2,816 research outputs found
Robust Cooperative Manipulation without Force/Torque Measurements: Control Design and Experiments
This paper presents two novel control methodologies for the cooperative
manipulation of an object by N robotic agents. Firstly, we design an adaptive
control protocol which employs quaternion feedback for the object orientation
to avoid potential representation singularities. Secondly, we propose a control
protocol that guarantees predefined transient and steady-state performance for
the object trajectory. Both methodologies are decentralized, since the agents
calculate their own signals without communicating with each other, as well as
robust to external disturbances and model uncertainties. Moreover, we consider
that the grasping points are rigid, and avoid the need for force/torque
measurements. Load distribution is also included via a grasp matrix
pseudo-inverse to account for potential differences in the agents' power
capabilities. Finally, simulation and experimental results with two robotic
arms verify the theoretical findings
An Omnidirectional Aerial Platform for Multi-Robot Manipulation
The objectives of this work were the modeling, control and prototyping of a new fully-actuated
aerial platform. Commonly, the multirotor aerial platforms are under-actuated vehicles, since the
total propellers thrust can not be directed in every direction without inferring a vehicle body rotation.
The most common fully-actuated aerial platforms have tilted or tilting rotors that amplify
the aerodynamic perturbations between the propellers, reducing the efficiency and the provided
thrust. In order to overcome this limitation a novel platform, the ODQuad (OmniDirectional
Quadrotor), has been proposed, which is composed by three main parts, the platform, the mobile
and rotor frames, that are linked by means of two rotational joints, namely the roll and pitch
joints. The ODQuad is able to orient the total thrust by moving only the propellers frame by
means of the roll and pitch joints.
Kinematic and dynamic models of the proposed multirotor have been derived using the Euler-
Lagrange approach and a model-based controller has been designed. The latter is based on two
control loops: an outer loop for vehicle position control and an inner one for vehicle orientation
and roll-pitch joint control. The effectiveness of the controller has been tested by means of numerical
simulations in the MATLAB
c SimMechanics environment. In particular, tests in free motion
and in object transportation tasks have been carried out. In the transportation task simulation, a
momentum based observer is used to estimate the wrenches exchanged between the vehicle and
the transported object.
The ODQuad concept has been tested also in cooperative manipulation tasks. To this aim, a
simulation model was considered, in which multiple ODQuads perform the manipulation of a
bulky object with unknown inertial parameters which are identified in the first phase of the simulation.
In order to reduce the mechanical stresses due to the manipulation and enhance the system
robustness to the environment interactions, two admittance filters have been implemented: an external
filter on the object motion and an internal one local for each multirotor.
Finally, the prototyping process has been illustrated step by step. In particular, three CAD
models have been designed. The ODQuad.01 has been used in the simulations and in a preliminary
static analysis that investigated the torque values for a rough sizing of the roll-pitch joint
actuators. Since in the ODQuad.01 the components specifications and the related manufacturing
techniques have not been taken into account, a successive model, the ODQuad.02, has been designed.
The ODQuad.02 design can be developed with aluminum or carbon fiber profiles and 3D
printed parts, but each component must be custom manufactured. Finally, in order to shorten the
prototype development time, the ODQuad.03 has been created, which includes some components
of the off-the-shelf quadrotor Holybro X500 into a novel custom-built mechanical frame
Safety-Aware Human-Robot Collaborative Transportation and Manipulation with Multiple MAVs
Human-robot interaction will play an essential role in various industries and
daily tasks, enabling robots to effectively collaborate with humans and reduce
their physical workload. Most of the existing approaches for physical
human-robot interaction focus on collaboration between a human and a single
ground robot. In recent years, very little progress has been made in this
research area when considering aerial robots, which offer increased versatility
and mobility compared to their grounded counterparts. This paper proposes a
novel approach for safe human-robot collaborative transportation and
manipulation of a cable-suspended payload with multiple aerial robots. We
leverage the proposed method to enable smooth and intuitive interaction between
the transported objects and a human worker while considering safety constraints
during operations by exploiting the redundancy of the internal transportation
system. The key elements of our system are (a) a distributed payload external
wrench estimator that does not rely on any force sensor; (b) a 6D admittance
controller for human-aerial-robot collaborative transportation and
manipulation; (c) a safety-aware controller that exploits the internal system
redundancy to guarantee the execution of additional tasks devoted to preserving
the human or robot safety without affecting the payload trajectory tracking or
quality of interaction. We validate the approach through extensive simulation
and real-world experiments. These include as well the robot team assisting the
human in transporting and manipulating a load or the human helping the robot
team navigate the environment. To the best of our knowledge, this work is the
first to create an interactive and safety-aware approach for quadrotor teams
that physically collaborate with a human operator during transportation and
manipulation tasks.Comment: Guanrui Li and Xinyang Liu contributed equally to this pape
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