Abstract Collaborative robots are increasingly common in modern production systems, since they allow to merge the productivity of automated systems with the flexibility and dexterity of manual ones. The direct interaction between the human and the robot can be the greatest advantage and the greatest limit of collaborative systems at the same time, depending on how it affects human factors like ergonomics and mental stress. This work presents an overview of collaborative robotics considering three main dimensions: robot features, modern production systems characteristics and human factors. A literature review on how such dimensions interact is addressed and a discussion on the current state of the art is presented, showing the topics that have been already widely explored and the research gaps that should be fulfilled in the future. 

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Human factors in cobot era: a review of modern production systems features

Vibration energy harvesters in industrial applications usually take the form of cantilever oscillators covered by a layer of piezoelectric material and exploit the resonance phenomenon to improve the generated power. In many aeronautical applications, the installation of cantilever harvesters is not possible owing to the lack of room and/or safety and durability requirements. In these cases, strain piezoelectric harvesters can be adopted, which directly exploit the strain of a vibrating aeronautic component. In this research, a mathematical model of a vibrating slat is developed with the modal superposition approach and is coupled with the model of a piezo-electric patch directly bonded to the slat. The coupled model makes it possible to calculate the power generated by the strain harvester in the presence of the broad-band excitation typical of the aeronautic environment. The optimal position of the piezoelectric patch along the slat length is discussed in relation with the modes of vibration of the slat. Finally, the performance of the strain piezoelectric harvester is compared with the one of a cantilever harvester tuned to the frequency of the most excited slat mode.

/pdf/vibration-energy-harvesting-by-means-of-piezoelectric-1jc7fk04.pdf

Vibration Energy Harvesting by Means of Piezoelectric Patches: Application to Aircrafts

Direct visual servoing and interaction control for a two-arms on-orbit servicing spacecraft

Collision risk assessment and automatic obstacle avoidance strategy for teleoperation robots

The vibrations of a Cartesian cutting machine caused by the pneumatic tool are studied with a sub-system approach. The cutting head is modeled as an equivalent robot arm which is able to mimic the measured resonances. The Cartesian structure is modeled according to the mode superposition approach. A global analytical model is obtained coupling the aforementioned models, and is solved in MATLAB. The full model is able to predict the variations in the response of the machine to tool excitation that are caused by the motion of the head along the rails of the Cartesian structure. Comparisons with experimental results are made.

https://www.mdpi.com/2075-1702/9/8/162/pdf

Analysis and Control of Vibrations of a Cartesian Cutting Machine Using an Equivalent Robotic Model

This paper deals with the control of the vibrations of an automatic cutting machine with a cartesian kinematic chain. A particular application of the method of structural modifications is considered, since a small number of frequency response function is available. The Sherman-Morrison formula is used to predict the effect of a tuned vibration absorber (TVA) on the vibrations of the machine generated by the cutting tool; the advantages and the limits of this method are discussed. In order to improve the cutting speed, the cutting head moves along the linear guides with relevant accelerations that can excite the TVA, motion induced vibrations are analyzed with a lumped element model.

Control of the Vibrations of a Cartesian Automatic Machine

In the last years, collaborative human-robot applications have become more and more appealing thanks to the robot’s easiness of programming and the promise of increasing precision and safety. However, by combining two resources (the cobot and the human operator) there is a problem of safety since cobot and human operator have to work in the same workspace. To ensure human safety, the distance between robot and operator must be assessed and the robot must adapt accordingly either by reducing its velocity or by modifying its trajectory. In this paper, we propose a new online method to adapt the trajectory of the robot to the human movements using a single depth camera. This algorithm eliminates the robot from the scene using a simple calibration process. Then, it interpolates the shared workspace, captured by the depth camera, using Radial Basis Functions (RBFs). The result is a continuous function that is representative of the risk of collision with obstacles on the plane. Its gradient is used as a repulsive potential in the Artificial Potential Field (APF) method to generate the path. This method eliminates the need to calculate the distance between operator and robot since it is intrinsically considered in the potentials. Results shows the validity of the method. 

A Radial Basis Functions approach to collision avoidance in collaborative tasks

In food industry, the market demand for product customization is increasing However, this task is mostly demanded to skilled operators that are very difficult to find in peak production periods Fortunately, some tasks, such as writing customized text and drawings on food, can be fulfilled by industrial robots

Giulio Cipriani

Papers

Control of the Vibrations of a Cartesian Automatic Machine

A Radial Basis Functions approach to collision avoidance in collaborative tasks

Optimal Path Planning of a Redundant Robot in Food Industry