Going with the flow

The pro­duc­tion halls are bustling: com­po­nents must arrive at the pro­duc­tion line just in time, pack­aging mate­rials at the pack­aging machine, pal­lets in the ware­house. Rail-bound sys­tems such as classic AGV sys­tems are sim­ilar to trains or trams and follow pre­de­fined routes. Freely ­nav­i­gating vehi­cles, so-called autonomous mobile robots (AMR), have flex­ible route deter­mi­na­tion. Together with the people, other AGV ­sys­tems and machines in their dynam­i­cally changing envi­ron­ment, both types of AGV ­sys­tems must be one thing above all: safe. But how does one best bring together pro­duc­tivity and safety in mobile robotics?

Following markings – but safely

“The com­plexity of the AGV sys­tems increases with their abil­i­ties,” states Manuel Schön, ­Robotics Product Man­ager at Pilz. “Mod­ular safety solu­tions enhance pro­duc­tivity indi­vid­u­ally for each appli­ca­tion.” Rail-bound AGV sys­tems must main­tain defined warning and safety zones according to their speed, which can lead to a stop in the event of an obstacle, for example. The safety laser scanner PSEN­scan from Pilz per­forms this type of safe­guarding and, at the same time, the pro­duc­tive area mon­i­toring for col­li­sion pro­tec­tion. If addi­tional safety func­tions such as the emer­gency stop are to be cov­ered, there is a flex­ible solu­tion package com­prising PSEN­scan and the mod­ular safety relay myPNOZ.

More safety zones

“Freely nav­i­gating mobile plat­forms can drive around obsta­cles or people without stop­ping. As a result, the required safety func­tions are more com­plex,” explains Schön. Safe laser scan­ners thus con­stantly reg­ister their sur­round­ings. The data can be directly read out via the ROS (Robot Oper­ating System) pack­ages from PSEN­scan. Users can use these for their own SLAM algo­rithm (Simul­ta­neous Local­i­sa­tion and Map­ping), thereby cre­ating maps of the envi­ron­ment for the nav­i­ga­tion.

“PSEN­scan has up to 70 pro­tected fields, which allows dynamic pro­tected field adjust­ment: These safety zones are larger at high speeds to detect obsta­cles in good time. And shorter at slow speeds to avoid stand­stills when­ever pos­sible,” states Schön. “This allows the AGV system to move effi­ciently.” The con­fig­urable small ­con­troller PNOZ­multi with motion mon­i­toring module (expan­sion module for drive mon­i­toring) reli­ably per­forms the selec­tion of the cor­re­sponding safety zone.

No free ride for manipulationpulation

“AGV sys­tems com­mu­ni­cate wire­lessly with their master con­troller in pro­duc­tion halls,” says Schön. “This makes them sus­cep­tible to external attacks or manip­u­la­tion. Map data can be queried, and in the worst case AGV sys­tems and thus ongoing pro­duc­tion can even be stopped.” Indus­trial secu­rity from Pilz is on board. The indus­trial fire­wall Secu­ri­ty­Bridge ­reli­ably ensures that no unau­tho­rised par­ties can access the internal IT net­work of the mobile plat­form during oper­a­tion. Making mod­ular safety – and secu­rity – work, even when mobile!