[机] approach distance of search unit

sōu xún dān wèi de jiē jìn jù lí ㄙㄡ ㄒㄩㄣˊ ㄉㄢ ㄨㄟˋ ㄉㄜ˙ ㄐㄧㄝ ㄐㄧㄣˋ ㄐㄩˋ ㄌㄧˊ