Dynamic assessment of center of pressure measurements from an instrumented AMTI treadmill with controlled precision

Abstract

With the increasing use of instrumented force treadmills in biomechanical research, it is imperative that the validity of center of pressure (COP) measurements is established. The study aims were to compare an instrumented treadmill’s static-belt COP accuracy to that of a floor-embedded platform, develop a novel method to quantify dynamic-belt COP accuracy with controlled precision and perform an initial investigation of how dynamic COP accuracy changes with weight and velocity. Static COP accuracy was assessed by applying a force while moving a rigid rod in a circular clockwise motion at nine positions of interest on the two treadmill and two ground-embedded force plates. Dynamic COP accuracy was assessed for weights (68.0, 102.1, and 136.1 kg), applied through a ball bearing of 2.54 cm circumference, with peak treadmill belt speeds of 0.5, 0.75, and 1.0 m/s. COP accuracy was assessed relative to motion capture marker trajectories. Statically, treadmill COP error was similar to that of the ground-embedded force plates and that reported for other treadmills. Dynamically, COP error appeared to vary systematically with weight and velocity and in the case of anteroposterior COP error, shear force, although testing with a larger number of weights and velocities is needed to fully define the relationship. This novel method can be used to assess any instrumented treadmill’s dynamic COP accuracy with controlled precision.

A Systematic Review of the Effectiveness of Tai Chi Exercises for Improving Balance and Lower Limb Muscle Strength of the Elderly in the Community

“…Several recent studies [4], [8], [9], [23], [24], [25], [26] reported that selected TC could give a better effect than tTC movements due to complex movements resulting in the elderly not moving actively. The selected TC movements were easily set by TC practitioners and determined through a center of pressure (COP) assessment classified into four levels of difficulty [9], [23], [27]. This classification allows the elderly or respondents to get TC movements according to their abilities [23].…”

A Perturbed Postural Balance Test Using an Instrumented Treadmill – Precision and Accuracy of Belt Movement and Test-Retest Reliability of Balance Measures

“…Finally, we suggest that COP accuracy during belt movement should be investigated if the information is not available for the particular device. A previous study showed that COP accuracy with an instrumented treadmill depended on belt speed and mass applied on the belt (Fortune et al, 2017).…”

“…Instrumented treadmills are susceptible to errors especially in ground reaction force and COP measurements (Sloot et al, 2015) because of mechanical noise or vibrations induced by the treadmill structure to the sensors (Willems and Gosseye, 2013). On the other hand, Fortune et al (2017) showed that the COP measurement accuracy of an instrumented treadmill can be on par with a traditional ground-mounted force plate, and Collins et al (2009) showed that COP error can be reduced to a similar level compared with a ground-mounted force plate using a calibration procedure. There can be also differences in the accuracy between devices from different manufacturers to deliver perturbations, which Crenshaw et al (2019) speculated to be due to unique control strategies and computations.…”