Washer control system and washer control device

A washer control system comprising:

• a situation monitoring device configured to monitor a situation related to traveling of a vehicle;
• a washer tank configured to store a washer fluid;
• a washer motor configured to perform washer spraying by suctioning the washer fluid stored in the washer tank and discharging the washer fluid in order to remove dirt that hinders monitoring by the situation monitoring device, in response to energization to the washer motor;
• a washer control device configured to control the washer spraying by controlling the energization to the washer motor;
• and
• a washer level sensor configured to detect that the remaining amount of the washer fluid in the washer tank reaches a predetermined value, wherein
• the washer control device includes a computer configured to:
• monitor a motor current value that is a value of electric current supplied to the washer motor;
• acquire an energization time for which the electric current is supplied to the washer motor;
• calculate a usage amount of the washer fluid from the motor current value and the energization time, and calculate, as a margin of the washer fluid, a remaining amount of the washer fluid in the washer tank based on the usage amount;
• calculate the remaining amount of the washer fluid by subtracting the usage amount of the washer fluid that is used after the remaining amount of the washer fluid reaches the predetermined value from the predetermined value;
• calculate a daily decrease in the remaining amount of the washer fluid for several consecutive days based on a change in the remaining amount of the washer fluid for the several consecutive days from an optional day;
• calculate an estimated line expressed by a linear equation by linearly approximating a relationship between the amount of decrease in the remaining amount of the washer fluid and days;
• and
• calculate, as the margin of the washer fluid, a usage time limit of the washer fluid based on the remaining amount of the washer fluid and the estimated line.