Servo Controller and control method using the same

A servo controller for assisting steering operation of a vehicle so that the vehicle travels keeping a predetermined position in a travel lane, comprising:

• a detector for detecting an offset, which is a deviation of a position of the vehicle from a desired position in a travel lane;
• and
• a control unit which performs
• a positive-integral calculation in which an integral calculation of the offset detected by the detector is performed, and in which, when a resulting offset integral value is positive, the integral calculation is continued, and
• a negative-integral calculation in which an integral calculation of the offset detected by the detector is performed, and in which, when a resulting offset integral value is negative, the integral calculation is continued, and
• a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that the position of the vehicle in the travel lane coincides with the desired position, wherein
• the control unit performs control so that the position of the vehicle in the travel lane coincides with the desired position, using one of the positive-integral calculation and the negative-integral calculation, which has been selected.

A control method using a servo controller which repeatedly performs a predetermined control process, and controls a state of a controlled system on the basis of a result of performing the control process, comprising the steps of:

• detecting the state of the controlled system;
• performing a positive-integral calculation in which performed is an integral calculation of a physical quantity representing the state of the controlled system detected, and, when a resulting integral value is positive, the integral calculation is continued;
• performing a negative-integral calculation in which performed is an integral calculation of the physical quantity representing the state of the controlled system detected, and, when a resulting integral value is negative, the integral calculation is continued;
• making a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that a value representing the state of the controlled system becomes equal to a desired control value;
• and
• performing control so that the value representing the state of the controlled system becomes equal to the desired control value, using one of the integral calculations, which has been selected.

A control method using a servo controller for assisting steering operation of a vehicle so that the vehicle travels keeping a predetermined position in a travel lane, comprising the steps of:

• detecting an offset, which is a deviation of a position of the vehicle from a desired position in the travel lane;
• performing a positive-integral calculation in which an integral calculation of the offset detected is performed, and in which, when a resulting offset integral value is positive, the integral calculation is continued;
• performing a negative-integral calculation in which an integral calculation of the offset detected is performed, and in which, when a resulting offset integral value is negative, the integral calculation is continued;
• making a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that the position of the vehicle in the travel lane coincides with the desired position;
• and
• performing control so that the position of the vehicle in the travel lane coincides with the desired position, using one of the positive-integral calculation and the negative-integral calculation, which has been selected.