Piezoelectric multilayer triaxial accelerometer C. Mangeot 1, B. Andersen 1, and M. Havránek 2 1 Noliac Motion, 2 Noliac Systems Hejreskovvej 18, Kvistgaard, 3470, Denmark Version: 200705
The accelerometer market Conventional systems Mostly piezoelectric Specific applications for piezoresistive Very mature market Families of sensors for each environment and performance range MEMS More recent developments Increasing number of applications
Conventional accelerometers Market dominated by shear mode sensors Mass Housing Piezoelectric element(s) (ring or plates) Acceleration direction
Conventional accelerometers A few bending type accelerometers Fulcrum Housing Acceleration direction Bending piezoelectric element(s) (ring or plates)
Conventional accelerometers + High performance (sensitivity, bandwidth, linearity) + Tolerant to environment + Large available range - Complex - Difficult to miniaturize, heavy - Costly
Conventional accelerometers Market status 1000 Endevco 35A Acceleration range (+/- G) 100 10 Brüel Kjaer 4524 Kistler 8690C10 1 1 10 100 1000 Mass (g)
MEMS accelerometers + Various principles + High volume, low cost + Light weight + Variable performance - Limited in terms of environment - Difficult to qualify for aerospace or military applications - Difficult to customize
Accelerometer development in the Noliac Group Cooperation within the group Noliac Motion (Denmark) Expertise in multilayer piezoelectric elements Noliac Ceramics (Czech Republic) Expertise in ceramic materials Noliac systems (Czech Republic) Expertise in piezo transducer development
Ceramic monolithic multilayer triaxial accelerometer () 6 regions electrically defined in the same piezoelectric body Patent pending Patent pending
Measurement principle X-Y axis Zones compressed by bending stresses Vibration direction Zones stretched by bending stresses Patent pending
Measurement principle X-Y axis: charge movements Patent pending
Measurement principle Z axis Vibration direction Stretched zone Compressed zone Patent pending
Measurement principle Z axis: charge movements Patent pending
Temperature compensation Temperature change: charge movements Patent pending
SWOT Expected advantages Low cost (simplicity) Compact, lightweight solution Temperature compensated High sensitivity Orthogonality of the axes Potential for high temperature application Potential disadvantages Heterogeneity X-Y vs. Z Low stiffness
Prototype design Dimensions Cross section 2 x 2 mm Free length 7 mm No seismic mass Symmetrical design Performance Calculated first resonance 15 khz Mass 0,68 grams
Prototype design Material Noliac Ceramics PCM53 Soft-doped PZT ceramic g 31 = -8,4.10 3 Vm/N T c = 350ºC Selected for its temperature stability Adaptable design High temperature versions possible High g versions possible
Prototype design Temperature stability 30% Impedance at serial resonance Relative impedance at serial resonance / 20ºC (%) 20% 10% 0% -10% -20% -30% -40% -50% -40-20 0 20 40 60 80 100 120 140 160 Temperature (ºC) PIC255 PCM53 Pz27
Prototype design Temperature stability 4 Sensitivity at serial resonance Relative sensitivity at serial resonance / 20ºC (db) 2 0-2 -4-6 -8-10 -12-14 -40-20 0 20 40 60 80 100 120 140 160 Temperature (ºC) PIC255 PCM53 Pz27
Prototypes Ceramic multilayer sensor
Prototypes Prototype on mount and demonstrator
Performance tests X axis 10 Sensitivity (pc/m.s-2) 1 0,75 0,72 0,76 0,69 0,62 0,62 0,63 0,65 0,65 0,66 0,69 0,71 1,00 0,63 0,86 0,1 10 100 1000 10000 Frequency (Hz)
Performance tests Y axis 10 0,66 0,68 0,66 0,70 0,76 0,75 0,74 0,70 4,20 4,06 Sensitivity (pc/m.s-2) 1 0,73 0,83 0,90 1,17 2,09 0,1 10 100 1000 10000 Frequency (Hz)
Performance tests Z axis 10 8,56 Sensitivity (pc/m.s-2) 1 0,87 0,78 0,87 0,81 0,85 0,89 0,87 0,82 0,88 1,09 1,31 2,35 0,95 0,28 0,1 10 100 1000 10000 Frequency (Hz)
Performance tests Homogeneity 10 Sensitivity (pc/m.s-2) 1 X-Axis Y-Axis Z-Axis 0,1 10 100 1000 10000 Frequency (Hz)
Performance Homogeneous results for all 3 axes Sensitivity 0,6-0,8 pc/m.s-2 for X-Y Sensitivity 0,8-1,0 pc/m.s-2 for Z Stable response over frequency range 10 Hz to 2 khz Low resonance (5 khz) due to the fixture
Summary + High sensitivity + Flat and homogeneous response + Light weight (0,68g ceramic) + Simple construction (low cost) - Bandwidth limited to 2 khz for this first prototype
Performance range Position on market 1000 Endevco 35A Acceleration range (+/- G) 100 10 Brüel Kjaer 4524 Kistler 8690C10 1 1 10 100 1000 Mass (g)
Conclusions Unique advantages Further development Packaging Integrated electronics Range adapted to each measurement Develop market potential High sensitivity, light weight, temperature stability, compatible with harsh environments Aerospace applications Instrumentation (f.ex. automotive)
Thank you for your attention NOLIAC A/S www.noliac.com Charles Mangeot cm@noliac.com Version: 200705