Answer

1. What is Torque Sensor?

Sensor measuring twisting moment $\tau = r \times F$ (Nm) on shaft.

2. How It Works

Twist angle $\theta = TL/(GJ)$ or strain on shaft. Transduction via strain gauges at 45° (max shear) on shaft, Wheatstone bridge measures $\Delta R$.

• Reaction: Static mount measures reaction torque.
• Rotary: Slip rings/telemetry for rotating shaft.

3. Types

Type	Principle
Strain gauge	$\Delta R/R$ on shaft
Magnetoelastic	Permeability change
SAW	Frequency shift
Optical	Twist angle via encoder

4. Advantages

• Control joint effort, assembly.
• Overload protection.
• Small, high sensitivity.

5. Disadvantages

• Temperature drift, needs calibration.
• Slip ring wear for rotary.
• Cross-sensitive to bending.

6. Applications

• Robot joint torque control, grinding, screwing.
• Automotive engine, steering.
• Prosthetics.

Final Answer

Torque = strain on shaft at 45° via bridge; types strain gauge/magnetoelastic; used for robot joint control with high sensitivity but temperature drift.