Spatial Constant-force Mechanism Of Single Degree Of Freedom With Compliant Joints

With the development of precision technology, in some workplaces, when industria l robots and machine tool grabbing, gr ind ing or polishing precision components, the contact forces need to be constant. However, the force-control based on sensors in actual industrial applicatio ns is difficult to achieve. Due to the limitation of equipment vibration, the bad external environment and the sensor technology, the signals from the sensors are messy. It is difficult to accurately turn out the desired force signa l. At this time, the research on spatial comp liant constant- force mechanism becomes very significant. In this paper, the configuration of spatia l compliant RSSP mechanism w ill be analyzed in detail. Then the structural parameters that result in a constant- force mechanis m will be optimized. What’s more, the design will be proposed to achieve the end-effector force adjustment.The configuration analys is of spatia l compliant RSSP mechanism is the basis for further research. First of all, this paper introduces the common method of analyzing the spatia l compliant mechanism, namely the pseudo rigid body model method. Secondly, this paper introduces the spatia l configuration of RSSP mechanis m, makes the structure parameters dimensionless, and analyzes the forward and inverse kinematics of RSSP mechanis m. Then, this paper selects the appropriate spatial compliant configuration, analyzes the general init ial configuration, obtains the general expression of the str ucture parameters, and calculates the expression of the hinge deformation.The optimal structural parameters of the comp liant constant- force mechanis m with a general initia l configuration are the most important indexes to guide the practical engineering design. In order to get these parameters, based on the configuration analys is of compliant RSSP mechanis m, this paper uses virt ual work principle to carry on the static analys is of the relationship between the end reaction force and the dimensionless parame ters. Suitable methods are adopted in this paper to establish the objective function that characterizes the fluctuation of the end force. The complex constraints are converted into a mult i-objective problem. The optimized structure parameters under various init ial configurations are obtained by using partic le swarm optimization algorithm. In the process of optimizat ion, a conclus ion is conducted to the optimized parameters of the first configuration and the second configuration.In order to make the complia nt constant- force mechanis ms used more widely, this paper makes the end force can be adjusted by introducing variable stiffness joints. According to related design princip les, this paper makes a relatively simp ler design, in which a detailed mechanical analysis is conducted. And the overall structural design of the variable stiffness joint is completed. Then, the stiffness of the joint is analyzed and the main transmission parts are selected. This paper designs a leaf spring of the joint, on which the stress analysis is conducted and a finite ele ment simulation is done to verify the above design analys is method. In order to verify the above optimization data’s validity and reflect its practicability, a spatial constant- force gripper is designed and experiments are carried out.