W2 IMU User Guide - Omni Instruments
Contents
1. 1234 The serial port settings are shown in Table 1 Serial Port Settings The IMU starts sending sample packets once a Bluetooth connection has been established with a host Interference from other devices which use the same frequency range 2 4GHz as Bluetooth such as 802 11 wireless networks can cause occasional packet loss Other potential interference sources include noisy devices such as microwaves and fluorescent lights Table 1 Serial port settings PARAMETER SETTING Bits per second 115200 Data bits 8 Parity None Stop bits 1 Flow Control No 2 2 Modes The W2 IMU operates in two communications modes data and configuration The default communication mode is the Data Mode where the IMU outputs data described in the sample format section The default settings for the W2 IMU are contained in Table 2 While operating in the Data Mode the IMU can be switched into the Configuration Mode by transmitting zzz r via the wireless connection Once the IMU is in the Configuration Mode commands can be sent that configure the gyroscope and accelerometer dynamic ranges as well as the sample rate Table 3 details the available configuration commands for the W2 IMU A power reset clears changes not saved to the IMU and returns operation to the Data Mode Table 2 W2 IMU Default Settings SETTING DEFAULT VALUE Accelerometer Dynamic Range 6 Gyroscope Dynamic Range 500 Output Sample Rate 152. if the Z axis is pointed straight down towards the earth it will produce 0 g for the X and Y axes and a positive 1 g for the Z axis A counterclockwise rotation of the IMU about any of the depicted axis will produce a positive angular rate output for the corresponding axis X Figure 3 Wireless IMU coordinate system Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 7 5 0 Electrical Specifications and Options 5 1 Part Numbering INSTRUMENTS Table 6 Standard part number Part Accel g Rate s W2 IMU 2 4 6 8 and 16 250 500 and 2000 5 2 W2 IMU Accessories The W2 IMU ships with a 3 foot micro USB cable used for charging and an ESD protective carrying case The use of any Bluetooth transceiver is possible however the optimal range will be achieved with transceivers using non chip based antennas Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 8 AN MEMSENSE INSTRUMENTS 5 3 Specifications Table 7 W2 IMU Specifications PARAMETER SPECIFICATION UNITS C
3. a TE E a T a a a a 8 5 3 SpecificatiON Ses minoori ei enia i EE ETERRA EREE E 9 6 0 Terms Conditions And Warranty seescscieireninc E E 10 Information provided in this document is believed to be accurate however it is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg iii 1 0 O a MEMSENSE INSTRUMENTS Introduction The W2 IMU is the second generation Memsense wireless IMU that provides wireless serial digital outputs of triaxial acceleration angular rate and magnetic field as well as temperature and barometric pressure via the Bluetooth wireless protocol The inertial outputs are compensated over temperature for bias scale factor and cross sensitivity The accelerometers and gyroscope within the W2 IMU can be configured to different dynamic ranges over the wireless connection with a simple command structure The available ranges for the gyroscopes are 250 500 or 2000 sec and 2 4g 6g 8g and 16g for the accelerometers With the Bluetooth capability the IMU can communicate with a wide variety of hosts such as PCs tablets phones and embedded systems The range of transmission can be affected by the environment but typical range capabilities are on the order of 60 feet An integrated rechargeable battery allows for up to 5 hours of power and can be charged
4. dynamic range to 16 g is provided below STEP COMMAND INFO 1 zzz r 2 a 16 r Serial Number 16274 Gyro Range 500 Accel Range 16 Sample Rate 150 3 d r 4 x r Sample Rate Default Example DESCRIPTION Enter Configuration Mode Change Accelerometer Dynamic Range to 16 IMU returns current settings Save the change to defaults Exit Configuration Mode A command sequence for changing the default sample rate to 100 Hz is provided below STEP COMMAND INFO 1 zzz r 2 s 100 r Serial Number 16274 Gyro Range 500 Accel Range 6 Sample Rate 100 3 d r 4 x r DESCRIPTION Enter Configuration Mode Change Sample Rate to 100 IMU returns current settings Save the change to defaults Exit Configuration Mode Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 3 AN MEMSENSE INSTRUMENTS 2 3 Sample Format An individual data packet is collectively referred to as a sample Data samples are formatted as shown in Table 4 Sample byte order format Each data channel is represented by a signed 2 s complement 2 byte short 16 bit integer that represents the output level of the signal To convert this value to its corresponding engineering unit see Section 2 4 Table 4 Sample Byte Order F
5. other than Seller The warranty period for Products repaired or replaced under this warranty shall be limited to the components repaired or replaced and shall run for a period of one hundred and eighty 180 days from the date of delivery or the balance of the original one 1 year Warranty Period excluding the time the Products were out of service and in Seller s plant whichever is longer EXCEPT AS STATED IN THIS SECTION SELLER MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE MERCHANTABILITY TITLE AND NON INFRINGEMENT OF THIRD PARTY RIGHTS LIMITATION OF LIABILITIES In no event shall Seller be liable to Buyer or any third party for consequential indirect punitive special or incidental damages including but not limited to loss of profits arising from or relating to the sale delivery or use of the Products Seller s total cumulative liability under this Agreement to Buyer or any third party including indemnity obligations whether in contract or tort or otherwise will not exceed the amount paid by Buyer to Seller for the Product sold hereunder giving rise to such liability DELAYS Seller shall not be liable for delay in delivery or for failure to manufacture due to causes beyond its reasonable control including but not limited to acts of God acts of any government acts of civil or military authority acts of Buyer application of US Government prioriti
6. the remainder of a divide by 256 Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 4 AN MEMSENSE INSTRUMENTS 2 4 Measurements The gyroscope accelerometer and magnetometer values may be converted to rotational rate acceleration and gauss respectively The data is transmitted as signed 2 s complement 16 bit integers The following function must be used for conversion of raw values Equation 1 result raw_payload x digital sensitivity where the result is the converted value in the appropriate units e g s raw value is the raw component specific value from the payload e g accelerometer X and digital sensitivity is the digital sensitivity of the sensors configuration found in Table 7 Candidate ranges are as shown in Table 5 Sensor Dynamic Ranges For example a 500 deg s 6 G W2 IMU the corresponding equations for the X component would be X Gyro Value Raw Payload Value x 2 28882 X Accelerometer Value Raw Payload Value x 2 74664 where the raw payload value is taken from the sample payload corresponding to the x components of the gyro and accelerometer respectively The resulting values have units of degrees sec and gs respectively Table 5 Sensor Dynamic Ran
7. 0 Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 2 AN MEMSENSE O TE INSTRUMENTS Table 3 Configuration Mode Commands COMMAND DESCRIPTION zzz r Enter Configuration Mode from Data Mode i r Request current settings information g lt space gt lt Dynamic Range gt r Change Gyroscope Dynamic Range to 250 500 or 2000 a lt space gt lt Dynamic Range gt r Change Accelerometer Dynamic Range to 2 4 6 8 or 16 s lt space gt lt Sample Rate gt r Change output Sample Rate to 100 125 or 150 d r Save current settings to Defaults x r Exit Configuration Mode to Data Mode Note r denotes a carriage return Gyroscope Default Dynamic Range Example A command sequence for changing the default gyroscope dynamic range to 2000 s is provided below STEP COMMAND INFO 1 zzz r 2 g 2000 r Serial Number 16274 Gyro Range 2000 Accel Range 6 Sample Rate 150 3 d r 4 x r DESCRIPTION Enter Configuration Mode Change Gyroscope Dynamic Range to 2000 IMU returns current settings Save the change to defaults Exit Configuration Mode Accelerometer Default Dynamic Range Example A command sequence for changing the default accelerometer
8. 2 A i eT Product Specification amp User Guide Document Number DOCO0298 Document Revision C l 888 668 8743 For pricing or any further information please contact Omni Instruments Ltd UK Europe Office Australian Office USA Canada Office O Tel 44 845 9000 601 Tel 61 282 442 363 Tel 1 866 849 3441 pter pa Fax 44 845 9000 602 Fax 61 294 751 278 Fax 1 866 625 8055 info omni uk com info omniinstruments com au info omniinstruments net Measurement and data acquisition solutions www omniinstruments co uk www omniinstruments com au www omniinstruments net AN MEMSENSE INSTRUMENTS Wireless IMU Product Specification amp User Guide Document Number Release Revision Release Revision Date DOC00298 C October 14 2014 Document Owner Design Engineering Information provided in this document is believed to be accurate however it is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg i a MEMSENSE O INSTRUMENTS Document Change History Rev Status Description Date A Superseded New Document 8 29 2013 Changed the magnetometer sensitivity This B Superseded new spec only applies to rev B or later 11 20 2013 product c ea Corrected units on magnetometer noise 10 14 2014 density Information pr
9. Document Number DOC00298 Document Revision C Product Number MP00048 pg 9 6 0 AN MEMSENSE INSTRUMENTS Terms Conditions and Warranty DEFINITION As used herein Seller means MEMSense 2693D Commerce Road Rapid City SD 57702 Buyer means the party purchasing Product s from the Seller Product means all articles materials work or services offered by the Seller and described in the accompanying quotation acknowledgement invoice or other Seller form Order means any purchase Order or contract issued by the Buyer for Products provided by the Seller WARRANTY Seller warrants that the Products will be free from defects in material and workmanship and conform in all material respects to their applicable specifications for a period of one 1 year from the date of delivery Warranty Period when operated under normal conditions and in accordance with their applicable specifications For any breach of this warranty Seller will at its option and expense and as its sole obligation and as Buyer s exclusive remedy repair or replace any defective Product returned to Seller during the Warranty Period provided that an examination by Seller discloses to Seller s reasonable satisfaction that a defect is covered by this warranty This warranty does not apply to any Products that have been i subject to misuse neglect or abuse ii improperly installed or maintained or iii repaired or altered by anyone
10. ONDITIONS Operational Requirements Charge Voltage 4 9 to 5 5 Charge Current 250 300 Charge Time 1 5 Run Time 4 5 Devices Node 6 Wireless Range Clear line of sight Physical Properties Alignment Error Mass Acceleration Dynamic Range 2 4 8 Bias In Run 0 20 0 34 0 56 1 06 Offset 40 40 40 40 Noise Density 0 2 0 4 0 3 0 6 5 0 0 6 0 9 1 6 2 8 Typical Max Digital Sensitivity Bandwidth 50 50 50 50 3dB point Note 1 Angular Rate Dynamic Range 250 500 2000 Bias In Run 0 03 0 03 0 06 s Offset 1 5 1 5 1 5 s Max Noise Density 0 04 0 07 0 04 0 07 0 05 0 09 s Hz1 2 Typical Max 10 Digital Sensitivity 1 1444 x 10 2 2888 x 107 9 1553 x 10 s bit Bandwidth 3dB point Note 1 Magnetic Field Dynamic Range Offset Noise Density X and Y Axes 0 4 0 8 Digital Sensitivity 1 8311 x 10 Temperature Digital Sensitivity 1 8165 x10 C bit Pressure Digital Sensitivity 2 44 x104 mBar bit Absolute Max Ratings Acceleration Powered 2000 max g Any axis 0 5ms Charging Voltage 0 3 min 6 0 max VDC Operating Temperature 0 to 50 C Storage Temperature 20 to 60 C Storage Temperature 0 to 30 C Long Term Typical Values at 25 C and 0 s unless otherwise noted Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice
11. es Government delays in granting Export Licenses fires strikes floods war terrorism riot or civil commotion delays in transportation difficulty in obtaining necessary labor or materials In the event of any such delay date of delivery shall be extended for a period of time equal to that lost by reason of the delay TAXES Prices do not include sales or excise tax VAT duties or other governmental charges resulting from this transaction or the manufacture sale ownership possession or use of the Products all of which must be paid by Buyer Buyer shall provide Seller a tax exemption certificate acceptable to the taxing authorities SHIPMENT Title to all purchased material and risk of loss therefore is passed from Seller to Buyer at the time of shipment from Seller s facility Unless otherwise agreed upon in writing all purchased material will be shipped uninsured Seller may request partial shipment and invoice therefore EXPORT LICENSE Buyer will comply with all applicable export and import control laws and regulations in its use of the Products and Buyer will not export or re export the Products or any technical data or confidential information derived from or pertaining to the Products without all required United States and foreign government licenses Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime with
12. ges Sensor Ranges Gyroscope 250 s 500 s 2000 s Accelerometer 2 g 4 g 6g 8 g 16 g Magnetometer 4 gauss Pressure Sensor 260 1260 mbar Although the sensor data is temperature compensated a customer s application may require the use of temperature information therefore a temperature measurement is provided The temperature data provided requires a different conversion process The data is transmitted as signed 2 s complement 16 bit integers The following equation must be used for conversion of temperature sample values Equation 2 Temperature Degrees C Raw Payload Value x 1 8165 x102 25 where the result is the converted value in degrees Celsius and raw value is the raw value from the payload The pressure sensor output is a 24 bit value and is located in bytes 33 35 The conversion of the raw output to millibar is accomplished using equation 3 below Equation 3 Pressure mbar a T Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 5 AN MEMSENSE VV te O INSTRUMENTS 3 0 LED Indication The green LED on the IMU will indicate when the device is powered on and when the Bluetooth connection has been established When the IMU is powered on and is n
13. ormat ELEMENT BYTE ELEMENT i Sample Counter ISB Sample Counter LSB All samples begin with four 4 synchronization bytes where each byte contains OxFF The details on the structure of a sample are as follows Note all byte offsets are zero 0 based BYTES ELEMENT DESCRIPTION 0 3 Synchronization bytes each byte encoded as OxFF hex 4 Message size Size in bytes of entire data packet including complete header 5 Product ID 3 for Wireless IMU 6 Message ID Type of message Data messages with MID 0x14 hex 20 decimal 7 8 Sample Counter Represents a 16 bit counter of value of the number of samples with a rollover value of 65 535 Each count represents sample rate 9 Gyro Range Sample Bits 7 4 identify gyro range 0000 250 s 0001 500 s 0010 2000 Rate ols Bits 3 0 identify sample rate 0000 100Hz 0001 125Hz 0010 150Hz 10 Accelerometer Range Bits 7 4 identify accel range 0000 2 g 0001 4g 0010 8g 0011 16 g 11 12 Serial Number Unique number identifying each device 13 36 Payload The payload size calculated as follows payload size message size 13 header 1 Checksum byte 37 Checksum byte 8 bit checksum byte Sum sample contents header payload DO NOT include the checksum byte The summed value should equal the checksum if the message is valid If larger than 8 bit addition is used to calculate the checksum the checksum will be
14. ot connected the LED will blink slowly at a rate of approximately every 2 seconds When a connection has been established the blink cycle rate will increase to approximately once every second A rapid 3 blink sequence followed by a 3 second off period indicates that the battery is low and should be charged There is approximately 10 minutes of operation possible once the battery low indication is initiated When the IMU is charging the inverse of the above described patterns will be indicated 4 0 Mechanical 4 1 Dimensions The W2 IMU has four evenly spaced mounting holes that allow for the use of 4 40 Socket Head Cap Screws Two evenly spaced slots near the edges provide for mounting with a strap 0 608 At and A j US 0 07 300 Figure 2 Physical dimensions inches Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOCO00298 Document Revision C Product Number MP00048 pg 6 MEMSENSE W2 O INSTRUMENTS 4 2 Coordinate System The coordinate system for the Wireless IMU follows the right hand rule convention The sign convention for the accelerometers is configured to produce a positive signal when the Wireless IMU is accelerated in the opposite direction of the axis As an example with the Wireless IMU pictured in Figure 3 Wireless IMU Coordinate System
15. out notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 10
16. ovided in this document is believed to be accurate however it is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg ii INSTRUMENTS TABLE OF CONTENTS L0 Introd cti N ssee oer bene tee meee er ree eee eea aa Seren ee eee ene eee E ne eee ere eee eee ere ere 1 2 0 COMMUNICATIONS snini aaee dy bine acces oe eee EEE aE A aii dein ana ie 2 2 1 Bluetooth Communications isa snc vnssincicncndenitrcndyniseenininpednnseandeansuaitodinoianditaastdnnsdanialetibbaniindedtandautneadiasegeatedas 2 Dik o Te E E A E eee ea E RRORUN Ne NUM ERIN AAT 2 23 Sample CN sea siniestra a aeren anea eee ueiewsemnecensans tetas 4 ZA Measurements erenn sea TEKA NE n EATE ESETE aE EATE EA 5 30 Led Indications ieee e aE Re Eia E Ee EE RAAE EE EEE ESEE ESEESE EERS 5 4 0 Me chanicalssssiiire jena de wats ee a o e dass a aea a e aae eaa aa a 6 AT DIMENSIONS icicccissccesesbecccecedspedvessuene cdots aaie ANEETA OE AAEE TENACE NEATE TaN ANO SEAE EE 6 4 2 Coordinate SyYStEM senisesse ie nain a aE EER ETARE AAEE EE ERREA DAA ERE 7 5 0 Electrical Specifications And Options s essssssssessssssressssssesrssststsrntsttesrstststnsnsnststntstntattseststntnsnsnstsentnttnte 8 Bid P rt NWIMDGRNAS socsresd ceccsancatialatystasnargatadaneediencanalariaksaamaaieiusaaxomeedialaaannaneaamnacenanemeiatenen 8 3 2 W2 IMUPACCESSOMOS sciori aeria an
17. via micro USB which makes the W2 IMU a convenient option for inertial measurement applications The device measures 1 58 x 1 32 x 0 60 and can be either screw mounted or easily strapped down with the built in strap bars Multiple Wireless IMUs can be utilized simultaneously allowing inertial motion capture of multi segmented objects common in human motion analysis The miniature size wireless multiple device connection and configurability of the W2 IMU makes it an exceptional sensor choice for applications such as human motion analysis biomechanics or animation Bluetooth Wireless Transceiver Triaxial Accel Triaxial Gyro Charge Controller Microcontroller Triaxial Mag Temp amp Pressure Rechargeable Lithium lon Battery Figure 1 Wireless IMU Functional Block Diagram Information provided in this document is believed to be accurate however is not guaranteed MEMSense LLC reserves the right to change product specifications at anytime without notice Document Number DOC00298 Document Revision C Product Number MP00048 pg 1 2 0 FX MEMSENSE VV O Communications INSTRUMENTS 2 1 Bluetooth Communications The W2 IMU incorporates a wireless serial port module with a unique Bluetooth address The address of each IMU is W2IMU lt device SN gt and can be found by a host system thru a discovery Authentication with the W2 IMU requires a passkey with a PIN of
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