Design And Fabrication Of Soft Robotic Finger Combined With Smart Material For Dexterous Grasping

In the field of robotics,soft robotic actuators drawn broad attention because of their versatility,different actuation modes,easy fabrication(by Molding and casting)for particular application,and more importantly at low cost.Thanks to the mechanical properties of complaint materials,such as silicone,which enable their potential use within the challenging environment such as minimal invasive surgery,or even task like search and rescue where spaces are confined,and also in manipulation task of delicate and deformable objects.Soft actuators also enhanced human safety mainly due to their inherent amenability to tolerate impact,and are highly adaptable to any working environmentConsidering the application of soft actuators in grasping tasks,soft hands possess several advantages compare with their rigid counterparts,such as better shape matching which offers lager contact area with the object surface,simple structure and control,robustness to avoid uncertainties from the environment without getting damage and reliability while interacting with humansWhile soft grippers possess several promising features,they have also shown some problems,such as insufficient force output while holding an object,difficulties in design,fabrication,effect of different materials on soft actuator performances(bending angle and force magnitude)and there continuous deformable bending motion upon pressurization(fluidic actuators).These problems significantly reduce their performances and needs to be taken into account before using soft actuators in grasping tasks.In this thesis,we comprehensively describe the design and fabrication of soft actuators The actuator design and fabrication method described in this thesis provide essentials guidelines for fabricating modular soft robots with body morphologies which are useful for various tasks.A soft robotic finger has been designed and the study of soft materials and their effect on soft actuator performances has been investigated through FEM simulations and experiments.A suitable comparison has been made between the FEM simulations and the experimental results to quantitatively analyze the performances of the soft actuator such as bending angle,stress distribution and resultant force magnitudesTo further extend the application of soft actuators and enhance their existing capabilities,we have integrated smart material with a soft robotic finger to improve its payload holding capability and also to solve the problem continuous bending motion.For that purpose,we combined the smart material "shape memory polymer" with a soft robotic finger and introduced a novel design of a heater compatible with soft actuators for electrically heating SMP.Following the Joule heating method,the proposed heater is soft,flexible and ideal for activating smart material(SMP)while combining with soft actuators.Experiments are performed to verify the repeatability as well as applying different voltages and their effect on heating SMP was discussed.Moreover,the easy bonding method between SMP and heater is presented and the feasibility of bonding layer is verified through shape recovery test.In addition to that,the customizability and rapid designing procedure of a heater allow us to introduce the concept of artificial joints within a soft actuator simply by combining SMP together with embedded heaters.Different bending motions of a soft finger are achieved by independently activating each heater and a dynamic motion of a soft finger is evaluated through experiments.It is also concluded that,thick SMP sheets can improve the payload capability of a soft finger but it will also increase the activation time.Therefore,thin and stiff SMP substrates are recommended for soft actuators.