The most striking development in video game technology in recent years has been the emergence of motion control, a trend that is expanding the industry beyond its traditional demographics by appealing to young and old alike.
The Nintendo Wii with its WiiMote controller drove this change by allowing players to direct the action of game characters with natural gestures instead of by pressing buttons and pushing on joysticks.
Motion control has raised the interest level in many game genres, notably sports titles such as golf, bowling and tennis, where a swing of the arm can control the club, ball or racquet. The worldwide success of the Wii was enabled by MEMS accelerometer technology and wireless personal area networking.
Sixense Entertainment has developed a technology for gaming, TrueMotion, which aims to take motion control a step further. See
Sixense TrueMotion Presentation at NVISION08
The system captures the controller’s exact location and orientation. A key component of the system is a SHARC digital signal processor (DSP) from Analog Devices, which translates the raw signals from the controller to the 3D locations, orientations, velocities, and accelerations that drive the games.
The ADSP21261 is a suitable device for this application from both a core DSP technology and a peripheral feature perspective, offering glue-less connectivity to a multi-channel ADC and RF transmitter, for instance.
“Analog Devices has been a genuine partner in the development of TrueMotion,” said Amir Rubin, CEO at Sixense Entertainment.“Beyond their products and technology, such as the SHARC DSPs, ADI’s engineers and executives have been instrumental in all aspects of our current success and in laying out a roadmap for the future.”
A seamless and immersive real-time experience depends on the accuracy, responsiveness, and dependability of the controller. Any latency or interference is felt as on-screen lag or stutters, which detract from this experience.
The TrueMotion system traces its roots to military, aerospace, and surgical simulators and Hollywood performance capture for animation. It has the capability to provide one-millimetre position and one-degree orientation tracking 100 times per second, with no line-of-sight considerations. It is wireless and requires no calibration.
The hardware consists of a small basestation that generates a magnetic field that is approximately 2% the strength of the Earth’s magnetic field.
As the controller moves through this field, the SHARC processor computes its position and orientation relative to the basestation and relays the data to the game console or PC.
This computation is a complex function of distance from the basestation combined with the controller’s orientation relative to the basestation. Since the position and orientation data are reported nearly 100 times per second with extreme accuracy, the signal processing performance (latency and accuracy) is critical to the success of the system.
The floating point DSP provides the signal processing power to perform the Fast Fourier Transforms (FFTs) and vector calculations that extract the six position and orientation components from the received magnetic signals.
The deterministic behaviour of the chip’s DMA allows data to be loaded efficiently, providing accurate real-time processing.
Tony Zarola is DSP product line manager at Analog Devices