Measuring and evaluating haptic devices and user interaction
Special Symposium at EuroHaptics 2010
Wednesday, July 7, 2010, Vrije Universiteit Amsterdam
Menu
- Evaluation
- Design Process
- Hardware Measures
- User Evaluation
- Registration
- Organization
- Back to the EuroHaptics Home Page
The Evaluation of Haptic/Tactile Interaction
Because of the very wide-ranging and varied nature of haptic devices, the part of the design process which deals with their validation and testing and, by implication, their compliance with standards and specifications is necessarily a complex area for consideration; probably an order of magnitude more complex than for visual displays, for instance. A structuring approach will require that certain tests are applied only to devices that use certain physical principles. This will necessitate the classification of devices according to physical principles used by them and/or according to some other regime. Each class of device would then have appropriately designed tests applied to them and the interaction with them. These tests originate from three disciplines: In the first instance, the design process of each class will be different. Secondly, the hardware measure to quantify the performance of the device will vary. Last but not least, the efficiency to be achieved during the actual haptic/tactile interaction with the user has to be determined.
This workshop is organized by the members of the ISO standardization committee for the group of standards within ISO 9241 – 9xx “Tactile and haptic interaction”. We invite the participants of this workshop to discuss in three small groups focusing on one topic each to identify and name the major trends. The collected results will then be presented to all participants. The overall scope of the workshop is interactive, so we are looking forward to an intensive exchange of experience and visions.
Back to top
Haptic interaction requires methods for prototyping during user centered design. Mock-ups, low-fidelity prototyping and high-fidelity prototyping are common for graphical user interfaces and are evaluated by walkthroughs, heuristic evaluation or screening techniques. Haptic mock-ups may be created from cardboard or plastic artifacts. They have been applied, for example, to the design of Braille-based user interfaces for blind people to create so-called routing. Another mock-up technique is the use of heavy gloves to resemble the effect of single point of contact typical for force feedback devices. Low fidelity haptic interaction, for example with planar tactile displays, benefits from printed tactile diagrams. Tools for drawing, creating textures or even writing Braille text require some expertise from the designer but may help to overcome the multimedia barrier due to their visual user interface. High fidelity prototyping includes implementation of some interaction techniques and depends on the tasks addressed by haptic interaction. Only a few appropriate tools exist and it is challenging to avoid misinterpretation of usability issues created from haptic feedback with usability issues created from other modalities such as auditory or visual. This topic of the session aims at the discussion of visualization methods both for the design of haptic interaction and the application of visualization to evaluation techniques. ISO 9241-210 covers the general methodologies for user centered design. This session may help to establish common ground for future standardization of the comparable approaches needed for haptic interaction among researches and practitioners in various settings.
Back to top
Quantification of haptic properties requires that the measurement technology be capable of acquiring the relevant tactile and kinaesthetic information. The design of such hardware and the underlying methodologies is stuck in a conflict, as the appropriate properties are not yet completely defined or even understood. Approaches from two directions provide a set of tools available today. Hardware designers tend to describe their systems in terms of workspace, static and dynamic forces, resolution and degrees of freedom. Psychophysics overlay such technical terms with just-notable-differences, two-point thresholds, dynamic perception of forces and/or displacements and perceptional thresholds. There have been trials to bring both together. Transfer functions have been defined to filter physical measurements and transfer them in a perceptional space. Additionally, measurement techniques were adjusted to reach the dynamics of haptic perception. They were applied, for example, to texture and gratings, showing surprising properties. The results indicated that it may be possible to identify physical effects, especially in highly dynamic interaction which can be transformed to tactile properties. Nevertheless, many questions are still open, such as the definition of the right mechanical load for a measurement device when it is applied to a technical system or the appropriate speed when exploring textures.
This session is to be regarded as a playground for discussions about suitable measurement techniques and the requirements a good measurement system may fulfill. As different haptic properties will need different technologies for their measurement, attendees are invited to do both; exchange their experience with the measurement and quantification of haptic properties and define suitable groups of possible measurement devices. If, in the end, a first set of requirements could be formulated, a valuable common basis for standardization among scientists and applicants of the technology would exist.
Back to top
The aim of user evaluations is to gain information about the functioning of a haptic display together with its specific software. This information includes both perceptual and motor aspects. In many contexts, the device with its software is expected to simulate reality. One example of this is the use of haptic displays for surgery training. In order to provide appropriate software it is necessary to know the physical properties of the tissues involved, as a user should receive the same, or at least very similar, information to that received when the surgery is performed on a real patient. A task for the evaluation is to decide to how successful this has been. Another example is the selling of products over the internet. If the product is textiles, for instance, the device should provide the users with the same haptic experience when handling the virtual textiles, as they do when they are handling real textiles. Again, knowledge about the physical properties involved is important for providing suitable software. The evaluation approach in such cases may be that experienced surgeons and textile experts judge the similarity in different respects between the real and the virtual objects. Evaluations on more limited perceptual aspects may be to study to what extent ordinary users can discriminate between different tissues and textile products, respectively.
Specific evaluations such as those described above may be complicated to achieve, but still more complex is to try to provide a more general evaluation of a device with its software. A general description of the real world cannot be given. A potential solution is to choose some physical properties of special importance for the haptic perception in question and study how participants can handle them. Examples of such basic properties are object form and surface texture, hardness/softness and friction. Absolute and differential thresholds can be determined, as well as scaling of supra-threshold properties. To provide guidelines for a general evaluation is a huge task. An issue for discussion is to what extent it is possible, and how suitably to limit the task.
Back to top
Required via the EuroHaptics 2010 registration website. After registering, please send an email to t.kern@hapticdevices.eu including a short note about your expertise and/or interest and the discussion session (Design, Hardware, User-Evaluation) you want to attend.
Back to top
Ian Andrew, Jim Carter, Jan van Erp, Gunnar Jansson, Thorsten A. Kern, Ki-Uk Kyiung, and Gerhard Weber.
Back to top