—whether or not another r...

Task assignment and routing are tightly coupled problems for teams of mobile agents. To fairly balance the workload, each agent should be assigned a set of tasks which take a similar amount of time to complete. The completion time depends on the time needed to travel between tasks which depends on the order of tasks. We formulate the task assignmen...

Tools from topological data analysis, in particular the concept of persistent homology, are applied to a subset of the point cloud to construct barcode diagrams, which are used to determine the numbers of different types of features in the domain. We demonstrate that our approach can correctly identify the number of topological features in simulati...

Save for some special cases, current training methods for Generative Adversarial Networks (GANs) are at best guaranteed to converge to a `local Nash equilibrium` (LNE). Such LNEs, however, can be arbitrarily far from an actual Nash equilibrium (NE), which implies that there are no guarantees on the quality of the found generator or classifier. This...

This paper describes an alternative path towards artificial life—one by which simple modular robots with novel hybrid motion control are used to represent artificial organisms. We outline conceptually how such a system would work, and present a partial hardware implementation. The hardware, a set of self-reconfigurable modules called the evo-bots,...

This paper presents HyMod, a hybrid self-reconfigurable modular robot, and its extensions. HyMod units feature three rotational degrees of freedom and four connectors, allowing them to move independently via differential wheels and group with other units to form arbitrary cubic lattice structures. The design is built around the high-speed genderles...

Synchronization can be a key requirement to perform coordinated actions or reach consensus in multi-robot systems. We study the effect of robot speed on the time required to achieve synchronization using pulse coupled oscillators. Each robot has an internal oscillator and the completion of oscillation cycles is signaled by means of short visual pul...

We propose a computation-free controller that enables a group of embodied agents to collectively choose one of multiple options in their environment. The agents are equipped with a line-of-sight sensor that extracts one ternary digit (trit) of information from the environment. At every time step, they directly map this information onto constant-val...

Distributed robotics is an interdisciplinary and rapidly growing area, combining research in computer science, communication and control systems, and electrical and mechanical engineering. Distributed robotic systems can autonomously solve complex problems while operating in highly unstructured real-world environments. They are expected to play a m...

Generative Adversarial Networks (GAN) have become one of the most successful frameworks for unsupervised generative modeling. As GANs are difficult to train much research has focused on this. However, very little of this research has directly exploited game-theoretic techniques. We introduce Generative Adversarial Network Games (GANGs), which expli...

Recently, a new class of machine learning algorithms has emerged, where models and discriminators are generated in a competitive setting. The most prominent example is Generative Adversarial Networks (GANs). In this paper we examine how these algorithms relate to the famous Turing test, and derive what - from a Turing perspective - can be considere...

We examine the problem solving capabilities of swarms of computation-and memory-free agents. Each agent has a single line-of-sight sensor providing two bits of information. The agent maps this information directly onto constant motor commands. In previous work, we showed that such simplis-tic agents can solve tasks requiring them to organize spatia...

Swarm robotics studies large groups of robots that work together to accomplish common tasks. Much of the used source code is developed in an ad-hoc manner, meaning that the correctness of the controller is not always verifiable. In previous work, supervisory control theory (SCT) and associated design tools have been used to address this problem. Gi...

In SCT, formal languages are used to model the capabilities of a system (free behaviour models) and restrict these capabilities in some desired way (control specifications). The words of these languages are made of two types of symbols: controllable events and uncontrollable events. SCT combines the languages into a supervisor (controller), which g...

We investigate synchronization in a population of mobile pulse-coupled agents with a view towards implementations in swarm robotics systems and mobile sensor networks. Previous theoretical approaches dealt with range and nearest neighbor interactions. In the latter case, a synchronization-hindering regime for intermediate agent mobility was found....

This paper presents OpenSwarm, a lightweight easy-to-use open-source operating system. To our knowledge, it is the first operating system designed for and deployed on miniature robots. OpenSwarm operates directly on a robot’s microcontroller. It has a memory footprint of 1 kB RAM and 12 kB ROM. OpenSwarm enables a robot to execute multiple processe...

This paper studies how an operator with limited situational awareness can collaborate with a swarm of simulated robots. The robots are distributed in an environment with wall obstructions. They aggregate autonomously but are unable to form a single cluster due to the obstructions. The operator lacks the bird’s-eye perspective, but can interact with...

This paper describes an alternative path towards artificial life—one by which simple modular robots with novel hybrid motion control are used to represent artificial organisms. We outline conceptually how such a system would work, and present a partial hardware implementation. The hardware, a set of selfreconfigurable modules called the evo-bots, o...

Synchronization can be a key requirement to perform coordinated actions or reach consensus in multi-robot systems. We study the effect of robot speed on the time required to achieve synchronization using pulse coupled oscillators. Each robot has an internal oscillator and the completion of oscillation cycles is signaled by means of short visual pul...

This paper presents HyMod, a hybrid self-reconfigurable modular robot, and its extensions. HyMod units feature three rotational degrees of freedom and four connectors, allowing them to move independently via differential wheels and group with other units to form arbitrary cubic lattice structures. The design is built around the high-speed genderles...

We propose Turing Learning, a novel system identification method for inferring the behavior of natural or artificial systems. Turing Learning simultaneously optimizes two populations of computer programs, one representing models of the behavior of the system under investigation, and the other representing classifiers. By observing the behavior of t...

This paper proposes a management algorithm that allows a human operator to organize a robotic swarm via a robot leader. When the operator requests a robot to become a leader, nearby robots suspend their activities. The operator can then request a count of the robots, and assign them into subgroups, one for each task. Once the operator releases the...

We study how a human operator can guide a swarm of robots when transporting a large object through an environment with obstacles. The operator controls a leader robot that influences the other robots of the swarm. Follower robots push the object only if they have no line of sight of the leader. The leader represents a way point that the object shou...

Currently, the control software of swarm robotics systems is created by ad hoc development. This makes it hard to deploy these systems in real-world scenarios. In particular, it is difficult to maintain, analyse, or verify the systems. Formal methods can contribute to overcome these problems. However, they usually do not guarantee that the implemen...

Endotherms such as rats and mice huddle together to keep warm. The huddle is considered to be an example of a self-organising system, because complex properties of the collective group behaviour are thought to emerge spontaneously through simple interactions between individuals. Groups of rodent pups display two such emergent properties. First, hud...

Recently, there has been growing interest in the synchronization of mobile pulse-coupled oscillators. We build on the work by Prignano et al. (Phys. Rev. Lett. 110, 114101) and show that agents that interact exclusively with others in their cone of vision can exhibit different synchronization regimes. Depending on their speed, synchronization emerg...

This paper proposes a strategy for transporting a large object to a goal using a large number of mobile robots that are significantly smaller than the object. The robots only push the object at positions where the direct line of sight to the goal is occluded by the object. This strategy is fully decentralized and requires neither explicit communica...

Swarm intelligence is an artificial intelligence discipline, which was created on the basis of the laws that govern the behavior of, for example, social insects, fish schools, and flocks of birds. The organization of these animal societies has always mesmerized humans. Therefore, it is surprising that it has only been in the second half of the last...

The practical effectiveness of modular robotic systems depends heavily on the connection mechanisms used to join their separate entities, particularly for those systems capable of self-reconfiguration. This work presents HiGen, a high-speed genderless mechanical connection mechanism for the docking of robotic modules. HiGen connectors can join with...

At present, most of the source code controlling swarm robotic systems is developed in an ad-hoc manner. This can make it difficult to maintain these systems and to guarantee that they will accomplish the desired behaviour. Formal approaches can help to solve these issues. However, they do not usually guarantee that the final source code will match...

At present, most of the source code controlling swarm robotic systems is developed in an ad-hoc manner. This can make it difficult to maintain these systems and to guarantee that they will accomplish the desired behaviour. Formal approaches can help to solve these issues. However, they do not usually guarantee that the final source code will match...

This paper presents a solution to the problem of self-organized aggregation of embodied robots that requires no arithmetic computation. The robots have no memory and are equipped with one binary sensor, which informs them whether or not there is another robot in their line of sight. It is proven that the sensor needs to have a sufficiently long ran...

We propose a coevolutionary approach for learning the behavior of animals, or agents, in collective groups. The approach requires a replica that resembles the animal under investigation in terms of appearance and behavioral capabilities. It is able to identify the rules that govern the animals in an autonomous manner. A population of candidate mode...

This paper has presented the simplest solution so far to the problem of clustering objects with a swarm of robots. The robots are memory-less and are unable to perform arithmetic computations. They are only able to detect the presence of an object or another robot in their line of sight. As they do not possess any distance information about a perce...

Huddling by endotherms is an important model through which to study the emergence of complexity. Canals et al. (2011) have recently described the emergence of huddling in rodents as a phase transition mediated by the ambient environmental temperature [1]. We present an agent-based model as a minimal account of the reported transition to huddling at...