Tactile displays are now becoming available in a form that can be easily used in a user interface. This paper describes a new form of tactile output. Tactons, or tactile icons, are structured, abstract messages that can be used to communicate messages non-visually. A range of different parameters can be used for Tacton construction including: frequency, amplitude and duration of a tactile pulse, plus other parameters such as rhythm and location. Tactons have the potential to improve interaction in a range of different areas, particularly where the visual display is overloaded, limited in size or not available, such as interfaces for blind people or in mobile and wearable devices. This paper describes Tactons, the parameters used to construct them and some possible ways to design them. Examples of where Tactons might prove useful in user interfaces are given.

Tactons: Structured Tactile Messages for Non-Visual Information Display

Tactile displays are now becoming available in a form that can be easily used in a user interface This paper describes a new form of tactile output Tactons, or tactile icons, are structured, abstract messages that can be used to communicate messages non-visually A range of different parameters can be used for Tacton construction including: frequency, amplitude and duration of a tactile pulse, plus other parameters such as rhythm and location Tactons have the potential to improve interaction in a range of different areas, particularly where the visual display is overloaded, limited in size or not available, such as interfaces for blind people or in mobile and wearable devices This paper describes Tactons, the parameters used to construct them and some possible ways to design them Examples of where Tactons might prove useful in user interfaces are given

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Tactons: structured tactile messages for non-visual information display

Objective: This article provides an overview of tactile displays. Its goal is to assist human factors practitioners in deciding when and how to employ the sense of touch for the purpose of information representation. The article also identifies important research needs in this area. Background: First attempts to utilize the sense of touch as a medium for communication date back to the late 1950s. For the next 35 years progress in this area was relatively slow, but recent years have seen a surge in the interest and development of tactile displays and the integration of tactile signals in multimodal interfaces. A thorough understanding of the properties of this sensory channel and its interaction with other modalities is needed to ensure the effective and robust use of tactile displays. Methods: First, an overview of vibrotactile perception is provided. Next, the design of tactile displays is discussed with respect to available technologies. The potential benefit of including tactile cues in multimodal inte...

Tactile displays: guidance for their design and application.

We investigated the relative effectiveness of tangential versus normal displacements of skin for producing tactile sensations. Subjects adjusted the magnitude of slow tangential and oblique displacements of a flat-ended, cylindrical, 1 mm diameter probe glued to the skin in order to match the perceived intensity of a reference displacement that indented the skin normal to the surface. At both the forearm and fingerpad, subjects chose tangential displacements only 0.3 to 0.6 times as large as the reference normal displacement, indicating a significantly higher sensitivity to tangential displacement. Based on measurements of the mechanical impedance of the skin to normal and tangential displacements, these results were also expressed in terms of forces. At the forearm, subjects were more sensitive to tangential forces than normal force. However, at the fingerpad, sensitivity to tangential forces was lower than sensitivity to normal force, due to the approximately five-fold greater stiffness of the fingerpad to tangential traction. These results provide guidance for development of tactile displays: (1) When an actuator is limited primarily in terms of peak displacement (e.g., the maximum strain of a ceramic piezoelectric actuator) then tangential stimulation is a superior choice for both body sites we tested. (2) When an actuator is limited primarily in terms of peak force (e.g., the stall torque of a DC micromotor) tangential stimulation is the superior choice for the hairy skin, but normal stimulation is the better choice on the fingerpad.

Tangential versus normal displacements of skin: relative effectiveness for producing tactile sensations

We present the results of experiments to compare vibration and skin stretch in a virtual proprioception task in which subjects used a force sensor to control the movement of a virtual aim. Pilot experiments pointed to the need to provide the arm with varying dynamics (like a real arm) and to scale the feedback from vibratory and skin stretch displays to demonstrate a clear improvement in the accuracy of movement. For the final experiments, ten subjects were first trained on the system with visual feedback and then tested with vibratory feedback, skin stretch feedback and no feedback. Both vibration and skin stretch improved the subjects' performance. For some subjects, a second no-feedback case showed improvement over the initial case, indicating learning; in other cases, the no- feedback performance deteriorated and subjects reported that they had become used to relying on feedback. Overall, skin stretch provided superior results, particularly when the virtual arm was in a low-inertia configuration and at low velocity. The results suggest that small skin-stretch devices could be worn on the body to provide useful proprioceptive information when interacting with virtual environments and in motion training for rehabilitation or sports.

/pdf/comparison-of-skin-stretch-and-vibrotactile-stimulation-for-zuc3rebg1l.pdf

Comparison of Skin Stretch and Vibrotactile Stimulation for Feedback of Proprioceptive Information

To establish the best strategy for transmitting speech‐derived information via a single tactile channel, measurements were made on the perception of frequency‐ and/or amplitude‐modulated pulse‐train stimuli, with a comparison of the electrotactile and vibrotactile modalities. In one experiment, vibrotactile perception of 2‐oct step changes in stimulus frequency was found to be significantly better than electrotactile on a timescale appropriate for the transmission of speech features (e.g., with practiced subjects, information transfer of 69% with 200‐ms vibrotactile stimuli, 32% with 200‐ms electrotactile stimuli). Perception of step changes in stimulus amplitude was similar in the two modalities when changes in amplitude were tailored to match the different dynamic ranges available. In a second experiment, vibrotactile perception of voice fundamental frequency with various codings was investigated. Both experiments showed information transfer for vibrotactile stimuli to be greater when frequency and amplitude modulation were used together rather than with one or the other in isolation (sentence‐stress identification scores: 66% for FM stimuli, 69% for AM stimuli, 80% for FM/AM stimuli). It is concluded that frequency‐ and amplitude‐modulated vibratory stimulation is a good choice in a practical device for the profoundly hearing impaired.

Brian H. Brown

Papers

Vibrotactile and electrotactile perception of time‐varying pulse trains