Motion control is traditionally based on DSP, real-time applications
running on remote desktops and field buses. Rapid prototyping and
time-to-market deployment within a DSP may require considerable efforts
in terms of cost and development resources. In the context of the
Real-time Colibri project , we have developed an integrated platform
combining, on the same board, the power of a 32-bits microcontroller
(PXA270) with a DSP for fast data processing in order to provide the
end user with a comfortable graphical touchscreen LCD based interface
combined with the robustness of a hard real-time 2-axis motion control.
The combination of hard real-time and non real-time applications such
as the GUI has been achieved thanks to the Xenomai real-time framework
based upon Linux, which makes the coexistence of both application
domains possible. Performance measurements revealed very low IRQ and
scheduling latencies. Consequently, the Real-time colibri should pave
the way to new approaches, in which the position control loop as well
as the current control loop can be performed either by the
microcontroller (uC) and/or by the DSP, thus leading to different
modes: full uC, mixed uC/DSP, or full DSP. The definition and real-time
computation of complex movements can then be managed by the
microcontroller more easily.
