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Indirect measurement of pinch and pull forces at the shaft of laparoscopic graspers.

Dobbelsteen JJ, Lee RA, Noorden Mv, Dankelman J - Med Biol Eng Comput (2012)

Bottom Line: Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed.The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements.We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod.

View Article: PubMed Central - PubMed

Affiliation: Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands. j.j.vandendobbelsteen@tudelft.nl

ABSTRACT
The grasping instruments used in minimally invasive surgery reduce the ability of the surgeon to feel the forces applied on the tissue, thereby complicating the handling of the tissue and increasing the risk of tissue damage. Force sensors implemented in the forceps of the instruments enable accurate measurements of applied forces, but also complicate the design of the instrument. Alternatively, indirect estimations of tissue interaction forces from measurements of the forces applied on the handle are prone to errors due to friction in the linkages. Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed. The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements. We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod.

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Predicted forces versus applied forces. The forces on the forceps were estimated from the forces on the rod and the opening angle of the forceps using a two-dimensional linear function. The results are plotted against the actual values used in the experiment. Error bars represent standard deviations in the estimated values across opening angles
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Fig10: Predicted forces versus applied forces. The forces on the forceps were estimated from the forces on the rod and the opening angle of the forceps using a two-dimensional linear function. The results are plotted against the actual values used in the experiment. Error bars represent standard deviations in the estimated values across opening angles

Mentions: Equation 17 was used to predict the forces applied on the forceps from the measured values of and the opening angles used in the experiment. In Fig. 10, the predicted forces are plotted against the forces that were actually applied in the experiment, averaged across the different opening angles. We found that the mean absolute error of the predicted force was 0.03 N with a standard deviation of 0.02 N.Fig. 10


Indirect measurement of pinch and pull forces at the shaft of laparoscopic graspers.

Dobbelsteen JJ, Lee RA, Noorden Mv, Dankelman J - Med Biol Eng Comput (2012)

Predicted forces versus applied forces. The forces on the forceps were estimated from the forces on the rod and the opening angle of the forceps using a two-dimensional linear function. The results are plotted against the actual values used in the experiment. Error bars represent standard deviations in the estimated values across opening angles
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3298650&req=5

Fig10: Predicted forces versus applied forces. The forces on the forceps were estimated from the forces on the rod and the opening angle of the forceps using a two-dimensional linear function. The results are plotted against the actual values used in the experiment. Error bars represent standard deviations in the estimated values across opening angles
Mentions: Equation 17 was used to predict the forces applied on the forceps from the measured values of and the opening angles used in the experiment. In Fig. 10, the predicted forces are plotted against the forces that were actually applied in the experiment, averaged across the different opening angles. We found that the mean absolute error of the predicted force was 0.03 N with a standard deviation of 0.02 N.Fig. 10

Bottom Line: Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed.The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements.We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod.

View Article: PubMed Central - PubMed

Affiliation: Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands. j.j.vandendobbelsteen@tudelft.nl

ABSTRACT
The grasping instruments used in minimally invasive surgery reduce the ability of the surgeon to feel the forces applied on the tissue, thereby complicating the handling of the tissue and increasing the risk of tissue damage. Force sensors implemented in the forceps of the instruments enable accurate measurements of applied forces, but also complicate the design of the instrument. Alternatively, indirect estimations of tissue interaction forces from measurements of the forces applied on the handle are prone to errors due to friction in the linkages. Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed. The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements. We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod.

Show MeSH
Related in: MedlinePlus