A wave of the hand - Optoelectronics

Designing a human-computer interface and the electronic components supporting it – which, increasingly, applies to anything from a washing machine to a gaming platform – is becoming more complicated. On/off, next/previous, forward/back and other binary choices are fast giving way to nuanced commands. Instead of, 'show the next choice', the command might be 'skip through most of these, but not all'. And, this type of command won't necessarily come from a keyboard or touch sensitive pad – in the near future, it will come from the wave of a hand. This is becoming possible thanks to 3d gesture recognition (GR) technology. The first mass market application of 3d GR systems is emerging in computer gaming, where innovative 3d tracking techniques will allow players to fully interact with the game by simply moving their hands and body. There is no longer any need for cumbersome wands or handheld devices, enabling a more intuitive and realistic gaming experience. The recent launch by Microsoft of the Kinect platform for the Xbox is an example of this new application. How does it work? The roots of gesture recognition technology go back to the use of a light pen to manipulate onscreen objects – moving them, changing sizes and using constraints. The light pen communicated 2d hand gestures to the computer. In the first Apple computers, the mouse replaced the light pen, still working in 2d, but adding several degrees of precision. More recently, capacitive touchscreens have proliferated to virtually all smartphones and remote controls with accelerometers, such as the Nintendo Wii, are now commonplace. While these technologies have come a long way, the day to day interaction between human and computer remains complicated and usually involves some sort of remote control, keyboard or handheld device. The aim of 3d GR is to simply this interaction by letting body movements effectively control the electronic environment. So how does a 3d GR sensor pick up commands without any physical connection to the user? By constantly sensing changes in light patterns reflected back to the eyes, the brain can create an exact 3d map of its immediate vicinity. This map allows the human to interact seamlessly with this environment, be it hitting a golfball or scanning through video selections on an on demand tv system. Controllerless 3d GR systems work in the same way. Let's take the example of a player swinging a golf club in computer game. A light source in the GR sensor head illuminates the area in front of it, including the player, with infrared light. An optical receiver detects the light that is reflected back. Optical filters in the sensor ensure that only reflected light is detected, with spurious and ambient light being filtered out. Fast electronics in the sensor then process the received information, turning it into a 3d map, which the computer or gaming console can interpret and use to insert the player real time into the game. Different proprietary techniques can produce this 3d map. For example, some techniques use the round trip time of the reflected light, while others use patterns encoded onto the light. Whatever the method, the end result is the same: a realistic gaming experience without any wires to trip over. Despite the number of different technologies that support these systems, all 3d GR sensors share a basic component list: * Light source. An led or laser diode typically generating infrared or near-infrared light. This light isn't normally noticeable to users and is often optically modulated to improve the resolution performance of the system. * Controlling optics. Optical lenses help to illuminate the environment optimally as well as focus reflected light onto the detector surface. A bandpass filter lets only reflected light that matches the illuminator's light frequency reach the light sensor, eliminating ambient and other stray light that would degrade performance. * Light detector. A high performance optical receiver detects the reflected, filtered light and turns it into an electrical signal for processing by the firmware. * Firmware. High speed asic or dsps process the received information and turn it into a format which can be understood by the application – for example, the computer game software. Applications The computer gaming market was the first mainstream application to emerge, but the huge volume of tvs and home entertainment systems in use worldwide offer an attractive new market for 3d GR systems. In the near future, you will be able to control most of the electronics in your living room from your chair using simple hand movements. Following on from this first wave of applications, one can envisage 3d GR control of car sound systems, phone links and environmental controls, making driving a safer and less stressful experience. 3d GR systems embedded in computer notebooks – and even in multifunctional mobile phones could facilitate easier and more intuitive interfaces. The potential applications are many. 3d GR systems are an elegant and effective way to free users from the burdens of electronic remote controls or wands or keyboards — hence, the intrinsic market demand for such systems is clear. The speed at which 3d GR is adopted will, however, depend on a number of factors: * Performance. The performance of human interface devices such as the gaming wand, the remote control or the computer mouse has been perfected over decades. For 3d GR systems to replace these devices, they must offer a similar degree of performance. The first generation of gesture recognition systems is already close, if not equal, in terms of speed, resolution, and accuracy, but further investment in high speed optics and electronics will be necessary to ensure widespread adoption. * Price. How much more the end user is prepared to pay for 3d GR functionality will be application dependent, but an attractive cost model is vital to drive market penetration into consumer markets. The optics and much of the electronics know how within 3d GR systems has been leveraged from the more mature telecommunications industry, enabling immediate competitive pricing as well as high volume manufacturing capability. However, challenges still remain, particularly for cost sensitive applications. * Size. 3d GR hardware for mobile applications will need to be compact and robust. First generation 3d GR systems are still relatively large, but investment has started the development of more integrated components to shrink the size of the sensor head significantly. Conclusion 3D GR is a fundamentally inexpensive, rapidly emerging technology. The hardware requires little in the way of raw materials and lends itself to high volume manufacturing. Whenever a control goes much beyond on/off in terms of complexity, the cost threshold for implementing 3d GR will be low and these new systems will improve the ease with which every one of us interacts with our electronic environment. This will be an exciting and fast moving market over the next few years. Author profile: Sinclair Vass is director of EMEA sales for JDSU.