Abstract The number of patients with knee impairments caused by a stroke, spinal cord injury, post-polio, injury, osteoarthritis, or other related diseases is increasing worldwide. Robotic devices such as knee exoskeletons have been studied and adopted in gait rehabilitation, as they can provide effective gait training for the patients and release the physical therapists from the intensive labor required by the traditional physical therapy. In addition, knee exoskeletons can augment human performance in normal walking, loaded walking, and even running by enhancing the strength of the wearers’ knee joints. A systematic review of knee exoskeletons is presented in this paper. The biomechanics of the human knee joint is firstly presented. Then, the design concepts of knee exoskeletons, including the actuators and sensors, are provided, followed by the introduction of the corresponding control strategies. Finally, the limitations of the available devices and the research and development directions in the field of knee exoskeletons are discussed, thus providing useful information to the researchers developing knee exoskeletons that are suitable for practical applications. Introduction Human knee joints play a crucial role in performing daily life activities, such as standing and walking. However, there are many patients worldwide with knee impairments such as muscle weakness, pain, paralysis, and gait disorders, which can be caused by a stroke, spinal cord injury, post-polio, injury, osteoarthritis, and other diseases [1], [2]. These patients are not able to perform daily life activities as normal people, so this significantly affects their quality of life. Therefore, devices that can help individuals with knee dysfunctions to regain the ability to walk with a natural gait are desirable, and they are designed to improve the physical and mental health of these patients. The traditional knee-ankle-foot orthoses (KAFOs) have been adopted to treat patients with knee impairments. In general, they comprise a rigid thermoplastic cast formed around the impaired leg and lock the wearer's knee joint throughout a gait cycle. The wearer has to perform unnatural movements such as hip elevation for compensation, which increases the wearer's metabolic cost. In addition, physically demanding tasks are generally needed in traditional physical therapies. Owing to the intensive labor required for physical therapists, the training sessions for the patients normally have limited duration, frequency, and availability. The stance-control KAFOs have been developed for patients with muscle paralysis at the knee joint [3], [4]. They lock the wearer's knee joint during the stance phase of a gait cycle and allow free rotation during the swing phase. Compared with the traditional KAFOs, the stance-control KAFOs could bring many medical benefits to their wearers, such as increased gait symmetry, step-length, walking speed, and reduced energy consumption [5], [6].

1. Presented by:-
Raj Shekhada
Trushal Shekhada
Satyajeet Sakariya
Gautam Joshi
Stuti Joshi
Diti Kelaiya
Electronics and Communication Department

2. • Causes of knee pain are :-
Injury/Accident
Aging Problems
Disable/polio
• For the better improvement we are modifying Knee brace device to Smart
knee actuator.
Knee braces
motion capabilities,
passive, respond to the
movement changes

3. • Exoskeleton External skeleton
boost
endurance
and
strength
• It will help needy people to walk better than
before
• they allow complex movements due to jointed
appendages
• they provide protection against physical
damage and abrasion

4. Types of knee actuators
Using spring
Using screw
Using motor
All are active devices

5. • Mechanism design that reduces joint misalignment
• Human–Exoskeleton Interaction Mode
• Source's energy into mechanical motion
• Lightweight, compact, highly-backdrivable actuation system
• Assistive torque