TNO performs new study on “The complementarity of soft and rigid back exoskeletons”

14 June 2022 - Published by Amy McCready
EXSKALLERATE’s TNO researchers are currently testing the Auxivo soft exoskeleton and Laevo’s rigid Exoskeleton FLEX, with the aim to identify the strengths and weaknesses of rigid and soft back exoskeletons and how they can be translated into potential use cases.

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Context

Lower-back pain (LBP) is the leading cause of worker absenteeism after the common cold, accounting for 15% of sick leaves and hundreds of millions of lost workdays annually. An important risk factor for the onset of LBP is mechanical loading of the back, for instance, during manual material handling and lifting. Despite the understanding that exposure to occupational lifting must be reduced, heavy work is still prevalent in many industrial sectors.

A relatively new approach to supporting workers that are exposed to heavy work is the use of exoskeletons. Exoskeletons are wearable devices that provide mechanical support during various working postures and movements. They are usually classified into two categories: rigid exoskeletons and soft exoskeletons.

Rigid exoskeletons are - as the name suggests - made of rigid components, and mostly provide mechanical support through a spring unit. Soft exoskeletons are made from textile straps with elastic segments, which allow the user more freedom of movement. However, these softer materials greatly limit the amount of torque that the device can transmit to the user. This may make them more suitable for applications that require minimal assistance but demand a high degree of mobility. Rigid exoskeletons, on the other hand, can deliver higher torques more quickly and accurately, but hinder the user in their freedom of movement due to the higher resistance of the spring element when in motion.

While rigid and soft exoskeletons have complementary properties, they can’t necessarily substitute one another. Their strengths also come with weaknesses. That’s why the varying properties of these two types of exoskeletons can be exploited to cover a broad range of applications and needs.

Research aims

TNO’s study aims to quantify the complementarity of rigid and soft back exoskeletons. Our main research question is: What are the strengths and weaknesses of rigid and soft back exoskeletons and how can they be translated into potential use cases?

TNO formulated the following research aims:

  1. Determine the strength and weaknesses of rigid and soft back exoskeletons
  2. Propose application areas for soft and rigid back exoskeletons

Study design

During the study, participants are performing different daily tasks – either static or dynamic tasks - wearing the Auxivo soft exoskeleton and Laevo’s rigid Exoskeleton FLEX. The amount of support given by the two exoskeletons during the static tasks is assessed by measuring back muscle activity. Oxygen consumption is used as a measure of support during the dynamic tasks.

It is expected that muscle activity will reduce and oxygen consumption decrease when participants are supported by the exoskeleton, as the back muscles need to perform less.

Participants are also asked to rate their level of perceived support and hindrance by the exoskeleton during each task and will be asked to rate the comfort level of the two devices.

The first results of this study will be published in early July, so stay tuned!