MEMS传感器融合，从软件着手天地更宽

随着越来越多的MEMS传感器出现在移动装置中，如今MEMS设计重点已经从分离式MEMS组件转向MEMS传感器数据整合。 美国新成立的公司Sensor Platforms Inc. (SPI)的执行副总裁Ian Chen表示，来自于多个传感器的原始数据如何“融合”与“诠释”，将会显著影响系统的功耗和应用性能。 以此作为公司使命的SPI，日前推出了一套中间件设计及软件算法库。该公司宣称，透过使用移动装置中的多个传感器数据，“能够诠释用户所处的情境架构与意图。” 目前在智能手机与平板电脑中常见的MEMS传感器包括加速度计、磁力计、陀螺仪与气压计(晴雨表)。 在《EETimes》日前发表的MEMS产业数据库与报告中，将多个MEMS传感器组件整合的趋势称为“传感器融合革命的崛起”。该报告中亦指出，当今的MEMS组件供货商和系统设计师正面临一个悬而未决的问题：谁将主导传感器的架构？包括将在何处进行处理，以及主板级传感器融合架构？ 虽然许多公司采用在单一芯片上整合所有传感器，并为智能化组件封装各种功能(这其实也并非易事)的方式，SPI公司却选择了另一种途径：提供一种独立于硬件之外，完全以软件为主的传感器融合方案。 该公司表示，这种基于程序代码的单一软件方案可在跨平台使用。它完全能够执行于应用处理器、传感器或整个系统上。 基于软件的传感器融合一个最显著的优势就是灵活性(flexibility)。Chen说：“我们的软件方案可让系统设计者为每个传感器选用不同的供应来源。这种供应来源的灵活性是至关重要的，因为各种传感器分别具有不同的价格与性能点。” 为移动设备整合进更多的传感器很容易，但如何尽可能地减少随之而来的功耗却是个问题。 但SPI公司的 FreeMotion软件库包含了一套专用算法，能够“在用户缓慢移动时，关闭较耗电的传感器，如陀螺仪，以其它低功耗传感器的方式仿真其功能。这将降低传感器约90%的功耗。”他补充道。 关于可靠性的问题，陈说，虽然知之者甚少，但有些智能手机的电子罗盘校正功能可能相差到90度。也因此，为保证精准，所有的传感器都需要经常进行校准。而FreeMotion软件库是建立在更可靠的取样以及持续不断进行交叉传感器校准的基础上，从而能为应用程序开发人员与终端用户提供更可靠的传感器信息。 总之，只是一味地将更多的MEMS传感器整合进系统中，并不足以改善功耗、弹性度、可靠性，以及应用的性能等。 Semico Research的首席技术分析师Tony Massimini说：“系统设计人员如何充分地加以利用所获得的繁多的数据呢？我们目前还可能只是蜻蜓点水而已。”此外，他坦言，“事实上，这个产业还处于早期发展阶段。许多甚至对于MEMS不熟悉的系统设计人员们需要这一类的软件开发工具。” 不仅是系统设计人员，应用程序开发人员可能也需要这类软件开发工具：他们正试着从移动设备的传感器取得更多动作数据，并加以利用于目前新开发的应用程序上。Chen表示，SPI正推出 FreeMotion软件库API，所以由其传感器校准和传感器融合所产生的数据为应用程序开发人员提供了具有更高准确性的有力数据。而应用程序需要与用户有关的各种信息及其情境架构，而不只是用户的位置或其动作与方向的变化而已。FreeMotion软件开发工具为扩展应用程序能从传感器数据取得信息的类型提供了重要的基础。 本文下一页：市场格局 本文授权编译自EE Times，版权所有，谢绝转载

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{pagination} 市场格局 SPI公司的主要竞争对手就是目前正自行开发传感器融合软件的MEMS传感器组件供货商。 2012年2月，飞思卡尔半导体(Freescale Semiconductor)为其电子罗盘推出Xtrinsic传感器融合软件。电子罗盘应用结合了磁力计提供的航向以及惯性传感器的校正数据，为磁场失真进行补偿。飞思卡尔为其MEMS传感器用户提供免费下载的传感器融合算法。 而意法半导体(STMicroelectronics；ST)于2011年秋天推出名为iNEMO引擎传感器融合套件的传感器融合算法。ST表示，其iNEMO引擎能结合其iNEMO惯性模块，共同打造完整且可客制化的硬件/软件多轴MEMS传感器解决方案，以强化动作并准确辨识方位。 这些MEMS传感器供货商使用专有的软件库，目的在锁定客户使用其产品；相形之下，Chen表示，SPI公司独立于硬件之外的传感器融合软件在这方面提供了更大的灵活性。 而Massimini认为，传感器融合仍处于早期发展阶段并预期未来在吸引更多的市场关注后，将会带来更多的创新。尽管目前尚未形成有效的竞争格局，Massimini认为Movea公司可能成为SPI的潜在对手。 Massimini说，SPI才刚成立进入这一市场之际，Movea公司已经为客户提供解决方案多年了。Movea为移动装置、平板电脑、互动电视，以及便携医疗电子(eHealth)等市场提供与运动响应相关的软件、固件与半导体IP。目前，Movea已经开发出一款可让开发人员用Movea IP模块建置算法的系统，现正与一家CAD供货商共同合作，期望开发出一款可用于设计ASIC的工具。 本文授权编译自EE Times，版权所有，谢绝转载 参考英文原文MEMS' new battleground: Hardware-agnostic sensor fusion?

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{pagination} MEMS' new battleground: Hardware-agnostic sensor fusion? Junko Yoshida 3/26/2012 12:01 AM EDT NEW YORK – As more and more MEMS sensors are showing up in mobile devices, the focus of MEMS design has begun shifting from discrete MEMS components to MEMS sensor data integration. How raw data from multiple sensors is “fused” and “interpreted” makes a noticeable difference in a system’s power consumption and apps performance, according to Ian Chen, executive vice president, Sensor Platforms, Inc., a San Jose, Calif.-based start-up. Keeping that premise as the company mission, Sensor Platforms is rolling out Monday (March 26th) a library of software algorithms and middleware designed, according to company claims, “to interpret users’ contexts and intents” by using data from multiple sensors in mobile devices. Commonly found MEMS sensors in today’s smart phones and tablets include accelerometers, magnetometers, gyroscopes and barometers. The recently published EE Times Confidential’s MEMS Sector Database and Report calls the trend for integration of multiple MEMS sensors “the rise of sensor fusion revolution.” The report points out that one unanswered question confronting today’s MEMS component suppliers and system designers is: “Who will determine the sensor architecture, where the processing will reside and the motherboard-level sensor fusion architecture?” While some companies may integrate all these sensors in a single monolithic device and wrap everything in smart components (although not an easy feat), Sensor Platforms has chosen another approach: offer sensor fusion in software that’s hardware agnostic. The company says that its single code-base software can be used across platforms. It can be run in its entirety on an apps processor, on a sensor hub, or spread over the system. That gives one clear advantage to Sensor Platforms’ software-based sensor fusion, said Chen: flexibility. “Our software allows system designers to pick and choose different supply sources for each sensor. The flexibility in sourcing is critical since these sensors come at different price and performance points.” Another advantage of Sensor Platforms’ software lies in the conservation of sensor power, according to the company. Throwing more sensors into a mobile device is one thing. But how to minimize the associated power consumption is another. Chen noted, “Up to 10mW is added in power consumption when sensors are in use.” Sensor Platforms’ software library, called “FreeMotion Library,” comes with a proprietary algorithm that can “turn off power hungry sensors, like the gyroscope, and emulate its function with lower power sensors when user movements are slow.” That translates into “dropping sensor power consumption by 90 percent,” he added. Then, there is the issue of reliability. Although not broadly advertised, some smart phones’ compass calibration can be off by 90 degrees, according to Chen. “All sensors require frequent calibration to maintain their data quality,” he noted. Sensor Platforms’ FreeMotion Library is built on an architecture that supports reliable sampling, and ongoing cross-sensor calibration to assure reliable sensor information – both for application developers and end users, the company said. In sum, just designing a number of MEMS sensors into one’s system is hardly enough to improve a system’s power consumption, flexibility in system designs, sensor data or reliability and apps’ performance. Tony Massimini, chief of technology at Semico Research, noted: “Now with all this data, how do the system designers fully utilize it? We may be just scratching the surface.” Further, he acknowledged, “The industry is at an early stage. System designers, many new to MEMS, need software development tools.” The need for SDK is not limited to systems designers. It extends to apps developers, who are trying to leverage motion data – collected by sensors in a mobile device – in their new apps. Chen said Sensor Platforms is rolling out the FreeMotion library’s API, so the data produced by its sensor calibration and sensor fusion provides apps developers robust data with better accuracy. Further, Chen said that “apps need information and context about the user, not just the user’s location or changes in his motion or direction.” The FreeMotion software development kit offers “a foundation to extend the type of information that applications can gain from sensor data,” according to Sensor Platforms. Competitive landscape Sensor Platforms’ key competitors are likely to be MEMS sensor component suppliers, who are developing their own sensor fusion software. Earlier this year, Freescale Semiconductor, for example, introduced its own sensor fusion algorithms called Xtrinsic for electronic compass. Electronic compass applications combine magnetometer-provided headings with corrections from inertial sensors that compensate for stray magnetic fields. Freescale is offering its sensor fusion algorithms as a free download for its MEMS sensor users. Meanwhile, STMicroelectronics last fall rolled out its own sensor fusion algorithms called iNEMO Engine Sensor Fusion Suite. According to ST, its iNEMO Engine can be combined with ST’s iNEMO Inertial Modules to create complete and customizable hardware/software multi-axis MEMS sensor solutions for enhanced motion and accurate heading recognition. These MEMS sensor vendors use proprietary libraries to lock customers into their products, explained Sensor Platforms’ Chen, in contrast to his company’s hardware-independent sensor fusion software. Semico’s Massimini, describing sensor fusion as “still at early stages,” expects “more innovation as it draws more attention.” While the competitive landscape remains far from being defined, Massimini mentioned Movea as a potential competitor. “Movea has been delivering solutions for several years while Sensor Platforms is a startup just hitting the market,” he said. Movea is offering motion-responsive software, firmware, and semiconductor IP for markets such as mobile and tablets, Interactive TV and sports and eHealth. Massimini noted, “Movea has developed a system that allows system developers to implement their algorithms using Movea IP blocks. Movea is working with a CAD vendor so the output of this tool can be used to design an ASIC.”