Fig. 1. Composition and installation of harmonic reducer

Fig. 2. Cloud chart of flex spline strain distribution

Fig. 3. Strain gauge attachment position

Fig. 4. Flex spline stress analysis

Fig. 5. Flex spline bottom circumferential path

Fig. 6. Circumferential strain curves

Fig. 7. Strain cloud map of flex spline bottom surface

Fig. 8. Structural parameters of sensitive grid

Fig. 9. Response surface of torque pearson correlation coefficient to grid length， grid spacing， and grid position

Fig. 10. Structure design of sensitive grid

Fig. 11. Wheatstone bridge circuit diagram

Fig. 12. Harmonic reducer integrated with torque sensor

Fig. 13. Experimental testing platform

Fig. 14. Experimental bench operational principle

Fig. 15. Calibration result

Fig. 16. Apply step torque

Fig. 17. Apply sinusoidal torque