DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com Applications y Hydrographic surveying Airborne survey and mapping INS (Inertial Navigation Systems) AHRS (Attitude and Heading Reference System) GPS drop-out aiding Maritime guidance and control GNSS (Global Navigation Satellite System) Autonomous vehicle control and ROVs Machine control MEMS alternative to FOG/RLG IMUs ar • • • • • • • • • • 1 General Description • Precision 6-DOF MEMS Inertial Measurement Unit • Silicon Sensing’s latest VSG3QMAX inductive gyro and capacitive accelerometer MEMS • Excellent Bias Instability and Random Walk Angular - 0.2°/hr, 0.02°/hr Linear - 30μg, 0.05m/s/hr • Non-ITAR • Compact and lightweight - 68 x 61 x 62h (mm), 300g • Internal power conditioning to accept 4.75V to 36V input voltage • RS422 interfaces • -40°C to +85°C operating temperature range • Sealed aluminium housing • RoHS compliant • In-house manufacture from MEMS fabrication to IMU calibration • Evaluation kit and integration resources available • First class customer technical support • Future developments and expansion capability Multi sensor MEMS blending Low power ‘sleep’ mode Over-range output (reduced specification) Additional sensor integration - GPS/ Magnetometer/Barometer North finding mode AHRS functionality Other interface protocols and specifications Custom and host application integration DMU30 is a full six-degree-of-freedom inertial measurement unit providing precise 3-axis outputs of angular rate and acceleration, delta angle and velocity, and temperature, at 200Hz. Pr el im in Features DMU30 is the first of a new family of High Performance MEMS IMUs (HPIMU) incorporating precision VSG3QMAX high-Q inductive resonating ring gyroscopes and capacitive accelerometers. DMU30 represents a realistic, alternative to established FOG/RLG based IMUs due to its exceptional bias stability and low noise characteristics, yet it is comparatively compact, lightweight and offers low cost of ownership. Designed specifically to meet the growing demand from high-end commercial and industrial market applications for a ‘tactical’ grade non-ITAR IMU, DMU30 utilises Silicon Sensing’s class leading MEMS inertial sensors integrated and calibrated using an in-house state-of-the-art test facility. HPIMU development takes advantage of Silicon Sensing’s wide-ranging multi sensor technologies in a unique architecture to achieve a highly versatile IMU design. Planned capabilities include common mode error reduction, dynamic over-range output, low-power ‘sleep’ mode and performance enhanced sensor blending. Future developments will feature GPS, magnetic and ambient pressure sensing, north finding and AHRS functions. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 4.75 to 36V 14 Regulators Power Return 15 MPU MOSI MISO Vref SS High Performance Gyro X Accelerometer (+X, +Z) High Performance Gyro Y Accelerometer (-X, -Y) High Performance Gyro Z Temperature Sensors C.G. 18733 im in Run Mode Sync Prog Reset Chassis GND SCLK Accelerometer (+Y, -Z) y Expansion Feature 4 3 2 1 13 12 11 10 9 Analogue to Digital Converters RS422 Driver ar 8 7 6 5 Tx_Hi Tx_Lo Rx_Lo Rx_Hi 62 Pr el Figure 1.1 DMU30 Functional Block Diagram 61 68 All dimensions in millimetres. Figure 1.2 DMU30 Unit Overall Dimensions © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 2 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 2 Ordering Information Item Overall Dimensions Description Part Number mm 68 x 61 x 62H DMU30-01-0100 y High Performance MEMS Inertial Measurement Unit. in Customer Evaluation Kit (EVK) comprising a DMU30-01-0100, RS422 to USB Connector, USB Driver and Data Logging Software, Cables and Connectors, Instruction Manual. ar DMU30 IMU DMU30-01-0500 Length 600mm DMU30-01-TBD im el DMU30 Evaluation Kit Not Applicable Pr Mating connector plug and cable for DMU30 DMU30 Mating Connector © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 3 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com Minimum Typical Maximum Notes Dynamic Range (°/s) -200 – +200 Clamped at ±205°/s during over-range Scale Factor Error (ppm) -500 ±100 +500 Factory fresh test Scale Factor Non-Linearity Error (ppm) -500 ±100 +500 Factory fresh test -20 ±15 Over operating temperature range factory fresh test Bias Instability (°/h) – < 0.2 ar 3 Specification Parameter Random Walk ( °/h) – Bias Repeatability (°/h) – Gyro Bandwidth (Hz) Noise (°/s rms) VRE (°/s/g2 rms) in +20 im 0.4 0.04 As measured using the Allan Variance method. 20 100 Bias Repeatability = √(Biaswarmup)2 + (Biastoto)2 + (Biasageing)2 + (Biastemperature)2 ±0.35 +0.7 Over operating temperature range 10 85 90 -3dB point User programmable – 0.15 0.25 Wide band noise at 100Hz bandwidth -0.006 ±0.002 +0.006 10g rms stimulus 20Hz to 2,000Hz -0.7 Pr Gyro Cross Coupling (%) < 0.02 el Bias (°/hr) y Angular (Roll, Pitch, Yaw) © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 4 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 3 Specification Continued Parameter Minimum Typical Maximum Notes -10 – +10 Clamped at ±10.01g during over-range Scale Factor Error (ppm) -500 ±100 +500 – Scale Factor Non-Linearity Error (ppm) -500 ±100 +500 Maximum error from best straight line over ±10g Bias (mg) -5.00 ±1.50 – – Bias Repeatability (mg) – ar Over operating temperature range 0.05 As measured using the Allan Variance method. 0.05 0.06 3.5 7 Bias Repeatability = √(Biaswarmup)2 + (Biastoto)2 + (Biasageing)2 + (Biastemperature)2 ±0.35 +0.70 Over operating temperature range 10 85 150 -3dB point User programmable Noise (mg rms) – 1.00 2.30 Wide band noise at 100Hz bandwidth VRE (mg/g2 rms) -0.15 ±0.10 +0.15 3g rms stimulus 20Hz to 2,000Hz -45 – 100 Note that this exceeds operational temperature range – ±3 – In the operational temperature range Acc Bandwidth (Hz) -0.70 Pr Acc Cross Coupling (%) el Random Walk (m/s/h) 0.03 im Bias Instability (mg) +5.00 in Dynamic Range (g) y Linear (X, Y, Z) Temperature Output Range (°C) Accuracy (°C) © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 5 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 4 Environment, Power and Physical 4.1 Normal Operation Parameter Minimum Typical Maximum Notes Operating Temperature Range (°C) -40 – +85 Full specification Storage Temperature Range (°C) -55 – +100 – Operational Shock (g) – – 95 6ms, half sinewave Operational Shock (g) (powered survival) – – 1,000 1.0ms, half sinewave Operational Random Vibration (g rms) – – Non-Operational Random Vibration (g rms) – – Humidity (% rh) – Immersion Depth (m) – ar y Environment 20Hz to 2KHz 10 20Hz to 2KHz – 85 Non-condensing – 1 IMU is sealed RS-422 – Full duplex communication – 200 (default) – User programmable * future feature – 460,800 (default) – User programmable * future feature – < 1.0 1.2 Time to operational output – <5 20 Time to full performance (mounting dependent) – <3 4 With 120 RS422 termination resistor +4.75 +8 +36 Unit is calibrated at 8 volts Size (mm) – 68 x 61 x 62H – – Mass (grams) – 300g – TBC Baud Rate (BPS) Startup Time (s) (operational output) Startup Time (s) (full performance) Power (watts) Supply Voltage (V) el Data Rate (Hz) – Pr Communication Protocol (standard) im Electrical and Interface in 3.0 Physical Notes: DMU30 is designed for 1m immersion in water (IP67). To maintain integrity around the connector, it is essential that the mating connector is a sealed type, or a suitable sealing compound should be applied around the connectors. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 6 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 4.2 Absolute Minimum/Maximum Ratings Minimum Maximum -0.3V +37V – 2kV HBM – 6,500g 0.1ms 1/2 sine Electrical: Vdd ESD protection Environmental: Shock (non-operational) 15 years 12,000 hours – im Notes: Improper handling, such as dropping onto hard surfaces, can generate every high shock levels in excess of 10,000g. The resultant stresses can cause permanent damage to the sensor. – in Powered ar Unpowered y Life: Pr el Exposure to the Absolute Maximum Ratings for extended periods may affect performance and reliability. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 7 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 5 Typical Performance Characteristics This section shows the typical performance of DMU30. 5.1 Performance Characteristics Pr el im in ar y This section will include comprehensive test result statistics of all main IMU performance parameters. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 8 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 6 Glossary of Terms 7 Interface ADC Analogue to Digital Converter ARW Angle Random Walk AWG American Wire Gauge BPS Bits Per Second (or Baud Rate) BW Bandwidth C Celsius or Centigrade DAC Digital to Analogue Converter DPH Degrees Per Hour DPS Degrees Per Second DRIE Deep Reactive Ion Etch EMC Electro-Magnetic Compatibility ESD Electro-Static Damage F Farads h Hour HBM Human Body Model HPIMU High Performance MEMS Inertial Measurement Unit Physical and electrical inter-connect and RS422 message information 7.1 Electrical Interface 4.75 to 36V Kilo MDS Material Datasheet Micro-Electro Mechanical Systems mV Milli-Volts NEC Not Electrically Connected NL Scale Factor Non-Linearity Pr MEMS OEM Original Equipment Manufacturer OT Over Temperature PD Primary Drive PP Primary Pick-Off RC Resistor and Capacitor filter RT Room Temperature s Seconds SF Scale Factor SMT Surface Mount Technology SOG Silicon On Glass SD Secondary Drive SP Secondary Pick-Off TBA To Be Advised TBC To Be Confirmed TBD To Be Determined V Volts y Tx_Lo Tx_Hi in ar SYSTEM HOST im Hertz, Cycles Per Second K Rx_Hi* el Hz 14 Rx_Lo* RESET* RUN MODE* SYNC* 0V 6 5 7 DMU30 8 10 13 12 15 * These connections are optional and can be left not connected. C.G. 18734 Figure 7.1 Required Connections for RS422 Communications with DMU30 7.2 Physical Interface 15 8 9 1 15 Way Micro-Miniature Connector Type DCCM-15S C.G. 18735 Figure 7.2 DMU30 Socket Connector © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 9 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 7.3 Connector Specification 7.5 Communications with DMU30 DMU30 uses a 15 way socket connector which is the micro-miniature ‘D’ type range of connectors, produced by Cinch, Glenair and others. The Run Mode pin on the connector is used to control the output from the DMU30. The “Free Run” or “Enabled” mode is active when the Pin is floating (not connected), and the output will be enabled. The DMU30 plug mating connector is a 15 way plug, for example DCCM-15P (DCCM-15P6E518). y Silicon Sensing can supply a mating plug and cable to interface to DMU30 (Part Number DMU30-01-TBD). ar 7.6 Operational Message Output In/Out 1, 2, 3, 4 Future A SPI® comm port for future expansion I/O 5 Rx_Hi The positive receive connection required for the RS422 communication I 6 Rx_Lo The negative receive connection required for the RS422 communication I 7 Tx_Lo The negative transmit connection required for the RS422 communication O 8 TX_Hi The positive transmit connection required for the RS422 Communication O 9 Chassis GND Chassis ground I 10 Reset Microprocessor reset. Pin is pulled low to reset the device. Suggested implementation using TTL logic I 11 Factory Use Used by SSSL for programming purposes and should not be interfaced with N/A Sync Output signal that can be used by an external system to synchronise with DMU30 O 13 Run Mode Device Enable/Disable. Pin is pulled high or not connected to enable the device. Pin is pulled low to disable the device. Suggested implementation using TTL logic I 14 +Volts Input voltage to the DMU30. Can be between 4.75V and 36V I 15 GND Ground connected to the DMU30 I 12 el Table 7.1 Pin Information The Output Message is output on a RS422 Serial output at 460,800 baud using a non-return to zero protocol. Each byte contains a start bit (logic 0), 8 data bits and 2 stop bits (logic 1). Data is output in big endian format by default. in Signal im Label Pr 7.4 Pin Information Pin The DMU30 output is disabled when the “Run Mode” Pin is pulled low. Data is output at a rate of 200 messages per second. Each message contains 33 words (66 bytes) as described in Table 7.2. The message is transmitted if the “Run Mode” Pin is floating/HIGH. If the “Run Mode” Pin changes to a LOW (Disable output), while the message is being transmitted, the message is completed before the output is disabled. 7.7 Sensor Sampling and Synchronisation The inertial sensors within DMU30 are all sampled at 1,000Hz. The ‘Sync Pulse’ on the connector is set HIGH at the start of the sampling and returned to LOW when the last inertial sensor is sampled. Pulses are therefore seen on the connector at 1,000Hz. The inertial sensor measurements are then filtered with a 2nd order low pass filter, also running at 1000Hz. The factory default setting for this filter has a corner frequency of > 85Hz. The internal sequence for DMU30 is: • Cycle 1: Sample Sensors, 2nd order Filter • Cycle 2: Sample Sensors, 2nd order Filter, Calculate Sensor Compensation • Cycle 3: Sample Sensors, 2nd order Filter, Apply Sensor Compensation • Cycle 4: Sample Sensors, 2nd order Filter, Calculate Delta Theta and Vels • Cycle 5: Sample Sensors, 2nd order Filter, Transmit Message The message is transmitted after the ‘Sync Pulse’ associated with Cycle 5 has returned LOW. The inertial data included in the message is generated when the ‘Sync Pulse’ associated with Cycle 3 is HIGH. This enables the external equipment to synchronise with the time when the inertial data is valid. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 10 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 7.8 Operational Message Definitions 7.9 System BIT Flags The data output message has the content and sequence as shown in the table below: 7.9.1 System Startup BIT Flags 0 0 Header 16 Bit, 0x55AA 1 1 Message Count 16 Bit, 0 to 65535 decimal 2 2-3 Axis X Rate 32 Bit Single Precision FP, (˚/s) 3 4-5 Axis X Acceleration 32 Bit Single Precision FP, (g) 4 6-7 Axis Y Rate 32 Bit Single Precision FP, (˚/s) 5 8-9 Axis Y Acceleration 32 Bit Single Precision FP, (g) 6 10-11 Axis Z Rate 32 Bit Single Precision FP, (˚/s) 7 12-13 Axis Z Acceleration 32 Bit Single Precision FP, (g) 8 14-15 Aux Input Voltage 9 16-17 Average IMU Temperature 10 18-19 Axis X Delta Theta 32 Bit Single Precision FP, (˚) 11 20-21 Axis X Delta Vel 32 Bit Single Precision FP, (m/s) 12 22-23 Axis Y Delta Theta 32 Bit Single Precision FP, (˚) 13 24-25 Axis Y Delta Vel 32 Bit Single Precision FP, (m/s) 14 26-27 Axis Z Delta Theta 32 Bit Single Precision FP, (˚) 15 28-29 Aux Z Delta Vel 32 Bit Single Precision FP, (m/s) 16 30 System Startup BIT Flags 16 Bit decimal value 17 31 System Operation BIT Flags 16 Bit decimal value 18 32 Error Operation BIT Flags 16 Bit decimal value 19 33 Checksum 16 Bit 2’s Complement of the 16 Bit Sum of the Previous 0-18 data items TBA y Value / Unit ar Data Item in Word el im Item 32 Bit Single Precision FP, (volts) Pr 32 Bit Single Precision FP, (˚C) Table 7.2 Operational Message Data Output Definitions © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 11 DMU30 Technical Datasheet www.siliconsensing.com 7.9.2 System Operation BIT Flags 7.9.3 System Error Indication BIT Flags TBA TBA Pr el im in ar y High Performance MEMS Inertial Measurement Unit (HPIMU) © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 12 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 8 Design Tools and Resources Available Part Number Order/Download DMU30 Brochure: A one page sales brochure describing the key features of the DMU30 Inertial Measurement Unit. DMU30-00-0100-131 Download (www.siliconsensing.com) DMU30 Datasheet: Full technical information on all DMU30 Dynamic Measurement Unit part number options. Specification and other essential information for assembling and interfacing to DMU30 Inertial Measurement Unit, and getting the most out of it. DMU30-00-0100-132 Download (www.siliconsensing.com) DMU30 Evaluation Kit: DMU30 delivered with an RS422 to USB interface, plug-and-play real time display and logging software and two interface cabling solutions DMU30-01-0100 unit included. DMU30-01-0500 DMU30 Presentation: A useful presentation describing the features, construction, principles of operation and applications for the DMU30 Inertial Measurement Unit. — Download (www.siliconsensing.com) DMU30-01-0100-408 Download (www.siliconsensing.com) DMU30-01-TBD Order (www.siliconsensing.com) ([email protected]) DMU30-01-0100-TBD Download (www.siliconsensing.com) — Download (www.siliconsensing.com) y Description of Resource im in ar Item el Solid Model CAD files for DMU30 Inertial Measurement Unit: Available in .STP and .IGS file formats. 68 26.5 33 76º Pr DMU30 Plug and Cable: A mating plug and 600mm long cable. DMU30 Installation Drawing: CAD file containing host interface geometry. Available in .STP and .IGS file formats. Order (www.siliconsensing.com) ([email protected]) 70 PCD 52.1 0.5 RoHS compliance statement for DMU30 : DMU30 is fully compliant with RoHS. For details of the materials used in the manufacture please refer to the MDS Report. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 13 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 8.1 DMU30 Evaluation Kit 9 Part Markings The DMU30 Evaluation Kit enables the output data from the DMU30 to be viewed and logged for testing and evaluation purposes. DMU30 is supplied with an adhesive label attached. The label displays readable DMU30 part and part identification numbers. The part identification number is a numeric code; WWYYXXXX R where: WW = Manufacturing week number YY = Manufacturing year number XXXX = Serial number = Revision y R im Figure 8.1 DMU30 Evaluation Kit in ar A 4x4 data matrix barcode containing the part identification number is also displayed on the label. DMU30 PT NO. DMU30-00-0100 SER NO. WWYYXXXX R 8.1.1 DMU30 Evaluation Kit Contents DMU30 IMU (part number DMU30-01-0100). Pr • MEV RS485i to USB converter. • CD containing the MEV drivers. • USB memory stick containing the data logging software. • Mating plug and cable. • User manual. 8.1.2 System Requirements The DMU30 Evaluation Kit requires a PC with a USB port. The requirements for the PC are as follows: • Microsoft® Windows® XP (SP3 or greater), Vista®, Windows 7 or Windows 8 Operating Systems. The software has not been tested on any other Operating System and therefore correct functionality cannot be guaranteed. MADE IN PLYMOUTH UK DMU30 el The DMU30 Evaluation Kit (part number DMU30-01-0500) contains the following: Figure 9.1 DMU30 Label • Minimum of 500Mb of RAM. • 500Mb of free hard drive space plus space for logged data (typical data rate ≈ 50kbit/s). • High power or self-powered USB 2.0 Port. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 14 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com Figures 10.1 show the installation drawing for the DMU30. The DMU30 is designed for 4 point mounting using M5.0 screws. During calibration alignment is achieved using two external reference dowel holes on the base of the DMU30. The dowel holes are designed to be used with two Ø3mm (in accordance with BS EN ISO 8734 or BS EN ISO 2338) dowel pins provided by the host. The DMU30 mounting screw torque settings will be dependent on the host application; it will for example vary depending on the specification of the screw, the material of the host structure and whether a locking compound is used. When securing a DMU30 to the host system using steel M5.0 screws and a thread locking compound the suggested torque setting is 0.2Nm for securing to an aluminium host structure. This information is provided for guidance purposes only, the actual torque settings are the responsibility of the host system designer. y 10 Installation Details 5.65 5.45 Ø 0.2 68 68 im 26.5 33 61 76º in ar 4x Ø 3.201 3.186 3.5 DP MIN Ø 0.2 SLOT Ø All dimensions in millimetres. el 62 3.201 Ø 3.186 3.5 DP MIN Ø 0.2 70 PCD 52.1 0.5 Pr Figure 10.1 DMU30 Installation Drawing + Roll (R) +X + Pitch (P) +Y + Yaw (Y) +Z Figure 10.2 Axis Definitions © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 15 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 11 Packaging 12 DMU30 Construction and Theory of Operation Full packaging specification including package labelling (TBD). 12.1 IMU Construction DMU30 is an aluminium alloy assembly comprising base, housing, sensor block, sensor assemblies and IMU electronics. ar y The base and housing are sealed using a self-forming gasket and secured by four machine screws to provide a waterproof enclosure. A micro-miniature ‘D’ type socket connector located on the top face of the housing provides the electrical interface to the host system. The top face of the housing displays the DMU30 part marking information. Pr el im in DMU30 is aligned to the host system using two Ø3mm dowels in the host platform which locate with matching dowel holes in the bottom face of the base. The IMU is secured to the host using M5.0 machine screws. A precision machined aluminium 3-Axis Sensor Block, secured to the DMU30 Base by machine screws provides accurate alignment and support for the DMU30 MEMS inertial sensor assemblies and IMU electronics. Internally generated heat from the sensor assemblies and IMU electronics is absorbed into the sensor block and surrounding housing and conducted to the host via the base and to the ambient atmosphere via convection cooling fins in the housing. The IMU electronics is a triple-stack PCB assembly which is affixed to the sensor block by six spacers and machine screws to provide stable and precise alignment between the sensor assemblies. 12.2 Sensor Construction and Theory of Operation Silicon MEMS Inductive Ring Gyroscope The silicon MEMS ring is 6mm diameter by 100μm thick, fabricated by Silicon Sensing Systems using a DRIE (Deep Reactive Ion Etch) bulk silicon process. The ring is supported in free-space by sixteen pairs of symmetrical legs which isolate the ring from the supporting structure on the outside of the ring. © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 16 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com The tracks along the top of the ring form two pairs of drive tracks and two pairs of pick-off tracks. Each section has two loops to improve drive and pick-off quality. C.G. 18619 Figure 12.1 Silicon MEMS Ring ν el im in The bulk silicon etch process and unique patented ring design enable close tolerance geometrical properties for precise balance and thermal stability and, unlike other MEMS gyros, there are no small gaps to create problems of interference and stiction. These features contribute significantly to DMU30’s bias and scale factor stability over temperature, and vibration immunity. Another advantage of the design is its inherent immunity to acceleration induced rate error, or ‘g-sensitivity’. ar y One pair of diametrically opposed tracking sections, known as the Primary Drive PD section, is used to excite the cos2 mode of vibration on the ring. This is achieved by passing current through the tracking and, because the tracks are within a magnetic field, causes motion on the ring. Another pair of diametrically opposed tracking sections are known as the Primary Pick-off PP section are used to measure the amplitude and phase of the vibration on the ring. The Primary Pick-off sections are in the segments 90° to those of the Primary Drive sections. The drive amplitude and frequency is controlled by a precision closed loop electronic architecture with the frequency controlled by a Phase Locked Loop (PLL), operating with a Voltage Controlled Oscillator (VCO), and amplitude controlled with an Automatic Gain Control (AGC) system. The primary loop therefore establishes the vibration on the ring and the closed loop electronics is used to track frequency changes and maintain the optimal amplitude of vibration over temperature and life. The loop is designed to operate at about 14kHz. Upper Pole Silicon Pedestal Glass Pr Can Lid Can Base Magnet Support Glass ν ν Lower Pole C.G. 18620 Figure 12.2 MEMS VSG3Q Cos2θ Vibration Mode at 14kHz MAX Sensor The ring is essentially divided into 8 sections with two conductive tracks in each section. These tracks enter and exit the ring on the supporting legs. The silicon ring is bonded to a glass pedestal which in turn is bonded to a glass support base. A magnet, with upper and lower poles, is used to create a strong and uniform magnetic field across the silicon ring. The complete assembly is mounted within a hermetic can. Zero Radial Motion at these points ν C.G 18623 Figure 12.3 Primary Vibration Mode © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 17 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com ν Resultant Radial Motion im Fc ν ν Fc Pr Applied Rate Fc el Fc = Coriolis Force ν Silicon MEMS Capacitive Accelerometer The accelerometer contains a seismic ‘proof mass’ with multiple fingers suspended via a ‘spring’, from a fixed supporting structure. The supporting structure is anodically bonded to the top and bottom glass substrates and thereby fi xed to the sensor package base. ar y When the accelerometer is subjected to a linear acceleration along its sensitive axis, the proof mass tends to resist motion due to its own inertia, therefore the mass and its fingers become displaced with respect to the interdigitated fi xed electrode fingers (which are also fi xed to glass substrates). Air between the fingers provides a damping effect. This displacement induces a differential capacitance between the moving and fi xed silicon fingers which is proportional to the applied acceleration. Capacitor plate groups are electrically connected in pairs at the top and bottom of the proof mass. In-phase and out of phase waveforms are applied by the ASIC separately to the ‘left’ and ‘right’ finger groups. The demodulated waveforms provide a signal output proportional to linear acceleration. in Having established the cos2 mode of vibration on the ring, the ring becomes a Coriolis Vibrating Structure Gyroscope. When the gyroscope is rotated about its sense axis the Coriolis force acts tangentially on the ring, causing motions at 45° displaced from the primary mode of vibration. The amount of motion at this point is directly proportional to the rate of turn applied to the gyroscope. One pair of diametrically opposed tracking sections, known as the Secondary Pick-off SP section, is used to sense the level of this vibration. This is used in a secondary rate nulling loop to apply a signal to another pair of secondary sections, known as the Secondary Drive SD. The current applied to the Secondary Drive to null the secondary mode of vibration is a very accurate measure of the applied angular rate. All of these signals occur at the resonant frequency of the ring. The Secondary Drive signal is demodulated to baseband to give a voltage output directly proportional to the applied rate in free space. Figures 12.5(a) and 12.5(b) provide schematics of the accelerometer structure and control loop respectively. Sensing axis Fixed support C.G 18400 Figure 12.4 Secondary Vibration Mode The closed loop architecture of both the primary and secondary loops results in excellent bias, scale factor and non-linearity control over a wide range of operating environments and life. The dual loop design, introduced into this new Sensor Head design, coupled with improved geometric symmetry results in excellent performance over temperature and life. The discrete electronics employed in DMU30 ensures that performance is not compromised. Fixed Electrode 1 Fixed Electrode 2 Proof mass (includes fingers) C.G. 18613 Figure 12.5(a) Schematic of Accelerometer Structure © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 18 DMU30-00-0100-132 Rev 1 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com 88kHz reference Electrode 2 Signal proportional to movement of proof mass Out of Phase Square Wave at 88kHz on Electrode 2 Sensing axis Demodulator Amplifier Electrode 1 Low pass filter In Phase Square Wave at 88kHz on Electrode 1 Output signal C.G. 18540 Pr el im in ar y Figure 12.5(b) Schematic of Accelerometer Control Loop © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. DMU30-00-0100-132 Rev 1 Page 19 DMU30 Technical Datasheet High Performance MEMS Inertial Measurement Unit (HPIMU) www.siliconsensing.com Pr el im in ar y Notes Silicon Sensing Systems Limited Clittaford Road Southway Plymouth Devon PL6 6DE United Kingdom Silicon Sensing Systems Japan Limited 1-10 Fuso-Cho Amagasaki Hyogo 6600891 Japan T: F: E: W: T: F: E: W: +44 (0)1752 723330 +44 (0)1752 723331 [email protected] siliconsensing.com +81 (0)6 6489 5868 +81 (0)6 6489 5919 [email protected] siliconsensing.com Specification subject to change without notice. © Copyright 2015 Silicon Sensing Systems Limited All rights reserved. Printed in England 03/2015 Date 06/03/2015 DMU30-00-0100-132 Rev 1 DCR No. 710008599 © Copyright 2015 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company. Specification subject to change without notice. Page 20 DMU30-00-0100-132 Rev 1