Soft exoskeleton vs rigid exoskeleton at work

Two axes: structure and energy

These are separate axes. Soft versus rigid describes how the device is built. Passive versus active describes where the assistive force comes from. A device can be rigid and passive, soft and active, or any other combination. Treat them as one scale and you end up with statements like "soft means gentle and powered" or "rigid means passive", neither of which holds in general.

There is a practical reason to keep them apart. When you shortlist a device for a task, the structure axis tells you about fit, comfort, how load reaches the body and how much freedom of movement you keep. The energy axis tells you about weight, cost, setup and how the support behaves through the movement. You need an answer on both, and they interact: a choice on one side can limit your options on the other.

The rest of this article concentrates on structure, bringing in the energy axis where it changes the decision. For the wider picture of passive and active devices, the Exoskeleton Advisor is a good starting point for matching a device to an operation.

What soft and rigid structures mean in practice

A classical exoskeleton has a rigid frame. Hard links run alongside the limbs or torso, pass forces to the body at defined contact points, and give the device a stable reference. Soft exoskeletons and exosuits, by contrast, do away with all of the hard, rigid frames of that classical design. They rely on textile and flexible components worn close to the body.

The difference brings a consistent set of consequences. The same source adds that soft devices are compliant, lighter and potentially cheaper. Their main drawback is the flip side of their main strength: with no external rigid frame, there is nothing stiff to push against, so anchoring the force and transferring it to the body becomes the central engineering challenge.

For a buyer, that translates into a few things worth checking on the shop floor.

• Load path. Where does the support force end up? A rigid frame can route it to the hips or ground through a defined structure. A soft device routes it through straps and fabric, so contact areas and tensioning matter more.
• Freedom of movement. A soft device tends to follow the body more closely. A rigid frame can restrict some movements, depending on how well its joints line up with the wearer's own.
• Fit range. Rigid frames usually have adjustable lengths and sizes. Soft garments depend on sizing and strap adjustment. Either can fit badly, and poor fit is a common reason workers stop wearing a device.
• Donning and doffing. How fast a worker can put the device on and take it off affects whether it gets used between tasks.

It also helps to check what is actually on offer for your body region. Browse the devices on the exoskeletons page and compare how each one is built before you decide which structure to test.

Strength, comfort and where the evidence stands

The most defensible claim in the literature concerns force. A comparison of a soft exosuit and a rigid exoskeleton notes that rigid exoskeletons can deliver higher forces more quickly. If a task involves heavy loads or demands strong support in specific postures, that capability matters. A frame that anchors firmly can resist large torques that a fabric structure may struggle to hold in place.

Comfort points the other way, at least in principle. Soft, compliant structures are lighter and conform to the body, which is why they attract interest for tasks where the wearer moves through many postures during a shift. But "in principle" is doing real work there. Comfort depends on strap pressure, heat, fit and the specific movement, and a lightweight device that digs in at the shoulders is not comfortable simply because it is soft.

The head-to-head evidence is thin. Treat any comparison between the two structures as laboratory evidence on a specific task, not as field evidence from your own operation. A few cautions follow:

• Findings from one task, such as symmetric lifting, do not carry over automatically to asymmetric handling, overhead work or mixed shifts.
• A comparison that mixes structure and energy source in one test cannot say how much of a result comes from the structure and how much from the actuation.
• Lab muscle-activity results do not guarantee that workers feel less strained or want to keep wearing the device.

The energy axis has its own trade-offs. Passive devices are lighter and cheaper than active ones and are reliable and intuitive to use, but their permanent upward support torque means the user works against the system during downward movements. That is a property of the energy source, not the structure, and it can show up in rigid and soft designs alike. Keeping the axes separate stops you pinning an effect on "rigid" or "soft" that really belongs to "passive" or "active".

Matching structure to the task and the workforce

Because the evidence cannot settle the question for you, start from the task and work backwards. A few questions narrow the field quickly.

What body region and movement dominate the work? Overhead assembly, drilling or installation points to shoulder support. Repeated lifting and bent-forward postures point to back support. Your answer decides which devices, and so which structures, are even on the table.

How much force is needed, and when? If the task needs strong support held in awkward postures, the ability of rigid frames to deliver higher forces more quickly is a relevant advantage. If the demand is lighter and the main goal is cutting accumulated strain over a long shift, a lighter, more compliant structure may suit better, provided one exists for the body region in question.

Who will wear it? Body size range, how many people share a device, and whether workers wear long sleeves, protective clothing or tool belts all affect fit. A device that suits one worker well may suit another poorly, and adoption tends to fall apart on exactly this point. Worker comfort and buy-in often decide whether a technically sound device stays in use.

What is the environment? Heat, confined spaces, ladders and vehicles change how a bulky frame or a close-fitting garment behaves. A rigid frame that snags on equipment is a problem in one setting and irrelevant in another.

How often is the device put on and taken off? If workers switch between tasks that need support and tasks that do not, quick donning and doffing matters more than a marginal difference in assistance.

Be clear about the limits here. Published comparisons are mostly laboratory studies, and public price comparisons by structure type are scarce. So you cannot assume that a soft device is cheaper in your situation, or that a rigid one is more durable. Those are reasonable expectations from the design logic, not verified findings for the products you will evaluate.

For a structured way to weigh these factors against your own tasks, the Exoskeleton Advisor recommends back or shoulder devices based on the operation, and the free ergonomic analysis can show which postures and tasks carry the most strain before you pick a structure at all.

Regulation, trials and measuring what matters

On regulation, there is still no uniform EU regulation or certification specific to exoskeletons. An EU-OSHA discussion paper on exoskeletons and occupational safety and health describes this gap, and the Federation of the European Ergonomics Societies explains that classification depends on intended use. That paper dates from 2021, so check the current position with your compliance team before relying on it. In practice, structure type does not by itself put a device in one regulatory category. Ask each vendor how the device is classified for its intended use and what documentation supports it, and bring your own risk assessment into the picture.

The better response to uncertain evidence is to test. Published comparisons are lab-based and narrow, so the only reliable way to learn which structure suits your workforce is to try candidates on your own tasks with your own people. A trial in your workplace answers questions no brochure can: whether workers keep wearing the device, whether it interferes with other equipment, and whether the support helps in the postures that actually cause strain. The guide to trying exoskeletons before you buy explains why this matters, and how a Ryggo order works shows how a Deploy & Decide trial is structured, so you can compare a rigid and a soft candidate under the same conditions where both exist for your task.

To make a trial worth running, decide in advance what you will measure. A short list tends to work better than a long one:

• Worker-reported comfort and strain, collected from the same people before and during the trial, since lower muscle load in a lab does not always mean a lower perceived workload.
• Adoption in practice: how many wear the device, for how long, and whether they take it off when they should not need to.
• Fit and donning issues, logged as they arise, because these predict whether use continues.
• Task performance and any new discomfort, including strain in areas the device does not support.
• Operational fit, such as interference with tools, vehicles or protective equipment.

Set these against a baseline recorded before the trial starts, and agree up front what result would count as success. That discipline also protects you from the opposite risk, a pilot that never converts into a decision. If the trial is meant to feed a business case, the payback period guide covers how to turn trial results into an ROI estimate.

The soft exoskeleton vs rigid exoskeleton question rarely has a universal answer. It has an answer for a specific task, a specific group of workers and a specific site, and a structured trial is the most direct way to find it.