An entrance system comprising: a swing door member having a door leaf, and a sensor unit (S1; S) mounted to the door leaf, the sensor unit comprising a door angle sensor; and an automatic door operator having a motor capable of causing movement of the door member, a controller for controlling operation of the motor, and a linkage connected to the automatic door operator and the door leaf for transferring torque generated by the motor to the door leaf, the automatic door operator being operable in a learn mode and an operational mode, wherein the controller is configured, in the learn mode, to: automatically establish a linkage reduction curve by determining, for a movement of said door member between a shut closed position of said door leaf and a swung open position of said door leaf, the torque required by said motor to cause movement of said door leaf at different door leaf angles (α), the different door leaf angles being determined from measurement readings of said door angle sensor; and wherein the controller is configured, in the operational mode, to: compensate for a non-linear torque transfer characteristic of said linkage by applying the linkage reduction curve when controlling said motor to cause the door member to swing open. a swing door member having a door leaf, and a sensor unit (S1; S) mounted to the door leaf, the sensor unit comprising a door angle sensor; and a door leaf, and a sensor unit (S1; S) mounted to the door leaf, the sensor unit comprising a door angle sensor; and an automatic door operator having a motor capable of causing movement of the door member, a controller for controlling operation of the motor, and a linkage connected to the automatic door operator and the door leaf for transferring torque generated by the motor to the door leaf, the automatic door operator being operable in a learn mode and an operational mode, wherein the controller is configured, in the learn mode, to: automatically establish a linkage reduction curve by determining, for a movement of said door member between a shut closed position of said door leaf and a swung open position of said door leaf, the torque required by said motor to cause movement of said door leaf at different door leaf angles (α), the different door leaf angles being determined from measurement readings of said door angle sensor; and wherein the controller is configured, in the operational mode, to: compensate for a non-linear torque transfer characteristic of said linkage by applying the linkage reduction curve when controlling said motor to cause the door member to swing open. a motor capable of causing movement of the door member, a controller for controlling operation of the motor, and a linkage connected to the automatic door operator and the door leaf for transferring torque generated by the motor to the door leaf, the automatic door operator being operable in a learn mode and an operational mode, wherein the controller is configured, in the learn mode, to: automatically establish a linkage reduction curve by determining, for a movement of said door member between a shut closed position of said door leaf and a swung open position of said door leaf, the torque required by said motor to cause movement of said door leaf at different door leaf angles (α), the different door leaf angles being determined from measurement readings of said door angle sensor; and wherein the controller is configured, in the operational mode, to: compensate for a non-linear torque transfer characteristic of said linkage by applying the linkage reduction curve when controlling said motor to cause the door member to swing open. automatically establish a linkage reduction curve by determining, for a movement of said door member between a shut closed position of said door leaf and a swung open position of said door leaf, the torque required by said motor to cause movement of said door leaf at different door leaf angles (α), the different door leaf angles being determined from measurement readings of said door angle sensor; and wherein the controller is configured, in the operational mode, to: compensate for a non-linear torque transfer characteristic of said linkage by applying the linkage reduction curve when controlling said motor to cause the door member to swing open.