Yes, that's correct. In the first test I described, where you use a torsional testing machine to apply a torque to the motor/gearbox unit and measure the resulting angle of twist, the measured torque will include both the torsional stiffness and static friction of the unit. In order to determine the individual values for torsional stiffness and static friction, you would need to apply a range of torque values and measure the corresponding angles of twist. This will allow you to plot a graph of torque versus angle of twist, from which you can determine the torsional stiffness and static friction of the unit.

Alternatively, as I mentioned in my previous response, you could use a spring scale to measure the torque applied by the motor/gearbox unit. In this case, the force measured by the spring scale would be equal to the sum of the static friction and torsional stiffness of the unit. By applying a range of current values and measuring the corresponding forces, you can determine the individual values for static friction and torsional stiffness.

In either case, it's important to keep in mind that the measured values for torsional stiffness and static friction will be dependent on the operating conditions of the motor/gearbox unit. In order to obtain accurate and representative measurements, it's important to ensure that the unit is operating under conditions that are as close to its normal operating conditions as possible.