關於 Hatpics 的五四三

Haptics 簡介

又到了寫論文的時間。每到這個時候總是要上網找一堆史料，塞一些研究相關的歷史背景以及實例，然後在論文中得把讀者當笨蛋一樣自問自答。昨晚瀏覽到 HowStuffWorks 這網站寫的一篇關於 Haptics 文章內容相當清楚易懂！除了學習他的寫作邏輯之外也翻譯了一下部分內文，這裏僅節錄了關於 haptic feeback的類型, haptic 系統, haptic 應用實例等等。

Type of Haptic Feedback

當我們用手觸碰身旁的東西時, 我們通常接受兩種類型的回饋 - kinesthetic 與 tactile. 那兩者的差別是什麼？這裡以籃球的三個可能動作為例: reach for, explore and pick up.
考慮當手觸碰到球時

1. 接觸點發生在 finger pad 與 ball surface 之間。
2. 每個 finger pad 都是一個複雜的 sensory system，包含多個 receptors, 負責接受多種刺激，ex. light touch, heavy touch, pressure, vibration and pain.
3. 當 finger explores時, 他們亦傳達某些訊息像是 smoother texture of leather, raised coarseness of the laces, the hardness of the ball as force is applied. 甚至 thermal properties of the balls（熱能）亦可透過 tacitle receptors得知.
4. 當 pick up 時，我們會去調整至其形狀去抓取，但事實上這動作包含了不同 receptors 所收集的資訊：A unique set of data points describing joint angle, muscle length, and tension is generated. This information is collected by a specialized groupd of receptors embedded in muscles, tendons, and joints.

就像 propriocetors 自動感知器，這些接收器將訊號傳遞給大腦，透過大腦中 cerebral cortex 的 somatosensory region 處理後將資訊提供給 muscle spindle 改變 muscle length（但有時也不需透過大腦傳遞），Golgi tendon organ 同 muscle spindle 般運做，改變的是 muscle tension。那處理的資訊是什麼？ 就是 kinesthetic information: 描述 gross size, shape, postion of hand, arm and body。這裡我的理解是：tactile 就是單獨 receptor 所傳遞的資訊，kinesthetic 則是藉由數個 receptors 更複雜的描述 tactile。講白一點就是，觸碰球時 tactile 指的是可以基本上感受到它存在，而 kinestic 則更真實感受到它的物理性質像是硬度，材質，大小等等。
對於新一代的 haptic system, 作者稱之為 unsurpassed level of performance, fidelity, and ease of use。這是優勢部分（筆記ing）

Haptic System

有很多種方式建立 hpatic 系統。雖然他們看起來差異很大，但有兩個很重要的部分原理是一樣的：
1 產生力的軟體 - 當使用者的 virtual identity 與 virtual object 互動時所產生的力的結果
2.產生力的裝置 - 將力施予人身上的裝置
以上整個過程稱作 haptic 渲染，即利用軟體計算並執行計算結果的過程。常見的渲染方式像是以polyhedral model來表示在虛擬世界中的物體。這些3d models 可以精確的描繪各種形狀，透過評估力線與虛擬物體各個面的結果計算出 touch data。這類 3d object 被塑造的感覺相當真實, 而且也有表面的質地（紋路），而傳遞 haptic image 於使用者的任務則落在 interface device。在很多方面, interface device被類比為 mouse。除了 mouse 是一個被動裝置，他無法通訊任何 synthesized haptic data 給 users。（mouse 的諸多問題 passive, unable to convey synthesized haptic data ）
以下談論一些特殊的haptic system來了解他們如何作業

(1)phantom
The PHANTOM® interface from SensAble Technologies was one of the first haptic systems to be sold commercially. Its success lies in its simplicity. Instead of trying to display information from many different points,
this haptic device simulates touching at a single point of contact. It achieves this through a stylus which is connected to a lamp-like arm. Three small motors give force feedback to the user by exerting pressure on the stylus.
So, a user can feel the elasticity of a virtual balloon or the solidity of a brick wall. He or she can also feel texture, temperature and weight. The stylus can be customized so that it closely resembles
just about any object. For example, it can be fitted with a syringe attachment to simulate what it feels like to pierce skin and muscle when giving a shot.

(2)cybergrasp
The CyberGrasp system, another commercially available haptic interface from Immersion Corporation, takes a different approach. This device fits over the user's entire hand like an exoskeleton
and adds resistive force feedback to each finger. Five actuators produce the forces, which are transmitted along tendons that connect the fingertips to the exoskeleton.
 With the CyberGrasp system, users are able to feel the size and shape of virtual objects that only exist in a computer-generated world. To make sure a user's fingers don't penetrate or crush a virtual solid object, the actuators can be individually programmed to match the object's physical properties.

(3)
Researchers at Carnegie Mellon University are experimenting with a haptic interface that does not rely on actuated linkage or cable devices. Instead, their interface uses a powerful electromagnet to levitate a handle that looks a bit like a joystick. The user manipulates the levitated tool handle to interact with computed environments. As she moves and rotates the handle, she can feel the motion, shape, resistance and surface texture of simulated objects.
This is one of the big advantages of a levitation-based technology: It reduces friction and other interference so the user experiences less distraction and remains immersed in the virtual environment. It also allows constrained motion in six degrees of freedom (compared to the entry-level Phantom interface, which only allows for three active degrees of freedom). The one disadvantage of the magnetic levitation haptic interface is its footprint. An entire cabinet is required to house the maglev device, power supplies, amplifiers and control processors. The user handle protrudes from a bowl embedded in the cabinet top.

可想像的，這些系統像我們所談述的是相當昂貴的. 這表示這些技術的應用仍然限制于某種產業，以及特定的環境。以下探索一些 haptics 技術的應用實例。

Application of Haptic Technology

1. Video game.  video game makers have been early adopters of passive haptics, 他們利用震動的手把，控制器以及方向盤來(reinforce)增強畫面上的動作 (on-screen activity)。但未來影片也能夠讓 players 去感受及控制 virtual solid, fluids, tools and avatars.The novint falcon haptic controller 已經將這些付諸實現！3D force feedback 能讓你辨認 pistol report 及 shotgun blast 的不同，或者像是當你箭頭往回拉，可以感受到長弓的繩子的阻力。
2. GUI. 需多作業系統亦能從 haptic interactions 中受益。想像能夠感覺到視覺的按鈕，當按下按鈕時能夠接收到 hatpic feedback。一些 touchscreen 的製造商已經實驗這些科技。Nokia phone designers 已經讓這些俱觸覺回饋的觸控銀幕更完美，這這些銀幕上的按鈕栩栩如生。當使用者按下按鈕，他可以感受到自按鈕move-in, move-out的感覺。同時他們也加入 audible click。（*1)
3. Training with haptic 是最常見的. 例如醫學系學生可以用來學習細緻的手術技巧。
4. Aircraft mechanics 也能夠完成複雜的部分。
5. Soldier 能夠學習如何拆除 bomb, 操作 直升機, 坦克, 飛機等等。
6. Haptics 亦被廣泛應用于 teleoperation or telerobotics. 在 telerobotic system 中, operator 操作機器人在某個空間中的移動。簡單的teleoperation 如瞄準相機 或者傳回 visual images。
7. 複雜一點的 teleoperation 稱作 telepresence，能讓 operator 真實感受到 robot 所在的環境。Haptics 讓這事情成為真實: inlude touch cues, audio cues and visual cues in telepresence models。

(*1) 雖然目前有不少公司加入 Novint 與 Nokia 為促進 haptics 成為主流產品，但價格仍是進入市場的一個障礙。目前最複雜的touch technology 仍被使用於工業，軍隊及醫學應用。

總結

•  In video games, it is nice to have
• In traiing, it is vital
• In learning, it is potential. [next-generation hand-on] Ex. probe 3-D rendering of cells; senese invisible forces like gravity and friction, more completity.

---

Source: Wikipedia.org, HowStuffWorks