In this paper, based on the structural similarity between the PHANToM haptic device and a six-DOF (Degrees of Freedom) articulated robot arm, a six-DOF virtual robot arm driven by the PHANToM device is modeled. In order to enable the virtual robot arm to haptically interact with virtual prototypes in a virtual assembly (VA) environment, a workspace mapping method based on robot kinematics analysis is proposed. The haptic-based virtual robot arm is used in interactive modeling in free path planning and constraintbased assembly path planning operations in the VA system. In both planning processes, the user can interactively edit an assembly path with the guiding forces as feedback. Lastly, A few experiments have been conducted to verify the effectiveness of the proposed methods. The haptic-based virtual robot arm presented in this paper provides a new humancomputer interaction method for a VA system.

In augmented reality (AR)-based assembly and disassembly guiding systems, the guiding effects mainly depend on display characters of virtual guiding scene. If the virtual guiding scene is not displayed properly, such as displaying out of the operator's view, overlaying on the interest region of the screen, selecting an inappropriate viewpoint of the three-dimensional (3D) guiding scene, and so on, it may disturb normal operation instead of guiding. To display the 3D virtual guiding scene on suitable screen region from a comfortable viewpoint, an adaptive guiding scene display method was proposed. In the adaptive selection of the display region, the display screen was divided into many grids. The screen projection coordinates for vertexes of CAD feature's bounding boxes, and the occupied index of each grid was calculated. The maximum connected region of empty grids was chosen as a non-interest region on the screen for displaying the 3D guiding scene. In the optimal viewpoint selection algorithm, a viewpoint information measurement operator was put forward, which took projection area, visible proportion, information entropy, and difference in depth of all visible vertexes of CAD feature's bounding box in 3D virtual guiding scene into account. Finally, based on the principle of perspective projection, the 3D virtual guiding scene was positioned into the virtual world and displayed from the specified viewpoint on the specified screen area. All algorithms proposed in this paper utilized the automatically extracted CAD feature's bounding box model of part as input data so they could be implemented for online planning of 3D assembly guiding scenes.

Unfortunately, Ref. [8] "Mikchevitch, A., Antoine, F.: Haptically generated paths of an AFM-based nanomanipulator using potential field. In: 4th IEEE Conference on Nanotechnology, pp. 355-357 (2004)" has been published incorrectly. The correct reference is mentioned below: Ammi, M., Ferreira, A.: "Haptically generated paths of an AFM-based nanomanipulator using potential fields". In: 4th IEEE Conference on Nanotechnology, pp. 355-357 (2004) The online version of the original article can be found under