Patent ID: 9482867
Filing Date: 2016-11-01
CPC Classification: G02B,G02F

Claim Text:
1. A method of compensating for hysteresis in a system, the method comprising: providing a system, the system comprising an actuator and one or more components that exhibit hysteresis including a deformable material, the components that exhibit hysteresis having a wiping-out property, the system comprising a system input and a system output, the system output being dependent on the system input; determining an inverse Preisach model for the system, the inverse Preisach model comprising a model input and a model output, the model output being dependent on the model input, the model input corresponding to the system output, the model output corresponding to the system input; ascertaining a desired system output; determining using the desired system output and the inverse Preisach model for the system, a required system input corresponding to the desired system output; and applying, to the system, the determined required system input to deform the deformable material using the actuator; wherein the step of determining the inverse Preisach model for the system comprises: defining a plurality of pairs of values, each pair of values comprising a first value and a second value, each of the first and second values being less than or equal to a maximum system output and greater than or equal to a minimum system output, the first value being greater than or equal to the second value within each pair; and for each pair of values, determining a system input corresponding to that pair of values, by: increasing the system input, from the minimum system input, until the system output is equal to the first value corresponding to the respective pair of values; and thereafter decreasing the system input until the system output is equal to the second value corresponding to the respective pair of values, the value that the system input is decreased to being the determined system input corresponding to that pair of values.