Dual-axes capacitive inclinometer/low-g accelerometer for automotive applications

In this thesis, a nonlinear model of the vestibular system is proposed, with special reference to humans and other locomoting animals. The vestibular system is essential for stable locomotion since it provides idiothetic measurements of spatial orientation that are needed for postural control. The model was constructed from general considerations regarding the Newton-Euler dynamics governing the three-dimensional movements of bodies constrained to oscillate in non-inertial frames, such as the otoliths, which were modeled as spherical damped pendula. Two configurations were considered. The medial model considered only one inner ear located in the center of a head. The lateral model considered two inner ears located laterally with respect to the center of rotation of the head. The differences between these two models were analyzed and the importance of having two vestibular organs discussed. To this end, a nonlinear algebraic observability test was used to verify whether the reconstruction of the head orientation with respect to the gravitational vertical was possible from otoliths measurements only. It could be shown that in order for the head vertical orientation to be observable, the head had to be stabilized during locomotion. Moreover, it was shown that the gravitoinertial ambiguity inherent to inertial idiothetic sensing could be resolved if the head was horizontally stabilized. These results were applied to solve the head vertical orientation estimation problem in the linearized case (Luenberger observer, Kalman filter) as well as in the nonlinear case (Extended Kalman filter, Newton method based observation). These observers were designed and tested in simulations. The simulations indicated that the estimation errors were smaller and the observers converged faster when head was stabilized during locomotion, leading to a nonlinear, combined observation-control system that could be stabilized with respect to the gravitational vertical based on no other information than the prior knowledge of the Newton-Euler dynamics. The results were further tested with a specifically designed experimental setup that comprised an actuated gimbal mechanism to represent the head-neck articulation and a liquid-based inclinometer that represented the otoliths organs. The findings derived from this research would be helpful for analyzing spatial perception in humans and animals, and for improving the perceptual capabilities of robotic systems, such as humanoid robots, rough terrain vehicles, or free-moving drones.Keywords: vestibular system, head-neck system, nonlinear system, observation, estimation, verticality, spatial perception, locomotion, humanoid robot. 3 RésuméDans cette thèse, nous proposons un modèle non-linéaire du système vestibulaire, en particulier chez l'humain et autres animaux mobiles. Le système vestibulaire est essentiel pour une locomotion stable dans la mesure où il fournit des mesures idiothétiques d'orientation spatiale nécessairesà la stabilité posturale. Le développement du modèle est basé sur l...

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“…Some examples of different technologies used in accelerometer design can be found in [119,4,150,29,162].…”

Section: Accelerometermentioning

confidence: 99%

Modeling Verticality Estimation During Locomotion

Farkhatdinov

Michalska

Berthoz

et al. 2013

Romansy 19 – Robot Design, Dynamics and Control

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“…The yaw rate sensor, which is used for vehicle control, is also required to be highly accurate as preventive safety systems become more sophisticated. In this context, efforts have been made to achieve a thick structure using SOI [5][6][7], the Si-glass anodic bonding technique [8], and the trench refill process [9] and to achieve high accuracy by improving the anchor structure to reduce impacts of thermal stress and packaging stress [10,11].…”

Section: Introductionmentioning

confidence: 99%

High Accuracy Yaw Rate Sensor for Preventive Safety System

Kawaguchi

Fujimoto

Katsumata

et al. 2012

Lecture Notes in Electrical Engineering

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With a recent growing awareness of vehicle safety, the need for preventive safety systems is also increasing. This has promoted the practical use of new preventive safety systems, notably Adaptive Cruise Control (ACC) and Lane Keeping Assist (LKA) and the compulsory installation of existing preventive safety systems such as Electronic Stability Control (ESC) in all vehicles. In ESC and other preventive safety systems, tracking of actual vehicle behavior is important, and the yaw rate sensor is a key sensor necessary to keep track of the behavior. The need for high-accuracy yaw rate sensors has been increasing day by day in the context of the practical use of new preventive safety systems and the need for upgrading existing preventive safety systems. We have already implemented the capacitive accelerometer for air bags that features an element configuration using a general-purpose single-crystal SOI wafer, and a stacked structure comprising a sensor chip and a circuit chip. This time we have successfully developed a high-accuracy yaw rate sensor by applying the technology of the capacitive accelerometer. (1) Optimization of the sensor element configuration (using a frame structure to reduce leakage vibrations). (2) Flip-chip bonding of the sensor chip and the circuit chip using a cross layout to achieve both the reduction of heat deformation/parasitic capacity and the avoidance of interference between resonance frequencies. Utilizing the above two techniques has enabled us to achieve the high accuracy of the yaw rate sensor. As a result, we have developed a yaw rate sensor with a zero-point accuracy of ±3°/s (actual value: ±0.5°/s) in the ±100°/s range.

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“…Although these typically rely on a proof mass being deflected, alternative approaches have been reported using convection [5] and optical micro-filters [6]. It has also been shown how to derive inclination using an unmodified accelerometer [7]- [9].…”

Section: Introductionmentioning

confidence: 99%

A Micropower Tilt-Processing Circuit

Constandinou

Georgiou

2009

IEEE Trans. Biomed. Circuits Syst.

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Abstract-This paper describes a novel analogue circuit for extracting the tilt angle from the output of a standard MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with devices operated in subthreshold, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The hardware has been implemented in AMS 0.35µm 2P4M CMOS technology.

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Dual-axes capacitive inclinometer/low-g accelerometer for automotive applications

Cited by 29 publications

References 2 publications

Modeling Verticality Estimation During Locomotion

Modeling Verticality Estimation During Locomotion

High Accuracy Yaw Rate Sensor for Preventive Safety System

A Micropower Tilt-Processing Circuit

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