Trans-radial prosthesis is a wearable device that intends to help amputees under the elbow to replace the function of the missing anatomical segment that resembles an actual human hand. However, there are some challenging aspects faced mainly on the robot hand structural design itself. Improvements are needed as this is closely related to structure efficiency. This paper proposes a robot hand structure with improved features (four-bar linkage mechanism) to overcome the deficiency of using the cable-driven actuated mechanism that leads to less structure durability and inaccurate motion range. Our proposed robot hand structure also took into account the existing design problems such as bulky structure, unindividual actuated finger, incomplete fingers and a lack of finger joints compared to the actual finger in its design. This paper presents the improvements achieved by applying the proposed design such as the use of a four-bar linkage mechanism instead of using the cable-driven mechanism, the size of an average human hand, five-fingers with completed joints where each finger is moved by motor individually, joint protection using a mechanical stopper, detachable finger structure from the palm frame, a structure that has sufficient durability for everyday use and an easy to fabricate structure using 3D printing technology. The four-bar linkage mechanism is the use of the solid linkage that connects the actuator with the structure to allow the structure to move. The durability was investigated using static analysis simulation. The structural details and simulation results were validated through motion capture analysis and load test. The motion analyses towards the 3D printed robot structure show 70–98% similar motion range capability to the designed structure in the CAD software, and it can withstand up to 1.6 kg load in the simulation and the real test. The improved robot hand structure with optimum durability for prosthetic uses was successfully developed.

Number of people with traumatic injury related to hand amputation is rising up day by day and it causes them to experience a lot of problems, especially in performing their daily life activities. There are many prosthetic hands that have been developed to assist people to do the activities like a normal person. The feature of the hand robot structure is the main issues to be studied in order to construct a user-friendly and high performance device. There are various considerations must be taken in order to identify the best type of material of the hand robot structure such as material durability, size, weight and fabrication cost. The objective is to present the static analysis of exoskeleton robotic hand structure for the evaluation on the selected material used such as aluminum and acrylonitrile butadiene styrene (ABS). From this, the effect of the material to the strength of the structure is observed. The 3D drawing and the static analysis of the hand robot structural design are performed by using Autodesk Inventor Professional software. The static analysis is focused on the safety factor evaluation of the structure by referring the ratio between the strength of the finger structure and the force (load) with a direction exerted on the tip of it. Hence, the maximum load withstood by the structure with the respective material can be determined. The results have shown that the maximum force that can be withstood by aluminum hand robot structure is much higher than ABS hand robot structure. The findings have shown that aluminum finger structure is able to withstand less than 3KG of load for no damage on the structure. Thus, the strength of robot structure is effected by the type of the material used and aluminum is more durable than ABS.

Developing an anthropomorphic robotic hand (ARH) has become a relevant research field due to the need to help the amputees live their life as normal people. However, the current state of research is unsatisfactory, especially in terms of structural design and the robot control method. This paper, which proposes a 3D printed ARH structure that follows the average size of an adult human hand, consists of five fingers with a tendon-driven actuator mechanism embedded in each finger structure. Besides that, the movement capability of the developed 3D printed robot hand validated by using motion capture analysis to ensure the similarity to the expected motion range in structural design is achieved. Its system functionality test was conducted in three stages: (1) muscular activity detection, (2) object detection for individual finger movement control, and (3) integration of both stages in one algorithm. Finally, an ARH was developed, which resembles human hand features, as well as a reliable system that can perform opened hand palm and some grasping postures for daily use.