Lorenzo Scalera

Airbrush Robotic Painting System: Experimental Validation of a Colour Spray Model

This research is focused on developing a robotic painting system for artistic and graphic applications by means of an anthropomorphic robot equipped with an airbrush. Firstly, we introduce a mathematical colour spray model, based on a radially symmetric Gaussian distribution of colour intensity within the spray cone. Then, we present an experimental characterization of colour intensity in a spot, by varying the distance between airbrush and target surface and the spraying time. The experimental results of this pilot study validate the paint intensity model and provide the basis for further investigations.

An experimental setup to test dual-joystick directional responses to vibrotactile stimuli

In this paper we investigate the influence of the location of vibrotactile stimulation in triggering the response made using two handheld joysticks. In particular, we compare performance with stimuli delivered either using tactors placed on the palm or on the back of the hand and with attractive (move toward the vibration) or repulsive prompts (move away from the vibration). The experimental set-up comprised two joysticks and two gloves, each equipped with four pager motors along the cardinal directions. In different blocks, fifty-three volunteers were asked to move the joysticks as fast as possible either towards or away with respect to the direction specified by a set of vibrating motors. Results indicate that participants performed better with attractive prompts (i.e., responses were faster and with fewer errors in conditions where participants were asked to move the joysticks in the direction of the felt vibration) and that the stimulation delivered on the back of the hand from the gloves gives better results than the stimulation on the palm delivered by the joysticks. Finally, we analyse the laterality, the relation between correct responses and reaction times, the direction patterns for wrong responses and we perform an analysis on the Stimulus-Response Compatibility and on the training effect.

Efficient closed-form solution of the kinematics of a tunnel digging machine

In this work the kinematics of a large size tunnel digging machine is investigated. The closed-loop mechanism is made by 13 links and 13 class 1 couplings, 7 of which are actuated. This kind of machines are commonly used to perform ground drilling for the placement of reinforcement elements durin g the construction of tunnels. The direct kinematic solution is obtained using three methods: the first two are based on the numerical solution of the closure equation written usin g the Denavit-Hartenberg convention, while the third is base d on the definition and solution in closed form of an equivalent spherical mechanism. The procedures have been tested and implemented with reference to a real commercial tunnel digging machine. The use of the proposed method for the closed–form solution of direct kinematics allows to obtain major reduction of the computation time in comparison with the standard numerical solution of the closure equation.

Evolution of a Dynamic Model for Flexible Multibody Systems

In this paper the evolution of a dynamic model for flexible multibody systems is presented. This model is based on an equivalent rigid-link system (ERLS) and, in the first formulation, has been exploited together with a FEM approach for the modeling of planar flexible-link mechanisms. Subsequently, the model has been linearized in order to be applied for control purposes and then it has been extended to the three-dimensional case. In the last years, a modal approach has been developed and the ERLS concept has been applied in order to formulate the dynamics of spatial flexible mechanisms with a component mode synthesis (CMS) technique.

A tracked mobile robotic lab for monitoring the plants volume and health

Precision agriculture has been increasingly recognized for its potential ability to improve agricultural productivity, reduce production cost, and minimize damage to the environment. In this work, the current stage of our research in developing a mobile platform equipped with different sensors for orchard monitoring and sensing is presented. In particular, the mobile platform is conceived to monitor and assess both the geometric and volumetric conditions as well as the health state of the canopy. To do so, different sensors have been integrated and effective data-processing algorithms implemented for a reliable crop monitoring. Experimental tests have been performed allowing to obtain both a precise volume reconstruction of several plants and an NDVI mapping suitable for vegetation state evaluations.

Experimental Evaluation of Vibrotactile Training Mappings for Dual-Joystick Directional Guidance

Two joystick-based teleoperation is a common method for controlling a remote machine or a robot. Their use could be counter-intuitive and could require a heavy mental workload. The goal of this paper is to investigate whether vibrotactile prompts could be used to trigger dual-joystick responses quickly and intuitively, so to possibly employ them for training. In particular, we investigate the effects of: (1) stimuli delivered either on the palm or on the back of the hand, (2) with attractive and repulsive mappings, (3) with single and sequential stimuli. We find that 38 participants responded quicker and more accurately when stimuli were delivered on the back of the hand, preferred to move towards the vibration. Sequential stimuli led to intermediate responses in terms of speed and accuracy.

A Look-Ahead Trajectory Planning Algorithm for Spray Painting Robots with Non-spherical Wrists

This paper proposes an innovative trajectory planning algorithm aimed at limiting the speed and accelerations for robots for spray painting. The algorithm can be applied to robots that, due to their kinematic structure, do not offer a closed-form solution to the inverse kinematic problem. The trajectory planning problem is cast for a predefined path, which can be described by a B-splines. Such path is then described by a set of discrete samples, that are filtered to achieve end-effector speed and joint acceleration constraints. The proposed method has been applied to a commercially available painting robot equipped with a non-spherical wrist. The experimental results show a reduction of the joint speed, acceleration, and a sensible reduction of the motor efforts.

Preloaded Structures for Space Exploration Vehicles

This paper is devoted to the design and simulation of a rover equipped with 4 preloaded structure legs. Space exploration vehicles (rovers) are employed for moving sensors, transporting planet samples and manipulating small modules. In order to perform such tasks with high accuracy, high mechanical stiffness frames are required. At the same time, a certain degree of compliance is required to mitigate mechanical stress caused by motion over a rough surface or in case of unexpected collisions. For this reasons, preloaded structures could represent a suitable solution. They present sharp stiff-to-compliant transitions at design-determined load thresholds. The paper describes the dynamic model of a single rover leg, the simulation of an impact event and the overall design of system.

Busker Robot: A Robotic Painting System for Rendering Images into Watercolour Artworks

In this paper we present Busker Robot, an innovative robotic painting system for rendering digital images into watercolour artworks. The installation is composed of a 6-degrees of freedom collaborative robot and a series of image processing and path planning algorithms. These non-photorealistic techniques elaborate a digital image into a sequence of trajectories that the robot reproduces on paper. Our painting machine is the first robotic system that uses watercolour technique for artistic rendering. The resulting artworks have been considered of interest by the public and the press in recent international fairs and exhibitions.

Watercolour Robotic Painting: a Novel Automatic System for Artistic Rendering

In this paper, we present a novel robotic system that produces watercolour paintings by means of a 6-degree-of-freedom collaborative robot. After an analysis of traditional watercolour, different non-photorealistic rendering techniques are applied in order to elaborate digital images into artworks. Several algorithms, aimed at processing both the backgrounds and the details, are implemented. Then, the resulting rendering is converted into a sequence of trajectories that the robot reproduces on paper. During the process, the artist controlling the system can change both the algorithm parameters and the hardware variables (e.g. brush type, colour dilution, etc.) in order to obtain a different artistic rendering. The challenge is indeed not to faithfully reproduce an image but to introduce a personal and original contribution to the artwork. The robotic painting system described in this paper was named “Busker Robot” and it is the first automatic system that uses the watercolour technique for artistic rendering. It was installed at the “Algorithmic Arts and Robotics” exhibition during the international event “Trieste Next” (Trieste, Italy, September 2017) and won an Honorable Mention at the 2018 International Robotic Art Competition (RobotArt).