This thesis focuses on mechanical design and simulation studies of a quadruped robot motion control system, targeting at designing an autonomous legged robot. The designed quadruped robot with ``X"-configuration is developed for traversing rocky and sloped terrain with a static walking gait. The mechanical design of the quadruped robot is illustrated in Chapter 2, including the main body design, leg design and component selection. In the design process, appropriate mechanical structures are utilized to minimize the energy consumption. To improve energy efficiency, a set of principles is proposed. Corresponding implementations are also concretely introduced in this chapter. In addition, to simplify the mechanical structure of the quadruped robot, the mass is symmetrically distributed about the frontal and lateral planes. To improve the leg agility, the leg mass is minimized. On the one hand, the lightweight design is implemented by optimizing the mass distribution of the leg mechanism. On the other hand, the key components are assembled in the body part instead of the legs as many as possible. A sufficient leg length is also selected not only to allow the robot to step on or over obstacles, but also to avoid the leg getting caught by objects. Particularly, the leg structure is demonstrated, including the hip joint, thigh part, knee joint and limb part with a telescoping joint. When the robot sustains extensive payload, the deformed shape in joints may lead to structural failures, thereby influencing the quadrupedal locomotion. Finite element analysis (FEA) is performed when designing the structural components in reasonable structures. The design processes of the shoulder part and brass rod are demonstrated as examples. Based on the setup of loads and fixtures, the maximum deformed shape of these structural components are analyzed. From FEA simulation results, the yield strength is two orders of magnitude larger than the maximum of von Mises stress. Hence, these components are suitable to be incorporated in the quadruped robot. Based on the designed mechanical structure, simulation studies of the quadruped robot motion control system are analyzed in Chapter 3, including the modeling for a robotic leg and animated simulation. Since the quadrupedal locomotion is executed by manipulating the postures of four legs, the leg model is significant to the motion control system, thereby being analyzed mathematically. Two links kinematic conversion is implemented between the foot-end trajectory and joint angles. The dynamic model of the leg is also computed to discovery the relationship between the actuating torques and joint angles. To animate the quadrupedal locomotion, a CAD robot model is converted into MATLAB. Following the predefined footfall pattern, four legs move in sequence to execute the creeping gait. The segment of the desired trajectory of the foot-end fits a fifth order polynomial and does not include the set of singular configurations. Then, the PD control is utilized to adjust the leg posture to track the desired path. Furthermore, the actual joint angles are calculated in the MATLAB/SimMechanics quadruped robot by using Euler-Lagrange equations. Lastly, simulation results are presented to analyze the tracking performance in the joint angles and foot-ends. Finally, conclusions of the thesis are summarized, and future work is presented in Chapter 4. / Graduate / 2019-03-07

In the field of robotics, quadrupedal robotics is a rapidly growing segment. Despite the large number of robotic quadrupeds developed so far, there is currently no platform specifically developed for use in an educational setting. Currently available quadrupeds have several aspects that restrict them to use only in the research labs that developed them, preventing them from being available for use in undergraduate-level classes. This constraint limits the number of people able to gain experience with these highly complex platforms. To enable further development into the field of quadruped robotics, more engineers with in-depth experience with these platforms and the knowledge required to develop and operate them are needed. In this thesis we present the SmallKat platform which strives to fill this space and allow for further development into the fields of dynamic quadruped robotics without the fear of damaging an expensive robot. This thesis proposes a robot designed specifically for the purpose of teaching multiple robotics concepts including kinematics, control, dynamics, trajectory planning, and gait generation. Like many other quadrupedal robots, SmallKat uses 3-DoF legs allowing for coordinated motion in all 3 axes. The size, modularity, cost, and capabilities of the platform are what suit it to teach at a variety of levels. With the integrated sensing and safety features, this platform lends itself to the development of an undergraduate robotics course on quadruped robots, a sample of which is discussed in this thesis. Through the distribution of the SmallKat robot to more schools and universities, the robotics curriculum offered by these universities could be expanded further to offer courses at the undergraduate level in legged robotics.

With the rapid expansion of the range of digital characters involved in film and game production, creating a wide variety of expressive characters has become a problem that cannot be solved efficiently through current animation methods. Key-frame animation is time-consuming and requires animation expertise. Motion capture is constrained by equipment and environment requirements and is most applicable to humanoid characters. Simulation can produce physically correct motion but does not account for expressiveness. This thesis focuses on developing a more efficient animation system using a procedural approach in which the skeletal structure and characteristics of motion that communicate weight and age in quadrupeds have been isolated and engineered as user-controlled tools and modifiers to build creature shape and synthesize cyclic gait animation. This new approach accomplished the goal of quick generation of expressive characters. It is also successful in achieving real-time animation playback and adjustment.

In recent decades, mobile robotics have become one of the fastest growing research fields. Compared with wheeled and tracked robots, legged robots can step over obstacles and traverse unstructured terrains. This thesis focuses on two main tasks for supporting the development of a quadruped robot, i.e., the robot embedded system design and the joint motion control. To develop the robot embedded system fulfilling the technical requirements, a controller board using an ARM-based STM32 microcontroller is designed. First, we select the key components properly, according to the practical requirements and the marketing research. Then the onboard hardware architecture is proposed, and the circuit schematic diagrams for all the functional modules are designed. The specifications and a comparison of two versions of PCBs are also presented and analyzed. Based on the designed embedded system, the actuators and sensors are tested, and selected to set up the robot experimental platform. Moreover, the firmware is configured, and the software is developed to control the position and velocity of the motors. Furthermore, the moving average filter (MAF) based cascaded PID control algorithm is designed, and is implemented to manipulate the robot joints. The experimental results demonstrate the effectiveness of the proposed control method. / Graduate

It is nice to give animators artistic freedom, but having to animate every bounce, sway, and counter-balancing movement of a rider on a horse isn't freedom at all. It is painstaking labor that could easily be prevented with an effective character setup. If an animation piece is only going to have a few shots with a horse and rider, then the trouble of setting up an automated character rig is not practical, but if there are a significant amount of shots with a horse and rider galloping across the prairie, doing death defying stunts, and walking for an extended time into the sunset then there needs to be a way to automate the reactions of the rider to the horse. This thesis focuses on what parts of a horse one can analyze to know at what point a rider will lean forward, bounce up from the saddle, or in any way react to a variety of different horse movements. The automated character setup, or rig, makes animating a rider on a horse much more efficient.

It is nice to give animators artistic freedom, but having to animate every bounce, sway, and counter-balancing movement of a rider on a horse isn't freedom at all. It is painstaking labor that could easily be prevented with an effective character setup. If an animation piece is only going to have a few shots with a horse and rider, then the trouble of setting up an automated character rig is not practical, but if there are a significant amount of shots with a horse and rider galloping across the prairie, doing death defying stunts, and walking for an extended time into the sunset then there needs to be a way to automate the reactions of the rider to the horse. This thesis focuses on what parts of a horse one can analyze to know at what point a rider will lean forward, bounce up from the saddle, or in any way react to a variety of different horse movements. The automated character setup, or rig, makes animating a rider on a horse much more efficient.

abstract: As the robotic industry becomes increasingly present in some of the more extreme environments such as the battle field, disaster sites or extraplanetary exploration, it will be necessary to provide locomotive niche strategies that are optimal to each terrain. The hopping gait has been well studied in robotics and proven to be a potential method to fit some of these niche areas. There have been some difficulties in producing terrain following controllers that maintain robust, steady state, which are disturbance resistant. The following thesis will discuss a controller which has shown the ability to produce these desired properties. A phase angle oscillator controller is shown to work remarkably well, both in simulation and with a one degree of freedom robotic test stand. Work was also done with an experimental quadruped with less successful results, but which did show potential for stability. Additional work is suggested for the quadruped. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2015

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We are currently in a revolution in robotics where more tasks are being handled by machines than ever before. For this reason, the goal of this project was to build a four-legged robot with an implementation of dynamic stability. The developed robot is a dog style robot with reversed knee joints. The robot is controlled by an Arduino UNO microcontroller, that processes information from a gyroscope to drive it’s servo motors. It is capable of maintaining it’s balance while standing on a varying incline. The motion is based upon an inverse kinematic model of the leg geometry and assumes a planar ground surface. / I dagsläget ser vi en snabb expansion i användningen av robotar för att utföra alltmer avancerade uppgifter. På grund av detta var målet med detta projekt att utveckla en fyrbent robot med en enkel implementation av självbalansering. Den framtagna prototypen är en robot av hundstil med bakåtgående knän. Styrenheten är en Arduino UNO mikrokontroller. Med information från ett gyroskop styr denna roboten med hjälp av dess servomorer. Prototypen är kapabel att hålla balansen då den står på lutande underlag. Rörelsen är baserad på en kinematisk modell av bengeometrin och förutsätter en plan markyta.