RESEARCH TOWARDS THE DESIGN OF A NOVEL SMART FLUID DAMPER USING A MCKIBBEN ACTUATOR

Vibration reducing performance of many mechanical systems, decreasing the quality of manufactured products, producing noise, generating fatigue in mechanical components, and producing an uncomfortable environment for human bodies. Vibration control is categorized as: active, passive, or semi-active, based on the power consumption of the control system and feedback or feed forward based on whether sensing is used to control vibration. Semi-active vibration control is the most attractive method; one method of semi-active vibration control could be designed by using smart fluid. Smart fluids are able to modify their effective viscosity in response to an external stimulus such as a magnetic field. This unique characteristic can be utilised to build semi-active dampers for a wide variety of vibration control systems. Previous work has studied the application of smart fluids in semi-active dampers, where the kinetic energy of a vibrating structure can be dissipated in a controllable fashion. A McKibben actuator is a device that consists of a rubber tube surrounded by braided fibre material. It has different advantages over a piston/cylinder actuator such as: a high power to weight ratio, low weight and less cost. Recently McKibben actuator has appeared in some semi-active vibration control devise. This report investigates the possibility of designing a Magnetorheological MR damper that seeks to reduce the friction in the device by integrating it with a McKibben actuator. In this thesis the concept of both smart fluid and McKibben actuator have been reviewed in depth, and methods of modelling and previous applications of devices made using these materials are also presented. The experimental part of the research includes: designing and modelling a McKibben actuator (using water) under static loads, and validating the model experimentally. The research ends by presenting conclusions and future work

The design and mathematical model of a novel variable stiffness extensor-contractor pneumatic artificial muscle

This article presents the design of a novel Extensor-Contractor Pneumatic Artificial Muscle (ECPAM). This new actuator has numerous advantages over traditional pneumatic artificial muscles. These include the ability to both contract and extend relative to a nominal initial length, the ability to generate both contraction and extension forces and the ability to vary stiffness at any actuator length. A kinematic analysis of the ECPAM is presented in this article. A new output force mathematical model has been developed for the ECPAM based on its kinematic analysis and the theory of energy conservation. The correlation between experimental results and the new mathematical model has been investigated and show good correlation. Numerous stiffness experiments have been conducted to validate the variable stiffness ability of the actuator at a series of specific fixed lengths. This has proven that actuator stiffness can be adjusted independently of actuator length. Finally a stiffness-position controller has been developed to validate the effectiveness of the novel actuator

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

Relationship Between Velocity of Contraction and Force Applied On Air Muscles

Air muscles are simple pneumatic devices that have high potential to be used as robotic manipulators, as they have a behavior similar to biological motors or muscles. Hence, they have a wide range of potential applications in areas such as robotics, bio-robotics, biomechanics, and artificial limb replacements. In addition to the similarity to biological muscle, air muscles have the advantages of good power-to-weight ratio, being compliant, and low cost. This thesis primarily quantifies the relationship between velocity of contraction of air muscles and the force applied on it, which is a key characteristic of biological skeletal muscle. First, an experimental test rig was used to measure the velocity of contraction of air muscles as a function of applied force, supply pressure, and supply volumetric flow rate. Second, a theoretical model is proposed to quantify the relationship between the velocity of contraction and force applied on it and to explain the experimental results. Three air muscles having different lengths and diameters were tested for loads ranging from 0 to 6 kg at 20 psi, 40 psi and 60 psi at two different flow rates. All three air muscles were made up of latex tubing sheathed with the Techflex, FlexoPet braided sleeve. The primary air muscle was 5 inches long, with the diameter of the inner tube measuring 3/4 of an inch. The second muscle had half the length (2.5 inches) and was the same diameter as the primary air muscle. The third air muscle was the same length as the first (5 inches long), but half of the diameter (3/8 of an inch). The velocity of the contraction was measured with the help of the linear potentiometer. Both the theoretical model and the experimental results found that as the force applied on the air muscles is increased, maximum length of contraction and velocity of contraction decrease. Both model and experiment showed that the velocity of contraction increases as a function of both pressure and volume flow rate

Design and Testing of a Biomimetic Pneumatic Actuated Seahorse Tail Inspired Robot

The purpose of this study is to build and test a pneumatically actuated robot based on the biomimetic design of a seahorse tail. McKibben muscles, a form of pneumatic actuator, have been previously used to create highly flexible robots. It has also been discovered that the seahorse tail serves as a highly flexible and prehensile, yet armored appendage. Combining these topics, this research aims to create a robot with the mechanical flexibility of a pneumatic actuator and the protection of a seahorse tail. First, the performance of a miniature McKibben muscle design is examined. Then, the artificial muscles are implemented into a 3D-printed seahorse tail-inspired skeleton. The robot\u27s actuation was observed to determine its maximum bending capacities. The results of the experiments revealed that the miniature McKibben muscles performed comparably to larger sized McKibben muscles previously reported in literature. The pneumatically actuated robot achieved a maximum bend angle of ~22°. Further research is recommended to determine the behaviors of similar robots with additional plates or McKibben muscles spanning shorter plate sequences

Design and Fabrication of Soft 3D Printed Actuators: Expanding Soft Robotics Applications

Soft pneumatic actuators are ideal for soft robotic applications due to their innate compliance and high power-weight ratios. Presently, the majority of soft pneumatic actuators are used to create bending motions, with very few able to produce significant linear movements. Fewer can actively produce strains in multiple directions. The further development of these actuators is limited by their fabrication methods, specifically the lack of suitable stretchable materials for 3D printing. In this thesis, a new highly elastic resin for digital light projection 3D printers, designated ElastAMBER, is developed and evaluated, which shows improvements over previously synthesised elastic resins. It is prepared from a di-functional polyether urethane acrylate oligomer and a blend of two different diluent monomers. ElastAMBER exhibits a viscosity of 1000 mPa.s at 40 °C, allowing easy printing at near room temperatures. The 3D-printed components present an elastomeric behaviour with a maximum extension ratio of 4.02 ± 0.06, an ultimate tensile strength of (1.23 ± 0.09) MPa, low hysteresis, and negligible viscoelastic relaxation

The design and mathematical modelling of novel extensor bending pneumatic artificial muscles (EBPAMs) for soft exoskeletons

This article presents the development of a power augmentation and rehabilitation exoskeleton based on a novel actuator. The proposed soft actuators are extensor bending pneumatic artificial muscles. This type of soft actuator is derived from extending McKibben artificial muscles by reinforcing one side to prevent extension. This research has experimentally assessed the performance of this new actuator and an output force mathematical model for it has been developed. This new mathematical model based on the geometrical parameters of the extensor bending pneumatic artificial muscle determines the output force as a function of the input pressure. This model is examined experimentally for different actuator sizes. After promising initial experimental results, further model enhancements were made to improve the model of the proposed actuator. To demonstrate the new bending actuators a power augmentation and rehabilitation soft glove has been developed. This soft hand exoskeleton is able to fit any adult hand size without the need for any mechanical system changes or calibration. EMG signals from the human hand have been monitored to prove the performance of this new design of soft exoskeleton. This power augmentation and rehabilitation wearable robot has been shown to reduce the amount of muscles effort needed to perform a number of simple grasps