Whether it involves a strain, torn ligament or broken bone – many injuries have to be stabilised so that they can heal. The old familiar plaster cast helps to do this, for example. It is part of the orthosis family, as are bandages and splints. These medical aids are used to restrain limbs, but also to mobilise or correct them, by supporting the required movements or not allowing damaging movements.
Stabilisation and mobilisation
Unlike prostheses, which replace a missing part of the body, orthoses support the function of a body part. They are used on different parts of the body such as the back, arm, leg, foot and hand. Besides supporting orthoses, there are also mobilising ones, for example when a movement has to be learned again after a operation or stroke. These so-called exoskeletons can be pulled on like suits.
Potential for the rehabilitation of stroke patients
The research into exoskeletons, which could help stroke patients during rehabilitation, is still in its infancy. In 2012, as part of the Bionic Learning Network Festo development the ExoHand, an active hand orthosis, as a future concept. It is put on like a glove. Eight pneumatic drives control the individual fingers on the orthosis. Patients with signs of paralysis can thus be helped to move their hands again independently. The ExoHand only exists as a prototype until now.
Force feedback for safe remote manipulation
The special feature of the ExoHand is the possibility of transferring forces to one's own hand in the form of force feedback from another environment as a physical feeling of shape. In this way, the human sense of touch can be used over great distances. The operator can feel shapes and resistances or force influences. If the ExoHand is used to remotely manipulate a robot's hand in an industrial environment, activities can be carried out in dangerous or unhealthy surroundings from a great distance. As a force-feedback system, the hand can significantly expand the human scope of action.
Other companies already put exoskeletons at our disposal for medical therapy. The ReWalk system produced by the Israeli company, ReWalk Robotics, is worn on the legs. This exoskeleton detects shifts in weight as the desire of the person wearing it to walk. Motors on the hip and knee then move the limbs. Training effects are achieved by using it on a regular basis.
HAL (Hybrid Assistive Limb), by the Japanese manufacturer, Cyberdyne, goes a step further. HAL is an active orthosis for the lower limbs. The exoskeleton can measure nerve impulses and thus detects the desire of the person wearing it to move. The brain is given feedback that the person wearing it is walking. It thus gradually learns to send out the signals needed to walk. This helps physically limited persons to learn to walk again on their own.
Application in industrial production
Apart from in medical therapy, active orthoses or exoskeletons offer other applications, for example as a power booster during assembly work in production. They act here as a strength support device to prevent signs of fatigue that occur especially when performing repetitive actions. They thus help employees to remain in the work process for longer without long-term physical damage. One example is the “Chairless Chair” by the Swiss company, noonee. This ergonomic “strap on chair” is worn on the back of the body and takes the strain off the legs during physically demanding assembly work, for example in the automotive industry.