Robotics

A robot with laser eyesight

Precise positioning with the sensor and software system from norisTEC

Source: noris­TEC F&E

Pre­cise posi­tion­ing of tools and work­pieces is among the most demand­ing tasks in automa­tion. Espe­cial­ly with flex­i­ble robot sys­tems, accu­ra­cy deter­mines whether machin­ing remains repro­ducible, effi­cient, and eco­nom­i­cal.
noris­TEC GmbH has devel­oped an inno­v­a­tive sys­tem of hard­ware com­po­nents and a mod­u­lar soft­ware tool­box for this pur­pose — a real laser eye for the robot.



The sys­tem makes it pos­si­ble to align the tool of a 6‑axis artic­u­lat­ed robot with the work­piece with high pre­ci­sion, with­out con­tact, quick­ly and with­out com­plex cal­i­bra­tion. The core com­po­nent is a laser line tri­an­gu­la­tor (LLT) that cap­tures height pro­files and edge struc­tures of the work­piece with impres­sive res­o­lu­tion and accu­ra­cy. In com­bi­na­tion with the noris
TEC
soft­ware, a dig­i­tal image of the envi­ron­ment is cre­at­ed, giv­ing the robot mil­lime­ter-accu­rate ori­en­ta­tion.

Why a laser triangulator instead of a camera?

While cam­era-based sys­tems are often sen­si­tive to ambi­ent light and require shield­ed mea­sur­ing cham­bers, the laser tri­an­gu­la­tor works almost inde­pen­dent­ly of ambi­ent light.
Its con­cen­trat­ed light line deliv­ers razor-sharp height pro­files even with short expo­sure times, entire­ly with­out a light cham­ber or spe­cial light­ing.

Source: Micro-Epsilon Messtech­nik GmbH & Co. KG

“The cam­era is essen­tial­ly wear­ing sun­glass­es and only sees the very bright laser,” one devel­op­er apt­ly put it.

Anoth­er advan­tage: The inte­grat­ed eval­u­a­tion sys­tem in the sen­sor direct­ly con­verts the record­ed height pro­file into real posi­tion val­ues in mil­lime­ters – dis­tor­tions such as those found in con­ven­tion­al cam­era optics are elim­i­nat­ed or com­pen­sat­ed for by the spe­cial­ized sen­sor soft­ware. This means that a kind of online pre­pro­cess­ing and scal­ing takes place direct­ly with­in the sen­sor itself.


Able to learn – thanks to its own specialized norisTEC image processing toolkit (NI Vision)


After the com­po­nents are scanned with the laser line, a 3D pro­file image is gen­er­at­ed and loaded into the image pro­cess­ing sys­tem. This involves reduc­ing the image to a pseu­do 2D height image, which can be fur­ther processed using var­i­ous selec­table mod­ules from the noris­TEC-MV-Toolk­it, based on NI Vision.

Source: noris­TEC F&E


By clev­er­ly com­bin­ing these mod­ules (edge detec­tion, line inter­po­la­tion, inter­sec­tion edge cal­cu­la­tion, area deter­mi­na­tion and much more), mark­er points can be deter­mined from the image, which are reflect­ed back and serve as posi­tion cor­rec­tion for the robot. These mod­ules can be learned by the user in your appli­ca­tion on com­po­nents, and can also be relearned, expand­ed, and mod­i­fied at any time. It fea­tures an intu­itive user inter­face. This allows the robot to see exact­ly where it needs to grip, almost down to the sub­mil­lime­ter. He has laser vision as a result.

Precision from a single source – hardware and software perfectly integrated

Source: Mit­subishi Elec­tric Europe B.V.

The solu­tion is designed for the entire Mit­subishi MELFA robot fam­i­ly, but can also be adapt­ed to sys­tems from oth­er man­u­fac­tur­ers.
The cur­rent appli­ca­tion uses a MITSUBISHI ELECTRIC MELFA ASSISTA RV-5AS‑D – a col­lab­o­ra­tive robot that com­bines the pre­ci­sion of clas­sic indus­tri­al robots with the safe­ty and flex­i­bil­i­ty of a cobot.

The sys­tem can be con­fig­ured in two hard­ware vari­ants:

  • Vari­ant 1: The laser tri­an­gu­la­tor is per­ma­nent­ly installed on the robot arm; tools such as screw­drivers, milling cut­ters, or test probes are mount­ed with a fixed ref­er­ence. The exact posi­tion­al rela­tion­ship between the laser and the tool is cal­i­brat­ed once.
  • Vari­ant 2: Lasers and tools can be flex­i­bly docked dur­ing the process using an auto­mat­ic tool change sys­tem.

Flexibility meets safety – automatic tool change system

In par­al­lel with the sen­sor solu­tion, noris­TEC has devel­oped a com­plete con­cept for safe auto­mat­ic tool chang­ing.
The dif­fer­ent robot hands – includ­ing the “scan­ner hand” – are docked via a pneu­mat­i­cal­ly con­trolled stan­dard sys­tem from Schunk. In addi­tion, a spe­cial­ly devel­oped tool park­ing sys­tem was cre­at­ed with locked, spring-sup­port­ed and safe­ty-mon­i­tored park­ing sta­tions.

Source: noris­TEC F&E + Kon­rad Lech­n­er GmbH & Co. KG

This allows the col­lab­o­ra­tive robot to pick up “dan­ger­ous” tools with­out endan­ger­ing the oper­a­tor’s safe­ty: The sys­tem auto­mat­i­cal­ly switch­es between col­lab­o­ra­tive and high-speed modes, depend­ing on the tool and oper­at­ing con­di­tion (safe­ty door con­di­tion).

A col­or-cod­ed sig­nal from the robot always informs the oper­a­tor about the cur­rent oper­at­ing mode. If the user opens a safe­ty door dur­ing a high-speed oper­a­tion, the robot stops safe­ly – if they enter the safe­ty zone dur­ing col­lab­o­ra­tive oper­a­tion, the robot auto­mat­i­cal­ly reduces its speed.

Well-thought-out integration – right down to cable management

Source: noris­TEC F&E

To make the sys­tem as com­pact and robust as pos­si­ble, noris­TEC also devel­oped an inter­nal mul­ti­plex sys­tem for the sig­nal rout­ing of the MELFA ASSISTA.
Depend­ing on the mount­ed robot hand, the same inter­nal cable pack­age can be used as a Giga­bit Eth­er­net line, as a dig­i­tal I/​O con­nec­tion, or for con­trol­ling pneu­mat­ic valves – auto­mat­i­cal­ly switched via the robot con­troller.
This elim­i­nates the need for dis­rup­tive exter­nal cables, and the hand change is ten­sion-free and reli­able.


Even the ASSISTA itself has been opti­mized: One of the fac­to­ry-installed elec­tri­cal lines was replaced by a pneu­mat­ic line, so that all sup­plies are now rout­ed inter­nal­ly to the tool hold­er and via the auto­mat­ic inter­change­able flange. The result is a clean, space-sav­ing and indus­tri­al-grade solu­tion.

Conclusion

With the com­bi­na­tion of laser tri­an­gu­la­tor, intel­li­gent soft­ware and sophis­ti­cat­ed sys­tem inte­gra­tion, noris­TEC has cre­at­ed a tool that teach­es robots to see – pre­cise­ly, robust­ly and flex­i­bly.
Whether for pre­cise posi­tion­ing, test­ing or assem­bly – the sys­tem offers a solu­tion that seam­less­ly mas­ters the tran­si­tion between clas­sic indus­tri­al automa­tion and mod­ern col­lab­o­ra­tive robot­ics.