{"id":25233,"date":"2020-03-25T20:06:55","date_gmt":"2020-03-25T20:06:55","guid":{"rendered":"https:\/\/www.immersion.com\/?p=25233"},"modified":"2020-07-14T23:18:16","modified_gmt":"2020-07-14T23:18:16","slug":"the-haptic-stack-hardware-layer","status":"publish","type":"post","link":"https:\/\/www.immersion.com\/zh\/the-haptic-stack-hardware-layer\/","title":{"rendered":"The Haptic Stack \u2013 Hardware Layer"},"content":{"rendered":"\n

By Chris Ullrich, CTO at Immersion <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Last month, I\nintroduced the haptic stack, a conceptual framework that we use at Immersion to\nthink about the key technology components of a delightful haptic experience. As\na quick refresher, the stack consists of three key layers: design, software,\nand hardware (see last month\u2019s post<\/a> for more detail). These layers work\ntogether in a highly interdependent way to create a tactile experience that is\nharmonious with the overall UX of a product or experience. Product designers\nneed to think carefully about the trade-offs in all three layers when designing\na product. <\/p>\n\n\n\n

This month, I\u2019m\ngoing to dive into the hardware layer and explain some of the key choices and\nconsiderations unique to this layer. More than any other part of the haptic\nstack, the hardware layer dictates the range of possible experiences that can\nbe created in a product;  careful\nevaluation of the price\/performance and complexity of each possible choice are\ncritical. As every product owner knows, hardware choices are extremely hard and\nexpensive to change as a product approaches its release date.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Psychophysics<\/h2>\n\n\n\n

The heart of any haptic system is the actuators, which are\nresponsible for converting electrical signals into tactile stimulation of the\nuser. To understand the specifications of actuators and how they relate to\nhaptics, it is first necessary to understand the psychophysics of the human\nmechanoreceptor system. <\/p>\n\n\n\n

This is analogous to visual displays; the color gamut,\nresolution, and refresh rate of a display work in a similar way in the human\nvision system. <\/p>\n\n\n\n

In haptics, we think broadly about the four classes of\nmechanoreceptors: Merkel, Ruffini, Pacinian, and Meissner. These four receptors\nbroadly sense vibration, surface texture, deformation, and pressure. They work\ntogether to provide nerve pulses to the brain that enable the tactile sensation\nof the world. The signals from these nerves are merged in the brain to create a\ntactile perception of the world. The goal of a haptic actuator is to stimulate\none or more of these mechanoreceptor systems to create a touch experience.<\/p>\n\n\n\n

\"\"<\/figure><\/div>\n\n\n\n

Actuator types<\/h2>\n\n\n\n

For a haptic system, it is useful to think about actuators\nfrom the perspective of the type of stimulation they provide. The various types\nare broadly summarized below.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Electromagnetic<\/h3>\n\n\n\n

Electromagnetic (EM) actuators are the most widely used for\nhaptic feedback. Nearly 100% of mobile phones and almost every game controller has\nsome type of electromagnetic actuator. There are four main sub-categories of EM\nactuators:<\/p>\n\n\n\n

Eccentric Rotating Mass (ERM): These are rotational motors with an off-center mass mounted on the shaft. When voltage is applied to these motors, they vibrate as the off-center mass spins around. ERMs are good for low-frequency rumble type sensations but are quite slow, so they are not useful for precise haptics. Precision Microdrives has a great video<\/a> showing how an ERM works.<\/p>\n\n\n\n

Linear Resonant Actuators (LRA): These are linear actuators that consist of a mass on a spring and an electromagnet. The electromagnet is alternately charged and discharged, which results in the mass vibrating at a specific frequency. LRAs are extremely power efficient, and this makes them a great choice for mobile phones and other battery-powered devices. Again, Precision Microdrives has a great video<\/a> showing how LRA\u2019s work.<\/p>\n\n\n\n

Voice Coil (VCM): These are basically identical to LRA\nactuators but also have a broad frequency response. VCMs are commonly found in\nspeakers but can be adapted to create vibration experiences. VCMs typically use\nmore power than LRAs but are also able to produce a much richer and more\nrealistic tactile stimulation.<\/p>\n\n\n\n

Solenoid: A solenoid is a type of electromagnetic actuator\nthat works by moving a mass mounted on a spring when a coil is charged. These\nare somewhat similar to LRAs in concept, but in practice, they draw a lot of\npower and have a purpose-built and limited range of experiences. These\nactuators are common in automotive haptic devices.<\/p>\n\n\n\n

Piezoelectric<\/h3>\n\n\n\n

Piezoelectric (PZT) actuators are also widely used in many products but have only recently become viable as haptic actuators. PZT actuators work by deforming a solid crystal structure when a charge is added or removed. They are widely used in precise positioning systems (e.g., atomic force microscope) but also as actuators in extreme environments (e.g., inside a combustion engine or in spacecraft). PZT actuators require higher voltages than electromagnetic actuators and also need to be integrated into a mechanical structure to produce useful haptic sensations. PZT haptic actuators are comparable to VCM\u2019s in their ability to generate rich vibration experiences.<\/p>\n\n\n\n

Kinesthetic<\/h3>\n\n\n\n

Kinesthetic haptics is haptic feedback that pushes on the\nuser. This type of feedback typically uses electromagnetic actuators, along\nwith a mechanical transmission to create forces on a user. Examples include force-feedback\njoysticks and steering wheels for gaming and the forthcoming trigger haptics on\nthe Sony PS5 controller. Kinesthetic feedback is normally only used in application-specific\ndevices due to its cost and mechanical complexity.<\/p>\n\n\n\n

Surface<\/h3>\n\n\n\n

In the past few years, surface haptics has become a viable\ncommercial solution. Surface haptics works by either increasing or reducing the\nfriction between a fingertip and a surface. The resulting haptic experience is\nvery different from vibration in the sense that a surface can feel sticky or\nslippery, and this is dynamically controllable. Two leading commercial solution\ncompanies in this area are Tanvas and Hapt2U. A key drawback of current surface\nhaptics solutions is that it is difficult to create confirmation type effects,\nso surface haptics is usually considered as a complementary technology to electromagnetic\nor piezoelectric.<\/p>\n\n\n\n

Others<\/h3>\n\n\n\n

There are a variety of other haptic actuator technologies, but\nnone of them are widely used in CE devices or automotive. Examples include ultrasonic,\nelectroactive polymers (EAP), electrorheological fluids (ER), and shape memory\nalloys (SMA). All of these other technologies have unique physical properties\nthat make them suitable for haptics but have not yet reached a level of\nmaturity where they are appropriate for mass-market product offerings.<\/p>\n\n\n\n

Electrical Considerations<\/h2>\n\n\n\n

Each of the actuator solutions described above needs to have a driver IC or amplifier that can convert haptic effect signals into drive signals to the actuators. In most cases, the electrical solution is dictated by the actuator, as each one requires a specific type of drive signal. When evaluating driver offerings, some of the key features that matter are: <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

There are many other driver specifications on the digital\nside that we won\u2019t get into this month, but needless to say, it is important to\nchoose a driver IC and an actuator together and with the haptic UX of the whole\nsystem in mind. <\/p>\n\n\n\n

Summary<\/h2>\n\n\n\n

Actuator selection for a haptic product is probably the most\nimpactful decision a product team can make, as it both drives the majority of\nthe cost and also defines what types of haptic experiences are possible. It is\nhard to overstate the importance of this. With the wrong selection, the haptic\nexperience can be irritating to the point where users disable it. With the\nright hardware selection, a haptic experience can engender delight and high-value\ninteractions. <\/p>\n\n\n\n

Choosing an actuator can be complex and confusing,\nparticularly since there are no standards to help product designers compare and\nevaluate the haptic capabilities of specific offerings. At Immersion, we\u2019re\nworking with the ecosystem to solidify and create common specifications for\nactuators so that end-users can more consistently get high quality, delightful\nfeedback from their devices.<\/p>\n\n\n\n

Immersion has published some guidelines on the types of tests that can help make this decision, see Immersion\u2019s HD Actuator Section and Testing Guidelines here<\/a>.  <\/p>\n\n\n\n

<\/p>\n\n\n\n

Related articles: <\/p>\n\n\n\n

The Haptic Stack<\/a><\/p>\n\n\n\n

The Software Layer<\/a><\/p>\n\n\n\n

The Design Layer<\/a><\/p>\n\n\n\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

By Chris Ullrich, CTO at Immersion Last month, I introduced the haptic stack, a conceptual framework that we use at Immersion to think about the key technology components of a delightful haptic experience. As a quick refresher, the stack consists of three key layers: design, software, and hardware (see last month\u2019s post for more detail). These […]<\/p>\n","protected":false},"author":6,"featured_media":25438,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-25233","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-haptic-learning"],"translation":{"provider":"WPGlobus","version":"3.0.0","language":"zh","enabled_languages":["en","ja","zh"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"ja":{"title":false,"content":false,"excerpt":false},"zh":{"title":false,"content":false,"excerpt":false}}},"acf":[],"yoast_head":"\nThe Haptic Stack \u2013 Hardware Layer - Immersion - Haptic Technology<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.immersion.com\/the-haptic-stack-hardware-layer\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The Haptic Stack \u2013 Hardware Layer - 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