Damjan Miklic

ASSISI: mixing animals with robots in a hybrid society

This paper describes the newly started EU-funded FP7 project ASSISI|bf, which deals with mixed societies: A honeybee society integrated with a group of stationary and interacting autonomous robotic nodes and a group of fish integrated in a society of autonomous moving robots.

Combined actuator sensor unit for interaction with honeybees

Interacting with a specific animal society by integrating autonomous robot/s into the society, has become a powerful method to influence the behaviour of animals and investigate collective behaviour of both, animal and robot societies. In order to interact with animals, artificial unit/s should be well integrated into their society. In the European project ASSISIbf, a network of static autonomous robots called CASUs (Combined Actuator Sensor Units) for interaction with young honeybees has been designed. In the proposed approach CASUs can affect honeybees using three types of physical stimuli: heat, vibration and light. To provide feedback signals necessary for controlling CASU interaction with honeybees, accurate and reliable measurements of the stimuli are necessary. This paper describes the mechanical and electronic design of CASUs, capable of emitting controllable heat, vibration and light stimulations. Each CASU is equipped with temperature sensors, 3-axis accelerometers, infrared proximity sensors and microcontroller for data processing. Preliminary experimental results with honeybee groups are presented.

Decentralized control of free ranging AGVs in warehouse environments

In this paper we propose an algorithm for decentralized control of Automated Guided Vehicles (AGVs) operating in automated warehouse environments. The motion planning part of the algorithm provides vehicles with capabilities for autonomous motion planning considering nonholonomic vehicle constraints and collision-free path execution. The decision making part of the algorithm ensures safe vehicle motions and reliable conflict situation resolution. The proposed control algorithm also prevents occurrence of deadlock and livelock situations. Stability of the algorithm has been proven by its analysis based on automata theory, while its performance has been validated by simulation on a system comprising twenty vehicles as well as experimentally on a laboratory setup comprising five Pioneer 3DX vehicles.

A discrete grid abstraction for formation control in the presence of obstacles

In this paper we present a formation reconfiguration methodology designed for controlling groups of autonomous agents in environments densely populated with obstacles. Our approach is based on abstracting the group of agents by a discrete rectangular grid. Agent and obstacle positions are mapped onto the formation grid. Then, collision free formation transition trajectories are computed using discrete event scheduling techniques that have been well-established in the manufacturing systems domain. The main contribution of this paper is a unified formation control framework that explicitly takes obstacles into account. Using discrete event system analysis tools we show that our approach guarantees convergence to the desired formation while avoiding obstacles and inter-agent collisions.

Decentralized Control of Multi-AGV Systems in Autonomous Warehousing Applications

In this paper, we present an algorithm for decentralized control of multiple automated guided vehicles performing transportation tasks within industrial and warehousing environments. By running on each vehicle in the system, the algorithm provides vehicles with capabilities for autonomous path planning and motion co-ordination. The path planning part of the algorithm implements a free-ranging motion scheme by determining the shortest feasible paths considering nonholonomic vehicle constraints. The motion co-ordination part of the algorithm ensures safe vehicle motions by reliable detection and resolution of different conflict situations with other vehicles in the shared workspace. Conflict resolution is based on a vehicle priority scheme and results in temporary stopping or removal of the lower priority vehicles taking part in the conflict. Removal action is always performed within the vehicles private zone, i.e., the pre-allocated local region of the workspace surrounding the vehicle. By encoding information on the vehicle size and its kinematic constraints, the introduced private zone mechanism provides the necessary physical space required for successful execution of every removal action. We also analyze the stability of the presented algorithm and discuss its deadlock-free and livelock-free properties. Algorithm performance has been validated by simulation using ten vehicles and experimentally on two different setups-a laboratory setup comprising five Pioneer 3DX vehicles and by two state-of-the-art autonomous forklifts in industrial-like operating conditions.

ASSISI: Charged Hot Bees Shakin' in the Spotlight

In this article we describe the concept of generating a mixed society of honeybees and artificial (robotic) agents in the project ASSISI|bf. We discuss the motivation of generating a mixed society as novel bio-hybrid system that can achieve self-awareness, self-regulation and environmental awareness through self-organization and collective information processing. In our approach the artificial agents communicate with the natural agents through 4 physical channels, which are emphasized in this article: temperature, vibration, electromagnetic fields, and light. We also discuss our methodology of automated model-generation and model-adaptation through evolutionary robotics principles.

Fuzzy logic navigation in multi agent systems

In this paper we present a methodology for decision making in multi agent system comprised of agents driven by repulsive force and attracting force. Navigation functions are expressed as a set of fuzzy rules obtained by fuzzy Lyapunov stability criteria, thus ensuring stability of the overall system. The goal of the proposed methodology is to create desired formations by moving agents from their initial positions to formation targets, while in the same time avoiding collisions. The destination targets are dynamically permutated as long as the required formation is achieved.

Collective search and decision-making for target localization

In this article we investigate the properties of collective search and decision-making in robotic swarm, inspired by a phenomena witnessed in bio-societies. The task of the proposed robotic swarm, comprising scouts and labourers, is to find the most hazardous target in a predefined area. Since in the proposed scenario the time interval for decision-making is predefined, robotic scouts have to detect targets within a particular amount of time. Hence, in the first part of the article, we define a model of scout movement that enhances the explored area. As we want to keep the searching process as simple as possible, and at the same time to mimic social insect behaviour, a particular type of correlated random walk is used for exploration. The second part of the article deals with modelling of the decision-making process in the robotic swarm. Using random walk theory we determine under which circumstances all agents (or a particular number of them) would be committed to the most hazardous target at the moment when the predefined time interval for decision-making expires.

A Grid-Based Approach to Formation Reconfiguration for a Class of Robots with Non-Holonomic Constraints

In this paper, we propose an architecture for safe, collision-free formation reconfiguration of a team of autonomous agents. Our approach is based on abstracting the agent formation by a rectangular grid. We develop a discrete-event coordination strategy that plans collisionfree transitions between arbitrarily defined formations. The coordination strategy implementation is based on a well-established control design methodology for manufacturing systems. Agent dynamics are modeled taking into account realistic, non-holonomic constraints. Using the concept of leader-to-formation stability, we propose controller tuning guidelines to ensure that the actual multiagent system behavior conforms to the discrete-event motion plan. Group navigation is achieved by integrating a way point controller with this novel grid-based formation reconfiguration scheme. The proposed hybrid architecture is capable of driving a group of agents through a cluttered environment, while maintaining specified formation constraints. We present simulated and experimental results verifying the validity of our methodology.

Decentralized grid-based algorithms for formation reconfiguration and synchronization

In this paper we present a formation synchronization and reconfiguration scheme based on distributed computation. In our previous work, we have introduced a formation abstraction by means of a virtual rectangular grid. The grid was used to ensure collision-free transitions between formations, coordinated by a centralized controller. This paper is an extension of that work, proposing control laws that are computed in a distributed way while still ensuring collision-free formation reconfigurations. Furthermore, we consider an extension of the group rendezvous problem. The agents are required to meet at the rendezvous point and establish consensus on formation state. Again, the grid abstraction is used to describe the formation state. Nonholonomic constraints of agent motion are taken into account explicitly. As our approach is communication-based, we also examine the effects of temporary communication loss.