Safety Options for Robotic Systems

Safe­ty equip­ment is an essen­tial part of any robot­ic sys­tem or work­cell to ensure the pro­tec­tion of your work­ers while your robot is in motion. There are a vari­ety of safe­ty options on the mar­ket today that will keep work­ers safe – phys­i­cal bar­ri­ers like fenc­ing, arc glare shield, and dividers, as well as invis­i­ble bar­ri­ers like light cur­tains and area scanners.

Fenc­ing, Arc Glare Shields and Dividers

These are the most com­mon safe­ty option. Fenc­ing pro­vides a phys­i­cal bar­ri­er that clos­es off the area around the robot itself, allow­ing peo­ple to see the set perime­ter of the work cell or sys­tem. These cages are sev­er­al feet tall, and their design depends on the appli­ca­tion and how much area needs to be safeguarded. 

Fenc­ing may also be cov­ered with cur­tains to keep debris from being thrown out­side of the perime­ter of the work cell or sys­tem. Some cur­tains pro­tect against debris and oth­ers pro­tect from arc glare. The bril­liant light present dur­ing an arc weld­ing process can cause eye irri­ta­tion or reti­nal dam­age if it is observed for long peri­ods. Weld­ing cur­tains pro­tect your eyes in a way sim­i­lar to a pair of sun­glass­es. Arc glare cur­tains, like Wil­son Spec­tra cur­tains, are avail­able in shades of yel­low, orange, grey and brown, and they are usu­al­ly fixed to the three sides of the work cell fenc­ing. This safe­ty option will absorb, fil­ter and scat­ter the light from the arc weld, reduc­ing the glare and improv­ing the work­ing envi­ron­ment for every­one in a weld­ing shop. 

Unlike arc glare shields, which are par­tial­ly trans­par­ent, met­al dividers work in a dif­fer­ent capac­i­ty to pro­tect a worker’s eyes from the impact of arc glare. When a 180-degree index­ing table is fixed inside the sys­tem, it will have a tall, ver­ti­cal met­al divider fixed in the cen­ter of the table, which blocks the robot oper­a­tion from the oper­a­tor. This not only pro­tects the eyes from arc glare, but also weld spray. 

Light Cur­tains and Area Scanners

Fenc­ing tends to have three sides, with one area open for load­ing parts. This area needs a dif­fer­ent set of robot­ic safe­ty options, like light cur­tains or an area scanner. 

Light cur­tains have an emit­ter and receiv­er that are lined up across from each oth­er. Once the light cur­tains are lined up and func­tion­al, they send an invis­i­ble beam across the area and give the robot a sig­nal that it is okay to oper­ate. If this area is invad­ed, the light cur­tains send a sig­nal to the robot to stop. This is caused by a break in the fence cir­cuit between the robot and the light cur­tains. When the fence cir­cuit is bro­ken, the robot can still be moved with a teach pen­dant.

SICK makes a vari­ety of light cur­tains used by Robots​.com in sev­er­al of their work cells and robot sys­tems. Accord­ing to SICK, safe­ty light cur­tains are a cost-effec­tive way to pro­tect the access point for your robot sys­tem entry point. They come in sev­er­al dif­fer­ent sizes, from com­pact to robust, and even have dif­fer­ent resis­tance variants. 

An area scan­ner is sim­i­lar to light cur­tains. How­ev­er, instead of hav­ing one spe­cif­ic area where light is trans­mit­ting from an emit­ter to receiv­er, an area scan­ner is one small device that is can scan an entire area. SICK also makes area scan­ners, and their scan­ners are pro­gram­ma­ble, allow­ing com­pa­nies a high lev­el of per­for­mance that can work for a vari­ety of appli­ca­tions. Since they can be pro­grammed, area scan­ners have a high­er lev­el of ver­sa­til­i­ty than light cur­tains, because they can have a more pre­cise area mut­ed out (a load­ing zone for exam­ple), mak­ing it eas­i­er to load and unload parts in a par­tic­u­lar sys­tem or work cell.

Emer­gency Stop (E‑Stop)

Emer­gency stop, or e‑stop, is a func­tion that is used in case of emer­gency. There are usu­al­ly one or more e‑stop but­tons around a robot­ic work cell or sys­tem, and these but­tons cause the robot to stop motion imme­di­ate­ly. Unlike the fence cir­cuit, when the e‑stop cir­cuit is bro­ken, the robot is unable to be moved at all, even with the teach pendant. 

When­ev­er some­thing breaks the e‑stop or fence cir­cuit for a robot sys­tem, the safe­ty reset light will come on. This light is usu­al­ly locat­ed at the oper­a­tor sta­tion. Once you have cor­rect­ed the safe­ty sit­u­a­tion, the oper­a­tor can press the safe­ty reset but­ton and then press start to resume oper­a­tion. If the safe­ty sit­u­a­tion has not been cor­rect­ed, the reset will not work, and the sys­tem will not work until the sit­u­a­tion is corrected. 

Safe­ty equip­ment, like that, fea­tured above, is required under the OSHA direc­tive regard­ing robot­ics. OSHA Direc­tive STD 1−12−002 states that one or more of these safe­ty meth­ods, be it bar­ri­er guards or elec­tron­ic safe­ty devices, shall be pro­vid­ed to pro­tect the oper­a­tor and employ­ees from haz­ards of oper­a­tion, such as fly­ing chips, sparks, rotat­ing parts, etc. While this is a typ­i­cal reg­u­la­tion for all machin­ery, there are oth­er reg­u­la­tions from OSHA and oth­er orga­ni­za­tions that are geared direct­ly toward robots. 

In 2012, the Robot­ics Indus­try Asso­ci­a­tion (RIA) com­plete­ly reassessed and rewrote their stan­dard prac­tices for safe­ty when deal­ing with indus­tri­al robot­ics. One of those changes was to the func­tion­al safe­ty guide­lines for robot­ics. Basi­cal­ly, accord­ing to RIA R15.06:2012, com­pa­nies must per­form risk assess­ments on their inte­grat­ed sys­tems and work cells and ensure that they are out­fit­ted with a func­tion­al safe­ty design to reduce risk to users. This can incor­po­rate one or many of the prod­ucts list­ed above. 

Dif­fi­cul­ty choos­ing the right safe­ty options for your sys­tem? Call us at 877−762−6881 or fill out a Con­tact Form here to get in touch with a specialist.