Position and/or angle control method and device without absolute positions sensor

A method for control of a stepper motor of a motor vehicle without an absolute position sensor, the stepper motor being coupled to a reduction ratio control device of the drive train of the motor vehicle and the stepper motor having a rotor having at least one known position, the method comprising the steps of:

• feeding at least one process parameter from the drive train of the motor vehicle to an electronic circuit connected to the stepper motor to facilitate control of the stepper motor;
• continuously storing in the electronic circuit actual position values of the rotor and selected values of the reduction ratio control device controlled by the stepper motor;
• establishing whether a stored position value in the electronic circuit is valid;
• monitoring at least one function of the reduction ratio control device with the electronic circuit and optionally deactivating at least one selected function;
• and
• comparing with the electronic circuit an actual state of the reduction ratio control device with an appertaining set state and, in case predetermined difference between the actual state and the appertaining set state occurs, producing control signals for controlling reduction ratio control device.

A control apparatus for a positioning device controlling a reduction ratio control apparatus in a motor vehicle without an absolute position sensor, the positioning device having at least one known position for a controllable part, the control apparatus having an electronic circuit comprising:

• a storage element in which are continuously stored actual values of a position of the positioning device and selected values of the continuously variable toroidal drive during a preset period of time;
• a validity device for establishing the validity of values stored in the storage element;
• a controller device for controlling the controllable part;
• a monitoring device for monitoring desired functions of the continuously variable toroidal drive;
• a comparator which compares an actual state of the continuously variable toroidal drive with a relative set state and if preset difference values between the actual state and the set state are exceeded, the comparator produces control signals for the controllable part of the positioning device to appropriately affect the state of the continuously variable toroidal drive;
• and
• communication means enabling the storage element, validity device, controller device, monitoring device, and comparator to communicate with each other.