Table 2.

Systems for measuring the different variables of interest for different types of tasks

Task	Variables of interest	Measurement system
Movement task	Position	Robotic devices or camera-based motion capture system to measure position in either task space or joint space. Wearable potentiometers for measuring joint position.
	Acceleration, angular rate	Inertial measurement units.
Isometric task	Force/Torque	Robotic devices for both task space and joint space measurements. Multi-axis load cells for measuring force and torque in different directions.
Movement or isometric task	Impedance	Robotic devices for measuring task or joint space impedance through appropriate perturbation methods. EMG recording of opposing muscle pairs to measure joint stiffness.