Monthly Archives: November 2013

Robust stability of teleoperation systems with time delay: a new approach

Authors: Amir Haddaid and Heyvan Hashtrudi-Zaad

Source: IEEE Transactions on Haptics, Vol. 6, No. 2, April-June 2013.

Overall Review:

This articles presents a new approach to the control of teleoperation systems under time delays. This new approach guarantees absolute stability of the controller for any amount of delays. And also it considers necessary condition for transparency. This method is superior because it directly exchange measured position signals and incorporate performance criteria in the design.

Theoretically and experimental comparisons between this method and a benchmark method are performed. Results show that this method is better.

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C-arm angle measurement with accelerometer for brachytherapy

Authors: Thomas Wolff, Andras Lasso, Markus Eblenkamp, Erich Wintermantel, and Gabor Fichtinger.

Source: Int J CARS, 2013.

Overall Review:

This article presents an experimental comparison between 3 methods (accelerometer, build-in encoder, and FTRAC). And a high-accuracy optical tracker is employed as a reference. The experiment measured the readings from these methods under 31 different configurations. The targeted application is prostate brachytherapy. Results show that accelerometer is a accurate and precise method which, at the same time, is cheap and easy to install and can work in real time.

Questions

Q: In Figure 1, the 3 axes are not right-handed coordinate system. Is this a special design or just a mistake?

Fusion of electromagnetic trackers to improve needle deflection estimation

Authors: Hossein Sadjadi, Keyvan Hashtrudi-Zaad, and Gabor Fichtinger.

Source: IEEE Transactions on Biomedical Engineering, VOL 60, NO 10, Oct 2013.

Overall Review:

This article presents a method to take advantages of two trackers (one on the base, the other one on the tip) to improve the accuracy of the needle deflection estimation. The main algorithm used is Kalman Filter and Extended Kalman Filter. Results show that this method can significantly reduce the error in needle deflection estimation.

Micro-manipulation using rotational fluid flows induced by remote magnetic micro-manipulators

Authors: Zhou Ye, Eric Diller, and Metin Sitti.

Source: Journal of Applied Physics 112, 064912 (2012).

Overall Review:

In this article, authors presented a non-contact manipulation method for micron scale objects using locally induced rotational fluid flows created by groups of untethered magnetic micro-manipulators. One single spherical micro-manipulator is used to manipulate one object at a time, while an array of micro-manipulators spin in synchrony on a surface patterned with magnetic micro-docks to create reconfigurable fluidic channels for simultaneous transportation of multiple objects. Physical theory of this method is discussed. Objects with different shape and size were used for experiments. Results show that this method could be used to quickly move fragile or non-fragile micro-objects in inaccessible or enclosed spaces.

Questions:

Q: It is believed there is a typo in this article. In Section 3 (Forces on micro-objects), Equation (4) is G = density * g * 3/4 * pi * a^3. I think the right equation should be G = density * g * 4/3 * pi * a^3.