FLORA is a semi-active ankle exoskeleton that modulates joint stiffness, rather than directly imposing motion and offers an important middle ground between passive and fully active designs. Compared with a passive ankle exoskeleton, it can adapt its mechanical behavior to different gait phases, walking speeds, terrains, or rehabilitation tasks. 

For example, it can provide higher stiffness during stance for support, energy storage, or stability, and lower stiffness during swing to avoid restricting natural ankle motion. This makes it more versatile than a passive device with fixed springs or dampers, while still preserving a relatively simple and lightweight architecture.

Compared with a fully active ankle exoskeleton, semi-active FLORA is generally safer, more energy-efficient, and less intrusive because it does not inject large amounts of mechanical power or force the user along a prescribed trajectory. Instead of driving the ankle, it shapes the joint impedance and lets the user’s own neuromuscular system generate the movement. This can improve comfort, transparency, and user acceptance, especially in rehabilitation or assistive walking, where over-assistance may reduce muscle engagement. It also reduces actuator power requirements, battery size, control complexity, risk of unintended motion and instability, while still enabling meaningful assistance through adaptive support and resistance for rehabilitation.

Potential users include post-stroke patients, people with incomplete spinal cord injury, individuals with cerebral palsy, people with multiple sclerosis, and patients recovering from ankle injury, orthopedic surgery, or prolonged immobilization. For these groups, a semi-active ankle exoskeleton could provide adjustable support without forcing the ankle through a predefined motion, which is useful when the user has remaining voluntary control but needs help with stability, push-off, foot clearance, or controlled resistance during rehabilitation.

It could also be useful for older adults, people with balance deficits or fall risk, and workers or soldiers who walk for long periods while carrying loads. In these cases, the device could increase ankle stability during stance, reduce fatigue, and adapt to different walking conditions without the complexity and power demands of a fully active exoskeleton. Another important user group is rehabilitation clinics and research labs, where adjustable ankle stiffness can be used to study gait mechanics, train motor control, or provide progressive assistance/resistance during therapy.