Simultaneous measurement of flexible robotic link deflection and rotation using position sensing detectors

It is well known that the flexibility of robotic links causes deformation and reduced positioning accuracy of the robot at the end-effector. This problem becomes more complicated when the links are made of new materials, such as composite. Various approaches including strain gauges, fiber Bragg grating, computer vision and optoelectronics have been applied to solve the problem. This work proposes an optoelectronic method with a reduced number of position sensing detectors and laser diodes to determine both bending and torsion deformations of a robotic link. The attachment of two optoelectronic sensors on the link and the two laser dots produced on these sensors by diodes provide the data required for computations. The tip deflection values are obtained using trigonometric functions. Both iterative and explicit methods of link tip movement have been analysed for efficiency and accuracy. The methods have been validated experimentally and error analysis has been performed.