Related Experiment Video
Updated: Jun 4, 2026
06:52
An Inertial Measurement Unit Based Method to Estimate Hip and Knee Joint Kinematics in Team Sport Athletes on the Field
Published on: May 26, 2020
A comparison between jerk-cost derived from a jaw-tracking system with that from an accelerometer
1Jaw Function and Orofacial Pain Research Unit, University of Sydney, NSW, Australia. minami.rpro@tmd.ac.jp
Journal of Oral Rehabilitation
|February 18, 2011
Summary
Jerk-cost, a measure of movement smoothness, calculated from jaw-tracking devices differs significantly from accelerometer data. These findings indicate jaw-tracking systems cannot replace accelerometers for accurate jerk-cost measurement.
Area of Science:
- Biomechanics
- Kinesiology
- Biomedical Engineering
Background:
- Jerk-cost quantifies movement smoothness, inversely related to smoothness.
- Traditionally calculated from acceleration (tri-axial piezoelectric accelerometer - TPA) or position derivatives (jaw-tracking device).
Purpose of the Study:
- To compare jerk-cost measures from the JAWS3D jaw-tracking device and a TPA.
- To assess the relationship and agreement between jerk-cost data from both devices during gum chewing.
- To evaluate device suitability for accurate jerk-cost assessment.
Main Methods:
- 10 asymptomatic subjects chewed gum while simultaneously recorded by JAWS3D and TPA.
- Jerk-cost calculated as the first derivative of acceleration (TPA) and third derivative of position (JAWS3D) in X, Y, Z directions.
- Analysis included opening, closing phases, and full chewing cycles; correlation and Bland-Altman tests performed.
Main Results:
- Significant correlations found between JAWS3D and TPA jerk-cost during full cycle (r=0.65) and jaw-opening (r=0.75).
- No significant correlation observed during the jaw-closing phase (r=-0.02).
- Bland-Altman analysis revealed substantial differences (JAWS3D: -78% to +21% of TPA).
Conclusions:
- Jerk-cost measurements from the JAWS3D jaw-tracking system are not interchangeable with those from a TPA.
- Accelerometers remain the preferred method for reliable jerk-cost quantification in jaw movement analysis.
- Jaw-tracking systems may not provide sufficient accuracy for jerk-cost assessment in this context.
Related Concept Videos
01:10Relative Motion Analysis - Acceleration
A slider-crank mechanism converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider. The movement of the slider-crank is an example of general plane motion as the fluctuating angle between the crank and the connecting rod. Consider a segment AB where point A is at the end of the slider and point B is on the diametrically opposite end to point A, on a crack. The variance in...
01:22Relative Motion Analysis using Rotating Axes - Acceleration
Consider a component AB undergoing a linear motion. Along with a linear motion, point B also rotates around point A. To comprehend this complex movement, position vectors for both points A and B are established using a stationary reference frame. The absolute velocity of point B is determined by adding the absolute velocity of point A, the relative velocity of point B in the rotating frame, and the effects caused by the angular velocity within the rotating frame.
Time differentiation is...
Time differentiation is...
01:12Measuring Acceleration Due to Gravity
Consider a coffee mug hanging on a hook in a pantry. If the mug gets knocked, it oscillates back and forth like a pendulum until the oscillations die out.
A simple pendulum can be described as a point mass and a string. Meanwhile, a physical pendulum is any object whose oscillations are similar to a simple pendulum, but cannot be modeled as a point mass on a string because its mass is distributed over a larger area. The behavior of a physical pendulum can be modeled using the principles of...
A simple pendulum can be described as a point mass and a string. Meanwhile, a physical pendulum is any object whose oscillations are similar to a simple pendulum, but cannot be modeled as a point mass on a string because its mass is distributed over a larger area. The behavior of a physical pendulum can be modeled using the principles of...
01:24Relative Motion Analysis - Velocity
A stroke engine has a slider-crank mechanism that converts rotational motion from the crank into linear motion of the slider or vice versa. This mechanism consists of three main parts: the crank, the connecting rod, and the slider.
When an external force is exerted, it sets the crank into a rotational movement. This, in turn, instigates the motion of the connecting rod, leading to what is referred to as a general plane motion. This process involves two key points - point A on the connecting rod...
When an external force is exerted, it sets the crank into a rotational movement. This, in turn, instigates the motion of the connecting rod, leading to what is referred to as a general plane motion. This process involves two key points - point A on the connecting rod...
01:25Relative Motion Analysis using Rotating Axes
Consider a component AB undergoing a linear motion. Along with a linear motion, point B also rotates around point A. To comprehend this complex movement, position vectors for both points A and B are established using a stationary reference frame.
However, to express the relative position of point B relative to point A, an additional frame of reference, denoted as x'y', is necessary. This additional frame not only translates but also rotates relative to the fixed frame, making it instrumental in...
However, to express the relative position of point B relative to point A, an additional frame of reference, denoted as x'y', is necessary. This additional frame not only translates but also rotates relative to the fixed frame, making it instrumental in...
01:30Average Acceleration
The importance of understanding acceleration spans our day-to-day experiences, as well as the vast reaches of outer space and the tiny world of subatomic physics. In everyday conversation, to accelerate means to speed up. For instance, we are familiar with the acceleration of our car; the harder we apply our foot to the gas pedal, the faster we accelerate. The greater the acceleration, the greater the change in velocity over a given time. Acceleration is widely seen in experimental physics. In...