Collaborative Robots

Index

• Industrial Context
• Robot vs Cobot
• Our Goal
• Equipment

Industrial Context

European industry is currently engaged in several challenges. First of all, re-shoring of production facilities has become a new important target to be competitive on the world markets. At the same time, ageing of workforce poses a challenge for health and safety in our countries, where a great deal of effort is now put into finding new ways to relieve people from repetitive, alienating and strenuous jobs.

Typically, industrial robots are used for repetitive tasks in a fixed working cell and the entire system is hardly reconfigurable. On the contrary, collaborative robots, or cobots, with their low installation cost and a high degree of flexibility, become versatile systems that can be set up-and-running in limited time. Additionally, and more importantly, their intrinsic safety-related features remove (or reduce) the need for protective fences, resulting in a negligible impact on the factory layout, without considering the significant potential in sharing a working environment with human operators. Moreover, cobots may be installed on top of an autonomous mobile platform, able to safely navigate in unstructured environments, and allowing the robotic system to transport material and serve multiple tasks/machines at once.

Robot vs Cobot

“An apparatus and method for direct physical interaction between a person and a general purpose manipulator controlled by a computer.”

1997 US Patent 5,952,796

Differently from the industrial robot, where interaction with humans is severely prohibited and prevented by protective barriers, collaborative robot are purposely designed to share the same workspace with human operators, under some limitations:

• the operator must have full control of the robot;
• in case of vicinity or interaction, speed and force exerted by the robot must be limited (or zeroed) by suitable sensors or other means.

European directives and standards are legislative instruments that guarantee the protection of people’s health at the workplace, and possibly that of the environment too. EU directives establish the essential safety requirements, while technical standards indicate the recommended solutions to achieve them. The scheme below shows the main standards and directives related to the safety of people working in environments with robots that perform collaborative operations, namely operations where the human operator is allowed to enter a monitored shared workspace and possibly interact with the robot.

In particular, ISO 10218-1/2 define four types of collaborative operations that are allowed:

• safety-related monitored stop: the robot motion ceases before an operator enters the collaborative workspace and autonomously resumes once the operator has exited;
• hand guiding: the operator uses a hand-operated device to transmit motion commands to the robot system;
• speed and distance monitoring: the robot system and operator may concurrently move in the collaborative workspace, while always maintaining a protective separation distance;
• power and force limiting: physical contact between the robot system and an operator can occur either intentionally or unintentionally. Risk reduction is achieved, either through inherently safe means in the robot or through a safety-related control system.

ISO/TS 15066, which is not a norm but a Technical Specification, analyse in further details the safety and efficiency of these operations, introducing the concept of dynamically changing thresholds, such as minimum safety distances or impact forces.
In general, using a collaborative robot does not make an application collaborative! It is important to remember that even if every single robot and component satisfies safety requirements, the risk assessment must be always carried out considering the whole application and context.

Our Goal

The main focus of our research group is the development and study of high-level, sophisticated applications that leverage this kind of technology. To this purpose, we resort to market-available appliances, such as collaborative robotic arms, autonomous mobile platforms or collaborative grippers, and test their capabilities and limitation by comparing different control methodologies, starting from industrial programming standards up to ROS-based open-source packages.
Investigated topics include, among the others, computer-vision-based applications to move and manipulate objects in unstructured environments, co-manipulation, smart material transportation and management (palletizing, loading, disposal, etc..) and support to assembly lines.
Our activities are often carried out in collaboration with industrial partners interested in evaluating new options to improve their productivity. Find below an up-to-date list of projects in this context:

• ROSSINI, in collaboration with IMA S.p.A. – R&I dept (in progress);
• FlexCobot, in collaboration with Bi–Rex Competence Center, 2020-2021;
• COORSA, in collaboration with Por-Fesr Emilia – Romagna 2014/2020.

Equipment