NANOMEFOS real-time path planning

High-performance optical systems rely more and more on aspherical and freeform optics to reduce or eliminate geometrical aberrations. A key element in the manufacturing and application of freeform optics is the availability of a suitable metrology instrument. Within the NANOMEFOS project such a measurement machine has been designed and built. The project was a joint effort of TNO Science & Industry, the Technische Universiteit Eindhoven and the Netherlands Metrology Institute Van Swinden Laboratory. The resulting measurement machine is capable of universal, non-contact and fast measurements of freeform optics up to 500 mm in diameter with an uncertainty of 30 nm.

The measurement machine contains several moving axes to position the laser beam (used for the coordinate measurements) on the freeform optic to be measured. The positioning and control of the various moving axes is done by a real-time controller, designed and implemented in Matlab^®/Simulink^® and dSPACE ControlDesk^®.

A part of the machine control system is the software to generate smooth trajectories for the movement of each individual axis. In addition, this software must carry out a collision check before a new trajectory is allowed to be executed. TNO Science & Industry approached IME Technologies to develop the real-time trajectory planning and checking software.

IME Technologies has implemented a third-order trajectory generator that operates in real-time at 10 kHz. Special care has been taken to exactly synchronize the trajectory generation code with the motion controllers for the machine. The real-time path planning and checking software were developed with Matlab^®/Simulink^® and IME Technologies cooperated with TNO Science & Industry to test and integrate the code into the machine control software.