Tomislav Haus

Bio: Tomislav Haus is an academic researcher from University of Zagreb. The author has contributed to research in topics: Robot & Multirotor. The author has an hindex of 11, co-authored 23 publications receiving 250 citations.

Aerial-ground robotic system for autonomous delivery tasks

Abstract: In this paper we present a study of a robotic system that consists of an unmanned aerial vehicle equipped with a pair of manipulator arms (MMUAV), and unmanned ground vehicles (UGVs). The envisioned application scenario includes autonomous packet transportation, where MMUAV is used for picking/placing packets, while both MMUAV and UGV can be used for packet transportation, with different energy consumption profiles. We propose a reactive method for decentralized task planning and coordination of robots using hierarchical task decomposition based on TAEMS framework. Our approach takes into account low-level motion-planning aspects of the system as well as high-level mission specification, making this a multi-layered system. For low-level planning we use sampling-based planner combined with obstacle-free trajectory generation. Methods are verified in simulations and on an experimental testbed, using 3D Robotics quadcopter and Pioneer 3DX mobile robots with the results showing stability and robustness of the presented methods.

Mathematical Modelling and Control of an Unmanned Aerial Vehicle with Moving Mass Control Concept

Abstract: In this paper we present a novel concept of attitude control for a multi-rotor unmanned aerial vehicle by actively controlling its center of gravity. This research is a part of our efforts to build a heavy lift multi-rotor platform capable of carrying over 50 kg of payload. To that end, we propose using miniature two-stroke combustion engines to supply the necessary lift and combine them with moving masses used to control the vehicle attitude. In this paper we present a complete nonlinear dynamical model of such a vehicle and use it to derive the transfer functions of roll and pitch dynamics. Furthermore, we formulate a detailed root-locus based stability and sensitivity analysis of the proposed control scheme and discuss its underlining effect on the mechanical parameter design. We present the experimental testbed, consisted of the vehicle mounted on a 2 degrees of freedom gimbal, and derive necessary conditions for testbed parameters in order to match the testbed and free-flight quadrotor dynamics. Finally, we present simulation results from a Gazebo based simulator and experimental results of the testbed. Both results confirm the findings of our mathematical analysis.

A robotic system for researching social integration in honeybees.

Abstract: In this paper, we present a novel robotic system developed for researching collective social mechanisms in a biohybrid society of robots and honeybees. The potential for distributed coordination, as observed in nature in many different animal species, has caused an increased interest in collective behaviour research in recent years because of its applicability to a broad spectrum of technical systems requiring robust multi-agent control. One of the main problems is understanding the mechanisms driving the emergence of collective behaviour of social animals. With the aim of deepening the knowledge in this field, we have designed a multi-robot system capable of interacting with honeybees within an experimental arena. The final product, stationary autonomous robot units, designed by specificaly considering the physical, sensorimotor and behavioral characteristics of the honeybees (lat. Apis mallifera), are equipped with sensing, actuating, computation, and communication capabilities that enable the measurement of relevant environmental states, such as honeybee presence, and adequate response to the measurements by generating heat, vibration and airflow. The coordination among robots in the developed system is established using distributed controllers. The cooperation between the two different types of collective systems is realized by means of a consensus algorithm, enabling the honeybees and the robots to achieve a common objective. Presented results, obtained within ASSISIbf project, show successful cooperation indicating its potential for future applications.

Can UAV and UGV be best buddies? Towards heterogeneous aerial-ground cooperative robot system for complex aerial manipulation tasks

Abstract: This paper presents the results of our efforts to build a heterogeneous robotic system capable of executing complex disaster response and recovery tasks. We aim to explore high level task scheduling and mission planning algorithms that enable various types of robots to cooperate together, utilizing each others strengths to yield a symbiotic robotic system. In the proposed scenario, a ground vehicle and an aerial robot work together to close a valve in a disaster stricken industrial environment. To that end we use TAEMS framework in order to specify interrelationships between mission subtasks and develop an effective scheduling and coordination mechanism, inspired by Generalized Partial Global Planning. We present simulation results with two different outcomes that show cooperative capabilities of the system.

Design considerations for a large quadrotor with moving mass control

Abstract: In this paper we present our ongoing efforts to build a heavy lift multirotor platform capable of lifting over 50kg of payload. Such a system requires a paradigm shift in the design of the UAV. Therefore we propose using miniature two stroke internal combustion engines to supply the necessary lift and endurance and combine them with a novel control concept based on the variations of the center of gravity (CoG) of the system. In this paper we present a detailed stability and sensitivity analysis of the proposed control scheme and discuss its underlining effect on the construction design parametrization. We present simulation results from a Gazebo based simulator that confirm the results of our mathematical analysis.

Overview and Current Status of Remote Sensing Applications Based on Unmanned Aerial Vehicles (UAVs)

Abstract: Remotely Piloted Aircraft (RPA) is presently in continuous development at a rapid pace. Unmanned Aerial Vehicles (UAVs) or more extensively Unmanned Aerial Systems (UAS) are platforms considered under the RPAs paradigm. Simultaneously, the development of sensors and instruments to be installed onboard such platforms is growing exponentially. These two factors together have led to the increasing use of these platforms and sensors for remote sensing applications with new potential. Thus, the overall goal of this paper is to provide a panoramic overview about the current status of remote sensing applications based on unmanned aerial platforms equipped with a set of specific sensors and instruments. First, some examples of typical platforms used in remote sensing are provided. Second, a description of sensors and technologies is explored which are onboard instruments specifically intended to capture data for remote sensing applications. Third, multi-UAVs in collaboration, coordination, and cooperation in remote sensing are considered. Finally, a collection of applications in several areas are proposed, where the combination of unmanned platforms and sensors, together with methods, algorithms, and procedures provide the overview in very different remote sensing applications. This paper presents an overview of different areas, each independent from the others, so that the reader does not need to read the full paper when a specific application is of interest

A Systems and Control Perspective of CPS Security

Abstract: The comprehensive integration of instrumentation, communication, and control into physical systems has led to the study of Cyber-Physical Systems (CPSs), a field that has recently garnered increased attention. A key concern that is ubiquitous in CPS is a need to ensure security in the face of cyber attacks. In this paper, we carry out a survey of systems and control methods that have been proposed for the security of CPS. We classify these methods into three categories based on the type of defense proposed against the cyberattacks: prevention, resilience, and detection & isolation. A unified threat assessment metric is proposed in order to evaluate how CPS security is achieved in each of these three cases. Also surveyed are the risk assessment tools and the effect of network topology on CPS security. Furthermore, an emphasis has been placed on power and transportation applications in the overall survey.

Stability and control of a quadrocopter despite the complete loss of one, two, or three propellers

Abstract: This paper presents periodic solutions for a quadrocopter maintaining a height around a position in space despite having lost a single, two opposing, or three propellers. In each case the control strategy consists of the quadrocopter spinning about a primary axis, fixed with respect to the vehicle, and tilting this axis for translational control. A linear, time- invariant description of deviations from the attitude equilibrium is derived, allowing for a convenient cascaded control design. The results for the cases of losing one and two propellers are validated in experiment, while the case of losing three propellers is validated in a nonlinear simulation. These results have application in multicopter fault-tolerant control design, and also point to possible design directions for novel flying vehicles.

Autonomous Exploration and Mapping System Using Heterogeneous UAVs and UGVs in GPS-Denied Environments

Abstract: In this paper, we present a novel integrated vehicular system using collaborative unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) for autonomous exploration, mapping, and navigation in GPS-denied 3-dimensional (3-D) unknown environments. The system implements a novel two-layered exploration strategy to decompose the perception task into a coarse exploration layer and a fine mapping layer. The coarse exploration makes use of a UGV to carry out fast autonomous exploration and active 2.5D simultaneous localization and mapping (SLAM) to generate a coarse environment model, which serves as a navigation reference for subsequent complementary 3-D fine mapping conducted by a UAV. The two layers share a novel optimized exploration path planning and navigation framework, which provides optimal exploration paths and integrates the collaborative exploration and mapping efforts through an OctoMap-based volumetric motion planning interface. The proposed system provides an efficient pipeline of fast environment perception taking advantages of the agility of the UAVs as well as the powerful computation resource aboard UGVs, also allowing assistive local perception with augmented object information when necessary. The effectiveness of our system is verified by both simulations and experiments, which demonstrate its capability of implementing heterogeneous UAV and UGV collaborative exploration and structural reconstruction of the environments through active SLAM, providing optimized perception for navigation tasks.

Design, Modeling, and Control of an Aerial Robot DRAGON: A Dual-Rotor-Embedded Multilink Robot With the Ability of Multi-Degree-of-Freedom Aerial Transformation

Abstract: In this letter, we introduce a novel transformable aerial robot called DRAGON, which is a dual-rotor-embedded multilink robot with the ability of multi-degree-of-freedom (DoF) aerial transformation. The new aerial robot can control the full pose in $\mathsf {SE}(3)$ regarding the center of gravity (CoG) of multilinks and can render the multi-DoF aerial transformation, which is accomplished by the original two-DoF force vectoring mechanism on each link called the dual-rotor gimbal module. The dynamics is derived on the basis of the special definition of CoG orientation, followed by a control method decoupled into thrust force control and rotor gimbal control. In the thrust force control, the minimum force norm is considered to avoid force saturation, and the rotor gimbal control method is developed to enhance both translational and rotational stabilities during hovering and large-scale aerial transformation. The prototype composed of four links is constructed, and associated preliminary experiments are performed. The feasibility of the novel mechanical design and the proposed control method for the aerial transformation is demonstrated.