Dynamic characteristics of piezoelectric six-dimensional heavy force/moment sensor for large-load robotic manipulator

Abstract. The flexible Cartesian robotic manipulator (FCRM) is coming into widespread application in industry. Because of the feeble rigidity and heavy deflection, the dynamic characteristics of the FCRM are easily influenced by external disturbances which mainly concentrate in the driving end and the load end. Thus, with the influence of driving base disturbance and terminal load considered, the motion differential equations of the FCRM under the plane motion of the base are constructed, which contain the forced and non-linear parametric excitations originated from the disturbances of base lateral and axial motion respectively. Considering the relationship between the coefficients of the motion differential equations and the mode shapes of the flexible manipulator, the analytic expressions of the mode shapes with terminal load are deduced. Then, based on multiple scales method and rectangular coordinate transformation, the average equations of the FCRM are derived to analyze the influence mechanism of base disturbance and terminal load on the system parametric vibration stability. The results show that terminal load mainly affects the node locations of mode shapes and mode frequencies of the FCRM, and the axial motion disturbance of the driving base introduces parametric excitation while the lateral motion disturbance generates forced excitation for the transverse vibration model of the FCRM. Furthermore, with the increase of the base excitation acceleration and terminal load, the parametric vibration instability region of the FCRM increases significantly. This study will be helpful for the dynamic characteristics analysis and vibration control of the FCRM.

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Dynamic Characteristics and Restraint Mechanism of Elastically Restrained Connecting Joints on the Flexible Robotic Manipulator

Shock and Vibration ◽

10.1155/2018/3217106 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12

Author(s):

Yufei Liu ◽

Han Xu ◽

Xi Zhang

Keyword(s):

Dynamic Model ◽

Dynamic Characteristics ◽

Robotic Manipulator ◽

Real Property ◽

Vibration Displacement ◽

Restraint Mechanism ◽

Elasticity Property ◽

Flexible Robotic Manipulator ◽

Elastically Restrained ◽

Dynamic Nonlinearity

Connecting joints are significant components in mechanical systems as well as the Cartesian flexible robotic manipulator (FRM) which consists of a flexible arm and a moving base through connecting joints. Uncertain factors, such as unqualified assembly, accidental collision, and longtime service, will reduce the restraint stiffness of the connecting joints and enhance the dynamic nonlinearity of the system subsequently. In this case, the traditional perfectly fixed restrained model cannot reflect the real property of the connecting joints. This paper focuses on the elasticity property of the connecting joints with uncertain restraint stiffness, which is defined as the elastically restrained connecting joints (ERCJ), and investigates the dynamic characteristics and restraint mechanism of the ERCJ. An elastic restrained model is proposed to describe the elasticity property of the connecting joints and determine the elastic restrained region of the ERCJ, and the frequency relationship equation in the elastic restrained region is simultaneously determined and verified. Based on the proposed elastic restrained model and Hamilton’s variational principle, the dynamic model and vibration displacement equation of the FRM with elastically restrained connecting joints (FRMERCJ) are established. The virtual prototype experiment of the FRMERCJ is conducted to verify the dynamic model and reveal the restraint mechanism of the ERCJ. The proposed elastic restrained model in this paper can accurately describe the elasticity property of the connecting joints, and the ERCJ is sensitive to motion velocities especially under higher velocities for higher-order vibrations in the initial stage. The results are meaningful for the dynamic analysis and vibration control of robotic manipulators.

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Numerical Analysis on Transmission Characteristics of Stephenson’s Six-Bar Punching Mechanism with Servo Input

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.86.623 ◽

2011 ◽

Vol 86 ◽

pp. 623-628 ◽

Cited By ~ 1

Author(s):

Jian Guo Hu ◽

You Song Sun ◽

Yong Qi Cheng ◽

Wei Ping Ruan

Keyword(s):

Numerical Analysis ◽

Dynamic Characteristics ◽

Production Efficiency ◽

Virtual Prototype ◽

Numerical Results ◽

Prototype Model ◽

Transmission Characteristics ◽

Output Link ◽

Manufacturing Costs ◽

Large Load

Punching mechanisms with servo input are typical variable-input controllable mechanisms. By means of extending the output link infinitely, the Stephenson Ⅲ six-bar linkage is evolved into a six-bar punching mechanism with a slide. A virtual prototype model of this novel punching mechanism was established by using the software ADAMS. The model includes geometry, load and drive, total three sub-models. Based on the model, the kinematic and dynamic characteristics of the slide with variable-input crank motion and instantaneous large load were simulated. The numerical results showed that the Stephenson’s six-bar punching mechanism had good transmission characteristics, improving the working performances and production efficiency, reducing the manufacturing costs of servo mechanical presses.

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