Spatial Mechanism Design in Virtual Reality With Networking

Mechanisms are used in many devices to move a rigid body through a finite sequence of prescribed locations. The most commonly used mechanisms are four-bar planar mechanisms that move an object in one plane in space. Spatial mechanisms allow motion in three-dimensions (3D), however, to date they are rarely implemented in industry in great part due to the inherent visualization and design challenges involved. Nevertheless, they do provide promise as a practical solution to spatial motion generation and therefore remain an active area of research. Spatial 4C mechanisms are two degree-of-freedom kinematic closed-chains consisting of four rigid links simply connected in series by cylindrical (C) joints. A cylindrical joint is a two degree-of-freedom joint, which allows translation and rotation about a line in space. This paper describes a synthesis process for the design of 4C spatial mechanisms in a virtual environment. Virtual reality allows the user to view and interact with digital models in a more intuitive way than using the traditional human-computer interface (HCI). The software developed as part of this research also allows multiple users to network and share the designed mechanism. Networking tools have the potential to greatly enhance communication between members of the design team at different industrial sites and therefore reduce design costs. This software presents the first effort to provide a three-dimensional digital design environment for the design of spatial 4C mechanisms.

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Spatial Mechanism Design in Virtual Reality With Networking

Volume 2B: 27th Design Automation Conference ◽

10.1115/detc2001/dac-21136 ◽

2001 ◽

Author(s):

John N. Kihonge ◽

Judy M. Vance ◽

Pierre M. Larochelle

Keyword(s):

Virtual Reality ◽

Finite Sequence ◽

Degree Of Freedom ◽

Three Dimensions ◽

Synthesis Process ◽

Spatial Mechanisms ◽

Cylindrical Joint ◽

In Series ◽

Simply Connected ◽

Two Degree Of Freedom

Abstract Mechanisms are used in many devices to move a rigid body through a finite sequence of prescribed locations in space. The most commonly used mechanisms are four-bar planar mechanisms that move an object in one plane in space. Spatial mechanisms allow motion in three-dimensions (3D). Spatial 4C mechanisms are two degree of freedom kinematic closed-chains consisting of four rigid links simply connected in series by cylindrical (C) joints. A cylindrical joint is a two degree of freedom joint which allows translation along and rotation about a line in space. This paper describes a synthesis process for the design of 4C spatial mechanisms in a virtual environment. Virtual reality allows the user to view and interact with digital models in a more intuitive way than using the traditional human-computer interface (HCI). The software developed as part of this research also allows multiple users to network and share the designed mechanism. Networking tools have the potential to greatly enhance communication between members of the design team at different industrial sites and therefore reduce design costs.

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Circuit and Branch Rectification of the Spatial 4C Mechanism

Volume 7A: 26th Biennial Mechanisms and Robotics Conference ◽

10.1115/detc2000/mech-14053 ◽

2000 ◽

Author(s):

Pierre M. Larochelle

Keyword(s):

Rigid Body ◽

Finite Sequence ◽

The Body ◽

Degree Of Freedom ◽

Motion Generation ◽

Moving Body ◽

In Series ◽

Simply Connected ◽

Two Degree Of Freedom ◽

Physical Dimensions

Abstract Spatial 4C mechanisms are two degree of freedom kinematic closed-chains consisting of four rigid links simply connected in series by cylindrical(C) joints. In this work we are concerned with the design of spatial 4C mechanisms which move a rigid body through a finite sequence of prescribed locations in space. This task is referred to as rigid-body guidance by Suh and Radcliffe (20) and as motion generation by Erdman and Sandor (6). When 4C mechanisms are synthesized for such a task, for example by utilizing Roth’s spatial generalization of Burmester’s planar methods (17; 18), the result is the physical dimensions which kinematically define the mechanism. However, the motion of the mechanism which takes the workpiece through the sequence of prescribed locations in space is not determined. In fact, it may be impossible for the mechanism to move the body through all of the desired locations without disassembling the mechanism. This condition is referred to as a circuit defect. Moreover, in some cases the mechanism may enter a configuration which requires an additional mechanical input to guide the moving body as desired. These are referred to as branch defects. This paper presents a methodology for analyzing spatial 4C mechanisms to eliminate circuit and branch defects in motion generation tasks.

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