scholarly journals Design, Development and Scaling Analysis of a Variable Stiffness Magnetic Torsion Spring

10.5772/57300 ◽  
2013 ◽  
Vol 10 (10) ◽  
pp. 372 ◽  
Author(s):  
Angelo Sudano ◽  
Dino Accoto ◽  
Loredana Zollo ◽  
Eugenio Guglielmelli
Keyword(s):  
Variable Stiffness ◽  
Scaling Analysis ◽  
Design Development ◽  
Torsion Spring

scholarly journals Analysis of Stiffness and Energy Consumption of Nonlinear Elastic Joint Legged Robot

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Dongliang Chen ◽  
Jindong Zhang ◽  
Xutao Weng ◽  
Yunjian Zhang ◽  
Zhonghui Shi
Keyword(s):  
Energy Consumption ◽  
Variable Stiffness ◽  
Legged Robot ◽  
Spring Stiffness ◽  
Simulation Experiments ◽  
Torsion Spring ◽  
Elastic Joint ◽  
Output Torque ◽  
Nonlinear Elastic ◽  
Elastic Unit

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.

scholarly journals Conceptual mechanical design of antagonistic variable stiffness joint based on equivalent quadratic torsion spring

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042094129
Author(s):  
Jishu Guo
Keyword(s):  
Degrees Of Freedom ◽  
Modular Design ◽  
Angular Displacement ◽  
Variable Stiffness ◽  
Human Robot Interaction ◽  
Design Calculation ◽  
Robot Arm ◽  
Compact Structure ◽  
Torsion Spring ◽  
Stiffness Characteristics

The variable stiffness joint is a kind of flexible actuator with variable stiffness characteristics suitable for physical human–robot interaction applications. In the existing variable stiffness joints, the antagonistic variable stiffness joint has the advantages of simple implementation of variable stiffness mechanism and easy modular design of the nonlinear elastic element. The variable stiffness characteristics of antagonistic variable stiffness joints are realized by the antagonistic actuation of two nonlinear springs. A novel design scheme of the equivalent nonlinear torsion spring with compact structure, large angular displacement range, and desired stiffness characteristics is presented in this article. The design calculation for the equivalent quadratic torsion spring is given as an example, and the actuation characteristics of the antagonistic variable stiffness joint based on the equivalent quadratic torsion spring are illustrated. Based on the design idea of constructing the antagonistic variable stiffness joint with compact structure and high compliance, as well as the different design requirements of the joints at different positions of the multi–degrees of freedom robot arm, nine types of mechanical schemes of antagonistic variable stiffness joint with the open design concept are proposed in this article. Finally, the conceptual joint configuration schemes of the robot arm based on the antagonistic variable stiffness joint show the application scheme of the designed antagonistic variable stiffness joint in the multi–degrees of freedom robot.

Mechanical design and robust tracking control of a class of antagonistic variable stiffness actuators based on the equivalent nonlinear torsion springs

2018 ◽  
Vol 232 (10) ◽  
pp. 1337-1355 ◽  
Author(s):  
Jishu Guo ◽  
Guohui Tian
Keyword(s):  
Tracking Control ◽  
Control Method ◽  
Sliding Mode ◽  
Input Saturation ◽  
Variable Stiffness ◽  
Robust Tracking ◽  
Torsion Spring ◽  
Saturation Constraints ◽  
Variable Stiffness Actuator ◽  
Input Saturation Constraints

The novel conceptual model of the antagonistic variable stiffness actuator based on the equivalent nonlinear torsion spring and the friction damper is demonstrated. For the dynamic model of the antagonistic variable stiffness actuator in the presence of parametric uncertainties, unknown bounded friction torques, unknown bounded external disturbance, and input saturation constraints, using the coordinate transformation, the state space model of the antagonistic variable stiffness actuator with composite disturbances and input saturation constraints is transformed into an extended integral chain–type pseudo-linear system with input saturation constraints. Subsequently, a combination of the linear extended state observer, sliding mode control, and adaptive input saturation compensation law is adopted for the design of the robust tracking controller that simultaneously regulates the position and stiffness of the antagonistic equivalent nonlinear torsion spring-based variable stiffness actuator. Under the proposed controller, the semi-global uniformly ultimately bounded stability of the closed-loop system has been proved via Lyapunov stability analysis. Simulation studies demonstrate the effectiveness and the robustness of the proposed robust adaptive tracking control method for the antagonistic variable stiffness actuator.

CRITICAL FIELD IN SPIN GLASSES : A SCALING ANALYSIS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1071-C8-1072
Author(s):  
M. A. Continentino ◽  
E. Szkatulla ◽  
B. Elschner ◽  
H. Maletta
Keyword(s):  
Critical Field ◽  
Spin Glasses ◽  
Scaling Analysis
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