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Guaranteeing Isochronous Control of Networked Motion Control Systems Using Phase Offset Adjustment.

Kim I, Kim T - Sensors (Basel) (2015)

Bottom Line: In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE).We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach.The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Information Engineering, University of Seoul, 163 Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea. ihkim@uos.ac.kr.

ABSTRACT
Guaranteeing isochronous transfer of control commands is an essential function for networked motion control systems. The adoption of real-time Ethernet (RTE) technologies may be profitable in guaranteeing deterministic transfer of control messages. However, unpredictable behavior of software in the motion controller often results in unexpectedly large deviation in control message transmission intervals, and thus leads to imprecise motion. This paper presents a simple and efficient heuristic to guarantee the end-to-end isochronous control with very small jitter. The key idea of our approach is to adjust the phase offset of control message transmission time in the motion controller by investigating the behavior of motion control task. In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE). We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach. The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives.

No MeSH data available.


Related in: MedlinePlus

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f3-sensors-15-13945: System model.

Mentions: As mentioned above, the control task, called τ, performs periodically a control sequence, which consists of retrieve, computation and publish operations. Note that the terms retrieve and publish are used instead of sampling and actuation, respectively, to emphasize that the operations are performed for motor drives distributed over the industrial communication link. In the retrieve phase, the control task reads the status information including current position and velocity reported by the motor drives during the previous control cycle. Using the information acquired in the retrieve phase, the control task checks if the motors are being moved properly according to the planned motion trajectory and, if not, generates correction commands in the computation phase. Finally, in the publish phase, the controller transmits motion commands to the motor drives. Figure 3 depicts the timing parameters deal with in our model.


Guaranteeing Isochronous Control of Networked Motion Control Systems Using Phase Offset Adjustment.

Kim I, Kim T - Sensors (Basel) (2015)

System model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507583&req=5

f3-sensors-15-13945: System model.
Mentions: As mentioned above, the control task, called τ, performs periodically a control sequence, which consists of retrieve, computation and publish operations. Note that the terms retrieve and publish are used instead of sampling and actuation, respectively, to emphasize that the operations are performed for motor drives distributed over the industrial communication link. In the retrieve phase, the control task reads the status information including current position and velocity reported by the motor drives during the previous control cycle. Using the information acquired in the retrieve phase, the control task checks if the motors are being moved properly according to the planned motion trajectory and, if not, generates correction commands in the computation phase. Finally, in the publish phase, the controller transmits motion commands to the motor drives. Figure 3 depicts the timing parameters deal with in our model.

Bottom Line: In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE).We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach.The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical and Information Engineering, University of Seoul, 163 Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea. ihkim@uos.ac.kr.

ABSTRACT
Guaranteeing isochronous transfer of control commands is an essential function for networked motion control systems. The adoption of real-time Ethernet (RTE) technologies may be profitable in guaranteeing deterministic transfer of control messages. However, unpredictable behavior of software in the motion controller often results in unexpectedly large deviation in control message transmission intervals, and thus leads to imprecise motion. This paper presents a simple and efficient heuristic to guarantee the end-to-end isochronous control with very small jitter. The key idea of our approach is to adjust the phase offset of control message transmission time in the motion controller by investigating the behavior of motion control task. In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE). We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach. The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives.

No MeSH data available.


Related in: MedlinePlus