And that contact force better be exactly the same as mg, but in opposite direction, otherwise there could never be equilibrium.
触点压力和，mg完全，相同，但是反向相反，否则永远都不会有平衡。
2
The contact pressure of the side cleaning brush during cleaning can be controlled by the tested reliable equilibrium technology.
侧面清洗刷清洗过程中的接触压力经过测试的可靠的均衡技术来控制。
3
Based on the force equilibrium equations, the relationship between the external wrench space and the manipulation force space at any contact is investigated.