Method for maintenance of a transportation device, software program, and controller

A controller configured to control a transportation device, the transportation device configured to be propelled by an electric motor, the controller comprising:

• a non-transitory data carrier carrying data representing a software program;
• and
• a computer configured to execute the software program to
• receive an output of an incremental encoder, the incremental encoder configured to sense motion of a moving part of the electric motor or a part configured to be moved by the electric motor;
• calculate a motor model associated with control of the electric motor;
• acquire a pulses-per-rotation configuration value (PPRconf), the pulses-per-rotation configuration value PPRconf being a drive parameter of the incremental encoder and representing a nominal/configured quantity of pulses which should be provided by the incremental encoder per one rotation of the electric motor when the incremental encoder is operating according to normal operation;
• derive a pulses-per-rotation estimation value (PPRest), the pulses-per-rotation estimation value PPRest representing an estimated quantity of pulses actually provided by the incremental encoder per one rotation of the electric motor, based on estimating speed and position of the electric motor independently of an encoder signal provided by the incremental encoder, based on the motor model used to control the electric motor;
• determine a pulses-per-rotation error value (PPRerr), the pulses-per-rotation error value PPRerr representing a deviation of the pulses-per-rotation estimation value PPRest from the pulses-per-rotation configuration value PPRconf, based on a relation that is one of
• PPRerr=PPRest−PPRconf,
• PPRerr=PPRconf−PPRest,
• PPRerr=PPRest/PPRconf, or
• PPRerr=PPRconf/PPRest;
• utilize the pulses-per-rotation error value PPRerr to generate an instance of maintenance information indicating that a maintenance operation should be performed on the transportation device;
• and
• transmit the instance of maintenance information as
• a message to a remote device via a device link, the message including a request to perform the maintenance operation, or
• a control signal to a control device to cause the control device to perform the maintenance operation based on controlling the transportation device and/or the electric motor.