Accurate force measurement during forceps manipulation is expected to have various applications such as surgical technique analysis. The calibration method is important for achieving accurate measurement. Previously, for a force measurable forceps (FMF) with 3 degrees of freedom (DOF), a calibration method using unbiased samples has been proposed. However, the required number of samples increases exponentially as the DOF increases. Here, we proposed a semi-automated sampling system for collecting unbiased samples from a FMF with 4DOF. We conducted a collection of unbiased samples, calibration, and compared the accuracy with the standard calibration method for linear force sensors. Sampling took around 10 seconds on average (n=1535). The accuracy, evaluated by the average error[N], for the unbiased sample calibration method (radial traction: −0.0565±0.0638, axial traction: −1.51±4.32, grip: 0.780±1.00) improved by approximatively two folds compared to the standard method (radial traction: −0.112±0.132, axial traction: −8.60±9.04, grip: −1.17±1.07), with maximum measurement ranges[N]of±2.00 for the traction, and±1.60 for the grip. We conclude that these results show the efficiency and accuracy of the proposed device, when compared to the conventional standard methodology.
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