3-Axis Consumer Accelerometer Applications and Challenges

Transcription

1 June16-19, Axis Consumer Accelerometer Applications and Challenges PC108 Vincent Ko Marketing Manager (Sensor Products) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

2 Outline Applications and Sensing Functions Technical Challenges of the Applications Algorithm Development Accelerometer Products Road Map of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

3 Three strongest growth areas identified: Cell Phones Gaming Toys Key Markets & High Revenue Potential *Similar challenges across other markets in other applications Example: Tilt in Gaming challenges compared to Tilt in a Remote Control of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

4 Sensing Functions & Challenges Tilt Resolution Accuracy Shock/Freefall Impact Tap sensing Motion Power consumption Vibration FFTs of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

5 Understanding TILT Pitch & Roll Tilting *Demo 1: (Open GL 3D Tilt Cube Program) When an object is moving it sees a dynamic acceleration When an object is not moving, the effect 9.8 m/s 2 of gravity is called static acceleration of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

6 Differences between Resolution and Accuracy? Resolution? Accuracy? High Resolution does NOT imply High Accuracy High Accuracy DOES imply High Resolution TILT: Resolution vs. Accuracy A 10-bit ADC system using 2 axes (X and Y) can achieve: resolution of +/- 0.3 degrees, assuming no errors A typical 2-axis accelerometer will provide: typical accuracy of +/- 10 degrees (no calibration) typical accuracy of +/- 2 degrees (calibration and temperature compensation) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

7 TILT Applications Cell Phones/PDAs: Scrolling, Menu Navigation, Tilt/Landscape Grades on a Treadmill Remote Controls E-compass for Dead Reckoning Automatic Leveling (boat lift, motor-home) Gaming Safety: Clothes Iron Survey Equipment Car Alarm Projector Keystone Correction Digital Camera Stability High Resolution? High Accuracy? Low Accuracy? of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

8 TILT Angle Resolution: Single-Axis (8-bit A/D) +x 1g θ = sin 1 ( A X ) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

9 TILT: Resolution Two Axes (8-bit A/D) y θ θ x 1g AX = sinθ A Y = cosθ θ A Y 1g θ A X A A X Y = tanθ *Demo 2: ZSTAR Tilt Dial Demo of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

10 1. A/D Conversion Limitations 2. Noise Resolution: A/D Converter 3.3 V input, Sensitivity 0.8V/g RESOLUTION = 3.3V 255* 0.8V / g Tilt Angle Bits Counts A/D Resolution 0º 20º 45º 90º mg per count 3.7º 3.95º 5.1º 10.8º mg per count 0.93º 0.99º 1.3º 9.3º mg per count 0.25º 0.25º 0.33º 5.2º Resolution mg per count 0.06º 0.06º 0.08º 2.2º mg per count 0.014º 0.015º 0.02º 1.03º mg per count 0.004º 0.004º 0.005º 0.33º Which A/D converter for what application? of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

11 Resolution Comparison: Noise R = N BWLPF 1.6 *N is the power spectral density in ug / Hz Applications Tilt for Scrolling: 4-16mg Image Rotation: 16 mg Tap Sensing: 4-16mg Part FSL: MMA7260L FSL: MMA7360L ADI: ADXL330 ST: LIS302ALB PSD Noise Resolution (BW=50Hz) 3.13mg 3.13mg 2.50mg 1.79mg Resolution (BW=10Hz ) ug / Hz 1.4mg 1.4mg 1.12mg 0.8mg Kionix: KXPS mg 0.7mg Bosch: SMB mg 0.64mg FSL: 14-bits digital (Feb 2009) mg mg of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

12 Signal: G-Cell Design Sense Gap spring Moving Finger Anchor proof mass Fixed Finger Fixed Finger Anchor + Sense - Sense C = Aε d of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

13 TILT: Accuracy Sources of Error Accuracy: How close to the MEASURED value from the accelerometer matches the TRUE value The purpose of 12-bits digital product - high accuracy for dead reckoning Determined by all sources of errors from the accelerometer A/D resolution limitations Zero-g offset error Sensitivity error Noise error Temperature change offset error Temperature change sensitivity error Cross axis sensitivity error Non-linearity error of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

14 TILT: Sources of Error MMA7361L Sources of Errors Delta (Range) Tilt Angle 0 Tilt Angle 20 Tilt Angle 45 Tilt Angle 90 0g Offset V (+/- 10%) Sensitivity 60 mv TCO (65 C) +/-2mg/degC TCS +/-0.03%/degC Noise 4.7mV RMS Non- Linearity +1% FSO Cross-Axis 5% FSO Total Errors Error- Offset of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

15 SHOCK/FREEFALL Applications Hard Disk Drive Protection Laptops Camcorders, MP3 Players Warranty Electronics, Shipping Packages Menu Selection/Tap Functions Cell Phones, Games of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

16 SHOCK: Challenges Low g accelerometers cannot determine high g Distinguishing tapping while walking/jumping Sampling time to detect a shock of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

17 Measuring SHOCK Previous sample Take current sample Compare current sample with previous sample, if there is a change greater than a minimum threshold we have a motion condition ADC Value (8-Bit) Shock X Y Z Time (s) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

18 SHOCK: Determining the Height of a Fall Freefall v = a * t d = ½ * a * t t=0.6s 1.8m So... 1ms=4.9µm! 10ms=0.49mm! ADC Value (8-Bits) X Y Z 100ms=49mm 1000ms=4.9m Time (s) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

19 More Realistic Fall Signature of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc X Y Z

20 SHOCK: Single and Double Click Detect Single Click Detect Double Click Detect *Demo 3 : Tap Sensing of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

21 MOTION Applications Handheld, battery operated devices Power consumption: detect on/off Human motion monitoring Toys Anti-theft Laptops, PDAs, cars of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

22 Measuring MOTION Previous sample Take current sample Compare current sample with previous sample, if difference is greater than predefined threshold then you have a motion condition ADC Value (8-Bit) Motion X Y Z Time (s) of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

23 No previous history! Planetary Model: check to see if X 2 + Y 2 + Z 2 = 1 Measuring MOTION When the accelerometer is not moving the 3D representation of the X, Y, Z outputs is a dot on the surface of the planet Allows for decision based on one reading, without previous history Ideal for low-battery applications, e.g. MCU wakes up for 5 ms every 1 s of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

24 MOTION: Power Cycling T ON (2ms) Sleep (3µA) Enable Time 998ms Sample Period 1000 ms 500 ms 250ms 100ms MMA7361L Idd (Typical) 4 ua 5 ua 7 ua 11 ua MMA7361L +MCU Idd 6 ua 9 ua 14 ua 27.5 ua *400 Hz LPF 2 ms Enable Time *Demo 4: Sampling Rate Demo of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

25 Motor health - predictive failure Cavitations in pumps Active vibration isolation VIBRATION Applications of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

26 Understanding VIBRATION Vibration signatures Processing FFTs requires time and RAM The frequency BW is limited to the roll-off *Demo 5: Tuning Fork Vibration of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

27 MMA73x1L Analog Accelerometer Family Members MMA7361L (1.5g, 6g) 0g detect pin MMA7341L (3g, 11g) MMA7331L (4g, 12g) Low current consumption: 400 ma 3 ma in Sleep mode Size 71% smaller by volume than QFN Low voltage operation: 2.2 V 3.6 V Z-axis self test for freefall function check Sleep* Vdd Gnd Zout Yout Xout N/C Top view N/C 0g det gsel N/C N/C Self-test N/C ASIC g-cell +X +Z +Y of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

28 Features 8-bit I 2 C or SPI digital output V Vdd operation 1.8 V compatible I/Os 400 ma IDD, 5 ma at sleep mode Selectable full scale range (2g, 4g, 8g) Programmable threshold interrupt Programmable pulse interrupt MMA745xL Digital Accelerometer Sleep* Vdd Gnd Zout Yout Xout N/C N/C 0g det Top view gsel N/C N/C Self-test N/C ASIC g-cell +X +Z +Y *Demo 6: Basic Functionality of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

29 MMA7660FC (September 2008) Features Portrait/Landscape solution for hand-held products with LCDs Operating current (data rate dependent) Standby current 10 µa Sample rate input for selectable response rate Auto wake-up/auto sleep interrupts Pulse (tap) function detects fast transitions Sensitivity 21.3 LSB/g (46.9 mg/bit) I 2 C interface 3x3x0.9 mm DFN Key Markets Mobile phones Portable media players Gaming Electronic learning toys Samples/sec Max µa µa 93.2 µa 68.6 µa 56.3 µa 50.1 µa 47.1 µa Typical µa µa 85.5 µa 61.3 µa 49.1 µa 43.1 µa 40 µa of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

30 One Accelerometer, Multiple Solutions Menu Navigation/Scroll Intelligent Ringer Motion dialing Pedometer 3D gaming Fall/Shock log (warranty) PowerSave ON/OFF Tap to Mute Virtual Mouse HDD Protection Intelligent Speaker phone Solutions with Additional Freescale Sensors: Altimeter/Barometric - - Pressure Sensor Compass GPS -- Magnetic (Earth Field) Sensor E-Compass Tilt Compensation GPS backup Camera Stabilization Image Rotation Proximity (E-Field) for Touchpad / Fingerprint MEMs Microphone (1-4) RF MEMs of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

31 Key Questions to Consider What is the application and what are the sensing functions? What are the power requirements/ limitations? What is the acceleration range required for detection? Sampling Requirements? How will the accelerometer be integrated into the product? Is there already a processor on board? Are there any environmental factors to consider? How accurate? What resolution? How will the customer use the end product? Calibration? Does the customer want a complete solution from FSL? Key Freescale contacts: Rod Borras: R.Borras@freescale.com Product Specialist Kim Tuck: kimtuck@freescale.com Applications Engineer of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

32 Conclusions 3-axis low-g accelerometer applications Challenges: tilt, shock, freefall, motion, vibration Consumer & industrial accelerometers roadmap of products of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

33 飞思卡尔低功率设计研讨会自 2008 年 11 月开始在亚洲 29 个城市举行 内容 时间 地点 独一无二的培训体验 了解如何设计一系列便携式产品, 从技术指标一直到原型, 注重电源管理 性能 响应能力和可扩展性. 不仅仅是推广展示和演示 设计采用 Flexis 系列 8/32 位 MCU 触摸感应和彩色图形显示硬件. 您不仅将学会如何节能, 而且我们将为您提供全套系统 自 2008 年 11 月 17 日开始, 一直持续到 2009 年 3 月. 不要犹豫, 马上预定 中国 (20 个城市 ) 台湾 新加坡 韩国 日本 (2 个城市 ) 印度 (3 个城市 ). 找到离您最近的位置 在哪里我能够找到更多信息和注册报名? 登陆 : 不要让低功率设计逼迫困扰您. 2008/09 年度最酷行业研讨会即将举行! 完全免费 of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. Freescale Semiconductor, Inc

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