Research On High Static Transparency Of Haptic Interface

Tele-operation system plays an important role in so many fields,such as anti-terrorist,space exploration,seafloor detection,MIS(minimally invasive surgery),virtual assembly and so on.Haptic master manipulator plays an important role in the surgical robot.Besides the tele-operation works with master-slave robot,It provides the operator with the information of feedback force feedback which is from the remote environment.Thanks to the technic the working time is decreased and the security level is enhanced.Our group has built a haptic master manipulator prototype,which achieved static balance,and can provide three DOF force feedback.In this paper,on the basis of the prototype,the static transparency and static balance condition will be further studied.The transparency performance will be improved and lay the foundation for the manufacturing.Transparency is one of the vital performance which affects the haptic and motion accuracy and operator's fatigue directly.When in a low velocity,the minimally invasive surgery for example,the inertia force is negligible and the external force is the major factor of static transparency.When the manipulator is static balanced,the operator cannot feel the gravity of the device;otherwise,the operator will feel the feedback force mixed with the gravity,and make mistakes.In this paper,the kinetic and dynamic analysis and static balance condition are proposed.Error sensitivities analysis on static balance condition is given,and error restriction is obtained to ensure the transparency performance when the manufacture is taken into consideration.Because the influence introduced by different parameters error on static balance condition is different,the corresponding method to eliminate or limit the external force is given.In order to ensure the response rate and decrease the fatigue,the mass should be limited to a certain degree.The mass is related to the stiffness.When the stiffness is insufficient,the feedback force will distort which exerts on the operator's hand.The force feedback is achieved based on the hypotheses that the bars are rigid.So the research goal is to get the minimal stiffness so the static transparency and the feedback accuracy are ensured.In this paper,the stiffness analysis on each link is given,and the weakest position of the master manipulator stiffness in working space is found out.The manipulator is topology optimized under the weakest position,and the effects of different parts of the bars on the stiffness are obtained.According to the topology optimization results,the reasonable cross sections are selected and a reasonable stiffness value is constructed.On the premise of guarantee the haptic performance,the inertial force is reduced.