Motion control technology incorporated in Camera Tracking’s latest mobile camera system is providing the first close-up filming of vertical sports action such as pole vaulting without track-side operators or cranes. Housed inside a 14cm-high case with a vertical slide for the video camera, the system is controlled remotely over a network from a terminal, which can be sited up to half a kilometre away.
Used for the first time at the Sydney Olympics to cover pole vault, shotput and football goalmouth action, the system includes a Baldor MintDrive, which integrates a separate motion controller and electric motor drive into one compact box and provides a fieldbus interface for communicating with it via a network.
These attributes allowed Camera Tracking Company (CTC) to construct the single-axis mobile camera controller in a little over half the space normally needed, and control it via a single cable – typically utilising standard microphone cabling which is often already in place at locations, or easily pre-rigged via contractors. The complete system is packaged in a box which stands 14cm high, with folding support legs.
‘The space saved allowed us to create an automated mobile camera that can be located right next to the action’, said Sam Heaphy, Director of CTC, part of the Aerial Camera Systems group. ‘The technology gives broadcasting companies the means to provide close-ups of a new class of sports events including pole vault, discus and shotput’.
The motion control system consists of a MintDrive with a matched performance brushless servo motor connected to a belt-driven linear slide to carry the camera. The slide is mounted on an aluminium extrusion, available in different lengths depending on the event being covered.
MintDrive’s integral Can fieldbus interfaces were key to CTC’s selection of the product, allowing it to send camera movement commands. The Can protocol provides a sizing mechanism, which allows data communications speed to be traded off against distance. In this instance, Can is typically providing a 100 kbit/s datalink over distances up to 500m. At the remote terminal end of the system, the operator uses a joystick and switches to manipulate the camera.
‘Normally, the Can network is used to link to I/O or other drives which might be up to a few metres distant around a machine’, suggested Baldor’s Eliza Rawlings. ‘In this instance the versatility of the bus is really being exploited, allowing a man-machine interface to be positioned at extreme range – in a truck compound outside the stadium – to ensure unimpeded visibility in the sports arena.’