Patent ID: 8791661

Claim:
A linear actuator comprising: an electrical motor, a transmission, a spindle, a spindle nut, an actuation element, and a control unit, wherein the electrical motor through the transmission and interaction between the spindle and the spindle nut drives the actuation element to move linearly between a first end stop and a second end stop, wherein to determine a position of the actuation element, the control unit provides an absolute rotary position sensor outputting a value representing an angle and includes a counter keeping a count, wherein the value is less than the angle through which the absolute rotary position sensor is subjected to during a movement of the actuation element between the first end stop and the second end stop, causing the value of the absolute rotary position sensor to under-flow or over-flow at least once during the movement and where the counter is arranged to keep track of the under-flows and over-flows of the value in the count, wherein the control unit is arranged to determine end stops of the linear actuator by driving the electrical motor in both directions until the absolute rotary position sensor indicates that the actuation element is not moving, and wherein the control unit comprises a non-volitile memory that is arranged to store the count of the counter when there is a shutdown of the linear actuator or when a rate of movement of the actuation element falls below a predetermined amount, or both.