Micromachined microaccelerometer for measuring acceleration along three axes

A microaccelerometer comprising:

• a thin planar sheet having first and second substantially planar surfaces, said sheet having a cavity extending between said first and second substantially planar surfaces, wherein said cavity has a cross-section which has a narrowest point at an interior location in said sheet;
• a free-mass having a pair of ends and a central portion between said ends, wherein said free-mass has a cross-section with said central portion being narrower than said narrowest point of said sheet and said ends being wider than said narrowest point of said sheet to locate said free-mass in a position relative to said sheet, whereby said free-mass is restrained by and moveable with respect to said sheet;
• sensing means for detecting said free-mass's position relative to said sheet and generating one or more signals indicative of said position of said free-mass;
• position correction means for receiving position indication signals from said sensing means, exerting a restorative force on said free-mass to an equilibrium position, and generating one or more signals indicative of said restorative force;
• and
• computing means for generating an acceleration value from said one or more signals indicative of said position of said free-mass and said one or more signals indicative of said restorative force.