Symbitron ‒ BioRob ‐ EPFL

Project Description

Symbitron: Symbiotic man-machine interactions in wearable exoskeletons to enhance mobility for paraplegics

2013-10-01 to 2018-03-31 (ongoing project)

The goal of Symbitron is to enable individuals with paraplegia to regain mobility with a novel lower-limb exoskeleton and a bio-inspired controller. BioRob’s role is to develop and test a neuromuscular controller that can produce various walking gaits with resemblance to human kinematics, kinetics, and muscle activations with few sensors and no pre-defined reference patterns.

Neuromuscular Controller

For real world function, wearable devices to assist gait should be highly responsive to both the user and the environment. Users should also be able to interact with the device in an intuitive manner. This positive shared control between machine and human is especially important for individuals with spinal cord injuries, where active recruitment of their own neuromuscular system could promote motor recovery. Here we demonstrate the capability of a biologically-inspired neuromuscular controller (NMC) and its use in assisting the gait of SCI test pilots.

The NMC was based on a sagittal plane neuromechanical simulation developed by Hartmut Geyer, which generates walking by activating simulated muscle reflex loops stimulated by few sensory imputs. Only the foot contact states and joint angles are needed to activate the simulated reflex loops of the Hill-type muscle models. The stance reflexes loop provides weight bearing support during the stance phase, and the swing reflexes allow the leg to flex and swing freely. The muscle forces generated from the virtual muscle dynamics combine to produce knee and hip torque commands to the gait trainer. The advantages of this controller over other approaches include robustness, modularity, and adaptability. In particular, the controller does not require filtering of its inputs (as with myoelectric control), can be decomposed into relevant modules (e.g. only knee or hip control), and can generate walking at different speeds and on different terrains in simulation.

For implementation on hardware, we developed a NMC Simulink library with control modules that allowed for tailoring to specific exoskeleton devices. So far we have tested the NMC on three different devices. The ankle module was tested on powered ankle exoskeleton Achilles, and the knee and hip modules were tested with gait trainer LOPES (both devices are from UTwente). We are currently testing the ankle and knee module on our new wearable exoskeleton. To provide subject-specific control for the SCI subjects, the NMC modules were designed to provide asymmetric control between the right and left legs, between extension and flexion, and among different muscles.

Tests with Human Subjects

We evaluated our controller with both healthy and paraplegic subjects. The modular nature of our controller enables us to test it on several different types of lower limb assistive devices. We evaluated subjects’ walking kinematics and kinetics, muscle activation levels, and metabolic power when possible.

Ankle Control

We tested the ankle module of the neuromuscular controller with a powered ankle exoskeleton (UTwente’s Achilles) on healthy subjects and paraplegic test plots with some mobility. For the healthy subjects, we evaluated the mechanics and energetics of walking with such a device and controller. This controller was designed to mimic human reflex patterns during locomotion, which we hypothesized would lead to lower energetic costs compared to walking with the added mass of the device only. Preliminary tests found that healthy-like gait patterns remained intact, and metabolic costs were reduced compared to the transparent mode of the device. Muscle activity of the tibialis anterior and soleus were also reduced with the assistive push-off. Please see Dzeladini et al. 2016 under Publications for more information.

Knee and Hip Control

We evaluated the neuromuscular controller on a lower-limb knee and hip robotic gait trainer (UTwente’s LOPES) with seven pilots with paraplegia (four complete, two incomplete) and one healthy subject. We determined that the NMC could enable normal-like walking gait kinematics at various walking speeds. We found that SCI pilots could walk at a range of normal walking speeds– from 0.6 m/s to 1.4 m/s. Despite a few differences between NMC-produced torques and healthy biological torques, the SCI joint kinematics were similar to healthy kinematics. With few sensors and no predefined gait patterns for multiple speeds or different subjects, the NMC could produce various walking patterns based on subject interaction with the environment. Please see Wu et al. 2017 under publications for more information.

WE1: Ankle and Knee Control

Our consortium partners at Delft and UTwente have developed a new ankle and knee wearable exoskeleton. Tests of the NMC with this device on paraplegic pilots are currently ongoing at the Fondazione Santa Lucia, another one of our consortium partners. Since this exoskeleton only actuates the ankle and knee, these pilots already have some volitional control of their hip joint.

WE2: Lower Limb Control (ankle, knee, hip)

Tests of the full lower limb exoskeleton and neurmuscular controller will be conducted in early 2018. These tests will involve paraplegic pilots who do not have volitional control of their hip joints.

Media

S08_LNMC_Symbitron_Video.mp4

Symbitron_WE1_promo_video.mp4Promotion video for WE1 (knee and ankle actuation) in zero impedance mode

Student Projects

Related student projects:

S. Berger. Energy consumption optimization and stumbling corrective response for bipedal walking gait.

F. Dzeladini. Implementation of a human feedback-based locomotion and its control by means of a feedforward component inspired by central pattern generators

A. di Russo. Biomechanical analysis of slow walking and stepping behavior in healthy subjects on treadmill

Researchers

<!– CORRECTED LINKS: BEGIN (textBox id=”455715″. lang=en. title=People being involved in these projects): –><!– CORRECTED LINKS: END (textBox id=”455715″. lang=en. title=People being involved in these projects). –>

Auke J. Ijspeert, Florin Dzeladini, Amy R. Wu

Publications

Learning-based techniques for lensless reconstruction

Y. Perron

2023-09-08.

Project Description

Neuromuscular Controller

Tests with Human Subjects

Ankle Control

Knee and Hip Control

WE1: Ankle and Knee Control

WE2: Lower Limb Control (ankle, knee, hip)

Media

Student Projects

Researchers

Publications

Learning-based techniques for lensless reconstruction

Traces of responsibility: Digital analysis of safety discourses and the language of a million patents

Refineries in plains and valleys. Debating the environmental problems of oil infrastructure in Switzerland (1958-1966)

Un avenir inévitable ? Les débats autour de la première raffinerie de pétrole en Suisse

“Moral pressure” or “self-interested balancing of costs and benefits”? International and domestic forces shaping the first Swiss patent system (1873-1908)

Recartographier l’espace napoléonien : Une lecture computationnelle du cadastre historique de Lausanne

Prediction of mycotoxin response of DNA-wrapped nanotube sensor with machine learning

How (not) to talk about climate change

La Suisse doit reprendre l’initiative en Europe avec une politique énergétique proactive

Can solar micro-grids deliver basic electricity access in Indian villages?

Off-grid solar power and the future of rural electrification in India

Off-grid power not a silver bullet for rural India

How India’s impressive electrification compares with South Asian nations

Six Nuclear Reactors Worth of Off-Grid Renewable Energy Deployed in Last 10 Years – But Sub-Saharan Africa Lagging

Middle-Income Countries Big Winner from Off-Grid Energy. Who’s Next?

Le mieux est l’ennemi du bien: les bienfaits de la loi sur le CO2 compensent ses carences

Enable a just transition for American fossil fuel workers through federal action

Access to Clean Cooking Energy and Electricity : Survey of States

Small off-Grid solar systems displace kerosene, but evidence for social and economic impact remain weak

Global Progress in Electrification

How to Target Residential Electricity Subsidies in India: Step 2. Evaluating policy options in the State of Jharkhand

How to Target LPG Subsidies in India: Step 2. Evaluating policy options in Jharkhand

Jharkhand Rural Energy Access: Enduring Challenges in Quality, Affordability, and Billing

Targeting Agricultural Electricity Subsidies in Haryana

Photochemical [2+2] Cycloaddition of Alkynyl Boronates

Twisting in the Wind: The Politics of Tepid Transitions to Renewable Energy

Political Economies of Energy Transition: Wind and Solar Power in Brazil and South Africa

The Politics of Sustainability: Energy Efficiency, Carbon Pricing, and the Circular Economy

Renewable Energy, Energy Poverty, and Climate Change

International Relations Theories and Climate Change Politics

Domestic Politics of Trade Policy

Does Central Bank Independence Increase Inequality?

Power Shifts, Emigration, and Population Sorting

Renewables: the politics of a global energy transition

Escaping the energy poverty trap: when and how governments power the lives of the poor

Debating clean energy: Frames, counter frames, and audiences

Understanding environmental policy preferences: New evidence from Brazil

Political Competition, Path Dependence, and the Strategy of Sustainable Energy Transitions

Perceptions of scientific dissent undermine public support for environmental policy

Who blames corruption for the poor enforcement of environmental laws? Survey evidence from Brazil

The Global Spread of Environmental Ministries: Domestic-International Interactions

Information and energy policy preferences: a survey experiment on public opinion about electricity pricing reform in rural India

Quantifying slum electrification in India and explaining local variation

The political economy of energy access: Survey evidence from India on state intervention and public opinion

Factors affecting household satisfaction with electricity supply in rural India

Re-exploring the Trade and Environment Nexus Through the Diffusion of Pollution

Does basic energy access generate socioeconomic benefits? A field experiment with off-grid solar power in India

Economics of household technology adoption in developing countries: Evidence from solar technology adoption in rural India

Geography, community, household: Adoption of distributed solar power across India

Social acceptance of new energy technology in developing countries: A framing experiment in rural India

A global analysis of progress in household electrification

How robust is the renewable energy industry to political shocks? Evidence from the 2016 U.S. elections

Moral Hazard and Financial Crises: Evidence from American Troop Deployments

Trials and tribulations: Lost energy access gains in rural India

Evidence of gender inequality in energy use from a mixed-methods study in India

The European Union Emissions Trading System reduced CO 2 emissions despite low prices

Prisoners of the Wrong Dilemma: Why Distributive Conflict, Not Collective Action, Characterizes the Politics of Climate Change

The Side Effects of Central Bank Independence

Inequality in policy implementation: caste and electrification in rural India

Electrification and productive use among micro- and small-enterprises in rural North India

The great equalizer: Inequality in tribal energy access and policies to address it

The hedonic treadmill: Electricity access in India has increased, but so have expectations

The evolving role of solar-based lighting solutions in rural India: Global lessons for distributed renewables

The off-grid catch-22: Effective institutions as a prerequisite for the global deployment of distributed renewable power

Do high electricity bills undermine public support for renewables? Evidence from the European Union

Supply preferences and productive electricity use constraints among micro and small enterprises in Bihar, India

Inflation concerns and mass preferences over exchange‐rate policy

Folding mechanisms of periplasmic proteins

Jobs for a just transition: Evidence on coal job preferences from India