Remote-controlled ambidextrous robot hand actuated by pneumatic muscles: from feasibility study to design and control algorithms

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThis thesis relates to the development of the Ambidextrous Robot Hand engineered in Brunel University. Assigned to a robotic hand, the ambidextrous feature means that two different behaviours are accessible from a single robot hand, because of its fingers architecture which permits them to bend in both ways. On one hand, the robotic device can therefore behave as a right hand whereas, on another hand, it can behave as a left hand. The main contribution of this project is its ambidextrous feature, totally unique in robotics area. Moreover, the Ambidextrous Robot Hand is actuated by pneumatic artificial muscles (PAMs), which are not commonly used to drive robot hands. The type of the actuators consequently adds more originality to the project. The primary challenge is to reach an ambidextrous behaviour using PAMs designed to actuate non-ambidextrous robot hands. Thus, a feasibility study is carried out for this purpose. Investigating a number of mechanical possibilities, an ambidextrous design is reached with features almost identical for its right and left sides. A testbench is thereafter designed to investigate this possibility even further to design ambidextrous fingers using 3D printing and an asymmetrical tendons routing engineered to reduce the number of actuators. The Ambidextrous Robot Hand is connected to a remote control interface accessible from its website, which provides video streaming as feedback, to be eventually used as an online rehabilitation device. The secondary main challenge is to implement control algorithms on a robot hand with a range twice larger than others, with an asymmetrical tendons routing and actuated by nonlinear actuators. A number of control algorithms are therefore investigated to interact with the angular displacement of the fingers and the grasping abilities of the hand. Several solutions are found out, notably the implementations of a phasing plane switch control and a sliding-mode control, both specific to the architecture of the Ambidextrous Robot Hand. The implementation of these two algorithms on a robotic hand actuated by PAMs is almost as innovative as the ambidextrous design of the mechanical structure itself

The development of artificial muscles using textile structures

The aim of this project was to investigate the use of textile structures as muscles to assist people with muscular deficiency or paralysis. Due to the average life expectancy continuing to increase, support for those needing assistance to move unaided is also increasing. The purpose of this project was to try to help a patient who would normally need assistance, to move their arm unaided. It could also help with rehabilitation of muscular injuries and increasing strength and reducing muscular fatigue of manual workers. The approach considered was to develop an extra corporal device for the upper limbs, providing the main required motions. Most devices currently available use motors and gearboxes to assist in limb movement. This study investigated a way of mimicking the contraction of biological skeletal muscles to create a motion that is as human as possible with a soft, flexible and lightweight construction. Electroactive polymers (EAPs) and pneumatic artificial muscles (PAMs) were investigated. It became clear that at present, the EAPs were unable to create the forces and speed of contraction required for this application. The use of pneumatics to create artificial muscles was developed upon. PAMs, like the McKibben muscle and the pleated pneumatic muscle mimic the natural contraction of skeletal muscle. These current PAMs were used as a basis to develop a new type of pneumatic artificial muscle in this project. A 90 mm ball-like structure was developed, produced from an air impermeable rubber coated cotton fabric. Joining three oval panels together created a 3-D spherical shape. Three of these structures were linked together, and when inflated, created an acceptable level of contraction and force. This method of producing artificial muscles created a soft, lightweight and flexible actuator with scope for different arrangements, sizes and positions of the muscle structure. The contraction process was mathematically modelled. This calculated the predicted rate and level of contraction of a 2-D muscle structure. These mathematical findings were able to be compared to the practical results, and produced similar contraction characteristics. The muscle structures were incorporated into a garment to form a type of muscle suit which could be worn to assist movement. This garment has an aluminium frame to protect the wearer's bones from stresses from the contracting muscles. This study has shown that the muscle suit developed can create movement for wearers that would normally need assistance, and also reduce muscle fatigue, which would be useful for manual workers. This is incorporated into a functional and wearable garment, which is easy to dress and more lightweight and aesthetically pleasing than current muscle suits.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

serial and parallel robotics: energy saving systems and rehabilitation devices

This thesis focuses on the design and discussion of robotic devices and their applications. Robotics is the branch of technology that deals with the design, construction, operation, and application of robots as well as computer systems for their control, sensory feedback, and information processing [1]. Nowadays, robotics has been an unprecedented increase in applications of industry, military, health, domestic service, exploration, commerce, etc. Different applications require robots with different structures and different functions. Robotics normally includes serial and parallel structures. To have contribution to two kinds of structures, this thesis consisting of two sections is devoted to the design and development of serial and parallel robotic structures, focused on applications in the two different fields: industry and health

Design and Evaluation of a Knee-Extension-Assist

Quadriceps muscle weakness is a condition that can result from a wide variety of causes, from diseases like polio and multiple sclerosis to injuries of the head and spine. Individuals with weakened quadriceps often have difficulty supplying the knee-extension moments required during common mobility tasks. Existing powered orthoses that provide an assistive knee-extension moment are large and heavy, with power supplies that generally last less than two hours. A new device that provides a knee-extension-assist moment was designed to aid an individual with quadriceps muscle weakness to stand up from a seated position, sit from a standing position, and walk up and down an inclined surface. The knee-extension-assist (KEA) was designed as a modular component to be incorporated into existing knee-ankle-foot-orthoses (KAFO). The KEA consists of three springs that are compressed, as the knee is flexed under bodyweight, by cables that wrap around a sheave at the knee. The KEA returns the stored energy from knee flexion as an extension moment during knee extension. During swing or other non-weight bearing activities, the device is disengaged from the KAFO by decoupling the sheave from the KAFO knee joint, allowing free knee joint motion. A prototype was built and mechanically tested to determine KEA behaviour during loading and extension and to ensure proper KEA function. For biomechanical evaluation, able-bodied subjects used the prototype KEA while performing sit-to-stand, stand-to-sit, ramp ascent, and ramp descent tasks. The KEA facilitated sitting and standing, providing an average of 53 % of the required extension moment for the two participants, which allowed one participant to reduce quadriceps usage by 38 % and the other to perform sit-to-stand in a slower and more controlled manner that was not possible without the KEA. KEA use during ramp gait caused an overall increase in quadriceps activation by 76 %, on average, with use. Future efforts will be made to modify the design to improve functionality, especially for ramp gait, and to reduce device size and weight

The Development of a Sensitive Manipulation End Effector

This thesis designed and realized a two-degree of freedom wrist and two finger manipulator that completes the six-degree of freedom Sensitive Manipulation Platform, the arm of which was previously developed. This platform extends the previous research in the field of robotics by covering not only the end effector with deformable tactile sensors, but also the links of the arm. Having tactile sensors on the arm will improve the dynamic model of the system during contact with its environment and will allow research in contact navigation to be explored. This type of research is intended for developing algorithms for exploring dynamic environments. Unlike traditional robots that focus on collision avoidance, this platform is designed to seek out contact and use it to gather important information about its surroundings. This small desktop platform was designed to have similar proportions and properties to a small human arm. These properties include compliant joints and tactile sensitivity along the lengths of the arms. The primary applications for the completed platform will be research in contact navigation and manipulation in dynamic environments. However, there are countless potential applications for a compliant arm with increased tactile feedback, including prosthetics and domestic robotics. This thesis covers the details behind the design, analysis, and evaluation of the two degrees of the Wrist and two two-link fingers, with particular attention being given to the integration of series elastics actuators, the decoupling of the fingers from the wrist, and the incorporation of tactile sensors in both the forearm motor module and fingers

Large Deformable Soft Actuators Using Dielectric Elastomer and Origami Inspired Structures

There have been significant developments in the field of robotics. Significant development consists of new configurations, control mechanisms, and actuators based upon its applications. Despite significant improvements in modern robotics, the biologically inspired robots has taken the center stage. Inspired by nature, biologically inspired robots are called ‘soft robots’. Within these robots lies a secret ingredient: the actuator. Soft robotic development has been driven by the idea of developing actuators that are like human muscle and are known as ‘artificial muscle’. Among different materials suitable for the development of artificial muscle, the dielectric elastomer actuator (DEA) is capable of large deformation by applying an electric field. Theoretical formulation for DEA was performed based upon the constitutive hyperelastic models and was validated by using finite element method (FEM) using ABAQUS. For FEM, multistep analysis was performed to apply pre-stretch to the membrane before applying actuation voltage. Based on the validation of DEA, different configurations of DEA were investigated. Helical dielectric elastomer actuator and origami dielectric elastomer actuator were investigated using theoretical modeling. Comparisons were made with FEM to validate the model. This study focus on the theoretical and FEM analysis of strain within the different configuration of DEA and how the actuation strain of the dielectric elastomer can be translated into contraction and/or bending of the actuator