Modeling, Analysis, and Control of SLIP Running on Dynamic Platforms

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Amir Iqbal ◽  
Zhu Mao ◽  
Yan Gu

Abstract The complex dynamic behaviors of legged locomotion on stationary terrain have been extensively analyzed using a simplified dynamic model called the spring-loaded inverted pendulum (SLIP) model. However, legged locomotion on dynamic platforms has not been thoroughly investigated even by using a simplified dynamic model such as SLIP. In this paper, we present the modeling, analysis, and control of a SLIP model running on dynamic platforms. Three types of dynamic platforms are considered: (a) a sinusoidally excited rigid-body platform; (b) a spring-supported rigid-body platform; and (c) an Euler–Bernoulli beam. These platforms capture some important domains of real-world locomotion terrain (e.g., harmonically excited platforms, suspended floors, and bridges). The interaction force model and the equations of motion of the SLIP-platform systems are derived. Numerical simulations of SLIP running on the three types of dynamic platforms reveal that the platform movement can destabilize the SLIP even when the initial conditions of the SLIP motion are within the domain of attraction of its motion on flat, stationary platforms. A simple control strategy that can sustain the forward motion of a SLIP on dynamic platforms is then synthesized. The effectiveness of the proposed control strategy in sustaining SLIP motion on dynamic platforms is validated through simulations.

Author(s):  
Chen Xiulong ◽  
Jiang Shuai ◽  
Deng Yu ◽  
Wang Qing

In order to understand dynamic responses of planar rigid-body mechanism with clearance, the dynamic model of the mechanism with revolute clearance is proposed and the dynamic analysis is realized. First, the kinematic model of the revolute clearance is built; the amount of penetration depth and relative velocity between the elements of the revolute clearance joint is obtained. Second, Lankarani-Nikravesh (L-N) and the novel nonlinear contact force model are both used to describe the normal contact force of the revolute clearance, and the tangential contact force of the revolute clearance is built by modified Coulomb friction model. Third, the dynamic model of a two degrees-of-freedom (2DOFs) nine bars rigid-body mechanism with a revolute clearance is built by the Lagrange equation. The fourth-order Runge–Kutta method has been utilized to solve the dynamic model. And the effects of different driving speeds of cranks, different clearance values, and different friction coefficients on dynamic response are analyzed. Finally, in order to prove the validity of numerical calculation result, the virtual prototype model of 2DOFs nine bars mechanism with clearance is modeled and its dynamic responses are analyzed by adams software. This research could supply theoretical basis for dynamic modeling, dynamic behaviors analysis, and clearance compensation control of planar rigid-body mechanism with clearance.


Author(s):  
Jimmy Sastra ◽  
Willy Giovanni Bernal Heredia ◽  
Jonathan Clark ◽  
Mark Yim

Reconfigurable Modular robots can adapt their morphologies and their gaits for locomotion through different environments, whether like a snake for moving through constrained spaces or in a wheel-like shape for efficient and fast rolling on flat terrain. This paper proposes a new, scalable biologically-inspired legged style of locomotion for this class of robots. Passively compliant leg attachments are utilized to achieve a dynamic running gait using body articulation. A dynamic simulation as well as experimental data showing that we have achieved stable dynamic locomotion is presented. Although the robot design and control strategy are, in principle, scalable to any number of leg pairs, results are given for a hexapedal robot configuration. This prototype represents the first example of dynamic legged locomotion driven only by body articulation.


2012 ◽  
Vol 229-231 ◽  
pp. 2361-2364 ◽  
Author(s):  
Zi Fan Fang ◽  
Bing Fei Xiang ◽  
Qing Song He ◽  
De Xin Wu ◽  
Hua Pan Xiao

The dynamic model of wire rope with contact is presented based on finite element method and the flexible multi-body dynamics theory by putting the contact force between the wire rope and drum. The unilateral anti-sway and tension control strategy is put forward, and the dynamic model and collaborative simulation of payload motion for deployment system is modeled by dynamic analysis software RecurDyn and control library Colink. The correctness of the collaborative simulation model and control strategy is validated by analysis and comparison , which lays the foundation for further research on dynamic simulation of virtual prototype in nonlinear and complex mechanical-control system.


2020 ◽  
Vol 13 (2) ◽  
pp. 156-170
Author(s):  
Bing Zhang ◽  
Saike Jiang ◽  
Ziliang Jiang ◽  
Jiandong Li ◽  
Kehong Zhou ◽  
...  

Background: The parallel mechanism is widely used in motion simulators, parallel machine tools, medical equipment and other fields. It has advantages of high rigidity, stable structure and high carrying capacity. However, the control strategy and control method are difficult to study because of the complexity of the parallel mechanism system. Objective: The purpose of this paper was to verify the dynamic model of a hydraulic driven 3-DOF parallel mechanism and propose a compound control strategy to broaden the bandwidth of the control system. Methods: The single rigid body dynamic model of the parallel mechanism was established by the Newton Euler method. The feed forward control strategy based on joint space control with inverse kinematic was designed to improve the bandwidth and control precision. The co-simulation method based on MATLAB / SIMULINK and ADAMS was adopted to verify the dynamics and control strategy. Results: The bandwidth of each degree of freedom in the 3-DOF parallel mechanism was used to expand about 10Hz and the amplitude error was controlled below 5%. Conclusion: Based on the designed dynamic model and composite control strategy, the controlled accuracy of the parallel mechanism is improved and the bandwidth of the control system is broadened. Furthermore, the improvements can be made in aspects of control accuracy and real-time performance to compose more patents on parallel mechanisms.


Author(s):  
Andre L. Kirsten ◽  
Jacson Hansen ◽  
Paulo C. V. da Luz ◽  
Cassiano Rech ◽  
Ricardo N. do Prado ◽  
...  

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 125
Author(s):  
Xiuhui Huang ◽  
Jun Wang ◽  
Zeqiu Li

In this study, a solvent dehydration column of purified terephthalic acid (PTA) plant was used as the research object. Based on a dynamic model of the solvent dehydration column, a dynamic sensitivity analysis of the key parameters was carried out using Aspen Dynamics. After the dynamic model reached stability, the reflux rate, methyl acetate concentration, and reflux temperature of the solvent dehydration column were adjusted and the changes of the key separation indexes under the corresponding disturbance were analyzed. According to the analysis results, a sensitive plate temperature controller was added to carry out the dynamic sensitivity analysis. In addition, the acetic acid (HAc) concentration of the bottom of the column was found to be unstable in the dynamic sensitivity analysis. Considering the HAc concentration controller of the column bottom, two control strategies were designed. By analyzing the dynamic response of the feed flow disturbance under different control strategies, a more suitable control strategy under different conditions was obtained. From this, a reasonable method could be derived to design the control strategy, thereby providing a theoretical basis for further real-time optimization and advanced control of solvent dehydration in a PTA plant.


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