scholarly journals One Novel Hydraulic Actuating System for the Lower-Body Exoskeleton

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Maowen Sun ◽  
Xiaoping Ouyang ◽  
Jouni Mattila ◽  
Huayong Yang ◽  
Gang Hou
Keyword(s):  
Power Density ◽  
Hydraulic System ◽  
High Speed ◽  
Dynamic Models ◽  
Human Motion ◽  
Knee Joints ◽  
High Power Density ◽  
Heavy Load ◽  
Motion Data ◽  
Micro Pump

AbstractThe hydraulic exoskeleton is one research hotspot in the field of robotics, which can take heavy load due to the high power density of the hydraulic system. However, the  traditional hydraulic system is normally centralized, inefficient, and bulky during application, which limits its development in the exoskeleton. For improving the robot’s performance, its hydraulic actuating system should be optimized further. In this paper a novel hydraulic actuating system (HAS) based on electric-hydrostatic actuator  is proposed, which is applied to hip and knee joints. Each HAS integrates  an electric servo motor, a high-speed micro pump, a specific tank, and other components into a module. The specific parameters are obtained through relevant simulation according to human motion data and load requirements. The dynamic models of the HAS are built, and validated by the system identification. Experiments of trajectory tracking and human-exoskeleton interaction are carried out, which demonstrate the proposed HAS has the ability to be applied to the exoskeleton. Compared with the previous prototype, the total weight of the HAS in the robot is reduced by about 40%, and the power density is increased by almost 1.6 times.

Design and Characteristics of Microfocus X-ray Source with Sealed Tube and Transmissive Target on Diamond Window

2021 ◽  
Vol 79 (6) ◽  
pp. 631-640
Author(s):  
Takaaki Tsunoda ◽  
Takeo Tsukamoto ◽  
Yoichi Ando ◽  
Yasuhiro Hamamoto ◽  
Yoichi Ikarashi ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Electronic Device ◽  
High Reliability ◽  
Electronic Devices ◽  
Lithium Ion ◽  
High Power Density ◽  
High Magnification ◽  
X Ray

Electronic devices such as medical instruments implanted in the human body and electronic control units installed in automobiles have a large impact on human life. The electronic circuits in these devices require highly reliable operation. Radiographic testing has recently been in strong demand as a nondestructive way to help ensure high reliability. Companies that use high-density micrometer-scale circuits or lithium-ion batteries require high speed and high magnification inspection of all parts. The authors have developed a new X-ray source supporting these requirements. The X-ray source has a sealed tube with a transmissive target on a diamond window that offers advantages over X-ray sources having a sealed tube with a reflective target. The X-ray source provides high-power-density X-ray with no anode degradation and a longer shelf life. In this paper, the authors will summarize X-ray source classification relevant to electronic device inspection and will detail X-ray source performance requirements and challenges. The paper will also elaborate on technologies employed in the X-ray source including tube design implementations for high-power-density X-ray, high resolution, and high magnification simultaneously; reduced system downtime for automated X-ray inspection; and reduced dosages utilizing quick X-ray on-and-off emission control for protection of sensitive electronic devices.

Research on a high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles

2021 ◽  
pp. 095440702110610
Author(s):  
Chao Wang ◽  
Weijie Zhang ◽  
Guosheng Wang ◽  
Yong Guo
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Excitation Amplitude ◽  
Suspension System ◽  
Level Energy ◽  
High Power Density ◽  
Damping Force ◽  
Tracked Vehicles ◽  
Energy Regeneration

High power density energy regeneration is one of the effective solutions to solve the contradiction between improving the damping performance and energy consumption of active suspension. The hydraulic commutator is used to realize hydraulic rectification and hydraulic variable speed/pump/motor with few teeth difference gear pairs is used to match the speed, combined with permanent magnet motor power generation and power supply to put forward kilowatt level high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles. The mathematical model and fluid-solid-thermo-magnetic multiphysics coupling model are built to analyze the damping performance and regenerative characteristics of the system under passive and semi-active working conditions. The simulation results show that the damping force of the system increases with the increase of the road excitation amplitude and the semi-active control can be realized by adjusting the duty cycle with the PWM control rectifier module. The high power density mechanical-electrical-hydraulic regenerative suspension system can realize kilowatt level energy regeneration, and the regenerative efficiency is more than 50% under low-frequency excitation. The temperature rise of the system is low during operation, which is helpful to improve the reliability and service life.

Design of Input Shaping Control for Planar Parallel Manipulators

2013 ◽  
Author(s):  
Madusudanan Sathia Narayanan ◽  
Venkat Krovi
Keyword(s):  
Structural Design ◽  
High Speed ◽  
Dynamic Models ◽  
Damping Ratio ◽  
Parallel Manipulators ◽  
Mobile Manipulators ◽  
Heavy Load ◽  
End Effector ◽  
Input Shaping Control ◽  
Basic Input

Parallel manipulators are well known for their superior stiffness, higher accuracy, lower inertia and faster response compared to the serial counterparts and hence is widely used for high-speed machining and heavy load applications. However, controller limitations as well as design constraints can result in un-optimized designs causing unsettling residual vibrations at the end effector and limit their applications. Though many have discussed improving the structural design, augmenting with redundant sensors/ dampers and advanced feedback control methods for serial and mobile manipulators for vibration attenuations, very few investigated such techniques for parallel manipulators (PM). In this manuscript, we evaluate a specific type of feed-forward technique for planar PM. Lagrangian based dynamic models of platform manipulators and a simple trajectory level proportional-derivative control will be used with the gains tuned to force oscillations at the end effector to ensure stability. We will then demonstrate the applicability of basic input shapers for PM based on computation of natural frequencies and damping ratio for each mode, and resulting improvements in terms of appropriate performance measures.

Configuration Design of Dual-input Compound Power-split Mechanism for In-Wheel Motor Driven Electrical Vehicles Based on An Improved Lever Analogy Method

2021 ◽  
pp. 1-30
Author(s):  
Xiaodong Yang ◽  
Yimin Shao ◽  
Liming Wang ◽  
Wennian Yu ◽  
Nian Yue ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Speed Ratio ◽  
High Power Density ◽  
Analogy Method ◽  
Electrical Vehicles ◽  
Power Split ◽  
Searching Method ◽  
Optimal Configurations

Abstract High power density in-wheel motor could be achieved by integrating a high speed ratio (larger than 25) compound power-split mechanism (CPSM) with small motors. However, due to the exhaustive searching method adopted by the traditional lever analogy method, it is time-consuming to design high speed ratio compound power-split mechanism configurations satisfying high power density of in-wheel motor. In this paper an improved lever analogy method is proposed to find the optimal configurations with high speed ratio to satisfy the high power density in-wheel motor. In this method, a judgment algorithm about the rank of structure matrix is proposed to identify 3-node compound lever models of the CPSM. The improved lever analogy method can filter out useless configurations which significantly improve the calculation efficiency. The simulation results show that the calculation efficiency is improved by 215 times higher than that of the lever analogy method. Finally, 16 reasonable and 14 new configurations are obtained. This indicates that the improved lever analogy method can provide an effective way to design the high speed ratio CPSM which is widely used in-wheel motor driven vehicles.

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