Pseudo-Haptics for Rigid Tool/Soft Object Interaction Feedback in Virtual Environments

This paper proposes a novel pseudo-haptics soft object stiffness simulation technique which is a marked improvement to currently used simulation methods and an effective low-cost alternative to expensive 3-DOF haptic devices. Soft object stiffness simulation is achieved by maneuvering an indenter avatar over the surface of a virtual soft object by means of an input device, such as a mouse, a joystick, or a touch-sensitive tablet. The alterations to the indenter avatar behavior produced by the proposed technique create for the user the illusion of interaction with a hard inclusion embedded in the soft object. The proposed pseudo-haptics technique is validated with a series of experiments conducted by employing three types of 2-DOF force-sensitive haptic surfaces, including a touchpad, a tablet with an S-pen input, and a tablet with a bare finger input. It is found that both the sensitivity and the positive predictive value of hard inclusion detection can be significantly improved by 33.3% and 13.9% respectively by employing tablet computers. Using tablet computers could produce results comparable to direct hand touch in detecting hard inclusions in a soft object. The experimental results presented here confirm the potential of the proposed technique for conveying haptic information in rigid tool / soft object interaction in virtual environments

Evaluation of Pseudo-Haptic Interactions with Soft Objects in Virtual Environments

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration-based feedback method based on both performance measures elapsed time and nodule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally invasive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user

Evaluation of Pseudo-Haptic Interactions with Soft Objects in Virtual Environments

This paper proposes a pseudo-haptic feedback method conveying simulated soft surface stiffness information through a visual interface. The method exploits a combination of two feedback techniques, namely visual feedback of soft surface deformation and control of the indenter avatar speed, to convey stiffness information of a simulated surface of a soft object in virtual environments. The proposed method was effective in distinguishing different sizes of virtual hard nodules integrated into the simulated soft bodies. To further improve the interactive experience, the approach was extended creating a multi-point pseudo-haptic feedback system. A comparison with regards to (a) nodule detection sensitivity and (b) elapsed time as performance indicators in hard nodule detection experiments to a tablet computer incorporating vibration feedback was conducted. The multi-point pseudo-haptic interaction is shown to be more time-efficient than the single-point pseudo-haptic interaction. It is noted that multi-point pseudo-haptic feedback performs similarly well when compared to a vibration-based feedback method based on both performance measures elapsed time and nodule detection sensitivity. This proves that the proposed method can be used to convey detailed haptic information for virtual environmental tasks, even subtle ones, using either a computer mouse or a pressure sensitive device as an input device. This pseudo-haptic feedback method provides an opportunity for low-cost simulation of objects with soft surfaces and hard inclusions, as, for example, occurring in ever more realistic video games with increasing emphasis on interaction with the physical environment and minimally invasive surgery in the form of soft tissue organs with embedded cancer nodules. Hence, the method can be used in many low-budget applications where haptic sensation is required, such as surgeon training or video games, either using desktop computers or portable devices, showing reasonably high fidelity in conveying stiffness perception to the user

錯触覚による硬軟感提示における視覚刺激の検討

人間にとって触覚は非常に重要な感覚である．現実世界において，人間は周囲に存在する物体の特性を知るために手を用いて対象物体を掴み，物体の材質や形状，硬さや重さなどを触覚として知覚する．このような触覚情報をバーチャルな環境とのインタラクションに用いるため，様々な触力覚ディスプレイが研究・開発されている．触力覚ディスプレイは接地型と非接地型に大別でき，PHANToMやSPIDARなどのデバイスが開発されているが，これらの多くは力の正確な再現を動作原理としており，精度や分解能を向上させるためにはワイヤなどによって構成される機構が複雑になるというトレードオフの関係にある．そのため，手術シミュレータやロボットの遠隔操作など限られた用途への応用にとどまっている．　これに対し本研究では錯触覚を利用することで，ユーザに触力覚提示を行う手法に着目した．錯触覚による触感覚は，力の再現をコンセプトとしたデバイスに比べて微弱なものしか発生させることができないという欠点はあるが，デバイス構成が簡素になるという利点もある．錯触覚の中でも，視覚刺激によって触覚的な知覚が生起される現象を視覚誘導性錯触覚と呼ぶ．これは，ユーザの動作に対して適切にコントロールされた視覚刺激を提示することにより，錯触覚を生起させるものである．木村はこの手法を用いた非接地型の錯触覚提示システムとして，把持動作を利用した硬軟感提示手法を提案した．これは小型ディスプレイの側面に圧力センサを設置し，手中のディスプレイ上に握力に応じた視覚刺激を提示することで，ユーザに硬軟を知覚させるものである．本論文では，木村が開発したハンドヘルド型錯触覚提示システムにおける視覚刺激と現実世界との差分に着目し，(1)矩形に対して力を及ぼしている要素(2)矩形の変形形状の2点について新たな視覚刺激を作成し，検証実験を通して硬軟感知覚への影響を評価する．電気通信大学201