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Ball swaging is a general method in head stack assembly process to permanently attach Head Gimbal Assemblies (HGA) on the actuator arm. In this process, the swage ball is guided by a pin through the inner base plate’s hole in order to deform the base plate to tightly attach to the actuator arm. However, the loosing problem can still be found quite often in the current swaging process. This research focuses on ball sizes and the number of balls used which currently no theoretical guidance in choosing the both parameters. Besides, the best combination of the both parameters can give the best swaging performance. The three-dimensional finite element model is created and analyzed to estimate the swaging performance according to the variation of both parameters by using the tightening torque and the fixing distance of base plate to determine the quality of the ball swaging process. The results from finite element method are treated as the sampling points which are used to create the interpolation in order to increase the considered cases to cover all happening cases from both parameters. After that, a searching algorithm is implemented to determine the most suitable ball size and the number of ball used for the process. By using the finite element analysis together with the interpolation and a searching algorithm, the optimal design parameters for a complex problem with multiple conditions of consideration can be easily found.

Most anthropomorphic robotic hands use a lot of actuators to imitate the number of joints and the movement of the human hand. As a result, the forearm of the robot hand has a large size for the installation of all actuators. This robot hand is designed to reduce the number of actuators, but also retain the number of movable joints like a human hand by using the fourbar linkage mechanism and only flexion-extension movements. This stamen is added in the problem statement according to the reviewer's comment. The special features of this robotic hand are the ability to adjust the link length and the range of rotation for each joint to suit various applications and can fabricate with 3D printing and standard parts with costing about $750. All hardware CAD files and equations are published on the GitHub website, which benefits for researchers to utilize as an open-source approach that their project might be further expanded in the future. The anthropomorphic robotic hand has five fingers, 16 joints, and 12 active Degrees of Freedom (DOFs) with 12 servo motors applied to finger motion and one for wrist motion. The structure of the hand is designed using the average of Asian human hands in combination with the golden ratio. All servo motors are installed in the forearm designed in a ventilated structure with 12V vent exhaust fan motor to stabilize the operating temperature of the robotic hand. Size and weight of the hand included with the forearm are 20×54×16.5 centimeters and 2.2 kilograms respectively. The hand has achieved human-like movement by using a four-bar linkage mechanism and tendon with PTFE tube to guide operation path of the tendon with the lowest friction force. This paper presents the design processes, the experimental set-up, and the evaluation of the finger movements. From the experiment of grasping objects, this hand was able to grasp 10 basic grasp types including 32 different objects, perform 9 common gestures, and lift the object to 450 grams. From this paper, the kinematic equation is proved that the designed finger structure can move exactly as the equation with maximum error of repeatability test around 1.6 degrees.

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