On Global Positional Stabilization of a Single-Link Manipulator with a Nonlinear Elastic Joint*

Author(s):  
A. S. Khoroshun
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Dongliang Chen ◽  
Jindong Zhang ◽  
Xutao Weng ◽  
Yunjian Zhang ◽  
Zhonghui Shi

In order to reduce the energy consumption of the legged robot in walking, this paper designs a kind of nonlinear elastic joint from the flexible variable-stiffness joint based on the mammal walking on the limb and optimizes the leg structure of the legged robot. The motor is rigidly connected to the articulated lever. When the lever is accelerated or decelerated, the elastic unit is introduced. The system can be considered as a special variable-rate elastic system. This paper will study it from theory and simulation experiments. Based on the dynamic analysis, a functional relationship between the output torque and the torsion spring stiffness and between the energy consumption and the torsion spring stiffness was established. By finding the extremum, the two optimum torsional spring stiffness that can minimize the required output average torque and the energy consumed during one cycle of motion were deduced. The results show that using this design in a reasonable position can effectively reduce the energy consumption of the system and can achieve up to a 50% reduction in energy consumption.


Author(s):  
A.S. Khoroshun ◽  

The law of rotation of the electric motor, which ensures a global asymptotic direction of the trajectory of the model of a single-link manipulator with an elastic joint to a given program trajectory is obtained The elasticity of the joint is modeled by a torsion spring, the elastic force of which is considered to be nonlinearly dependent on the displacement. This fact makes it impossible to apply the usual approach and greatly complicates the task of control construction. The fact that some parameters of the model can be uncertain and, in some way, depend on some numerical parameter, the area of change of which is unknown in advance, also adds complexity. However, the use of DSC (Dynamic Surface Control) technique allows us to get the desired control. The development of the DSC technique, which consists in a specific choice of parameters and constants of filters, is proposed. It avoids the growth of the order of the auxiliary system, as well as a significant complication of the form of both the auxiliary system of differential equations and the control law, the so-called “explosion of terms”. It allows us to obtain explicitly the corresponding auxiliary function and to prove that the proposed control law solves the control problem. The robustness of such control is also proved, and the region of robustness in the system parameters space is defined. The obtained results are illustrated by the example of a mechanical model.


2015 ◽  
Vol 48 (11) ◽  
pp. 137-142 ◽  
Author(s):  
Michael Ruderman ◽  
Makoto Iwasaki

2020 ◽  
Vol 26 ◽  
pp. 121
Author(s):  
Dongbing Zha ◽  
Weimin Peng

For the Cauchy problem of nonlinear elastic wave equations for 3D isotropic, homogeneous and hyperelastic materials with null conditions, global existence of classical solutions with small initial data was proved in R. Agemi (Invent. Math. 142 (2000) 225–250) and T. C. Sideris (Ann. Math. 151 (2000) 849–874) independently. In this paper, we will give some remarks and an alternative proof for it. First, we give the explicit variational structure of nonlinear elastic waves. Thus we can identify whether materials satisfy the null condition by checking the stored energy function directly. Furthermore, by some careful analyses on the nonlinear structure, we show that the Helmholtz projection, which is usually considered to be ill-suited for nonlinear analysis, can be in fact used to show the global existence result. We also improve the amount of Sobolev regularity of initial data, which seems optimal in the framework of classical solutions.


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