Motion and I/O control

A moving role in sports history: Using mobile cameras to track athletes and events has made a huge difference to the quality of TV coverage. We've all grown used to seeing the determination and effort of athletes as they race for the line, but for the companies that design the camera tracking systems that give us these exciting images, the technical demands are escalating rapidly.

Media companies want better and better views, with centimetre-perfect tracking, and they want to see the technology applied to more and more sports disciplines. For the UK-based pioneer, Camera Tracking Company (CTC) - who have been at the forefront of this field since their inception in 1991 - this meant a system re-design to cope with the escalating application program sizes forced by spiralling I/O levels.

Originally based on a Baldor UK SmartMove - a standalone servo motion controller with a 16-bit processor and 64kbytes of battery-backed RAM - the company recently upgraded its motion control systems to the NextMove BX. This boxed module comes with a 32-bit DSP and 0.5Mbyte of RAM for program storage, providing both the speed and memory for considerable expansion and growth.

The results could be viewed at the recent Commonwealth Games in Malaysia, which provided the venue for CTC to introduce new variations of its technology including a system whichn tracks gymnasts on the run up the vault, and a vertical system for tracking pole vaulters - a world first.

The motion part of CTC's system is based on a capstan-like drum driven by a brushless AC servo motor, to pull a gyro-stabilised camera payload along a carbon fibre track. Over the past few years, more and more digital I/O has been integrated into this system to allow the operators to program in specific positions, accelerations, decelerations etc, in order to optimise the camera views and movement for specific events.

In total, around 100 digital channels are currently utilised, which are interfaced economically using options from Baldor's CAN-based I/O expansion range. CTC's system also employs NextMove BX's built-in analog I/O to give the operators fine control over acceleration and deceleration to make real-time adjustments to tracking specific athletes' performances.

"The analog I/O handling built into the Mint control language was one of the key features for us when we originally chose using the SmartMove system," notes Sam Heaphy, Director of the Camera Tracking Company. "The new NextMove controller has now provided us with much greater hardware capability, giving us the speed and the program space to add sophisticated new motion control features."

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