Design and prototype manufacture of a wearable lower extremity exoskeleton

Wearable technology is such a topic which can be traced back to 1980 and has been attraction ever-increasing attention for 40 years from the robotic community. As the name implies, these devices can be worn and manipulated by humans and can also control the movements of the wearer. This potential has made wide range of areas such as military and rehabiliatation in which human body involves strive for being utilizing the wearable technology. In this thesis, a werable exoskeleton was developed to help people who partly or completely lost their walking ability or to support people who are in need of a rehabilitation treatment. This device which is powered by pneumatic artificial muscles provides the wearer with a walking motion which in fact is a function of lower limbs such as hip, legs and foot, thus makes the person walk again. First, mechanical design of the device was performed. A person of 187 cms and 80 kgs was used as a model and body proportions were determined accordingly. After the mechanical design was achieved, a walking cycle that satisfies several criterias was schemed and inverse kinematics operation was performed to obtain the required joint angles which form this cycle. However, these angles can't be applied directly because the current device uses pneumatic artificial muscles instead of electric motors. This situation leaded to necessity of obtaining a mathematical relationship between the muscle length and the joint angle which makes it possible to use joint angles as the inputs. Next part of the study is the assessment of the design by means of strength and balance. A finite element analysis was conducted to examine the structures load bearing capability for each critical point of the walking cycle. As a result, it is observed that the maximum gerilmes is lower than the materials yield strength and the structure is in balance during the cycle. Lastly, a prototype of the structed was manufactured via a 3D printer by 25% scaling. As an actuator, a pneumatic artificial muscle which utilizes latex as bladder material and swells/shortens with pressurized air were manufactured. Mini human model was printed and the device was mounted. Whole system was connected to an artificial muscle test unit and the behaviour was observed. As a result, muscles produced succeeded in pulling two limbs together as predicted and it's observed that the mechanism is able to pass the gait cycle points with bending issues.