COMBINED MEMS ACCELEROMETER AND GYROSCOPE
First Claim
1. A combined accelerometer and gyroscope unit comprising:
- a proof mass;
primary actuating means operable to actuate the proof mass along a primary axis;
secondary actuating means operable to actuate the proof mass along a secondary axis;
secondary sensing means operable to sense the position of the proof mass along the secondary axis; and
primary sensing means operable to sense the position of the proof mass along the primary axis wherein Σ
Δ
force-feedback loops are set up for both the secondary axis and the primary axis.
2 Assignments
0 Petitions
Accused Products
Abstract
A MEMS structure for a combined gyroscope and accelerometer unit (100) based on in-plane vibratory movements comprises a proof mass (101) and comb-drives (102) operable to cause the proof mass (101) to resonate in the x-direction, commonly referred to as the primary mode. Under the influence of a rotation Ωz around the z-axis, a Coriolis force acting in the y-direction results. This excites the secondary (or sense) mode. A set of parallel-plate capacitors 103 are provided to enable position readout along the secondary axis. In addition to the above, the comb-drive capacitors (102) of the primary mode can also be used for readout of position along the primary axis, and the parallel-plate capacitors (103) for actuation along the secondary axis. This can be achieved either by time-multiplexing these capacitors (102, 103) or by providing separate sets of capacitors (102, 103) for sensing and actuation along each axis. The unit can operate in separate ΣΔ force-feedback loops with respect to both axes. This force-feedback approach is already known for readout of the secondary mode of MEMS gyroscopes. It has not previously been applied to the primary mode of a gyroscope for the measurement of a component of acceleration.
-
Citations
29 Claims
-
1. A combined accelerometer and gyroscope unit comprising:
-
a proof mass; primary actuating means operable to actuate the proof mass along a primary axis; secondary actuating means operable to actuate the proof mass along a secondary axis; secondary sensing means operable to sense the position of the proof mass along the secondary axis; and primary sensing means operable to sense the position of the proof mass along the primary axis wherein Σ
Δ
force-feedback loops are set up for both the secondary axis and the primary axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29)
-
-
28. A method of operating a combined accelerometer and gyroscope unit having a proof mass;
- primary actuating means operable to actuate the proof mass along a primary axis;
secondary actuating means operable to actuate the proof mass along a secondary axis;
secondary sensing means operable to sense the position of the proof mass along the secondary axis; and
primary sensing means operable to sense the position of the proof mass along the primary axis, the method comprising the steps of;
setting up Σ
Δ
force-feedback loops for the both the secondary axis and the primary axis to measure both a component of rotation and two components of acceleration.
- primary actuating means operable to actuate the proof mass along a primary axis;
Specification