Wiper control method and wiper control device

A control device for a wiper device, the wiper device including a wiper blade disposed on a surface to be wiped and an electric motor for reciprocating the wiper blade on the surface to be wiped, the electric motor being subjected to PWM duty control based on a target speed of the wiper blade set according to a position of the wiper blade on the surface to be wiped,

• the control device comprising:
• a blade position detection section that detects a current position of the wiper blade;
• a blade speed detection section that detects a current moving speed of the wiper blade;
• a blade speed determination section that compares a blade target speed tgt spd corresponding to the current position of the wiper blade and the current speed of the wiper blade;
• a motor rotation number calculation section that calculates a rotation number of the electric motor based on a result of the determination made by the blade speed determination section;
• and
• a drive control instruction section that controls operation of the electric motor based on an instruction from the motor rotation number calculation section, wherein
• after a deceleration start position at which a speed of the wiper blade is made to start being reduced in a wiping operation of the wiper blade, the motor rotation number calculation section uses a PWM duty value (ffc sta duty×Ksd) obtained by multiplying a PWM duty value (ffc sta duty) at a feedforward control start position set before the deceleration start position by a predetermined deceleration coefficient Ksd set according to the position of the wiper blade on the surface to be wiped.