The successful rehabilitation of lower limb including hip, knee and ankle requires an intensive and task-specific therapy approach. Physicians are usually prone to prescribe treatments including intense, highly repetitive, and task-oriented movements. Over the last decade, several lower-limb rehabilitation robots have been developed to restore mobility of the affected limbs.
The lower limb joints are complex bony structures in the human skeleton and plays a significant role in maintaining body balance during ambulation. Traditionally lower limbs are rehabilitated via physiotherapy but evidence suggests that without sufficient rehabilitation: 44% of people will have future problems; ambulation is markedly compromised; re-injury prevalence is high; and approximately 38% of people will have recurrent activity limitations affecting their function. Robotics technology can provide an overdue transformation of rehabilitation clinics from labor-intensive operations to technology-assisted operations as well as a rich stream of data that can facilitate patient diagnosis, customization of the therapy, and maintenance of patient records (at the clinic and at home).
The usage of robotic systems allows precise measurement of movement kinematics and dynamics, which should be used for assessing patient recovery ability and progress.
The Robots are controlled by the “Human-Machine Interface”. The robot manipulator (RM) can perform all active and passive exercises as well as learn specific exercise motions and perform them without the physiotherapist (PT) through the Human–Machine Interface. Furthermore, if a patient reacts against the robot manipulator during the exercise, the robot manipulator can change the position according to feedback data. Thus, the robot manipulator can serve as both therapeutic exercise equipment and as a physiotherapist in terms of motion capability. Experiments carried out on healthy subjects have demonstrated that the RM can perform the necessary exercise movements as well as imitate the manual exercises performed by the PT.
Many systems have been developed to enforce or restore these ankle and knee motions specifically. The Rutgers Ankle was the first of this kind. It is a Stewart platform-type haptic interface that supplies 6 DOF resistive forces on the patient’s foot, in response to virtual reality-based exercises. Many clinical trials have been conducted with this system, showing the improvement of the patient on clinical measures of strength and endurance. The system was extended to a dual Stewart platform configuration to be used for gait simulation and rehabilitation.
The Istituto Italiano di Tecnologia (IIT) has developed a High Performance Ankle Rehabilitation Robot. The proposed device allows plantar/dorsiflexion and inversion/eversion using an improved performance parallel mechanism that makes use of actuation redundancy to eliminate singularity and greatly enhance the workspace dexterity.
A more recent system, the Active Knee Rehabilitation Orthotic Devices (AKROD), provides variable damping at the knee joint, controlled in ways that can facilitate motor recovery in post stroke and other neurological disease patients and to accelerate recovery in knee injury patients. Although it has been grouped as a stationary system, future work is focused on an actuated AKROD during walking.
The Osaka University has developed a leg-shaped robot (Leg-Robot) with a compact magneto rheological fluid clutch to demonstrate several kinds of haptic control of abnormal movements of brain-injured patients. This system can be used in the practical training for students of physical therapy.
The Gwangju Institute of Science and Technology (GIST) has developed a reconfigurable ankle/foot rehabilitation robot to cover various rehabilitation exercise modes. The robot can allow desired ankle and foot motions, including toe and heel raising as well as traditional ankle rotations. The system was designed to perform strengthening and balance exercises.