Design of Powered Ankle-Foot Prosthesis With Nonlinear Parallel Spring Mechanism

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Fei Gao ◽  
Yannan Liu ◽  
Wei-Hsin Liao
Keyword(s):  
Energy Consumption ◽  
Design Method ◽  
Mechanical Energy ◽  
Power Requirement ◽  
Human Ankle ◽  
Cam Profile ◽  
Quadratic Bézier Curve ◽  
Spring Mechanism ◽  
Power And Energy ◽  
And Control

In this paper, a powered ankle-foot prosthesis with nonlinear parallel spring mechanism is developed. The parallel spring mechanism is used for reducing the energy consumption and power requirement of the motor, at the same time simplifying control of the prosthesis. To achieve that goal, the parallel spring mechanism is implemented as a compact cam-spring mechanism that is designed to imitate human ankle dorsiflexion stiffness. The parallel spring mechanism can store the negative mechanical energy in controlled dorsiflexion (CD) phase and release it to assist the motor in propelling a human body forward in a push-off phase (PP). Consequently, the energy consumption and power requirements of the motor are both decreased. To obtain this desired behavior, a new design method is proposed for generating the cam profile. Unlike the existing design methods, the friction force is considered here. The cam profile is decomposed into several segments, and each segment is fitted by a quadratic Bezier curve. Experimental results show that the cam-spring mechanism can mimic the desired torque characteristics in the CD phase (a loading process) more precisely. Finally, the developed prosthesis is tested on a unilateral below-knee amputee. Results indicate that, with the assistance of the parallel spring mechanism, the motor is powered off and control is not needed in the CD phase. In addition, the peak power and energy consumption of the motor are decreased by approximately 37.5% and 34.6%, respectively.

Study and Simulation on the Energy Efficiency Management Control Strategy of Ship Based on Clean Propulsion System

2015 ◽  
Author(s):  
Kai Wang ◽  
Xinping Yan ◽  
Yupeng Yuan
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Control Strategy ◽  
Control Strategies ◽  
Management Control ◽  
Propulsion System ◽  
Power Requirement ◽  
Doubly Fed ◽  
System Configurations ◽  
And Control

Nowadays, with the higher voice of ship energy saving and emission reduction, the research on energy efficiency management is particularly necessary. Energy efficiency management and control of ships is an effective way to improve the ship energy efficiency. In this paper, according to the new clean propulsion system configurations of 5000 tons of bulk carrier, the energy efficiency management control strategy of the clean propulsion system is designed based on the model of advanced brushless doubly-fed shaft generator, propulsion system using LNG/diesel dual fuel engine and energy consumption of the main engine for reducing energy consumption. The simulation model of the entire propulsion system and the designed control strategy were designed. The influence of the engine speed on the ship energy efficiency was analyzed, and the feasibility of the energy efficiency management control strategies was verified by simulation using Matlab/Simulink. The results show that the designed strategies can ensure the power requirement of the whole ship under different conditions and improve the ship energy efficiency and reduce CO2 emissions.

THE IMPACT OF SOURCE CODE TRANSFORMATIONS ON SOFTWARE POWER AND ENERGY CONSUMPTION

2002 ◽  
Vol 11 (05) ◽  
pp. 477-502 ◽  
Author(s):  
CARLO BRANDOLESE ◽  
WILLIAM FORNACIARI ◽  
FABIO SALICE ◽  
DONATELLA SCIUTO
Keyword(s):  
Energy Consumption ◽  
Power Consumption ◽  
Source Code ◽  
Code Transformations ◽  
C Language ◽  
Energy Consumption Reduction ◽  
Set Up ◽  
Power And Energy ◽  
And Control ◽  
The Impact

Software power consumption minimization is increasingly a very relevant issue in the design of embedded systems, in particular those dedicated to mobile devices. The paper aims to review the state of the art source code transformations in terms of their effectiveness on power and energy consumption reduction. A design framework for the C language has been set up, using the gcc compiler with SimplePower as the simulation kernel. Some new transformations have also been identified with the aim of reducing the power consumption. Four classes of transformations will be considered: loop transformations, data structures transformations, inter-procedural transformations and control structure transformations. For each transformation, together with the evaluation of the energy and power consumption, some applicability criteria have been defined.

scholarly journals Trajectory Planning and Optimization for a Par4 Parallel Robot Based on Energy Consumption

2019 ◽  
Vol 9 (13) ◽  
pp. 2770
Author(s):  
Xiaoqing Zhang ◽  
Zhengfeng Ming
Keyword(s):  
Energy Consumption ◽  
Trajectory Planning ◽  
Design Method ◽  
Mechanical Energy ◽  
Parallel Robot ◽  
Sixth Order ◽  
Function Parameter ◽  
Pick And Place ◽  
Order Polynomial ◽  
Fifth Order

A study on trajectory planning and optimization for a Par4 parallel robot was carried out, based on energy consumption in high-speed picking and placing. In the end-effector operating space of the Par4 parallel robot, the rectangular transition of the pick-and-place trajectory was rounded by a Lamé curve. A piecewise design method was adopted to accomplish trajectory shape planning for displacement, velocity and acceleration. To make the Par4 robot’s end run more smoothly and to reduce residual vibration, asymmetric fifth-order and sixth-order polynomial motion laws were employed. With the aim of reaching the minimum mechanical energy consumption for the Par4 parallel robot, the recently proposed Grey Wolf Optimizer (GWO) algorithm was adopted to optimize the planning trajectory. The validity of the design method was verified by experiments, and it was found that the minimum mechanical energy consumption of the optimal trajectory planned under the law of fifth-order polynomial motion is lower than that of sixth-order polynomial motion. In addition, the experiments also revealed the optimal values of Parameters e and f, which were the parameters of the Lamé curve function. Parameter e can be calculated as half the pick-up span for the minimum mechanical energy consumption, unlike parameter f, whose optimal value depends on specific circumstances such as the pick-and-place coordinates and the pick-up height.

Cam Profile Generation for Cam-Spring Mechanism With Desired Torque

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Fei Gao ◽  
Yannan Liu ◽  
Wei-Hsin Liao
Keyword(s):  
Friction Coefficient ◽  
Analytical Solution ◽  
Friction Force ◽  
Design Method ◽  
Nonlinear Behavior ◽  
Direct Derivation ◽  
Cam Profile ◽  
Derivation Method ◽  
Spring Mechanism ◽  
Pitch Curve

Commercial springs have linear characteristics. Nevertheless, in some cases, nonlinear behavior (e.g., nonlinear torque) is desired. To handle that, a cam-spring mechanism with a specified cam profile was proposed in our previous work. In this paper, to further study the cam profile generation, a new convenient design method is proposed. First, the model of cam-spring mechanism considering the friction force is analyzed. Based on this model, sorts of derivation processes are conducted for obtaining the expression of spring torque. When the friction coefficient is zero, the analytical solution of the equation (spring deformation) is derived. However, in practice, where the friction coefficient is not zero, an analytical solution is not available. Therefore, a numerical solution is sought. Then, with the obtained spring deformation, the cam profile and pitch curve are generated. Results of an experiment conducted to verify the new method show that the cam profile generated by the direct derivation method can precisely mimic the desired torque characteristics. In addition, the hysteresis induced by the friction force in the cam-spring mechanism is also studied. By increasing the spring stiffness, spring free length, and the cam eccentricity, the hysteresis in the cam-spring mechanism can be decreased.

Interference mitigation in point to point wireless sensor networks using LSP protocol and time division multiplexing approach

2020 ◽  
Vol 39 (4) ◽  
pp. 5449-5458
Author(s):  
A. Arokiaraj Jovith ◽  
S.V. Kasmir Raja ◽  
A. Razia Sulthana
Keyword(s):  
Energy Consumption ◽  
Large Scale ◽  
Control Parameter ◽  
Interference Mitigation ◽  
Wireless Sensor ◽  
Point To Point ◽  
A Minor ◽  
Two Stages ◽  
Time Division ◽  
And Control

Interference in Wireless Sensor Network (WSN) predominantly affects the performance of the WSN. Energy consumption in WSN is one of the greatest concerns in the current generation. This work presents an approach for interference measurement and interference mitigation in point to point network. The nodes are distributed in the network and interference is measured by grouping the nodes in the region of a specific diameter. Hence this approach is scalable and isextended to large scale WSN. Interference is measured in two stages. In the first stage, interference is overcome by allocating time slots to the node stations in Time Division Multiple Access (TDMA) fashion. The node area is split into larger regions and smaller regions. The time slots are allocated to smaller regions in TDMA fashion. A TDMA based time slot allocation algorithm is proposed in this paper to enable reuse of timeslots with minimal interference between smaller regions. In the second stage, the network density and control parameter is introduced to reduce interference in a minor level within smaller node regions. The algorithm issimulated and the system is tested with varying control parameter. The node-level interference and the energy dissipation at nodes are captured by varying the node density of the network. The results indicate that the proposed approach measures the interference and mitigates with minimal energy consumption at nodes and with less overhead transmission.

Using advanced control, post-denitrification and equalisation to improve the performance of a submerged filter

2000 ◽  
Vol 41 (4-5) ◽  
pp. 177-184 ◽  
Author(s):  
K.H. Sørensen ◽  
D. Thornberg ◽  
K.F. Janning
Keyword(s):  
Energy Consumption ◽  
Total N ◽  
Control Loops ◽  
Effluent Quality ◽  
Advanced Control ◽  
Before And After ◽  
And Control ◽  
Side Flow ◽  
Configuration Control ◽  
Control Post

In 1998, the capacity of the BIOSTYR® submerged biofilter at Nyborg WWTP was extended from 48,000 PE to 60,000 PE including advanced sensor based control, post-denitrification in BIOSTYR® and equalization of side flows. The existing configuration with 8 BIOSTYR® DN/N cells is based on pre-denitrification and an internal recirculation of 600–800%. The extended plant comprises 7 BIOSTYR® DN/N cells with 50–225% recirculation followed by 3 BIOSTYR DN cells for post-denitrification. The advanced control loops include blower control, control of the number of active cells (stand-by), automatic switch to high load configuration, control of the side flow equalization, control of the internal recirculation and control of the external carbon source dosing. In this paper, the achieved improvements are documented by comparing influent and effluent data, methanol and energy consumption from comparable periods before and after the extension. Although the nitrogen load to the plant was increased by 20% after the extension, the effluent quality has improved significantly with a reduction of Total-N from 7–8 mg/l to 3–4 mg/l. Simultaneously, the methanol consumption has been reduced by more than 50% per kg removed nitrogen. The energy consumption remained constant although the nitrogen load was increased by 20% and the inflow by 80%.

scholarly journals Current Knowledge and Future Directions for Improving Subsoiling Quality and Reducing Energy Consumption in Conservation Fields

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 575
Author(s):  
Shangyi Lou ◽  
Jin He ◽  
Hongwen Li ◽  
Qingjie Wang ◽  
Caiyun Lu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Cover Crops ◽  
Current Knowledge ◽  
High Energy ◽  
Field Application ◽  
Research Progress ◽  
Monitoring And Control ◽  
Future Directions ◽  
Tillage Depth ◽  
And Control

Subsoiling has been acknowledged worldwide to break compacted hardpan, improve soil permeability and water storage capacity, and promote topsoil deepening and root growth. However, there exist certain factors which limit the wide in-field application of subsoiling machines. Of these factors, the main two are poor subsoiling quality and high energy consumption, especially the undesired tillage depth obtained in the field with cover crops. Based on the analysis of global adoption and benefits of subsoiling technology, and application status of subsoiling machines, this article reviewed the research methods, technical characteristics, and developing trends in five key aspects, including subsoiling shovel design, anti-drag technologies, technologies of tillage depth detection and control, and research on soil mechanical interaction. Combined with the research progress and application requirements of subsoiling machines across the globe, current problems and technical difficulties were analyzed and summarized. Aiming to solve these problems, improve subsoiling quality, and reduce energy consumption, this article proposed future directions for the development of subsoiling machines, including optimizing the soil model in computer simulation, strengthening research on the subsoiling mechanism and comprehensive effect, developing new tillage depth monitoring and control systems, and improving wear-resisting properties of subsoiling shovels.

scholarly journals Energy absorption at lower limb joints in different foot contact strategies while descending stairs

2021 ◽  
Vol 29 ◽  
pp. 433-440
Author(s):  
Hyeong-Min Jeon ◽  
Ki-Kwang Lee ◽  
Jun-Young Lee ◽  
Ju-Hwan Shin ◽  
Gwang-Moon Eom
Keyword(s):  
Knee Joint ◽  
Potential Energy ◽  
Energy Absorption ◽  
Lower Limb ◽  
Mechanical Energy ◽  
Connective Tissues ◽  
Stair Descent ◽  
Young Subjects ◽  
Power And Energy ◽  
Joint Loads

BACKGROUND: Joint loads in different walking strategies during stair descent have been investigated in terms of the joint moment in association with the risk of osteoarthritis. However, the absorption mechanisms of the potential energy loss are not known. OBJECTIVE: This study aims to compare the mechanical energy absorptions in lower limb joints in different initial foot contact strategies. METHODS: Nineteen young subjects walked down on instrumented stairs with two different strategies, i.e., forefoot and rearfoot strike. Power and energy at lower limb joints during stance phase were compared between strategies. RESULTS: Lower limb joints absorbed 73 ± 11% of the potential energy released by descending stairs and there was no difference between strategies. Rearfoot strategy absorbed less energy than forefoot strategy at the ankle joint in the 1st phase, which was compensated mainly by more energy absorption at the knee in the 2nd phase and less energy generation at the hip joints in the 3rd phase. CONCLUSION: The results suggest that a leg absorbs most of the potential energy while descending stairs irrespective of the walking strategies and that any reduction of energy absorption at one joint is compensated by other joints. Greater energy absorption at the knee joint compared to the other joints suggests high burden of knee joint muscles and connective tissues during stair-descent, which is even more significant for the rearfoot strike strategy.

scholarly journals Reducing the metabolic energy of walking and running using an unpowered hip exoskeleton

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Tiancheng Zhou ◽  
Caihua Xiong ◽  
Juanjuan Zhang ◽  
Di Hu ◽  
Wenbin Chen ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Design Method ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Spring Stiffness ◽  
Spatiotemporal Parameters ◽  
The Common ◽  
Hip Flexion ◽  
Optimal Stiffness ◽  
Insight Into

Abstract Background Walking and running are the most common means of locomotion in human daily life. People have made advances in developing separate exoskeletons to reduce the metabolic rate of walking or running. However, the combined requirements of overcoming the fundamental biomechanical differences between the two gaits and minimizing the metabolic penalty of the exoskeleton mass make it challenging to develop an exoskeleton that can reduce the metabolic energy during both gaits. Here we show that the metabolic energy of both walking and running can be reduced by regulating the metabolic energy of hip flexion during the common energy consumption period of the two gaits using an unpowered hip exoskeleton. Methods We analyzed the metabolic rates, muscle activities and spatiotemporal parameters of 9 healthy subjects (mean ± s.t.d; 24.9 ± 3.7 years, 66.9 ± 8.7 kg, 1.76 ± 0.05 m) walking on a treadmill at a speed of 1.5 m s−1 and running at a speed of 2.5 m s−1 with different spring stiffnesses. After obtaining the optimal spring stiffness, we recruited the participants to walk and run with the assistance from a spring with optimal stiffness at different speeds to demonstrate the generality of the proposed approach. Results We found that the common optimal exoskeleton spring stiffness for walking and running was 83 Nm Rad−1, corresponding to 7.2% ± 1.2% (mean ± s.e.m, paired t-test p < 0.01) and 6.8% ± 1.0% (p < 0.01) metabolic reductions compared to walking and running without exoskeleton. The metabolic energy within the tested speed range can be reduced with the assistance except for low-speed walking (1.0 m s−1). Participants showed different changes in muscle activities with the assistance of the proposed exoskeleton. Conclusions This paper first demonstrates that the metabolic cost of walking and running can be reduced using an unpowered hip exoskeleton to regulate the metabolic energy of hip flexion. The design method based on analyzing the common energy consumption characteristics between gaits may inspire future exoskeletons that assist multiple gaits. The results of different changes in muscle activities provide new insight into human response to the same assistive principle for different gaits (walking and running).

Operation and control of a stand-alone power system with integrated multiple renewable energy sources

2021 ◽  
pp. 0309524X2110241
Author(s):  
Nindra Sekhar ◽  
Natarajan Kumaresan
Keyword(s):  
Renewable Energy ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Solar Pv ◽  
Power Requirement ◽  
Squirrel Cage ◽  
Hysteresis Controller ◽  
Squirrel Cage Induction Generator ◽  
And Control

To overcome the difficulties of extending the main power grid to isolated locations, this paper proposes the local installation of a combination of three renewable energy sources, namely, a wind driven DFIG, a solar PV unit, a biogas driven squirrel-cage induction generator (SCIG), and an energy storage battery system. In this configuration one bi-directional SPWM inverter at the rotor side of the DFIG controls the voltage and frequency, to maintain them constant on its stator side, which feeds the load. The PV-battery also supplies the load, through another inverter and a hysteresis controller. Appropriately adding a capacitor bank and a DSTATCOM has also been considered, to share the reactive power requirement of the system. Performance of various modes of operation of this coordinated scheme has been studied through simulation. All the results and relevant waveforms are presented and discussed to validate the successful working of the proposed system.

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