Alcherio Martinoli

Related publications (269)

Online Kinematic and Dynamic Parameter Estimation for Autonomous Surface and Underwater Vehicles

Alcherio Martinoli, Anwar Ahmad Quraishi

One of the main challenges in underwater robot localization is the scarcity of external positioning references. Therefore, accurate inertial localization in between external position updates is crucial for applications such as underwater environmental sampling. In this paper, we present a framework for estimating kinematic and dynamic model parameters used for inertial navigation. Accurate values of these parameters result in better trajectory estimation. Our approach can run online as well as offline, with either choice providing different advantages. Further, our framework can correct errors in the past trajectory at each estimation step. By doing so, we are able to provide improved geo-references for past as well as future spatial measurements made by the robots. This has an impact on adaptive sampling methods, which use geo-tagged measurements for building local spatial distributions and choose future sampling points. We present results from field experiments and demonstrate improvement in trajectory estimation accuracy. We also experimentally show that with optimal parameter estimates, robots can tolerate longer intervals in external positioning updates for a specified acceptable level of estimation error.

2021

Robust Localization for Multi-robot Formations: An Experimental Evaluation of an Extended GM-PHD Filter

Michiaki Hirayama, Alcherio Martinoli, Alicja Barbara Roelofsen

This paper presents a thorough experimental evaluation of an extended Gaussian Mixture Probability Hypothesis Density filter which is able to provide state estimates for the maintenance of a multirobot formation, even when the communication fails and the tracking data are insufficient for maintaining a stable formation. The filter incorporates, firstly, absolute poses exchanged by the robots, and secondly, the geometry of the desired formation. By combining communicated data, information about the formation, and sensory detections, the resulting algorithm preserves accuracy in the state estimates despite frequent occurrences of long-duration sensing occlusions, and provides the necessary state information when the communication is sporadic or suffers from short-term outage. Differently from our previous contributions, in which the tracking strategy has only been tested in simulation, in this paper we present the results of experiments with a real multi-robot system. The results confirm that the algorithm enables robust formation maintenance in cluttered environments, under conditions affected by sporadic communication and high measurement uncertainty.

Springer Nature2021

3D Odor Source Localization Using a Micro Aerial Vehicle: System Design and Performance Evaluation

Chiara Ercolani, Alcherio Martinoli

2020

A Distributed Source Term Estimation Algorithm for Multi-Robot Systems

Alcherio Martinoli, Faezeh Rahbar

Finding sources of airborne chemicals with mobile sensing systems finds applications in safety, security, and emergency situations related to medical, domestic, and environmental domains. Given the often critical nature of all the applications, it is important to reduce the amount of time necessary to accomplish this task through intelligent systems and algorithms. In this paper, we extend a previously presented algorithm based on source term estimation for odor source localization for homogeneous multi-robot systems. By gradually increasing the level of coordination among multiple mobile robots, we study the benefits of a distributed system on reducing the amount of time and resources necessary to achieve the task at hand. The method has been evaluated systematically through high-fidelity simulations and in a wind tunnel emulating realistic and repeatable conditions in different coordination scenarios and with different number of robots.

2020

Particle Source Localization with a Low-Cost Robotic Sensor System: Algorithmic Design and Performance Evaluation

Xinxing Chen, Jian Huang, Ali Marjovi, Alcherio Martinoli

In this paper we tackle the problem of finding the source of particulate matter with a mobile robot equipped with a low-cost multi-channel optical particle counting sensor. The proposed method is based on the Infotaxis odor source localization algorithm and makes multiple modifications to adapt it to particle plumes. In particular, we propose three simple but efficient ways to fuse multiple probability maps associated with various particle sizes and use the resulted integrated map to guide the robot’s movements. A refined measurement data collection is conducted in a wind tunnel to fit the particle plume model. The method with three proposed integration strategies is evaluated in simulation and in the wind tunnel emulating realistic environmental conditions in a repeatable fashion. In particular, we have investigated the impact of two environmental parameters - the wind speed and source release rate on the algorithm performance. The proposed algorithm with the weighted multi-modality map integration strategy outperforms the original Infotaxis and the other two variants. In high wind speed, the proposed algorithm is able on average to estimate the source location with less than 1 meter error in the 80 m2 wind tunnel arena.

2020

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Over the past years, the field of small unmanned aerial vehicles has grown significantly and several applications have appeared, requiring always more autonomous flight. An important remaining challenge for fully autonomous unmanned aerial vehicles is collision avoidance between aircraft. In this work, we will compare two collision avoidance algorithms in terms of performance and robustness to sensor noise. We will leverage both experiments with real vehicles and calibrated, realistic simulations to get an insight of the effect of noise on collision avoidance. Our results show that although algorithms that use velocity as input are better in minimizing velocity variation and generally produces more efficient trajectories, they are less robust to perception noise. On the other hand, position-based algorithms that typically generate slower and longer avoidance maneuvers, become competitive at high levels of sensor noise.

SPRINGER INTERNATIONAL PUBLISHING AG2019

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2019

A robust localization system for multi-robot formations based on an extension of a Gaussian mixture probability hypothesis density filter

Alcherio Martinoli

This paper presents a strategy for providing reliable state estimates that allow a group of robots to realize a formation even when communication fails and the tracking data alone is insufficient for maintaining a stable formation. Furthermore, the tracking information does not provide the identity of the robot, therefore a simple fusion of tracking and communication data is not possible. We extend a Gaussian mixture probability hypothesis density filter to incorporate, firstly, absolute poses exchanged by the robots, and secondly, the geometry of the desired formation. Our method of combining communicated data, information about the formation and sensory detections is capable of maintaining the state estimates even when long-duration occlusions occur, and improves awareness of the situation when the communication is sporadic or suffers from short-term outage. The proposed method is validated using a high-fidelity simulator in scenarios with a formation of up to five robots. The results show that the proposed tracking strategy allows for sustaining formations in cluttered environments, with high measurement uncertainty and low quality communication.

2019

A Rule Synthesis Algorithm for Programmable Stochastic Self-Assembly of Robotic Modules

Bahar Haghighat, Alcherio Martinoli

Programmable self-assembly of modular robots offers promising means for structure formation at different scales. Rule-based approaches have been previously employed for distributed control of stochastic self-assembly processes. The assembly rate in the process directly depends on the concurrency level induced by the employed ruleset, i.e. the number of concurrent steps necessary to build one instance of the target structure. Our aim here is to design a formal synthesis algorithm to automatically derive rulesets of high concurrency for a given target structure composed of robotic modules. In the literature, self-assembly of (simulated or real) robotic modules has been realized through manually designed rulesets or manually adjusted rulesets generated by employing graph-grammar formalisms or metaheuristic methods. In this work, we employ an extended graph-grammar formalism, adapted for self-assembly of robotic modules, and propose a novel formal synthesis algorithm capable of generating rulesets for robotic modules by natively considering the morphology of their connectors. The synthesized rulesets induce a high level of concurrency in the self-assembly scheme by exploiting controlled information propagation, using solely local communication. Simulation results of microscopic (non-spatial) and submicroscopic (spatial) models of our robotic platform confirm higher performance of rulesets synthesized by our algorithm compared to related work in the literature.

SPRINGER INTERNATIONAL PUBLISHING AG2019

Adaptive Risk-Based Replanning For Human-Aware Multi-Robot Task Allocation With Local Perception

Alcherio Martinoli, Zeynab Talebpour

In this letter, we propose an adaptive risk-based replanning strategy in the context of multirobot task allocation for dealing with limitations of local perception and unpredicted human behavior. Our replanning method is based on the variations of social risk and humanmotion prediction uncertainty. The performance of our method is studied through an extensive suite of experiments of increasing complexity. Results obtained using both a high-fidelity simulator and real robots confirm that this strategy outperforms a nonadaptive replanning strategy in all cases with respect to the chosen social metrics. First, the overall performance of the team depends on its replanning strategy, and second on the available information about the humans. Although an adaptive replanning strategy with global perception leads to the best performance, it is computationally expensive and infeasible in some real applications. Local perception shows comparable results as long as updates of relevant human poses affecting a task's risk are available within the execution time of that task. Conversely, the nonadaptive replanning strategy is shown to have degraded results with global perception as decisions in this case can be based on outdated information that lead to invalid plans.

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2019