Research On Untethered Magnetic Force Actuated Three Dimensional Haptic Rendering

Haptic rendering is a crucial method for human-computer interaction(HCI)in the field of virtual reality,and the development of multi-mode(visual,auditory and force)HCI technology provides operators with a kind of more realistic,immersive and natural interaction experience.Research on untethered magnetic force actuated haptic rendering removes the constraints of mechanical linkages in traditional haptic rendering devices,making human operation more flexible.It can provide continuous and stable electromagnetic force compared with other non-contact haptic rendering methods,thus has been a research topic of great significance.Based on the principle of magnetic force actuation,this paper carries out research work on natural and untethered haptic rendering method for human-computer interaction.Beginning with the basic theory of electromagnetic field,this paper elaborates the generation mechanisms of electromagnetic field.First of all,through theoretical analyzing,the distribution of magnetic induction intensity in hollow coils applied with different currents is obtained.Secondly,the common finite element analysis(FEA)methods of electromagnetic field are discussed.Based on the theoretical analysis,the overall scheme of a non-contact 3D haptic rendering system based on magnetic actuation is provided,including a visual rendering module,a haptic rendering module,and a hand position detection module.Thirdly,a haptic rendering prototype system has been developed in this thesis,which is constructed by electromagnet coil module,a fingertip wearable permanent magnet module,a SA306 based drive module,and a TM4C1294 drive control module.Furthermore,a human hand position detection method combining Leap Motion and Azure Kinect sensors is proposed.In order to determine the magnitude of the electromagnetic force on the fingertip-mounted permanent magnet at different positions in the whole operating workspace,research on the relationship between the electromagnetic force on the permanent magnet and the current of a single electromagnet coil and the magnetic induction intensity is carried out based on the ANSYS finite element simulation.Furthermore,the relationship between the magnitude of the current flowing through Helmholtz-like coil and the electromagnetic force on the permanent magnet is simulated.An electromagnetic force control method based on discrete simulation data is proposed to control the magnitude and direction of the electromagnet coil current.Besides,based on the hardware system and simulation data,the system software is designed,including the electromagnet drive control algorithm,the fusion detection algorithm for fingertip position detection,the collision detection algorithm in the virtual environment,the electromagnetic force control algorithm,and the communication modules.To verify the feasibility and effectiveness of the 3D magnetic force actuated haptic rendering system,a haptic rendering application system is developed with CHAI3 D library.Relevant experiment S have been conducted,including the 3D virtual object contour perception experiment in collaboration with the LCD display,the rendering reality evaluation experiment,and a box pushing with/without force feedback experiment.According to the experimental results,the recognition accuracy of the virtual object contour perception experiment designed for this system is as high as91.25%.The average score of the subjects' rating of the realistic evaluation of virtual object is 8.3(10points in toal).The results of the cube pushing experiment show that subjects can complete the tasks more quickly with the existence of haptic rendering than tasks without haptic rendering,leading to an average time saving of 22%.The developed 3D magnetic actuated haptic rendering system provides new ideas for a more natural HCI mode and lays the research foundation for the development of non-contact HCI.