New tools for human robot collaboration
In the context of HR-recycler project the collaboration between human and robot is a crucial aspect allowing a safe and dynamic sharing of the operational area. Due to peculiar environment conditions of the recycling factory that include presence of dust, dirty surfaces, and a not completely structured setup, the use of a robust and flexible device for the safety detection and monitoring in the classification and disassembling areas is required.
After an extended investigation of the several options present on the market, a specific solution based on radar technology by the company Inxpect has been selected. This product presents interesting features that fit quite well with the requirements of recycling factory: resistance to environmental disturbances, high sensitivity, 3D safety monitoring, several configurable fields of detection.
The radar (Radio Detecting and Ranging) is a well-known detection system that uses radio waves for detection and localization. It can measure the distance, angle, or velocity of objects and it consists of a transmitter, a receiver and a processor to carry out the low-level computations. Radio waves (pulsed or continuous) emitted from the transmitter reflect off the object and return to the receiver, giving information about the object location and speed. Electromagnetic waves are extremely resistant to disturbances like dust, debris, smoke or darkness, and they travel close to the speed of light (300,000 km/s).
Figure 1: safety radar sensor and its own controller
For the HR-Recycler projects after some preliminary feasibility studies, COMAU together with the sensors’ supplier and the involved partners opted for a solution that includes six different radar sensors placed in specific spots of the cell. These are arranged to cover all the possible interference area between human and machine, in particular monitoring the dangerous area where an industrial and not-collaborative robot (COMAU NJ 220) is used in the classification process for the pick and place of WEEE components.
The safety signals from the sensor are collected in a specific controller that send the output to a safe PLC. The robot controller is in turn connected to the safe PLC trough safe signals allowing an overall safe management of the cell. When the operator accesses a safeguarded area, the sensor triggers the movement and the robot is stopped immediately; moreover, until the presence is detected inside the specific area (even micro movements as breathing can be detected), the system is prevented from restarting, avoiding in this way any dangerous condition for the worker.
The two different monitoring states of the sensors, namely access and presence of the worker to/in the dangerous area, are showed in the following pictures:
Figure 2: access monitoring of HR-recycler robot station
If the worker enters inside the working area the safety radar sensors detect its movement (figure 2) and consequently stop the robot; after the access, the sensors change their configuration (figure 3) and prevent the restart of the system until the worker is inside the area.
Figure 3: presence monitoring of HR-recycler robot station
The complete cell will be setup and tested in the following months in COMAU premises, where a replica of the real recycling cell has been arranged for testing purposes. After the assessment of the overall solution the entire cell will be moved and deployed in the end user facilities for the final evaluation of the industrial process.