Abstract
This paper investigates the dynamic of a flexible robotic manipulator (FRM) which consists of rigid driving base, flexible links, and flexible joints. With considering the motion fluctuations caused by the coupling effect, such as the motor parameters and mechanism inertias, as harmonic disturbances, the system investigated in this paper remains a parametrically excited system. An elastic restraint model of the FRM with elastic joints (FRMEJ) is proposed, which considers the elastic properties of the connecting joints between the flexible arm and the driving base, as well as the harmonic disturbances aroused by the electromechanical coupling effect. As a consequence, the FRMEJ accordingly remains a flexible multibody system which conveys the effects of rigid-flexible couple and electromechanical couple. The Lagrangian function and Hamilton’s principle are used to establish the dynamic model of the FRMEJ. Based on the dynamic model proposed, the vibration power flow is introduced to show the vibration energy distribution. Numerical simulations are conducted to investigate the effect of the joint elasticities and the disturbance excitations, and the influences of the structure parameters and motion parameters on the vibration power flow are studied. The results obtained in this paper contribute to the structure design, motion optimization, and vibration control of FRMs.
Highlights
Flexible robotic manipulators (FRMs) which consist of driving base, flexible links, and flexible joints are typical electromechanical coupling systems and have been extensively used in scientific fields, such as robotic fields and aerospace fields, which can satisfy the demands of high productivity, high speed, and lower energy consumption thanks to their lightweight advantage [1,2,3]
As the effector is clamped on the tip of the flexible arm, from Figures 7 and 8, we can see that the vibration responses of the effector with elastic restraint joints (ERJ) are larger than that of fixed restraint joints (FRJ), and this reveals that, under the motion disturbances, the vibration responses of the effector are enlarged, which is contrary to the demands of operating accuracy and decreases the service life of the system; this further shows that the motion disturbances affect the dynamic performance and enlarge the vibration responses, especially for the FRM with ERJ, which should be suppressed in actual engineering applications
Without motion disturbances, the joint elasticities present suppressing effect on the vibrations responses, which is meaningful for the structure design of the FRM, while the motion disturbances have considerable influences on the dynamic performance of the FRME
Summary
Flexible robotic manipulators (FRMs) which consist of driving base, flexible links, and flexible joints are typical electromechanical coupling systems and have been extensively used in scientific fields, such as robotic fields and aerospace fields, which can satisfy the demands of high productivity, high speed, and lower energy consumption thanks to their lightweight advantage [1,2,3]. The dynamic modeling of the FRM, which is essential to investigate and control these undesirable elastic deformations and residual vibrations, generally regards the driving base as a rigid body. In this case, the elastic deformations and residual vibrations in the flexible links will be coupled with the rigidbody motion of the driving base via the flexible joints [6]; as a result, the FRM conveys rigid-flexible couple and remains a flexible multibody system. Some researchers have proposed the dynamic models of flexible multibody systems with multiple links and joints [5,6,7,8]. The connecting joints have certain elasticities and the ideal rigid restraint assumed is difficult to achieve
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