自行车仿真器中力反馈技术的研究与实现
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摘要
随着虚拟现实技术的发展，虚拟驾驶系统、虚拟漫游系统成为了研究的热点。但是，在现有系统中，存在着反馈力计算精度不高、虚拟场景对用户指令的响应速度偏慢等问题，这直接导致了虚拟漫游的沉浸感、真实性不高，严重制约了虚拟驾驶、虚拟漫游的质量。本文从虚拟现实的3个特性(沉浸感、交互性、多感知性)入手，分析了目前国内外力反馈系统中存在的问题，建立了自行车仿真器力反馈系统。在建立自行车动力学模型过程中，提出了人车分离的重心计算方法，有效的提高了反馈力的计算精度；在对虚拟场景的简化过程中，通过建立多分辨率的地形模型来对地形进行简化，有效的提高了虚拟场景响应用户指令的实时性，提高了系统仿真的真实性。本文按照自行车仿真器力反馈系统的组成模块，主要从系统的动力学建模、具有DEM高程数据的虚拟场景的绘制和简化、力反馈技术在系统中的实现以及动感平台的设计等几方面进行了深入地研究。本文的主要研究工作如下：
1．在自行车仿真器中加入了力反馈技术，以此增强虚拟漫游系统的沉浸感和真实性。
2．在建立系统的动力学模型过程中，提出了人车分离的重心计算方法，经试验检验，该方法能够有效的提高建模的准确度，提高反馈力的计算精度。
3．基于Arc／Info建立具有DEM高程值的虚拟场景，使场景中地形具有坡度数据，为实现力反馈技术提供数据源。
4．建立具有动态多分辨率的地形模型，根据用户视点远近的不同，显示不同分辨率的地形，以此实现对场景的简化，提高虚拟场景系统响应速度，增强人在漫游过程中的沉浸感和虚拟骑行的真实性。
5．研究并设计了3自由度自行车动感平台，利用动感平台，模拟用户在虚拟骑行中的位姿变化，以此提高虚拟骑行的真实性。同时，利用Adams软件对平台进行仿真试验，检验平台的可操作性。
在设计过程中，综合利用虚拟现实技术、动力学／运动学建模技术、DSP控制技术、3维地形建模与简化技术、力反馈技术，建立了自行车仿真器力反馈系统，经过试验验证，该系统满足虚拟漫游的要求，使用户获得如在真实场景中漫游的感受。
With the development of Virtual Reality, Virtual driving system and Virtual Roaming system have become the focus. But in these systems, because low accuracy level in feedback force system and long time is needed when virtual environment responses user's commands, the senses of immersion and reality are extremely low which make a bad effect on the quality of virtual driving and roaming. This paper starts from three characters of virtual reality: (Imagination、Interaction、Immersion), analyzes the problems exist in these force feedback systems, during building the bicycle dynamic, this paper brings forward a proposal to calculate the gravity center which first calculates user and bicycle's gravity centers, then calculates the unitary gravity center. In this way, the feedback force's calculation accuracy is highly improved; During predigesting the virtual environment, the paper builds a dynamic multi-resolution terrain models. In this way, response time is reduced and system's third dimension is highly improved. According to the modules of bicycle simulator feedback force system, this paper makes several researches as follows: building bicycle simulator's dynamics, building and predigesting the virtual environment, implementation of the feedback force in bicycle simulator system, and designing the dynamic plate. In this paper, the following problems are being solved:
1. The feedback force has been realized in the bicycle simulator system, the sense of imagination is highly improved.
2. During building the dynamics, this paper brings forward a new proposal to calculate the gravity centre which first calculates the user and bicycle's gravity centers, then calculates the unitary gravity center. According to experiment's test, this proposal is able to improve accuracy of building the dynamics and calculation of feedback force.
3. Building the virtual environment with DEM data, it will supply force feedback system with terrain data.Building dynamic multi-resolution terrain models, according to the difference of user sight's distance, virtual environment displays terrain with different resolution. in this way, it reduces the response time and improves environment menu's switch speed and sense of immersion.
4. Building dynamic multi-resolution terrain models, according to the difference of user sight's distance, virtual environment displays terrain with different resolution. in this way, it reduces the response time and improves environment menu's switch speed and sense of immersion.
5. Designing the 3 DOF bicycle dynamic plate. With the plate, users can get different gestures during driving, it increases the realistic of virtual driving. In the same time, this paper makes several experiments to check whether the plate answers for the requirements using Adams, and experiments demonstrates that the plate satisfies the requirements of virtual riding.
During designing, integrated with technologies of virtual reality, dynamics and kinematics modeling and feedback force, this paper builds a bicycle simulator system, after a series of experiments, these experiments demonstrate that bicycle simulator system satisfies all the requirements of virtual roaming.
1．在自行车仿真器中加入了力反馈技术，以此增强虚拟漫游系统的沉浸感和真实性。
2．在建立系统的动力学模型过程中，提出了人车分离的重心计算方法，经试验检验，该方法能够有效的提高建模的准确度，提高反馈力的计算精度。
3．基于Arc／Info建立具有DEM高程值的虚拟场景，使场景中地形具有坡度数据，为实现力反馈技术提供数据源。
4．建立具有动态多分辨率的地形模型，根据用户视点远近的不同，显示不同分辨率的地形，以此实现对场景的简化，提高虚拟场景系统响应速度，增强人在漫游过程中的沉浸感和虚拟骑行的真实性。
5．研究并设计了3自由度自行车动感平台，利用动感平台，模拟用户在虚拟骑行中的位姿变化，以此提高虚拟骑行的真实性。同时，利用Adams软件对平台进行仿真试验，检验平台的可操作性。
在设计过程中，综合利用虚拟现实技术、动力学／运动学建模技术、DSP控制技术、3维地形建模与简化技术、力反馈技术，建立了自行车仿真器力反馈系统，经过试验验证，该系统满足虚拟漫游的要求，使用户获得如在真实场景中漫游的感受。
With the development of Virtual Reality, Virtual driving system and Virtual Roaming system have become the focus. But in these systems, because low accuracy level in feedback force system and long time is needed when virtual environment responses user's commands, the senses of immersion and reality are extremely low which make a bad effect on the quality of virtual driving and roaming. This paper starts from three characters of virtual reality: (Imagination、Interaction、Immersion), analyzes the problems exist in these force feedback systems, during building the bicycle dynamic, this paper brings forward a proposal to calculate the gravity center which first calculates user and bicycle's gravity centers, then calculates the unitary gravity center. In this way, the feedback force's calculation accuracy is highly improved; During predigesting the virtual environment, the paper builds a dynamic multi-resolution terrain models. In this way, response time is reduced and system's third dimension is highly improved. According to the modules of bicycle simulator feedback force system, this paper makes several researches as follows: building bicycle simulator's dynamics, building and predigesting the virtual environment, implementation of the feedback force in bicycle simulator system, and designing the dynamic plate. In this paper, the following problems are being solved:
1. The feedback force has been realized in the bicycle simulator system, the sense of imagination is highly improved.
2. During building the dynamics, this paper brings forward a new proposal to calculate the gravity centre which first calculates the user and bicycle's gravity centers, then calculates the unitary gravity center. According to experiment's test, this proposal is able to improve accuracy of building the dynamics and calculation of feedback force.
3. Building the virtual environment with DEM data, it will supply force feedback system with terrain data.Building dynamic multi-resolution terrain models, according to the difference of user sight's distance, virtual environment displays terrain with different resolution. in this way, it reduces the response time and improves environment menu's switch speed and sense of immersion.
4. Building dynamic multi-resolution terrain models, according to the difference of user sight's distance, virtual environment displays terrain with different resolution. in this way, it reduces the response time and improves environment menu's switch speed and sense of immersion.
5. Designing the 3 DOF bicycle dynamic plate. With the plate, users can get different gestures during driving, it increases the realistic of virtual driving. In the same time, this paper makes several experiments to check whether the plate answers for the requirements using Adams, and experiments demonstrates that the plate satisfies the requirements of virtual riding.
During designing, integrated with technologies of virtual reality, dynamics and kinematics modeling and feedback force, this paper builds a bicycle simulator system, after a series of experiments, these experiments demonstrate that bicycle simulator system satisfies all the requirements of virtual roaming.
引文
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[2] 王洪瑞。液压6-DOF并联机器人操作手运动和力控制的研究[M]。河北：河北大学出版社，2001，123-124。
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[4] Dong-Soo Kwon, etc. KAIST Interactive Bicycle Simulator, Proceedings of ICRA 2001 Conference, Seoul, Korea, May, 2001, 2313-2318.
[5] Dong-Soo Kwon, Gi-Hun Yang, etc. KAIST Interactive Bicycle Racing Simulator: The 2nd Version with Advanced Features[J]. IEEE/RSJ Intl. Conference on Intelligent Robots and Systems EPFL, Switherland, 2002, 2961-2966.
[6] 何其昌，范秀敏，等。交互式自行车模拟器的力觉反馈研究[J]。系统仿真学报，2005：17(4)：795-797。
[7] ZHU YUAN CHENG. A new scheme for View-Dependent Level of Detail rendering of meshes[J]. IEEE Transactions on Visualization and Computer Graphics, 2005, 11(3): 326-338.
[8] Li Jie. Simplification and Multiresolution Representation of Triangular Mesh [PhD Dissertation]. Beijing: Tsinghua University, 1998 (in Chinese)。
[9] Hugues Hoppe. Progressive eshes. SIGRAPH'96 Proceedings, Los angels, USA, 1996, 30: 99-108.
[10] L. Scarlatos. Hugues Hoppe. Progressive eshes. SIGRAPH'96 Proceedings, Los angles, USA, 1996, 30: 85-91.
[11] R Cignoni, E. Puppo, R. Scopigno. Representation and visualization of terrain surfaces at variable resolution. The Visual Computer, 1997, 13(5): 199-217.
[12] Peter Lindstrom, David Koller, William Ribarsky, etc. Realtime, continuous level of detail rendering of height fields. SIGGRAPH'96 Proceedings, Los Angeles, California, 1996. 109-118.
[13] LEVENBERG J. Fast view-dependent level of detail rendering using cached Geometry[C]. IEEE Visualization, 2002: 259-266.
[14] David Luebke, Carl Erikson. View dependent simplification of arbitrary polygonal environments. SIGGRA PH'97 Proceedings, Los Angeles, California, 1997. 324-330.
[15] Hugues Hoppe. Smooth view dependent level of detail control and its application to terrain rendering, http:www.microsoft.Com.
[16] 高欣，孙汉旭，贾庆轩等。自行车仿真健身器的设计与实现[J]。系统仿真学报，2005：17(5)：1163-1167。
[17] 刘合平等。TMS320LF240x DSP C语言开发应用。北京：北京航空航天大学出版社。2003，110-123。
[18] 赵铁石，黄真。一种三维移动并联平台机构的运动学分析。中国机械工程，2001，12(6)：613-616。
[19] 黄真等。并联机器人机构学理论及控制[M]。北京：机械工业出版社，1997，34-45。
[20] Innocenti C., Castelli V R, Forward Kinematics of the General 6-6 Fully Parallel Mechanism. An Exhaustive Numerical Approach Via a Mono-Dimensional-Search Algorithm[J]. ASME Journal of Mechanical Design, Vol. 115, 1993.
[21] 丁志刚。微特直线电机及控制[M]。杭州：浙江大学出版社，1987，229—248。
[22] 郭宗仪，王宗培。步进电动机及其控制系统[M]。哈尔滨：哈尔滨工业大学出版社，1984，79—98。
[23] 王晓明。电动机的单片机控制[M]。北京：北京航空航天大学出版社。2002，165-166。
[24] 杨秀芳，郭彦珍。交流光栅位置检测系统[J]。西安理工大学学报，2001，17(3)：301-3-4。
[25] 马瑞卿，刘卫国，李钟明。有限转角无刷力矩电机位置伺服控制[D]。中国航空电气工程第三届学术会议(庐山)，1999，146-148。
[26] Analytic Cycling [EB/OL]. http://www.analyticcycling.com.
[2] 王洪瑞。液压6-DOF并联机器人操作手运动和力控制的研究[M]。河北：河北大学出版社，2001，123-124。
[3] Brogan D. C., Metoyer R. A., Hodgins J. K., Dynamically Simulated Characters in Virtual Environments[J]. Computer Graphics and Applications, IEEE, Sept. -Oct. 1998, 18(5): 58-69.
[4] Dong-Soo Kwon, etc. KAIST Interactive Bicycle Simulator, Proceedings of ICRA 2001 Conference, Seoul, Korea, May, 2001, 2313-2318.
[5] Dong-Soo Kwon, Gi-Hun Yang, etc. KAIST Interactive Bicycle Racing Simulator: The 2nd Version with Advanced Features[J]. IEEE/RSJ Intl. Conference on Intelligent Robots and Systems EPFL, Switherland, 2002, 2961-2966.
[6] 何其昌，范秀敏，等。交互式自行车模拟器的力觉反馈研究[J]。系统仿真学报，2005：17(4)：795-797。
[7] ZHU YUAN CHENG. A new scheme for View-Dependent Level of Detail rendering of meshes[J]. IEEE Transactions on Visualization and Computer Graphics, 2005, 11(3): 326-338.
[8] Li Jie. Simplification and Multiresolution Representation of Triangular Mesh [PhD Dissertation]. Beijing: Tsinghua University, 1998 (in Chinese)。
[9] Hugues Hoppe. Progressive eshes. SIGRAPH'96 Proceedings, Los angels, USA, 1996, 30: 99-108.
[10] L. Scarlatos. Hugues Hoppe. Progressive eshes. SIGRAPH'96 Proceedings, Los angles, USA, 1996, 30: 85-91.
[11] R Cignoni, E. Puppo, R. Scopigno. Representation and visualization of terrain surfaces at variable resolution. The Visual Computer, 1997, 13(5): 199-217.
[12] Peter Lindstrom, David Koller, William Ribarsky, etc. Realtime, continuous level of detail rendering of height fields. SIGGRAPH'96 Proceedings, Los Angeles, California, 1996. 109-118.
[13] LEVENBERG J. Fast view-dependent level of detail rendering using cached Geometry[C]. IEEE Visualization, 2002: 259-266.
[14] David Luebke, Carl Erikson. View dependent simplification of arbitrary polygonal environments. SIGGRA PH'97 Proceedings, Los Angeles, California, 1997. 324-330.
[15] Hugues Hoppe. Smooth view dependent level of detail control and its application to terrain rendering, http:www.microsoft.Com.
[16] 高欣，孙汉旭，贾庆轩等。自行车仿真健身器的设计与实现[J]。系统仿真学报，2005：17(5)：1163-1167。
[17] 刘合平等。TMS320LF240x DSP C语言开发应用。北京：北京航空航天大学出版社。2003，110-123。
[18] 赵铁石，黄真。一种三维移动并联平台机构的运动学分析。中国机械工程，2001，12(6)：613-616。
[19] 黄真等。并联机器人机构学理论及控制[M]。北京：机械工业出版社，1997，34-45。
[20] Innocenti C., Castelli V R, Forward Kinematics of the General 6-6 Fully Parallel Mechanism. An Exhaustive Numerical Approach Via a Mono-Dimensional-Search Algorithm[J]. ASME Journal of Mechanical Design, Vol. 115, 1993.
[21] 丁志刚。微特直线电机及控制[M]。杭州：浙江大学出版社，1987，229—248。
[22] 郭宗仪，王宗培。步进电动机及其控制系统[M]。哈尔滨：哈尔滨工业大学出版社，1984，79—98。
[23] 王晓明。电动机的单片机控制[M]。北京：北京航空航天大学出版社。2002，165-166。
[24] 杨秀芳，郭彦珍。交流光栅位置检测系统[J]。西安理工大学学报，2001，17(3)：301-3-4。
[25] 马瑞卿，刘卫国，李钟明。有限转角无刷力矩电机位置伺服控制[D]。中国航空电气工程第三届学术会议(庐山)，1999，146-148。
[26] Analytic Cycling [EB/OL]. http://www.analyticcycling.com.