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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Inertial Technology For North Finding Steve Clarke, Applications Engineer.
December 2013
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
To be the leading provider of affordable, high
performance, high integrity MEMS inertial products
and foundry services
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Contents
• Who we are
• What a gyroscope does
• Current products
• Typical applications
• MEMS gyroscopes – how they work.
• High precision gyroscope
• North finding
– Techniques
– Important parameters
– Test Results
• Summary
• Questions/Discussion
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
A UTC/SPP Joint Venture Company
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Silicon Sensing
Systems Japan
UTC Aerospace
Systems
Sumitomo
Precision
Products
Silicon Sensing
Systems Ltd
Silicon Sensing
Products Japan
Silicon Sensing
Products UK
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Who we are
5
BAE Systems
acquires
Condor Pacific &
forms
Inertial Products
(2002)
J.F. Lehman
acquires Inertial
Products &
forms Atlantic
Inertial Systems
(2007)
UTC acquires
Goodrich and
forms UTC
Aerospace
Systems
(2012)
Goodrich
acquires AIS
(2009)
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
What a gyroscope does
• Angular rate sensors, are used whenever rate of turn sensing is required without a fixed
point of reference. This separates gyros from any other means of measuring rotation,
such as a tachometer.
• Traditionally, gyros (gyroscopes) were much like the children’s toy – a spinning mass
supported such that its position in inertial space remains fixed and allowing rotation of its
support structure to be measured.
• The world of inertial sensors has turned on its head with the emergence of ’solid state’
non-rotating rate sensors, still colloquially known as gyros. Their construction in silicon
(or sometimes quartz) explains their other descriptive name of ‘MEMS’ (Micro-machined
Electro-Mechanical Systems) devices.
• MEMS gyros emerged through the need to overcome the biggest problems associated
with traditional spinning wheel gyros – mechanical issues such as fragility, reliability,
stiction, wear, backlash and overall life.
• Based on a vibrating element, MEMS gyros sense rotation rate through a phenomenon
known as coriolis.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Current Product Range
• Single Axis Gyroscopes
– PinPoint®
– CRS09/CRS39
– CRH01
– CRG20
– CRS03/CRS07
• Combination Sensors
– Orion ®
• Accelerometers
– Gemini ®
• Multi-axis
– DMU02
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Applications
• Platform Stabilisation:
Camera Stabilisation
• Antennas
• Agriculture Spray Booms
Cranes
• Fork Lift Trucks
• Vehicle Dynamic Measurements
• Proving and Qualification
• Motorsport
Black box/accident recorders
• Lean Angle Measurement
Ride monitoring
• Flight Instruments and Avionics
• AHRSs, VRUs, VRSs
Autopilots
UAVs
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Applications
• GPS Integration and Augmentation:
Autosteer – Precision Agriculture
Auto-helms
Tilt Compensation – Precision Agriculture
Navigation
• Guidance Navigation and Control:
Vehicle Navigation
Position Monitoring
Surveying
Vehicle Guidance and Control
• Rail:
Surveying and Track Condition Monitoring
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Applications
• Automotive:
Black box/accident recorders
Navigation
• Technical Toys
Model Helicopters
Robotics
Education Kits
Inverted Pendulum
• Plant and Power Equipment:
Power Tools, safety and control
Lawn Mowers
Domestic/Industrial Robots
Torque Wrenches
Robotic Vacuum Cleaners
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
A Vibrating Structure Gyroscope, VSG
Sensor Head
A Gyroscope consists of a vibrating structure plus controlling electronics.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
• Silicon Sensing’s gyroscopes are Vibrating Structure Gyroscopes, VSGs
• These VSGs use shell (cylinder or ring) structures and work on the Coriolis principle where forces are observed when a linear motion occurs in a rotating frame.
• The closed loop technology provides excellent scale factor and performance over wide rate and temperature ranges.
• The technology has a very rugged design and construction and delivers superior performance than its competitors using other structures (e.g. tuning fork).
Vibrating Structure Gyro (VSG) Technology
VSG5
2010
“Evolution not Revolution”
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
SGH01 Head
• Deep trench etched in bulk silicon
• Stable and robust crystalline silicon - 100µm thick
• Planar construction
• Single crystal pane
• Stability of key parameters (fn, f1-f2, Q1-Q2)
• 8 dog Legs to support the vibrating ring.
• Ring diameter: 6mm
• Leg width: 60m
• Each leg carries three electric tracks
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
How the VSG works
No angular rate applied
n
n
n
n n
n
n
n
c
n
n
n
n n
n
n n
n
n
n n
n
n
n
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
With angular rate applied
How the VSG works
n
n
n
n
F c = Coriolis Force
n
n
n
n
F c
F c
F c
Resultant
Radial Motion
Applied Rate n
n
n
n n
n
n
n
F c = Coriolis Force
n
n
n
n n
n
n
n
F c
F c
F c
Resultant
Radial Motion
Applied Rate
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
VSG3 Sensor Head Construction
can base
support glass lower pole
upper pole
silicon
magnet
can lid
pedestal glass
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Electronic Control Closed Loop Operation
Sensor Head
Electronic control loop and the sensor head needed to make a gyroscope. Electronic control loop and the sensor head needed to make a gyroscope.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
• CRS09
• Rate Ranges ± 100º/s and ± 200º/s
• Bias Instability ~ 0.6º/h
• CRS39-01 (unpackaged) CRS39-02 (packaged)
• Rate Range ± 25º/s
• Bias Instability ~ 0.3º/h typical
• CRS39-03 (unpackaged)
• Rate Range ± 25º/s
• Bias Instability ~ 0.08º/h typical
• CRH01 and CRH02
• Rate Range ± 25º/s ± 100º/s ± 200º/s and ± 400º/s
• Bias Instability ~ 0.2º/h (CRH01), ~ 0.1º/h (CRH02) typical
• CRH01
High Performance MEMS Gyroscopes
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CRS09
CRS39-01
CRS39-03
CRS39-02
CRH01
CRH02
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding – Indexing Technique.
Sensitive Axis
Table
0°
Indexing Table
CRS39
NORTH
Measurement 1
Measurement 2
Measurement 3
Measurement 4
0°
180°
90°
270°
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding – Indexing Technique.
Measurement 1
Measurement 2
Measurement 3
Measurement 4
0°
180°
90°
270°
Heading = ATAN2 ( Meas1 – Meas2)
( Meas3 – Meas4)
where
Meas1 = EarthRate1+FixedErrors1+VariableErrors1
Meas2 = EarthRate2+FixedErrors2+VariableErrors2
Meas3 = EarthRate3+FixedErrors3+VariableErrors3
Meas4 = EarthRate4+FixedErrors4+VariableErrors4
but
EarthRate2 =-EarthRate1 and EarthRate4 = -EarthRate3
FixedErrors2=FixedErrors1 and FixedErrors4=FixedErrors3
therefore
( Meas1 – Meas2) = 2xEarthRate1 + ΔVariableErrors12
( Meas3 – Meas4) = 2xEarthRate3 + ΔVariableErrors34
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Bias Instability and Angle Random Walk
• The standard deviation of the bias changes between successive averages is plotted against the averaging period (or Correlation Time).
• Raw noise from the gyroscopes can be seen at the sampling frequency (there is no averaging here) at the left side of the chart, i.e. at 0.002 seconds above.
• Angle Random Walk can be calculated from the point where the -0.05 Gradient for a particular plot intercepts the 1 second point and then divided by 60. For the CRS09 above, the gradient intercepts at 2.8 deg/h, giving an ARW = 0.047 deg/√h.
• Bias Instability is read from the lowest part of the plots, 0.6 deg/h for CRS09.
Allan Variance
0.1
1.0
10.0
100.0
1000.0
10000.0
0.001 0.010 0.100 1.000 10.000 100.000 1000.000
Correlation Time (sec)
Bia
s S
tan
dar
d D
evia
tio
n
deg
/h
CRS09 CRG20 PinPoint
Gradient = -1
Gradient = -0.5
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
CRS39: Allan Variance.
CRS39-01 CRS39-03
Bias instability improved from 0.3º/h to 0.08º/h
Angle Random Walk improved from 0.013º/√h to 0.0083º/√h
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding Accuracy – Raw Measurements
Single Measurements Unit 2. Single Measurements Unit 1.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding Accuracy – Improvements
• Use more than one device
• Use n devices to get √n improvement factor.
• Use multiple measurements
• Use n measurements to get √n improvement factor.
• Ensure the device is warmed up
• Stable temperature improves bias instability.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding Accuracy – Averaged
Averaged Measurements. Single Measurements.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
North Finding Accuracy – After Warm Up.
Averaged Measurements Unit 2
After Warm Up.
Averaged Measurements Unit 1
After Warm Up.
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Summary
• Who we are
• What a gyroscope does
• Current products
• Typical applications
• MEMS gyroscopes – how they work.
• High precision gyroscope
• North finding
– Techniques
– Important parameters
– Test Results
• Summary
• Questions/Discussion
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Questions/Discussion
Contact Details:
Silicon Sensing Systems Ltd.,
Clittaford Road
Plymouth
Devon
PL6 6DE
Tel: +44 (0) 1752 723330
www.siliconsensing.com
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Silicon Sensing is a joint venture between Atlantic Inertial Systems and Sumitomo Precision Products
Inertial Technology For North Finding
December 2013