Controlling of industrial robotic manipulators operating with flexible tools

Olesen, Rasmus Bank Breiner

10. term

Elektronik og IT, Kandidatuddannelsen (Spec. Intelligent Autonomous Systems)

2012

2012-05-31

Formålet med dette masterprojekt var at forbedre reguleringen af end-effectoren for en industriel robotmanipulator, der anvender fleksible værktøjer. En REIS RV15 robot samt forskellige sensorer var til rådighed for forsøg. Forbedring af reguleringen involverer dæmpning af svingninger i det fleksible værktøj, hvilket vil forøge nøjagtigheden af TCP-positionen og nedbringe tiden, det tager at færdiggøre opgaven. Der blev udviklet en model for både robotten og det fleksible værktøj. En sliding mode regulator blev valgt for at dæmpe svingningerne i værktøjet, og regulatoren anvendte den dynamiske model i processen. Methoder til systemidentifikation blev anvendt for at tilpasse modellen til den praktiske opstilling under anvendelse af sensormålinger. Både offline og online metoder blev beskrevet. Sensor information fusion blev deslige taget i betragtning for at forbedre tilstandsestimaterne. Et Kalman filter blev anvendt til at kombinere modelestimater og sensormålinger heriblandt strain for værktøjet. Reguleringssystemet blev testet i praksis for at måle dets ydeevne mht. nøjagtigheden af TCP position og indsvingningstid for strain-målingerne. Alle delsystemer blev testet separat. Relætuning estimerede værktøjets egenfrekvens inden for 8-11 % af den korrekt værdi, og støj kunne fjernes med Kalman filteret. Regulatoren reducerede indsvingningstiden fra 50,85 s til 3,85 s i et af tilfældene, men nåede ikke i sliding mode under testen. Robottens båndbredde var ikke tilstrækkelig, og reguleringssignalet måtte desuden begrænses.

The objective of this Master's thesis was to improve end-effector control for an industrial robotic manipulator operating with flexible tools. A REIS RV15 manipulator including different sensors was at disposal for experiments. Improving the control involves damping the oscillations of the flexible tool, which will increase the accuracy of the TCP position and decrease the task completion time. A dynamic model was derived for both the manipulator and the flexible tool. A sliding mode controller structure was selected to damp the tool oscillations, and the controller applied the dynamic model in the process. System identification methods were used to adapt the model to the practical tool configuration using sensor measurement. Both offline and online methods were described. Sensor information fusion was also considered to improve model state estimates. A Kalman filter was used to combine the estimates and various sensor measurements including strain of the tool. The control system was empirically tested to measure its performance regarding TCP accuracy and settling time of the strain response. All parts were tested separately. The relay tuning method estimated the eigenfrequency of the tool to within 8-11 % of the correct value, and the Kalman filter showed noise removal properties. The controller reduced the settling time from 50,85 s to 3,85 s in one case, but did not reach sliding mode during the test. The bandwidth of the manipulator was not adequate, and the control signal had to be limited.

Sliding mode control ; Flexible dynamics ; Robotic manipulator

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