Patent ID: 7049728

Claim:
An adjustable structure, comprising: a stationary part ( 1 , 3 ), an adjustable element ( 5 ) connected therewith, a drive unit ( 8 ) for causing adjustment of the element ( 5 ), said drive unit ( 8 ) with a movable activation element ( 14 ; 38 ) and another part ( 13 : 41 ) being secured to the adjustable element and to the stationary part, respectively, said drive unit comprising an electric motor ( 10 ) for the driving thereof, a control unit ( 6 ) for controlling the drive unit, a sensor ( 15 ) connected to the control to currently record deviations in the load on the adjustable element in operation and, in response to this, to signal the control unit to stop/reverse the motor, and wherein the sensor is formed by a piezo element ( 20 ) arranged in connection with one of the attachment points of the drive unit ( 8 ) or in the drive unit itself to record deviations in the force extending between the attachment points of the drive unit.