The results of this test (Table.\ref{ForceExerted}) has shown that Finger Mechanism with V-shape cutting designs at the side of the origami/kirigami folding enables the servomotor to exert a much smaller force during the actuation of the prototype. Thus, the mechanism of Design 2 better fits the movement of the fingers in flexion/extension.
Full System Test
As shown in Fig. \ref{FullMechanicalSystemofHandExoskeletalSystem}, a full system test was finally conduct to see if the hand exoskeletal system is able to fufil its rehabilitation purpose. A circuit system that comprises of four TowerPro MG995 servomotors was been created and attached to the hand exoskeletal system as shown in figure. The circuit system was successful in actuating all four servomotors together. A hand support system was made and modifications on the finger mechanisms were been made so that the finger mechanisms can be tightly connected onto the hand support base using nuts and screws.
The first test was conducted to see if each servomotor is able to perform its actuation. For movement of flexion/extension, all the fingers are able to perform partial flexion according to the actuation of the fingers. However, for the movement of abuction/abduction, the servomotor was unable to perform due to the friction between the metal wire thread and the finger mechanism itself.
In addition, the elasticity of the finger mechanism enables hand exoskeletal system to exert an equal and opposite force when a flexion was been initiated by the hand itself without the aid of the servomotor, therefore causing a reactionary extension.
Remarks and Discussion
The hand exoskeletal system has a better potential to be a rehabilitative device rather than using it as a robotic hand to grip stuff. Due to the results of partial flexion of fingers and the elasticity of the finger mechanisms, the hand exoskeletal system will have a difficulty in using as an automated gripping device. For the hand exoskeletal system to fully fulfill its requirement as a gripping device, a change in the material for the finger mechanism might be needed or the much hard actuating system is needed for the hand exoskeletal system.
Recommendations for Further Work
The mechanical system of each finger (excluding the thumb mechanism) can be further designed and improved to have two DOF to increase flexibility and maneuverability of the hand exoskeletal system.
Stress sensors can also be attached to the mechanical system to test each stress point on the finger for data collection and stress analysis, which can convert the hand exoskeletal system as a master/slave control system.
The elasticity of the finger mechanism may have potential for origami-inspired structure to be used in other application such as virtual reality in the future.