Which treadmill to choose for scientific studies about walking meditation (part II)?

Part I can be found here:

It eventually works without replacement of the treadmill motor, but we have to proof this. Still the method of fellnr how to calibrate a treadmill is one of the best we know. But we have to validate the treadmill for our specific application such as walking meditation. We do not know of any validation papers about treadmills.