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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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Forces on the rod. Forces for the different opening angles and forces applied on the forceps. Error bars represent standard deviations around the mean for the three repeated measurements of each combination of opening angle and applied force. Opening angles represent the angle between the two forceps
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Fig8: Forces on the rod. Forces for the different opening angles and forces applied on the forceps. Error bars represent standard deviations around the mean for the three repeated measurements of each combination of opening angle and applied force. Opening angles represent the angle between the two forceps

Mentions: Figure 8 displays the force on the rod for each combination of the opening angle and mass, averaged across the three repeated measurements. The transmission from the rod to the forceps for each measurement was computed using formula 3. The values thus obtained are plotted in Fig. 9.Fig. 8


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)

Forces on the rod. Forces for the different opening angles and forces applied on the forceps. Error bars represent standard deviations around the mean for the three repeated measurements of each combination of opening angle and applied force. Opening angles represent the angle between the two forceps
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3298650&req=5

Fig8: Forces on the rod. Forces for the different opening angles and forces applied on the forceps. Error bars represent standard deviations around the mean for the three repeated measurements of each combination of opening angle and applied force. Opening angles represent the angle between the two forceps
Mentions: Figure 8 displays the force on the rod for each combination of the opening angle and mass, averaged across the three repeated measurements. The transmission from the rod to the forceps for each measurement was computed using formula 3. The values thus obtained are plotted in Fig. 9.Fig. 8

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