Force matching

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Force matching is a research method consisting of test subjects attempting to produce a set forces that are equal to a set of more reliable reference forces.

Types

Biomechanical

A subject’s maximum voluntary contraction (MVC) is recorded and used to normalize both reference forces and results between subjects.^[1] During the test subjects are assisted in producing a reference force using various types of feedback (static weight or visual display of force generated). This is followed by an attempt of the subject to generate the reference force without assistance. The duration for both reference and matching tasks is usually four seconds. Results are taken as a mean value of force generated over a time interval set by the researcher. Time intervals are generally one second long and near the end of the attempt. Reference forces are typically set as a percentage of a subject’s MVC while error is typically reported as a percentage of a subject’s MVC.

Atomic

It is one of the effective research method to obtain realistic classical

where ε is the depth of the potential well, σ is the finite distance at which the inter-particle potential is zero, r is the distance between the particles. These two unknown parameters can be fitted to reproduce experimental data or accurate data obtained from first principle calculations. Differentiating the L-J potential with respect to r gives an expression for the net inter-molecular force between 2 molecules. This inter-molecular force may be attractive or repulsive, depending on the value of r. When r is very small, the molecules repel each other. In force matching method the forces from classical potential

${\displaystyle F_{\text{LJ}}=-{\frac {dV_{\text{LJ}}}{dr}}=4\varepsilon \left[\left({\frac {12}{r}}\right)\left({\frac {\sigma }{r}}\right)^{12}-\left({\frac {6}{r}}\right)\left({\frac {\sigma }{r}}\right)^{6}\right]}$ are compared with reference force ${\displaystyle F^{0}}$ calculated from ab initio method to determine ${\displaystyle {\sigma }}$ and ${\displaystyle {\varepsilon }}$.

Applications

Biomechanical force matching has been used by researchers to describe the accuracy of muscle contractions under various conditions. It has been observed that the thumb is more accurate in force matching than fingers are.