Advances in Robotics: New Joint Angle Measurement and Shape Sensing Systems

Researchers at Brunel University London have made a significant breakthrough in robotics by developing a novel design for a two-axis joint angle sensor, which can accurately estimate roll and pitch in flexible or continuum manipulators. The sensor uses two optoelectronic sensors integrated into a spherical-joint inspired structure with an internal locking mechanism to eliminate unwanted torsional motion. The researchers employed non-linear regression for calibration, resulting in robust and accurate joint angle measurement.

Key Takeaways:

• The new joint angle measurement sensor uses a two-unit tendon actuated joint structure with two optoelectronic sensors integrated into a spherical-joint inspired structure.
• The sensor features an innovative internal locking mechanism to eliminate unwanted torsional motion, increasing the accuracy of sensing in pitch and roll orientations.
• Calibration validation results show that the sensor can estimate roll and pitch with good accuracy, with RMSE values of 0.46° and 4.23° respectively.
• The researchers employed non-linear regression for calibration of the joint angle sensor, demonstrating its effectiveness in accurate sensing.
• The sensor's design allows for stable and accurate position control and actuation in flexible or continuum manipulators.
• The researchers' work has significant implications for the development of innovative robotics and machine learning technologies.
• Brunel University London researchers, Osman Dalia and Murali Madeshwaran, led the study along with Noh Yohan.
• The study, titled "Design of a two axis optoelectronic joint measurement sensor using orientation constraining mechanism for flexible robotic application," was published in the MATEC Web of Conferences.

Statistics:

• RMSE values: 0.46° for roll and 4.23° for pitch.
• The sensor uses two optoelectronic sensors integrated into a spherical-joint inspired structure.
• The study employed non-linear regression for calibration, which resulted in accurate joint angle measurement.

Sources:

• MATEC Web of Conferences. "Design of a two axis optoelectronic joint measurement sensor using orientation constraining mechanism for flexible robotic application." (2025): 04003. doi: 10.1051/matecconf/202541304003.
• Brunel University London. "Design of a two axis optoelectronic joint measurement sensor using orientation constraining mechanism for flexible robotic application." Journal of Engineering. October 20, 2025; p 137.
• EDP Sciences. MATEC Web of Conferences.