Success Story

Con­trol of ser­vo dri­ves with ctrlX

As part of his bachelor thesis at the FH Aachen, Mr. Sebastian Kröbel developed a function module that can be used flexibly to control servo drives with the Bosch Rexroth ctrlX system.

The goal

As a Certi­fied Excel­lence Solu­tion Part­ner and offi­cial sys­tem inte­gra­tor of Bosch Rexroth, it is of great inter­est to us to be able to use the new ctr­lX CORE con­trol sys­tem in the most effi­cient way for our cus­tomers. The aim of the bach­e­lor’s the­sis was to devel­op an indus­try stan­dard for con­trol­ling open-loop and closed-loop dri­ves with the ctr­lX. Con­trol and mon­i­tor­ing of the dri­ves as well as inter­faces to the HMI with basic func­tion­al­i­ties such as oper­at­ing modes, user admin­is­tra­tion and alarm han­dling were to be integrated.

The project structure

The soft­ware devel­oped was to be used and test­ed in a lab­o­ra­to­ry set­up at Qual­i­ty Automa­tion GmbH. The set­up con­tains the ctr­lX CORE con­troller with a QA base project includ­ing the new­ly devel­oped func­tion blocks, an HMI pan­el with a spe­cial­ly devel­oped user inter­face in the QA cor­po­rate design and a three-phase motor with a cor­re­spond­ing Bosch fre­quen­cy invert­er (EFC 5610). In addi­tion, a ctr­lX Dri­ve ser­vo­mo­tor with ser­vo invert­er was installed in the lab­o­ra­to­ry set­up.
The devel­oped func­tion mod­ule con­tains all the func­tion­al­i­ties required and com­mon­ly used in indus­try. Switch­ing between man­u­al and auto­mat­ic mode, read­ing in dig­i­tal and ana­log inputs and set and actu­al val­ues as well as resets and emer­gency stops are mapped.

Project result

The invert­er can be con­trolled as desired via the ctr­lX con­troller. All vari­ables and the FB were doc­u­ment­ed very pre­cise­ly for inter­nal pur­pos­es. The absolute posi­tion­ing, rel­a­tive posi­tion­ing, speed con­trol and torque con­trol oper­at­ing modes have been suc­cess­ful­ly imple­ment­ed.
In posi­tion con­trol, a tar­get posi­tion with a ramp pro­file is approached after the start com­mand. The ramp pro­file con­tains accel­er­a­tion, decel­er­a­tion and a max­i­mum speed. The set­point is spec­i­fied either as an absolute or rel­a­tive posi­tion off­set.
With speed con­trol, a set speed with ramp pro­file is approached after the start com­mand. The ramp pro­file con­tains accel­er­a­tion and decel­er­a­tion. Torque con­trol can be con­trolled con­tin­u­ous­ly. The tar­get torque is applied in real time. This allows torque curves to be real­ized.
In addi­tion, a mod­ule was devel­oped to use the ser­vos to dri­ve a lin­ear axis. This FB in turn uses the ser­vo FB. The axis can mea­sure itself dur­ing ini­tial­iza­tion, which means that the axis can be posi­tioned rel­a­tive­ly and absolute­ly and a speed spec­i­fi­ca­tion is also pos­si­ble.
In addi­tion, an HMI user inter­face was cre­at­ed with which the PLC pro­gram can be con­trolled and mon­i­tored. This includes var­i­ous switch­able menus, user admin­is­tra­tion and alarm man­age­ment with acknowl­edge­ment function.

Contact Person
Sebastian Kröbel,
Marcel Martis
Sebastian Kröbel, Bachelorand FH Aachen; Marcel Martis, Softwareentwickler
Schwerpunkte: Antriebstechnik, Steuerungstechnik
In Kooperation mit

Rexroth – A Bosch Company

Bosch Rexroth AG
Vertrieb Europa Mitte
Borsingstraße 15
40880 Ratingen
Nordrhein-Westfalen, Deutschland