A BMBF funded project
Forschungszentrum Karlsruhe - Institut
für Prozeßdatenverarbeitung
und Elektronik (IPE) - is a subcontractor of the
partners participating in the BMBF (ministry of education and research)
funded project "KOMET". The objective of this project is to develop
"compact modules for inertial measurement technology". This
document gives a brief introduction to the project, which is based on readout
circuits for micromechanical inertial sensors developed by IPE. The project's
own website (in German) is at
Motivation
Great demand for miniaturized
low-cost Inertial Measurement Units (IMUs)
- Land/marine
vehicles, aviation, medical science, multi-media, robots...
- Position and
orientation sensing over limited time periods without external reference
systems
Example
1: Hand-held power screw driver
- tracking of tool
movements => verification if all screws tightened
- + torque data => quality management report
- reference position
for IMU i.e. at the rest position for the tool
- small size IMU !!
Example 2: Rehabilitation
- Monitoring/report
generation for home training
- small size & low cost
IMU !!
Example 3: Virtual Reality
- Position and
orientation tracking without complicated mechanics
- small size & low cost
IMU !!
Solution
Micromechanical acceleration and
angular rate sensor elements
- Miniature size (mm-range)
- Can replace
expensive precision mechanical components.
- Low-cost manufacturing
Requirements for readout electronics
- High precision up to
physical limits of sensing elements
- High degree of miniaturization
- Low-cost
=> Application Specific
Integrated Ciruits (ASICs)
- Precision readout
circuits, originally for LIGA sensor elements,
also suitable for other (Si-)micromachined
capacitve sensor elements.
Readout
Circuits for IMUs at IPE
- Repeatedly improved
readout circuit, SMD components:
3D, high resolution (ug/sqrt(Hz) range), good
linearity (force-feedback)
3D, miniaturization, superior linearity, immediate digitization,
self-test capability, adjustment/configuration by software
- Readout circuit, SMD components:
low noise, good linearity
- Readout concept
suitable for an ASIC implementation, based on accelerometer ASIC,
digital output
- High precision up to
physical limits of sensor elements
- Miniaturization
- Low cost
BMBF-funded
Project 'KOMET'
"Compact Modules for
Inertial Measurement Technology" - Development of low-cost miniature IMUs based on uST (Micro
Systems Technology)
- Adaption to different
demands ("2+1 IMU", "3+3 IMU", etc.)
- Adding new
developments (i.e. future angular rate ASIC)
- Application-specific
interface modules (i.e. CAN, ProfiBus)
=> Module concept
("piggyback system") for system evaluation, based on the presented
readout circuits
- Analog 3-axis
accelerometer module (needs ADC module)
- Digital 3-axis
accelerometer module with readout ASIC (doesn't need ADC module)
- 3-channel 24-bit ADC
modules for angular rate and acceleration
- 3-axis angular rate
sensor interface module connects commercial angular rate sensors to ADC
module
- CPU module (Infineon
80C164) with 256k RAM, 256k ROM, CAN interface, RS-232 interface
(program debugging)
- Power supply module
operating from a single 10...25V supply
- Module system
extendable for other micro systems technology applications
Complete 6-axis IMU using Systron-Donner 'Horizon' angular rate
sensors and the following modules:
Power-supply, CPU, Digital 3-axis accelerometer, 3-channel 24-bit ADC, angular
rate interface
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