[计] mechanical hardware system design

jī qì yìng jiàn xì tǒng shè jì ㄐㄧ ㄑㄧˋ ㄧㄥˋ ㄐㄧㄢˋ ㄒㄧˋ ㄊㄨㄥˇ ㄕㄜˋ ㄐㄧˋ