With dynamometer tests, we get torque values. However torque = distance x force. Since the biodex (or the labchart if you're reading the data from the data from the computer) does not ask for the lever length (e.g. for knee extensions, we have to adjust the attachment length accordingly to the participant's shin length), and since the motor of the dynamometer measures the force in the point of rotation, how can it calculate the torque without knowing the distance?
The motor of a dynamometer is calibrated against a series of known torques. In theory, it could be calibrated using one load while varying moment arm length. Alternatively, it could be calibrated using a constant moment arm length while varying load. It doesn't matter.
Hi,
Adding to Mr. Warren's reply, it is stated by this document also;
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https://m.biodex.com/support/faq/physical-medicine/product/167
"How does the system know the lever length of the adapter shaft for calculation of torque?
It doesn't and is not required as torque is a rotational force measured at the axis of rotation. "
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قياس عزم الدوران الآتي
(τ=F⋅rsin(θ، حيث يُرمز لمتّجه العزم بالرمز τ، وللقوّة المطبّقة بالرمز F، وطول الذّراع بالرمز r، وθ للزاوية الواقعة بين القوّة المطبّقة وعزمالذّراع، وتُقاس الكميّة الناتجة بوحدة نيوتن ت