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Development and Control of a Humanoid Robot with Articulated SpineAuthor: Divyanshu Goel Date: 2019-03-05 Report no: IIIT/TH/2019/10 Advisor:Suril Shah,Madhava Krishna AbstractThe problem of developing a good humanoid platform that can operate in diverse environments is very demanding as it not only requires a considerable amount of time in hardware development but also takes into account significant effort in software development. It requires to go through various iterations to zero down on the design and remove any other potential issues associated with the hardware. In this thesis, we focus on design and development of one such humanoid platform which is modular, open source, stable, cost-effective and easy to build using modern techniques like rapid prototyping. The first and foremost reason for the development of such a platform is that it can be very useful in verification of the various algorithms, which are critical for the operation of humanoid. Secondly, in a long run, it may help in understanding the complexities of human motion in various environments and then replicate it efficiently on the robot. Such an evolution may help us to revolutionize Human-Robot Interaction (HRI). Such a humanoid robot can evolve and learn, allowing for safer interaction without any harm to either robot or the user. But there are inherent problems associated with this notion of development of software and hardware for humanoids. For humans, walking and balancing seem like a trivial task which comes naturally to us, but such is not the case for the robots. They have to be programmed and equipped with sufficient feedback to leverage their body structure and then stand in a stable posture accordingly with continuous control and feedback. A very prominent factor in achieving this stability is that humanoids have to be morphologically designed which assist in the manipulation tasks or gait to be performed by the robot. The robot should have sufficient motor torque and longevity to stand and should be able to take into account the dynamic forces acting on the body. Motors should be able to execute the given motion profiles concurrently so that the robot doesn’t fall due to conflict of joint motion. The electrical hardware has to be powerful enough to have good response time and reliability. Since there are a lot of variations in sizes of humanoids and difficulties associated with each type and sizes, It was decided to go for a miniature humanoid as it is relatively easier and cheaper to build and it still allows exploration of most important research problems. Building on Poppy project, INRIA,France, we develop a humanoid with a 5-Degree-of-Freedom (5-DoF) torso with some key changes. The benefit of such a torso is enormous as it allows for distribution of impact forces evenly on the body without destabilizing it. In contrast to Poppy robot, the ankle joint of the leg has 2-DoF joint in place of the 1-DoF joint. This enables the robot to adapt to different terrains more effectively. Humanoid was made using the rapid prototyping techniques, which reduces the hardware construction time and any reiteration occurring due to flaws. The major efforts have been made in building a humanoid platform with robust hardware and feedback modules. This is achieved by designing the structure of the robot, ensuring proper joint motion feedback, and enabling feedback from the environment through sensors in a reliable and robust manner. All these problems require painstaking effort to build and test for the whole system to work in a holistic manner. We have tried to keep the structure of the robot as close to a human morphology as possible and showed that it is stable when it stands and can perform necessary motor manipulations with large enough support polygon formed by the extremities of the foot. Incorporation of sensors like force sensing resistors, position sensors, IMU, etc. with an embedded hardware helped in coming up with a reliable platform. This was followed by the development of the algorithm for joint control by commanding the individual motors of the humanoid concurrently. The stability of humanoid is monitored by experimental calculation of Zero Moment Point (ZMP) which enables future usage of the hardware to test complicated motion planning algorithms. In order to work safely with the hardware, a MATLAB/Simulink based simulator is also developed which allows the first level of testing through simulations. This helps in understanding the implications of the developed algorithms before implementing on the real robot. With the simulation environment in place, It is easy to directly connect such an environment and the robot using a middle-ware like ROS to perform experimental validation. The platform is intended to be used for testing of various algorithms of humanoid motion in various Full thesis: pdf Centre for Robotics |
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