Abstract
In this research, deflection-load relation of in-plane free-form curved rod is derived, and further obtains the path of deflection at each point of the curved rod, so as to design a suitable elastic curved rod assisting patients who have injured knees. The curved rod will be assembled to the lower-limbs assistant device. By retraction and relaxation of the air muscle, the curved rod will be bended and will spring back respectively. With the reaction and the guidance of the curved rod, patients who suffer from osteoarthritis or sports injury would easily walk, stand up (sit to stand), climb stairs and feel comfortable.