Body levelling of a hexapod robot using the concept of sensor fusion

Contrary to their wheeled counterpart, multi-legged robots are capable of easily changing their body posture through reconfiguration of the legs (i.e. inclination or posture control). This capability is exploited in the paper at hand to level out a six-legged robot when placed on a plain slope with adjustable inclination. By extension such inclination control could then be used to let the legged robot mount plain slopes with its body horizontally which greatly benefits the way the robot absorbs the load posed on its mechanics. The implemented body levelling algorithm uses the hexapod's forward and inverse kinematic model, basic geometry, and the Cartesian plane equation to calculate the leg tip displacements able of counteracting the fused orientation data obtained from an inertial measurement unit (IMU). Experimental results show the approach to be successful, although the speed of the levelling process leaves room for improvement. To address the latter a more powerful processing unit and/or, more importantly, a simpler redesign of the legs is advised

Analytical Workspace, Kinematics, and Foot Force Based Stability of Hexapod Walking Robots

Many environments are inaccessible or hazardous for humans. Remaining debris after earthquake and fire, ship hulls, bridge installations, and oil rigs are some examples. For these environments, major effort is being placed into replacing humans with robots for manipulation purposes such as search and rescue, inspection, repair, and maintenance. Mobility, manipulability, and stability are the basic needs for a robot to traverse, maneuver, and manipulate in such irregular and highly obstructed terrain. Hexapod walking robots are as a salient solution because of their extra degrees of mobility, compared to mobile wheeled robots. However, it is essential for any multi-legged walking robot to maintain its stability over the terrain or under external stimuli. For manipulation purposes, the robot must also have a sufficient workspace to satisfy the required manipulability. Therefore, analysis of both workspace and stability becomes very important. An accurate and concise inverse kinematic solution for multi-legged robots is developed and validated. The closed-form solution of lateral and spatial reachable workspace of axially symmetric hexapod walking robots are derived and validated through simulation which aid in the design and optimization of the robot parameters and workspace. To control the stability of the robot, a novel stability margin based on the normal contact forces of the robot is developed and then modified to account for the geometrical and physical attributes of the robot. The margin and its modified version are validated by comparison with a widely known stability criterion through simulated and physical experiments. A control scheme is developed to integrate the workspace and stability of multi-legged walking robots resulting in a bio-inspired reactive control strategy which is validated experimentally

DESIGN AND IMPLEMENTATION OF AN INTELLIGENT HEXAPOD

Robots are used to replace humans in some hazardous duty service like bomb disposal and capture information on places that cannot be reached. However, most of the robots used are wheeled robots. Walking machines have the potential to transverse rough terrain that is impossible for standard wheeled vehicles. The mobility of animals, including many insects is typically superior to current legged robots. However, the reality of current technology often encourages engineers to use different designs for the purposes of reducing the number of actuators or simplifying control problem. Thus, the main aim of this project is to design and implement a hexapod walking robot using servo drive mechanism and light weight material for easier control. The project includes constructing the hardware of the machine which is building the structure using appropriate material. The structure is built in the workshop by hand. All sawing and drilling is done using the equipment available in the workshop in Building 22, UTP. To have a stable and rigid structure, the machine is designed to be at its minimum size. This hexapod is designed to move using tripod gait controlled by 3 servo motors. The whole structure is controlled by microcontroller PIC16F877 programmed using C language. The hexapod is able to be controlled manually to move forward, reverse, turning left and right. The walking can be adjusted in 3 different speeds. This hexapod has the object avoidance intelligence using limit switches. The hexapod is able to reverse and find a new walking path if it encounters objects in front of it. With the wireless camera attached in front of the structure, it is able to be used for remote monitoring and rescue operations. The final design is cost effective, light, robust, has easy control and intelligently applicable

Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field

Design and control of amphibious robots with multiple degrees of freedom

This thesis presents the design and realization of two generations of robot elements that can be assembled together to construct amphibious mobile robots. These elements, designed to be individually waterproof and having their own battery, motor controller, and motor, have been used to actually construct a snake, a boxfish and a salamander robot. Central pattern generator (CPG) models inspired from those found in vertebrates have been used for online trajectory generation on these robots and implemented on their onboard locomotion controllers. CPGs proved to be an interesting way of controlling complex robots, providing a simple interface which hides the complexity of the robot to the end user. Online learning algorithms that can be used to dynamically adapt the locomotion parameters to the environment have been implemented. Finally, this work also shows how robotics can be a useful tool to verify biological hypotheses. For instance, the salamander robot has been used to test a model of CPG for salamander locomotion

Humanoid Robots

For many years, the human being has been trying, in all ways, to recreate the complex mechanisms that form the human body. Such task is extremely complicated and the results are not totally satisfactory. However, with increasing technological advances based on theoretical and experimental researches, man gets, in a way, to copy or to imitate some systems of the human body. These researches not only intended to create humanoid robots, great part of them constituting autonomous systems, but also, in some way, to offer a higher knowledge of the systems that form the human body, objectifying possible applications in the technology of rehabilitation of human beings, gathering in a whole studies related not only to Robotics, but also to Biomechanics, Biomimmetics, Cybernetics, among other areas. This book presents a series of researches inspired by this ideal, carried through by various researchers worldwide, looking for to analyze and to discuss diverse subjects related to humanoid robots. The presented contributions explore aspects about robotic hands, learning, language, vision and locomotion

ENABLING HARDWARE TECHNOLOGIES FOR AUTONOMY IN TINY ROBOTS: CONTROL, INTEGRATION, ACTUATION

The last two decades have seen many exciting examples of tiny robots from a few cm3 to less than one cm3. Although individually limited, a large group of these robots has the potential to work cooperatively and accomplish complex tasks. Two examples from nature that exhibit this type of cooperation are ant and bee colonies. They have the potential to assist in applications like search and rescue, military scouting, infrastructure and equipment monitoring, nano-manufacture, and possibly medicine. Most of these applications require the high level of autonomy that has been demonstrated by large robotic platforms, such as the iRobot and Honda ASIMO. However, when robot size shrinks down, current approaches to achieve the necessary functions are no longer valid. This work focused on challenges associated with the electronics and fabrication. We addressed three major technical hurdles inherent to current approaches: 1) difficulty of compact integration; 2) need for real-time and power-efficient computations; 3) unavailability of commercial tiny actuators and motion mechanisms. The aim of this work was to provide enabling hardware technologies to achieve autonomy in tiny robots. We proposed a decentralized application-specific integrated circuit (ASIC) where each component is responsible for its own operation and autonomy to the greatest extent possible. The ASIC consists of electronics modules for the fundamental functions required to fulfill the desired autonomy: actuation, control, power supply, and sensing. The actuators and mechanisms could potentially be post-fabricated on the ASIC directly. This design makes for a modular architecture. The following components were shown to work in physical implementations or simulations: 1) a tunable motion controller for ultralow frequency actuation; 2) a nonvolatile memory and programming circuit to achieve automatic and one-time programming; 3) a high-voltage circuit with the highest reported breakdown voltage in standard 0.5 μm CMOS; 4) thermal actuators fabricated using CMOS compatible process; 5) a low-power mixed-signal computational architecture for robotic dynamics simulator; 6) a frequency-boost technique to achieve low jitter in ring oscillators. These contributions will be generally enabling for other systems with strict size and power constraints such as wireless sensor nodes

2023- The Twenty-seventh Annual Symposium of Student Scholars

The full program book from the Twenty-seventh Annual Symposium of Student Scholars, held on April 18-21, 2023. Includes abstracts from the presentations and posters.https://digitalcommons.kennesaw.edu/sssprograms/1027/thumbnail.jp

Development of a Wall Climbing Robot and Ground Penetrating Radar System for NonDestructive Testing of Vertical Safety Critical Concrete Structures

This research aims to develop a unique adhesion mechanism for wall climbing robot to automate the technology of non-destructive testing (NDT) of large safety critical reinforced concrete structures such as nuclear power plants, bridge columns, dams etc. This research work investigates the effect of key design parameters involved in optimizing the adhesion force achieved from rare earth neodymium magnets. In order to penetrate a nominal concrete cover to achieve magnetic coupling with buried rebar and generate high enough adhesion force by using minimum number of permanent magnets, criteria such as distance between multiple magnets, thickness of flux concentrator are evaluated by implementing finite element analysis (FEA). The proposed adhesion module consists of three N42 grade neodymium magnets arranged in a unique arrangement on a flux concentrator called yoke. The preliminary FEA results suggest that, using two yoke modules with minimum distance between them generate 82 N higher adhesion force compared to a single module system with higher forceto-weight ratio of 4.36. Presence of multiple rebars in a dense mesh setting can assist the adhesion module to concentrate the magnetic flux along separate rebars. This extended concentration area has led to higher adhesion force of 135.73 N as well as enabling the robot to take turns. Results suggest that, having a 50×50 mm rebar meshing can sustain steep robot rotational movement along it’s centre of gravity where the adhesion force can fall as low as 150 N. A small, mobile prototype robot with on-board force sensor is built that exhibited 3600 of manoeuvrability on a 50×50 mm meshed rebars test rig with maximum adhesion force of 108 N at 35 mm air gap. Both experiment and simulationresults prove that the magnetic adhesion mechanism can generate efficient adhesion force for the climbing robot to operate on vertical reinforced concrete structures. In terms of the NDT sensor, an in-depth analysis of the ground penetrating radar (GPR) is carried out to develop a low cost operational laboratory prototype. A one-dimensional numerical framework based on finite difference time domain (FDTD) method is developed to model response behaviour of a GPR. The effects of electrical properties such as dielectric constant, conductivity of the media are evaluated. A Gaussian shaped pulse is used as source which propagates through the 1D array grid, and the pulse interactions at different media interfaces are investigated. A real life application of GPR to detect a buried steel bar in 1 m thick concrete block is modelled, and the results present 100% accurate detection of the steel bar along with measured depth of the concrete cover. The developed framework could be implemented to model multi-layer dielectric blocks with detection capability of various buried objects. Experimental models are built by utilizing a proposed antenna miniaturization technique of dipole antenna with additional radiating arms. The resultant reflection coefficient values indicate a reduction of 55% and 44% in length reduction compared to a conventional 100 MHz and 200 MHz dipole antenna respectively. The GPR transmitting pulse generator features an enhanced tuneable feature to make the GPR system more adaptable to various environmental conditions. The prototype pulse generator circuit can produce pulses with variable width from 750 ps to 10 ns. The final assembled robotic GPR system’s performance is validated by its capability of detecting and localizing an aluminium sheet and a rebar of 12 mm diameter buried under a test rig built of wood to mimic the concrete structure environment. The final calculations reveal a depth error of +0.1 m. However, the key focus of this work is to prove the design concept and the error in measurement can be addressed by utilizing narrower bandwidth pulse that the proposed pulse generator is capable of generating. In general, the proposed robotic GPR system developed in this research proves the concept of feasibility of undertaking inspection procedure on large concrete structures in hazardous environments that may not be accessible to human inspector