| Author: | Wu, Zeyu |
| Title: | Biologically inspired models and controls for hybrid soft-rigid robots |
| Degree: | M.Sc. |
| Year: | 2021 |
| Subject: | Robots -- Design and construction Robotics Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Mechanical Engineering |
| Pages: | xii, 97 pages : color illustrations |
| Language: | English |
| Abstract: | Humanoid robots are popular in the feld of research on robotics. In recent years, with the progress of materials, motors, batteries, sensors, etc., more and more humanoid robots have emerged. Among them, the Bionic Robotic Hand (BRH) is one of the most important components. The structure of the human hand is completely different from the mechanical structure of a traditional robotic arm. Therefore, the fabrication and control techniques of BRH becomes necessary and urgent. In this paper, we introduce and verify a kinematic model which is suitable for BRH. We also introduce a variety of bionic tissue fabrication methods and processes, these methods provide a basis for the rapid construction of a BRH experimental platform. In order to better describe the process of human fnger movement, we propose a new type of kinematics model based on elliptical joints. This model is closer to the real situation of human hand joint movement than traditional revolution joints. In the joint with 2 degrees of freedom, we further combine the two ellipse trajectories into a curved surface and obtain the curved surface equation. In addition, we also use Monte Carlo method to draw the work space of fingers with elliptical joints. Because of the particularity of the elliptical joint motion, in the process of solving inverse kinematics, we not only consider the rotation, but also the displacement of elliptical joints. In the method of solving inverse kinematics, we use two methods. The first method is a mixed of analytical and numerical methods. The equations of joint rotation angle and fingertip position are calculated by analytical method, and then equations are solved by numerical method. The second method is to first generate a Point Cloud Library (PCL) of the fingertips and record the corresponding joint angles to each fingertip position. When solving the inverse kinematics, search for the point in the PCL which is the closest to the target and output the corresponding joint angles. In this article, we also introduce the fabrication method and process of the bionic tendon, ligament, joint capsule, bone and muscle. For the Bionic Tendon (BT), we show the fabrication process of three types of BT: In the first method, we put the carbon fiber into the silicone with a curved shape, and the curved shape becomes straight when the BT is stretched, so that we obtain nonlinear strength BT. This means that as the BT is stretched, there will be a sudden change in its strength. The second method is to wrap the carbon fiber in vinyl tape. This kind of BT cannot be stretched, but it can be made very thin under the condition of meeting the strength requirements, so it can be well embedded in the finger. The third method is using crochet wire as BT, this kind of BT is fexible and easy to fabricate. It is also an ideal BT material. For the Bionic Ligament (BL), we introduced a method of design and fabrication of Bionic Ligament Unit (BLU). This method combines multiple BL of the joint into one BLU. Rivets are used to reinforce the strength of the junction between BLU and bionic bones, and BLU are fixed on the 3D printed bionic bones with screws. For the material of BL, we chose 3D printed TPU material. By changing the thickness of the material to make the BL as close as possible to the characteristics of the human hand ligament. For the Bionic Joint Capsule (BJC), we introduce two fabrication methods, one is rotational molding, another is injection molding. We choose Ecofex 00-10 and T10 silicon rubber as the material of BJC. After fnishing the fabrication of BJC, we connect it to the bones and inject lubricating fluid into it, and then seal it with waterproof glue. We also introduce two fabrication process of two types of bionic muscles. The first is an improved Pneumatic Artificial Muscles (PAMs), and the second is a silicone muscle based on a sarcomere-like bionic structure. We have also developed a pneumatic system to control the bionic muscle. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 5938.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 70.19 MB | Adobe PDF | View/Open |
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