The SPARKy (Spring Ankle With Regenerative Kinetics) Project: Design and Analysis of a Robotic Transtibial Prosthesis With Regenerative Kinetics

2007 ◽  
Author(s):  
Joseph K. Hitt ◽  
Ryan Bellman ◽  
Matthew Holgate ◽  
Thomas G. Sugar ◽  
Kevin W. Hollander
Keyword(s):  
Peak Power ◽  
Sagittal Plane ◽  
Mechanical Design ◽  
Energy Requirement ◽  
Human Gait ◽  
Total System ◽  
Power Requirement ◽  
Prosthetic Devices ◽  
Ankle Motion ◽  
Continuous Power

Even today’s most sophisticated microprocessor controlled ankle-foot prosthetic devices are passive. They lack internal elements that actively generate power, which is required during the “push-off” phase of normal able-bodied walking gait. Consequently, lower limb amputees expend 20–30% more metabolic power to walk at the same speed as able-bodied individuals. Key challenges in the development of an active ankle-foot prosthetic device are the lack of high power and energy densities in current actuator technology. Human gait requires 250W of peak power and 36 Joules of energy per step (80kg subject at 0.8Hz walking rate). Even a highly efficient motor such as the RE75 by Maxon Precision Motors, Inc. rated for 250W continuous power with an appropriate gearbox would weigh 6.6 Kg. This paper presents the first phase of the Spring Ankle with Regenerative Kinetics (SPARKy 1), a multi-phased project funded by the US Army Military Amputee Research Program, which seeks to develop a new generation of powered prosthetic devices based on the Robotic Tendon actuator, that significantly minimizes the peak power requirement of an electric motor and total system energy requirement while providing the amputee enhanced ankle motion and “push-off” power. This paper will present data to show the kinetic advantages of the Robotic Tendon and the electro-mechanical design and analysis of SPARKy 1 that will provide its users with 100% of required “push-off” power and ankle sagittal plane range of motion comparable to able-bodied gait.

Kinematic Coordination in Human Gait: Relation to Mechanical Energy Cost

1998 ◽  
Vol 79 (4) ◽  
pp. 2155-2170 ◽  
Author(s):  
L. Bianchi ◽  
D. Angelini ◽  
G. P. Orani ◽  
F. Lacquaniti
Keyword(s):  
Energy Expenditure ◽  
Energy Cost ◽  
Time Course ◽  
Sagittal Plane ◽  
Dimensional Space ◽  
Mechanical Energy ◽  
Direction Cosine ◽  
Lower Limbs ◽  
Human Gait ◽  
Plane Orientation

Bianchi, L., D. Angelini, G. P. Orani, and F. Lacquaniti. Kinematic coordination in human gait: relation to mechanical energy cost. J. Neurophysiol. 79: 2155–2170, 1998. Twenty-four subjects walked at different, freely chosen speeds ( V) ranging from 0.4 to 2.6 m s−1, while the motion and the ground reaction forces were recorded in three-dimensional space. We considered the time course of the changes of the angles of elevation of the trunk, pelvis, thigh, shank, and foot in the sagittal plane. These angles specify the orientation of each segment with respect to the vertical and to the direction of forward progression. The changes of the trunk and pelvis angles are of limited amplitude and reflect the dynamics of both right and left lower limbs. The changes of the thigh, shank, and foot elevation are ample, and they are coupled tightly among each other. When these angles are plotted one versus the others, they describe regular loops constrained on a plane. The plane of angular covariation rotates, slightly but systematically, along the long axis of the gait loop with increasing V. The rotation, quantified by the change of the direction cosine of the normal to the plane with the thigh axis ( u 3 t ), is related to a progressive phase shift between the foot elevation and the shank elevation with increasing V. As a next step in the analysis, we computed the mass-specific mean absolute power ( P u ) to obtain a global estimate of the rate at which mechanical work is performed during the gait cycle. When plotted on logarithmic coordinates, P u increases linearly with V. The slope of this relationship varies considerably across subjects, spanning a threefold range. We found that, at any given V > 1 m s−1, the value of the plane orientation ( u 3 t ) is correlated with the corresponding value of the net mechanical power ( P u ). On the average, the progressive rotation of the plane with increasing V is associated with a reduction of the increment of P u that would occur if u 3 t remained constant at the value characteristic of low V. The specific orientation of the plane at any given speed is not the same in all subjects, but there is an orderly shift of the plane orientation that correlates with the net power expended by each subject. In general, smaller values of u 3 t tend to be associated with smaller values of P u and vice versa. We conclude that the parametric tuning of the plane of angular covariation is a reliable predictor of the mechanical energy expenditure of each subject and could be used by the nervous system for limiting the overall energy expenditure.

scholarly journals Optimal Stiffness Design for an Exhaustive Parallel Compliance Matrix in Multiactuator Robotic Limbs

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Nathan M. Cahill ◽  
Thomas Sugar ◽  
Yi Ren ◽  
Kyle Schroeder
Keyword(s):  
Energy Efficient ◽  
Peak Power ◽  
Performance Metrics ◽  
Slow Growth ◽  
Legged Robots ◽  
Power Requirement ◽  
Compliance Matrix ◽  
Performance Metric ◽  
Stiffness Design ◽  
Optimal Stiffness

Comparatively slow growth in energy density of both power storage and generation technologies has placed added emphasis on the need for energy-efficient designs in legged robots. This paper explores the potential of parallel springs in robot limb design. We start by adding what we call the exhaustive parallel compliance matrix (EPCM) to the design. The EPCM is a set of parallel springs, which includes a parallel spring for each joint and a multijoint parallel spring for all possible combinations of the robot's joints. Then, we carefully formulate and compare two performance metrics, which improve various aspects of the system performance. Each performance metric is analyzed and compared, their strengths and weaknesses being rigorously presented. The performance benefits associated with this approach are dramatic. Implementing the spring matrix reduces the sum of square power (SSP) exerted by the actuators by up to 47%, the peak power requirement by almost 40%, the sum of squared current by 55%, and the peak current by 55%. These results were generated using a planar robot limb and a gait trajectory borrowed from biology. We use a fully dynamic model of the robotic system including inertial effects. We also test the design robustness using a perturbation study, which shows that the parallel springs are effective even in the presence of trajectory perturbation.

scholarly journals The scaling or ontogeny of human gait kinetics and walk-run transition: The implications of work vs. peak power minimization

2018 ◽  
Vol 81 ◽  
pp. 12-21 ◽  
Author(s):  
J.R. Usherwood ◽  
T.Y. Hubel ◽  
B.J.H. Smith ◽  
Z.T. Self Davies ◽  
G. Sobota
Keyword(s):  
Peak Power ◽  
Human Gait ◽  
Power Minimization

Muscle Contributions to Balance Control During Amputee and Nonamputee Stair Ascent

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Nicole G. Harper ◽  
Jason M. Wilken ◽  
Richard R. Neptune
Keyword(s):  
Angular Momentum ◽  
Lower Limb ◽  
Sagittal Plane ◽  
Balance Control ◽  
Dynamic Balance ◽  
Frontal Plane ◽  
Rate Of Change ◽  
Prosthetic Devices ◽  
Stair Ascent

Abstract Dynamic balance is controlled by lower-limb muscles and is more difficult to maintain during stair ascent compared to level walking. As a result, individuals with lower-limb amputations often have difficulty ascending stairs and are more susceptible to falls. The purpose of this study was to identify the biomechanical mechanisms used by individuals with and without amputation to control dynamic balance during stair ascent. Three-dimensional muscle-actuated forward dynamics simulations of amputee and nonamputee stair ascent were developed and contributions of individual muscles, the passive prosthesis, and gravity to the time rate of change of angular momentum were determined. The prosthesis replicated the role of nonamputee plantarflexors in the sagittal plane by contributing to forward angular momentum. The prosthesis largely replicated the role of nonamputee plantarflexors in the transverse plane but resulted in a greater change of angular momentum. In the frontal plane, the prosthesis and nonamputee plantarflexors contributed oppositely during the first half of stance while during the second half of stance, the prosthesis contributed to a much smaller extent. This resulted in altered contributions from the intact leg plantarflexors, vastii and hamstrings, and the intact and residual leg hip abductors. Therefore, prosthetic devices with altered contributions to frontal-plane angular momentum could improve balance control during amputee stair ascent and minimize necessary muscle compensations. In addition, targeted training could improve the force production magnitude and timing of muscles that regulate angular momentum to improve balance control.

Towards Robustly Stable Musculo-Skeletal Simulation of Human Gait: Merging Lumped and Component-Based Modeling Approaches

2012 ◽  
Author(s):  
Justin Seipel
Keyword(s):  
Inverted Pendulum ◽  
Dynamic Models ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Human Model ◽  
Whole Body ◽  
Human Gait ◽  
Slip Model ◽  
Spring Loaded Inverted Pendulum ◽  
Low Dimensional

The objective of work presented in this paper is to increase the center-of-mass stability of human walking and running in musculo-skeletal simulation. The approach taken is to approximate the whole-body dynamics of the low-dimensional Spring-Loaded Inverted Pendulum (SLIP) model of locomotion in the OpenSim environment using existing OpenSim tools. To more directly relate low-dimensional dynamic models to human simulation, an existing OpenSim human model is first modified to more closely represent bilateral above-knee amputee locomotion with passive prostheses. To increase stability further beyond the energy-conserving SLIP model, an OpenSim model based upon the Clock-Torqued Spring-Loaded-Inverted-Pendulum (CT-SLIP) model of locomotion is also created. The result of this work is that a multi-body musculo-skeletal simulation in Open-Sim can approximate the whole-body sagittal-plane dynamics of the passive SLIP model. By adding a plugin controller to the OpenSim environment, the Clock-Torqued-SLIP dynamics can be approximated in OpenSim. To change between walking and running, only one parameter representing the preferred period of a stride is changed. The result is a robustly stable simulation of the center-of-mass locomotion for both walking and running that could serve as a first step toward increasingly anatomically accurate and robustly stable musculo-skeletal simulations.

scholarly journals A Geothermal-Solar Hybrid Power Plant with Thermal Energy Storage

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1018 ◽  
Author(s):  
Brady Bokelman ◽  
Efstathios E. Michaelides ◽  
Dimitrios N. Michaelides
Keyword(s):  
Power Plant ◽  
Peak Power ◽  
Solar Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Solar Power Plant ◽  
Electricity Grid ◽  
Early Evening ◽  
Binary Geothermal Power Plant ◽  
Continuous Power

The concept of a geothermal-solar power plant is proposed that provides dispatchable power to the local electricity grid. The power plant generates significantly more power in the late afternoon and early evening hours of the summer, when air-conditioning use is high and peak power is demanded. The unit operates in two modes: a) as a binary geothermal power plant utilizing a subcritical Organic Rankine Cycle; and b) as a hybrid geothermal-solar power plant utilizing a supercritical cycle with solar-supplied superheat. Thermal storage allows for continuous power generation in the early evening hours. The switch to the second mode and the addition of solar energy into the cycle increases the electric power generated by a large factor—2 to 9 times—during peak power demand at a higher efficiency (16.8%). The constant supply of geothermal brine and heat storage in molten salts enables this power plant to produce dispatchable power in its two modes of operation with an exergetic efficiency higher than 30%.

Gait of a Biped Robot Implemented on a FPGA

2014 ◽  
Vol 1016 ◽  
pp. 705-709
Author(s):  
Crhistian C.G. Segura ◽  
Jairo Cortes
Keyword(s):  
Sagittal Plane ◽  
Mechanical Design ◽  
Biped Robot ◽  
Lower Limbs ◽  
Fast Reaction ◽  
Human Movements ◽  
Multiple Processes ◽  
Multiple Paths ◽  
Reaction Speed

A biped robot based its mobility imitating human movements; this development is focused on the movement of the lower limbs. The mobility of the robot is made by servomotors; because they work in a very similar way as the joints of the human’s lower limbs but with some restrictions. The logic of this system was coded on VHDL language to be implemented in a FPGA. The reason for using this hardware; is because it had fast reaction speed, its implementation is friendly and versatile also is able to handle multiple processes in parallel. This paper describes the servo characteristics and how it was used to through an FPGA make possible move a robot who imitates the human movements in the sagittal plane, also show the mechanical design. Shows that the FPGA is better suited in this case than a micro controller to follow multiple paths at the same time.

Effect of prosthetic ankle units on the gait of persons with bilateral trans-femoral amputations

2008 ◽  
Vol 32 (1) ◽  
pp. 111-126 ◽  
Author(s):  
Lexyne L. McNealy ◽  
Steven A. Gard
Keyword(s):  
Power Generation ◽  
Range Of Motion ◽  
Ankle Joint ◽  
Lower Limb ◽  
Stance Phase ◽  
Sagittal Plane ◽  
The Body ◽  
Control Group ◽  
Initial Contact ◽  
Ankle Motion

In able-bodied individuals, the ankle joint functions to provide shock absorption, aid in foot clearance during the swing phase, and provides a rocker mechanism during stance phase to facilitate forward progression of the body. Prosthetic ankles currently used by persons with lower limb amputations provide considerably less function than their anatomical counterparts. However, increased ankle motion in the sagittal plane may improve the gait of persons with lower limb amputations while providing a more versatile prosthesis. The primary aim of this study was to examine and quantify temporal-spatial, kinematic, and kinetic changes in the gait of four male subjects with bilateral trans-femoral amputations who walked with and without prosthetic ankle units. Two prosthesis configurations were examined: (i) Baseline with only two Seattle LightFoot2 prosthetic feet, and (ii) with the addition of Endolite Multiflex Ankle units. Data from the gait analyses were compared between prosthetic configurations and with a control group of able-bodied subjects. The amputee subjects' freely-selected walking speeds, 0.74 ± 0.19 m/s for the Baseline condition and 0.81 ± 0.15 m/s with the ankle units, were much less than that of the control subjects (1.35 ± 0.10 m/s). The amputee subjects demonstrated no difference in walking speed, step length, cadence, or ankle, knee, and hip joint moments and powers between the two prosthesis configurations. Sagittal plane ankle range of motion, however, increased by 3–8° with the addition of the prosthetic ankle units. Compared to the control group, following initial contact the amputee subjects passively increased the rate of energy storage or dissipation at the prosthetic ankle joint, actively increased the power generation at the hip, and increased the extension moment at the hip while wearing the prosthetic ankle configuration. The amputee subjects increased the power generation at their hips, possibly as compensation for the reduced rate of energy return at their prosthetic ankles. Results from subject questionnaires administered following the gait analyses revealed that the prosthetic ankle units provided more comfort during gait and did not increase the perceived effort to walk. The subjects also indicated that they preferred walking with the prosthetic ankle units compared to the Baseline configuration. The results of the study showed that the prosthetic ankle units improved sagittal plane ankle range of motion and increased the comfort and functionality of the amputee subjects’ prostheses by restoring a significant portion of the ankle rocker mechanism during stance phase. Therefore, prosthetic ankle mechanisms should be considered a worthwhile option when prostheses are prescribed for persons with trans-femoral amputations.

Estimation of Metabolical Costs for Human Locomotion

2005 ◽  
Author(s):  
Werner Schiehlen ◽  
Marko Ackermann
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Human Locomotion ◽  
Human Gait ◽  
Joint Torques ◽  
Gait Quality ◽  
Analysis Laboratory ◽  
Muscle Models

Metabolical energy is the chemical energy consumed by skeletal muscles to generate force. This quantity is useful to understand the comfort of human gait and to evaluate, in terms of effort required, the performance of devices or therapies designed to improve gait quality of persons presenting gait disorders. Firstly, this paper presents the frequently used estimations of energy expenditure based lonely on joint torques and mechanical costs obtained by inverse dynamics of passive and active walking devices. Secondly, a more advanced approach is discussed consisting of modeling the musculoskeletal system with Hill-type phenomenological muscle models and computing the metabolical expenditure adopting expressions recently proposed in the literature. As an example a musculoskeletal model of the lower limb in the sagittal plane consisting of thigh, shank and foot with three degrees of freedom and actuated by eight muscles is considered. This model is used to estimate metabolical costs for known normal gait kinematical data obtained in a gait analysis laboratory.

Thermo/Mechanical Design, Modeling, and Testing of Shape Memory Actuated Minimal and Micro Invasive Probe Systems

2002 ◽  
Author(s):  
David R. Wulfman ◽  
Arthur G. Erdman ◽  
Paul J. Strykowski
Keyword(s):  
Shape Memory ◽  
Solid Phase ◽  
Mechanical Design ◽  
Phase Changes ◽  
Segment Length ◽  
Great Promise ◽  
Small Scale ◽  
Neutral Position ◽  
Total System ◽  
Physical Scale

Small scale probes implementing shape memory alloy (SMA) actuation show great promise in applications requiring remote and minimally invasive access to small environments. Such environments include physiological spaces like those located in human and animal bodies as well as cavities within mechanical systems. Probes examined here are generally snake like in appearance composed of one or multiple independent segments, which in turn are made up of one or multiple SMA actuators performing work against an elastic spine. As the actuator(s) of a given segment are activated, the spine bends causing the probe to bend in the area of that segment. When the actuator(s) are deactivated, the force generated in the bending of the spine returns the segment to its neutral position. Activation and deactivation of actuators is accomplished by heating and cooling respectively, enacting the solid phase changes that are characteristic to the shape memory effect. The gage of control over probe shape depends on the number of independent segments that are available per unit length and the degree of control an operator has over each of the segments. The work presented here discusses the constraints imposed on the design of SMA actuated probes, and how those constraints become more critical and limiting with reduced physical scale and refinement of motion control. Numerical and finite element models have been developed showing the interrelationship between mechanical design, the thermal and phase states of the SMA actuator(s), and the mechanical performance of the total system. Performance concerns examined include probe shape control and the limits of shape change as a function of physical scale. Comparative data is presented between behavior predicted by the models developed and performance observed during the testing of prototypes. It is concluded that segment length, linked to refinement of probe control, is limited by its thermal boundary conditions.

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