6.2 Parametrization of the Haptic Virtual Environment
6.2.4 Haptic Scene Creator Evaluation
As shown previously, the Haptic Scene Creator includes many features aiming at simpli- fying the task of a Haptic application designer who is using the MHaptic framework. To evaluate it, we asked a programmer with knowledge in Virtual Reality to augment a visual Virtual Environment as much as he can. We gave him the the user manual of the software that can be found in the Appendix III: HSC User Manual, page 145.
The test scene is a quite complex. It represents a four-rooms house (kitchen, bathroom, bed, office and living-room), and contains 398 visual nodes. It is presented in figure 6.11. The main goal is to use the Haptic Scene Creator to augment every touchable object with a good level of approximation in order to manipulate objects easily. This task took almost three hours, time to create 612 geometries for 167 static objects and 114 dynamic objects. The advanced functionalities (copy-pasting, vertex selection, PCA) were of course exten-
Figure 6.11: The augmentation of the 3D House.
sively used. We do not have performed the same procedure on the full scene without using the advanced functionalities (and neither using a simple text editor to write by hand the XML file). But, to give an idea of the improvements, augmenting a chair without advanced functionalities took five (tedious!) minutes, whereas it took around 1 minute using the PCA.
We remarked that sometimes it is difficult to find the good approximation of an object. It is also sometimes not trivial to find the proper way to select the vertices of a mesh, in order to have the good results of the PCA. But most of the time, a solution can be found. We present an evaluation of the manipulation of this model in section 7.2.2.
Synthesis of Part II
In this chapter we proposed a study on the parametrization of the virtual objects properties. We demonstrate the importance of the parameters for the surface to increase the efficiency of the manipulation tasks. Then, we proposed a tool for easily augmenting the existing visual Virtual Environment by including haptic properties.
The framework that we proposed in the second part of this thesis reach the expected goal: proposing two-handed haptic feedback and virtual manipulation in generic Virtual Environments. We exposed the difficulties and the problems faced during the creation of this framework as well as their solutions. In the next part of this thesis, we present some applications that we built using this framework.
Part III
Applications
Chapter 7
Realistic Manipulation
T
HE PREVIOUS PARTSof this thesis have presented many algorithms, techniques and innovations related to the control of a two-handed haptic device. We embedded most of this research into a framework: MHaptic. But the primary intention when designing a haptic library (like any other kind of library), is that it can be used by software developers to create at least one application.The Haptic Interface enables Human Computer communication trough touch, in re- sponse to user movements. This communication is bidirectional in the sense that the same device conveys information from Human to Computer, by the mean of movements, and from Computer to Human by the mean of touch or kinesthesia. This characteristic makes the field of Haptics to have numerous applications. Obviously a two-handed haptic device is not thought for a particular application. It can work with every virtual applications that simulates a real life scenario with hand’s interaction. But it can also be applied to any context that needs a complex human computer interaction. Considering this flexibility, we believe that we should not bound the evaluation of such two-handed devices to a specific field, as well as we should not make only studies that concerns the realistic manipulation. We will present in this chapter applications with realistic or pseudo-realistic interaction, whereas in chapter 8, we present experiments with interaction paradigms that could not be considered as realistic, because they use metaphors or gestures.
The word realistic has many definitions. In this chapter, it is used with the sense of “conform to a reality” or believable. The first section present a feasibility study in the context of virtual training. The objective is to explore the haptic virtual manipulation in a Mixed-Reality Environment. Then, in the second section, we present two applications that uses MHaptic and its Virtual Environments interaction functionalities.
Figure 7.1: A Mixed-Reality industrial training environment [115]
7.1
Two-handed Haptic Manipulation in Mixed-reality En-
vironments
In the industry, the traditional training of workers to use special equipment is normally carried out using a part or full real equipment. This could be afforded by the industry itself or specialized centers for training. But it brings many drawbacks like: the cost of equip- ment just for training is too high; machines are innovating and training equipment should change; new products or improvements of the production line which implies new training; outsourcing training with specialized centers, etc. Beside this kind of training there is also more specialized training like aviation or surgery where it is not always possible to use the real equipment and to check all the cases that the trainee could face.
Because of this, the help of computer solutions has been considered. They offer lower cost and more adaptability. The simulation of a working environment with computers is done by means of Virtual Reality (VR). In these applications we are able to build any kinds of scenarios, tools and equipment. However, a complete and detailed simulation of some scenarios appears to be very complex to develop, and moreover it is still difficult to produce truly convincing results.
Thus, to reduce the programming effort and also to simulate better the reality, Mixed Reality (MR) provides a good solution [110]. The principe of Mixed-Reality consists in superpositioning real images (pictures or video) inside of virtual world or vice versa. It can provide a complete real scene with virtual elements that help with the training process, as it is shown on the figures 7.1 achieved in the framework of the STAR European project.
These technologies are affordable and good enough to simulate working cases. They can show the proper way to play a role inside a context which is the primary goal of training. But usually these technologies are limited to keyboard or mouse interaction. In some cases other user interfaces are used, like large screens or touch screens. It is of course a big issue in a context like training. This is the reason that convinced us to study the integration of a two-handed device: The benefit of manipulating objects is to teach the user in a practical
7.1. HAPTIC MANIPULATION IN MIXED-REALITY 93
manner the proper way of performing tasks. For example, in assembly process: the user can manipulate virtual objects and position them directly.
In this section, we present a first a brief review of existing applications taking advan- tage of Mixed or Virtual Reality environment for manipulation or assembly training, with some of them providing force feedback. We remark these applications do not provide the ability to interact with real and virtual objects at the same time. It convince us to present a system that allows this kind of interaction. with the help of the Haptic WorkstationTMand
of MHaptic. Then, by the mean of a simple feasibility study, we evaluate the benefits of such Haptic Mixed-Reality platform in the context of virtual assembly.