scholarly journals Variable Impedance Control of Powered Knee Prostheses Using Human-Inspired Algebraic Curves

2019 ◽  
Vol 14 (10) ◽  
Author(s):  
Alireza Mohammadi ◽  
Robert D. Gregg
Keyword(s):  
Algebraic Curve ◽  
Algebraic Curves ◽  
Controller Design ◽  
Impedance Control ◽  
Knee Prosthesis ◽  
Knee Prostheses ◽  
Computationally Efficient ◽  
Prosthetic Joints ◽  
Hip Motion ◽  
Curve Representation

Abstract Achieving coordinated motion between transfemoral amputee patients and powered prosthetic joints is of paramount importance for powered prostheses control. In this article, we propose employing an algebraic curve representation of nominal human walking data for a powered knee prosthesis controller design. The proposed algebraic curve representation encodes the desired holonomic relationship between the human and the powered prosthetic joints with no dependence on joint velocities. For an impedance model of the knee joint motion driven by the hip angle signal, we create a continuum of equilibria along the gait cycle using a variable impedance scheme. Our variable impedance-based control law, which is designed using the parameter-dependent Lyapunov function framework, realizes the coordinated hip-knee motion with a family of spring and damper behaviors that continuously change along the human-inspired algebraic curve. In order to accommodate variability in the user's hip motion, we propose a computationally efficient radial projection-based algorithm onto the human-inspired algebraic curve in the hip-knee plane.

Walking-Stair Climbing Control for Powered Knee Prostheses

2016 ◽  
Author(s):  
Molei Wu ◽  
Xiangrong Shen
Keyword(s):  
Impedance Control ◽  
Knee Prosthesis ◽  
Stair Climbing ◽  
Knee Joints ◽  
Knee Prostheses ◽  
Control Approach ◽  
Prosthetic Joints ◽  
Real Time Measurement ◽  
Human Subject Testing ◽  
Finite State

Recent progresses in powered lower-limb prostheses have the potential of enabling amputee users to conduct energetically demanding locomotive tasks, which are usually beyond the capability of traditional unpowered prostheses. Realizing such potential, however, requires responsive and reliable control of the power provided by prosthetic joints. In this paper, an integrated walking-stair climbing control approach is presented for transfemoral prostheses with powered knee joints. Leveraging the similarities between walking and stair climbing, this new approach adopts the general finite-state impedance control framework. Furthermore, important modifications are introduced to model the biomechanical characteristics that are beyond the capability of standard impedance control. The transition between the walking and stair-climbing modes is triggered through the real-time measurement of the spatial orientation of the user’s thigh, which provides a reliable indicator of the user’s intention of making such transition. This new control approach has been implemented on a powered knee prosthesis, and its effectiveness was demonstrated in human subject testing.

Influence of Cyclic Loading on Mechanical Loosening of Hinged Knee Prostheses

1978 ◽  
Vol 7 (4) ◽  
pp. 235-239 ◽  
Author(s):  
D. H. van Campen ◽  
H. W. Croon ◽  
J. Lindwer
Keyword(s):  
Experimental Investigation ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Knee Prosthesis ◽  
In Vitro Experiments ◽  
Knee Prostheses ◽  
Normal Walking ◽  
Fresh Cadaver ◽  
Unfavourable Effect

A combined theoretical and experimental investigation is reported with respect to the influence of mechanical loading on loosening at the cement bone interface of knee prostheses with intermedullary stems. The in vitro experiments have been performed under cyclic loading conditions with the tibial part of a Shiers knee prosthesis implanted in fresh cadaver tibiae. The experimental results indicate an unfavourable effect of peak loading (as occurring in walking up stairs) on loosening as compared with loading due to normal walking conditions.

scholarly journals Design and evaluation of a hybrid passive–active knee prosthesis on energy consumption

2020 ◽  
Vol 11 (2) ◽  
pp. 425-436
Author(s):  
Xiaoming Wang ◽  
Qiaoling Meng ◽  
Zhewen Zhang ◽  
Jinyue Sun ◽  
Jie Yang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Knee Prosthesis ◽  
Metabolic Cost ◽  
Knee Prostheses ◽  
Hydraulic Damper ◽  
Operating Modes ◽  
Gait Characteristics ◽  
Energy Consumption Model ◽  
Active Motor ◽  
Damping Torque

Abstract. The existing lower limb prostheses with passive knees have disadvantages, causing an asymmetric gait and higher metabolic cost during level walking which is in contrast with a normal gait. However, most existing active knee prostheses need a significant amount of energy. In this paper, a novel hybrid passive–active knee prosthesis (HPAK) that allows passive and active operating modes is proposed, which contains an active motor unit and a novel hydraulic damper with an electrically controlled valve that adjusts the damping torque dynamically during each gait cycle. An energy consumption model was built to evaluate the energy consumption when walking on level ground in three different simulation conditions to, respectively, simulate the complete HPAK, an ordinary active prosthesis (AKP) and an ordinary passive prosthesis (PKP). The results show that, in a cycle, the HPAK consumes only 16.19 J, which is 3.6 times lower than the AKP (58.95 J), and the PKP consumes only 1.24 J due to the novel spring–hydraulic damper structure designed and presented in this paper. These results indicate that the proposed novel hybrid passive–active knee prosthesis can have a positive effect on reducing energy consumption and improving the approximation of healthy gait characteristics when walking on level ground, contrasting with active or passive knee prostheses.

scholarly journals Development and Examination of a Knee Prosthesis Geometry

2019 ◽  
Vol 11 (1) ◽  
pp. 27-30
Author(s):  
Gábor Péter Balassa
Keyword(s):  
Knee Joint ◽  
Research Team ◽  
Knee Prosthesis ◽  
Experimental Measurements ◽  
Joint Movement ◽  
Knee Prostheses ◽  
Healthy Human ◽  
Human Knee ◽  
Human Knee Joint ◽  
Number Of Patients

Abstract The necessity for the knee prosthesis is confirmed by the large increase in the number of patients suffering from arthrosis, which is a present-day disease. Despite this need, there doesn’t exist an optimal knee prosthesis. Nowadays the development of the knee prostheses is progressing. It is very difficult to define the required geometry with traditional methods, because the movement conditions to be created by the prostheses should be similar to the movements of the human knee. During previous research the biomechanical research team of the Szent István University occupied with experimental measurements of the healthy human knee joint movement. In this paper I would like to introduce a method of prosthesis geometry development. As a result, a knee prosthesis geometry has been created which is approaching the movement form of the real human knee joint.

scholarly journals High-Bandwidth Active Impedance Control of the Proprioceptive Actuator Design in Dynamic Compliant Robotics

Actuators ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 71 ◽  
Author(s):  
Simon Hjorth Jessing Lund ◽  
Peter Billeschou ◽  
Leon Bonde Larsen
Keyword(s):  
Pulse Width Modulation ◽  
Compliant Mechanisms ◽  
Controller Design ◽  
Impedance Control ◽  
Experimental Tests ◽  
Angle Sensor ◽  
High Performing ◽  
High Bandwidth ◽  
Torque Observer ◽  
Active Impedance

Dynamic compliant robotics is a fast growing field because of its ability to widen the scope of robotics. The reason for this is that compliant mechanisms may ensure safe/compliant interactions between a robot and an external element—for instance, a human operator. Active impedance control may widen the scope even further in relation to passive elements, but it requires high-bandwidth robust torque and active impedance control which induces high-noise issues even if high-end sensors are used. To address these issues, a complete controller design scheme, including Field-Oriented Control (FOC) of a Brushless Direct Current (BLDC) motor, is proposed. In this paper, controller designs for controlling the virtual impedance, motor torque and field are proposed which enables high-bandwidth robust control. Additionally, a novel speed and angle observer is proposed that aims to reduce noise arising in the angle sensor (typically a 12-bit magnetic encoder) and a Kalman/Luenberger based torque observer is proposed that aims to reduce noise arising in the phase current sensors. Through experimental tests, the combination of the controller designs and observers facilitated a closed-loop torque bandwidth of 2 . 6 k Hz and a noise reduction of 13 . 5 (in relation to no observers), at a sample rate and Pulse Width Modulation (PWM) frequency of 25 k Hz . Additionally, experiments verified a precise and high performing controller scheme both during impacts and at a variety of different virtual compliance characteristics.

scholarly journals Least Squares Fitting of Piecewise Algebraic Curves

2007 ◽  
Vol 2007 ◽  
pp. 1-11 ◽  
Author(s):  
Chun-Gang Zhu ◽  
Ren-Hong Wang
Keyword(s):  
Least Squares ◽  
Algebraic Curve ◽  
Algebraic Curves ◽  
Scattered Data ◽  
Energy Term ◽  
Bivariate Spline ◽  
Piecewise Algebraic Curve ◽  
Piecewise Algebraic Curves ◽  
The Given

A piecewise algebraic curve is defined as the zero contour of a bivariate spline. In this paper, we present a new method for fittingC1piecewise algebraic curves of degree 2 over type-2 triangulation to the given scattered data. By simultaneously approximating points, associated normals and tangents, and points constraints, the energy term is also considered in the method. Moreover, some examples are presented.

Passivity-based cruise control of high speed trains

2016 ◽  
Vol 24 (3) ◽  
pp. 492-504 ◽  
Author(s):  
Mohammadreza Faieghi ◽  
Aliakbar Jalali ◽  
Seyed Kamal-e-ddin Mousavi Mashhadi ◽  
Dumitru Baleanu
Keyword(s):  
High Speed ◽  
Controller Design ◽  
Longitudinal Motion ◽  
Computationally Efficient ◽  
Cruise Control ◽  
Tracking Errors ◽  
High Speed Trains ◽  
Control Feedback ◽  
Bounded Perturbations ◽  
Velocity Tracking

The cruise control problem of high speed trains (HSTs) is revisited in this paper. Despite the ongoing trend of using Lyapunov-based approaches, the concept of passivity is used as the basis of cruise controller design. To begin with, the Euler–Lagrange modeling of longitudinal motion of HST is introduced. Consequently, passivity properties of the system is investigated and it is shown that the system presents a strictly passive input–output map output. This property is utilized to design a controller based on an energy-shaping method. Since the controller benefits from the passivity property of the train, it is structurally simple and computationally efficient while ensuring asymptotic velocity tracking. In addition, as revealed in our robust analysis, the controller is capable of dealing with bounded perturbations. That is to say, boundedness of velocity tracking errors is guaranteed for sufficiently large control feedback gains. The obtained theoretical results have been verified by numerical simulation.

Modular Concept in a Multi-Functional above Knee Prosthesis

1981 ◽  
Vol 10 (3) ◽  
pp. 155-158 ◽  
Author(s):  
K K Chaudhry ◽  
S K Guha ◽  
S K Verma
Keyword(s):  
Knee Prosthesis ◽  
New Technology ◽  
Prosthesis Design ◽  
Modular System ◽  
Knee Prostheses ◽  
Normal Walking ◽  
Asian Countries ◽  
Modular Concept

Conventional designs of above knee prostheses do not permit squatting and sitting cross-legged (SCL) on the floor. These postures are commonly adopted in India and other Afro-Asian countries. A new prosthesis design permitting these postures has been evolved. Further, a modular system has been prepared to fit into a number of different leg sizes. As a result of the new technology, the ankle remains fixed in normal walking and automatically flexes during squatting. Also for SCL, the thigh rotation is automatic. Thus, no hand manipulations are needed and the movements, both going down and arising are similar to normal movements.

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