Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: Method for Testing Motion Analysis Laboratory Measurement Systems J Biomech Eng. 2010;132(11): doi: / Test device used in this study. The device has four retroreflective targets for the camera based motion tracking and two triaxial accelerometers firmly attached into different locations in the shaft. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: Method for Testing Motion Analysis Laboratory Measurement Systems J Biomech Eng. 2010;132(11): doi: / Schematic diagram of measured and true acceleration components of one accelerometer and measured force components. All three-dimensional accelerations and forces are reduced to two-dimensional space by combining their x and y components. The acceleration components aN and aT, which include the gravitational acceleration, are measured by the accelerometers. The components an and at are the true normal and tangential accelerations in the measurement point, respectively, and g is the gravitation. Thin arrow indicates direction of the movement. The distance of the two accelerometers from the bottom tip is R1 and R2, respectively, and the angle of test device relative to the x-y plane of the FP is α. The components Fxy and Fz are forces measured by the force plate. Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: Method for Testing Motion Analysis Laboratory Measurement Systems J Biomech Eng. 2010;132(11): doi: / The angle of rod respect to x-y plane derived from motion capture data (thick black line), from force plate data (thin black line), and from accelerometer data (gray line) Figure Legend:

Date of download: 6/26/2016 Copyright © ASME. All rights reserved. From: Method for Testing Motion Analysis Laboratory Measurement Systems J Biomech Eng. 2010;132(11): doi: / The effect of improper calibration of the accelerometer signal. Measured acceleration component aT1 was added with constant error of 0.1g (thick gray line) and relative error of −5% (thin gray line). The angle estimates from properly calibrated signal (thin black line) and from motion capture data (thick black line) are plotted for reference. Figure Legend: