US 11,056,985 B2
Microelectromechanical system and control method to control a piezoelectric drive based on an admittance or impedance of the piezoelectric drive
Michael Curcic, Stuttgart (DE)
Assigned to Robert Bosch GmbH, Stuttgart (DE)
Appl. No. 15/767,976
Filed by Robert Bosch GmbH, Stuttgart (DE)
PCT Filed Oct. 19, 2016, PCT No. PCT/EP2016/075047
§ 371(c)(1), (2) Date Apr. 12, 2018,
PCT Pub. No. WO2017/067963, PCT Pub. Date Apr. 27, 2017.
Claims priority of application No. 102015220291.7 (DE), filed on Oct. 19, 2015.
Prior Publication US 2018/0358908 A1, Dec. 13, 2018
Int. Cl. H02N 2/00 (2006.01); H01L 41/04 (2006.01); B81B 7/00 (2006.01); G02B 26/08 (2006.01)
CPC H02N 2/008 (2013.01) [B81B 7/008 (2013.01); H01L 41/042 (2013.01); B81B 2207/03 (2013.01); G02B 26/0858 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A microelectromechanical system comprising:
a piezoelectric drive; and
a control unit coupled to the piezoelectric drive, wherein the control unit is configured to control the piezoelectric drive based on a change of at least one of an admittance and an impedance of the piezoelectric drive, including by, in a normal operation:
providing a control voltage, which includes a DC voltage component and an AC voltage component overlaid on the DC voltage component, to vibrate the piezoelectric drive;
receiving, from a current measuring device, a current flowing through the piezoelectric drive while the piezoelectric drive is vibrated via the control voltage;
determining an amplitude of the vibration based on a first impedance and the detected current; and
regulating an amplitude of the vibration by adjusting the control voltage based on the determined amplitude and a predefined setpoint amplitude.