Simplectic Architectures for True Multi-axial Accelerometers: A Novel Application of Parallel Robots

Several triaxial accelerometers are known. However, to the knowledge of the authors, no true, triaxial accelerometers are commercially available. By true we mean an accelerometer which would pick up the three components of point-accelerations using one single proof-mass. What we propose is novel architecture classes of parallel-kinematics-machine for multi-axial accelerometers, that is, accelerometers that can measure n components of point-accelerations, where n = 1, 2, 3. We call these architectures simplectic, as they use n + 1 legs oriented normally to the n + 1 faces of the regular simplex associated with the n-dimensional subspace of measured acceleration components. We show that the simplectic biaxial accelerometer can be fabricated using micromachining MEMS techniques, while the simplectic triaxial accelerometer lends itself to compliant-mechanism fabrication techniques. CAD models of the prototypes proposed are provided for all of the three novel mechanical architectures proposed. Finally, the direct kinematics problems associated with the simplectic biaxial and triaxial accelerometers are shown to be linear in both cases. This feature simplifies the estimation of the proof-mass displacement from piezoresistive or piezoelectric measurements taken at the flexible joints connecting the legs of the mechanism to the rigid body whose acceleration is under estimation.