Haptics advancements put us in touch with

Haptic advancements
put us in touch with
complex systems
Brian Burk
Applications Manager,
Haptics Business Unit,
Texas Instruments
Haptics, the use of advanced electronic technology
to simulate “touch and feel,” is rapidly spreading
from a handful of consumer applications to a much
wider range of industrial, commercial, automotive,
medical and other systems. The technology
promises to bring new forms of tactile experience
that will expand our interaction with equipment
and make them feel more natural – while improving
productivity, safety and control.
Anyone who has typed a message into a smartphone or touchpad and not just
heard but felt the click of a key on the smooth screen has experienced haptics,
the use of electronic technology to simulate the sensation of touch. While haptic
experiences are a recent addition to consumer products with touchscreens, the
technology has been around for some time in video games and training simulation
systems. In these systems, joysticks, sliding knobs, pedals, steering wheels and
other electromechanical controls have electronic effects supplied to simulate the
way a real system feels. Now, similar effects are at the fingertips of a much larger
group of people every time they enter a phone number or send an email.
Haptic applications like these may seem to be
haptics has a role to play. These simulated tactile
just another electronic curiosity, but in fact they
experiences are not only important for our pleasure
represent the leading-edge of an important change
and ease of use, they can also add new functions,
in how we deal with machines. Touchpads and
provide useful new information, enhance control,
other human interfaces featuring haptics are in
improve safety of operation, and enable new forms
development for industrial systems, robotics,
of product differentiation.
automobiles, home appliances, point-of-sale
The underlying semiconductor technology that
and order entry systems, new forms of training
enables haptics is available, inexpensive and easy
simulation, and remote equipment operation among
to design with. Texas Instruments (TI) has applied its
other application areas (Figure 1). In fact, just about
innovation design and integration expertise to create
everywhere that people have to touch a screen
differentiated haptic solutions with wide-ranging
or operate some other kind of electronic control,
possibilities in a number of emerging applications.
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Figure 1. Haptics technology is appearing in a growing number of applications.
As system designers and manufacturers discover
nothing like that unless haptics in the system simulate
how adding haptic features can benefit their
the drag of turning. Similarly, touchscreens, valuable
products, they will use integrated circuit (IC) devices
as they are, don’t feel anything like mechanical
to create a variety of applications with simulated
keypads unless haptics provides some sort of
tactile feedback to make our interaction with a
clicking or bumping sensation for the finger when
variety of equipment seem more natural.
a key is pressed (with perhaps a “click” sound to
reinforce the action through another sense modality).
Bringing back the physical sense of
control
Haptics brings back something important that we’ve
lost, and in doing so they can make products easier
As electronic control systems replace older
to use and more enjoyable.
mechanical ones, we lose the physical feedback of
Not surprisingly, haptic feedback has been
operation. That is, we lose the sensation that comes
extensively incorporated in simulated training for
from touching, holding, sliding, turning, gripping,
systems where operation is complex and needs to
pushing, pulling and otherwise manipulating the
be executed flawlessly. For example, aircraft pilots
system and feeling it respond. Haptic features
train extensively in simulated cockpits before they
simulate this feedback, so that a completely
fly a different type of plane. As important as it is for
electronic human interface responds as if it were a
the pilots to learn the procedures and “see” out the
familiar mechanical or electromechanical control.
cockpit windows with video simulation, they also
For example, a video gamer knows how it feels to
need to learn how the plane feels in response to the
turn a car with a steering wheel and mechanical
controls as it takes off, climbs, flies through smooth
linkage, but a steering wheel on a plastic panel feels
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and rough weather, descends and lands. Haptics
Among the most promising applications for haptic
helps provide these sensations, so that when the
innovation is keypad input, where flat electronic keys
time comes to sit in a real cockpit, the pilot not only
have been displacing mechanical keys for years,
knows how to use the controls, but also how the
with an increasing appearance of touchpads and
plane and controls feel in operation.
touchscreens recently for more variable tasks. For
example, consider a worker on an assembly line,
Haptic feedback is also used in training for
who may need to punch data into a flat-screen
surgery, where it adds the sense of touch to three-
panel while keeping an eye on different gauges,
dimensional graphic visualization of human tissue.
instruments, products moving on the line, and many
Surgeons get a sense of how the tissue feels, and
other functions. The worker has to stop watching
they learn to manipulate their instruments in tight
everything else in order to look at the panel and
spaces where the body pushes back against their
push the right button or series of buttons, creating
hands and instruments. For laparascopic surgeries
possibilities for missing some event or simply making
and other forms of endoscopy, simulated training with
mistakes from visual overload. It would help matters
haptic feedback is crucial for learning how to use the
if the panel offered some non-visual feedback to help
miniscule instruments involved. In some experimental
the worker register that the data entry is correct.
cases, expert surgeons are using simulation tools
Adding sounds for each button may not help much
with haptics—aided by live video, monitoring
because factories are often noisy, but bumping
instrumentation and a support staff with the patient—
sensations can report by touch whether the data
to perform real surgeries at distant sites.
is being entered. The result of one detail—adding
Putting haptics to work in new ways
haptic “bumps” to the human interface—can enable
Simulated training represents the high end of haptic
a better functioning assembly line that is not only
application, where system cost is less critical than
more productive, but also safer.
achieving something difficult but indispensable.
If the previous example seems remote from everyday
In contrast, with mass market items such as
experience, consider how useful it would be to sense
smartphones, tablets and video games, doing
tactile feedback from the buttons on the smooth
something innovative matters but must have minimal
keypad of a microwave oven the next time you need
effect on the shelf price. Today, the frontier of haptic
to use it in the dark, or to confirm through fingertip
application is in areas between these extremes,
feedback that you’ve found the right controls on
where some increase in price will afford tactile
the complicated dashboard of a rental car. Haptic
features that can extend the product’s function,
features help provide these experiences and others,
make it easier to use, increase safety or otherwise
such as:
differentiate it. Such applications are found in robots
• Giving a distracted waiter a specific tactile
and other equipments for transportation, building
response for selecting a menu item on a touchpad
automation, home appliances, commercial systems,
• Making a computer touchpad feel more as if it is
office equipments, and a variety of other products
tracking over a solid surface
where users can benefit from haptic interaction with
machines.
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• Providing a variety of new directional movement
where the entire surface shakes, as with an alarm
sensations for pointing devices such as computer
or ring vibration on a smartphone. By contrast, local
mice and TV remote controls
vibrations slightly, briefly deform the surface where it is
touched, creating a bump or dip under the fingertip.
• Giving control sensations in the steering wheel and
Some systems are now appearing that can move
driver’s seat of a car, or
the deformation along to lead or follow the fingertip.
• Adding subsonic vibration to headphones to
enhance the physical sensation of deep bass
The brain interprets the resulting sensation in a way
sounds
that corresponds to feeling a button pressed, a
Seemingly simple haptic sensations can have
knob sliding, a different surface texture, and other
profoundly significant applications: the same kind
expectation.
of physical resistance that a video gamer feels in
moving a joystick can also help the remote operator
of a machine used in hazardous rescue, exploration,
mining, manufacturing and other environments where
human beings need to go but can’t do so safely.
In the future, applying haptics in new areas will, in
turn, create demand for even more sophisticated
forms of tactile experience. For instance, one day
when you select a garment online, you may be able
to feel the difference between silk, cotton, wool and
synthetic materials through your touchpad. Although
the technology isn’t in place yet for creating such
sophisticated tactile experiences economically, new
areas of application for haptics are creating a market
Different application requirements, including size
environment that will favor its development.
and vibrating characteristics, determine the type of
actuator that the system uses to create its haptic
Technology for haptics
effects. For instance, whole-body effects can be
While the psychology of tactile simulation and its
created by an electric rotating mass (ERM), which
interpretation can be complex, creating haptic effects
is a small rotating motor with an off-center mass
themselves is relatively straightforward. Manipulable
that spins at various speeds to create vibrating
controls, such as joysticks, convey haptic information
effects. Button or key effects in fixed positions may
through shaking and bumping, as well as through
be implemented using an array of linear resonant
resistance that can increase, decrease and even stop
actuators (LRAs), which are spring-mass systems
movement altogether.
that vibrate up and down in response to changes in a
magnetic field.
On flat surfaces such as touchscreens, one way
to create effects is through whole-body vibration,
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More complicated local vibrations can be achieved
sends to an actuator. In the actuator an appropriate
with actuators that employ the piezo effect (Figure
mechanical vibration for the bump, click, swipe
2), the tendency for certain materials, to change
or whatever is created. The only devices added
shape when a voltage is applied. Piezo actuators
for haptic effects are the driver and actuator.
enable precision actuation for high-definition haptics
Other devices are already part of the system. In
and are being increasingly used for novel effects in
addition, the system requires software for the MCU
touchscreens, including the sensation of friction or
to generate the waveform as a constant voltage,
even texture recreation. Since the piezo effect is two-
sine-wave or pulse-width modulate or (PWM) driven
way, with deformation creating a voltage as well as
waveform, depending on the actuator type and
voltages deforming the materials, piezo devices are
properties.
capable of serving for sensing as well as actuating, so
The haptic devices themselves must feature a high
that the same device handles both pressure input and
level of integration and a small footprint, since a
tactile output. The devices are very thin compared
human interface is limited in scale, however large
with other actuators, giving them an advantage in
the system it is meant to control. In handheld,
low-profile systems such as keyboards in portable
battery-operated applications, extremely low-power
computing.
consumption is essential—a feature that is beneficial
in wired systems as well, though less significant.
Since haptic technology is a new area of design for
almost everyone, the IC hardware has to be easy
to design into new systems and add onto existing
ones, and the software must be straightforward to
operate using standard MCU interfaces. Moreover,
because technology applications are growing,
system developers need haptic solutions from IC
providers who will continue to offer more advanced
options in their products in the years ahead.
TI haptic solutions
As the industry’s leading provider of analog
Figure 2. Haptic actuators help achieve vibrations by employing the
piezo effect.
technology, including sensors and drivers for
system interfaces, TI has spent years developing
an extensive portfolio of solutions to help system
Haptic system components
developers introduce differentiated haptic features
The elements of a haptic system (Figure 3) include a
in their products quickly and economically. TI
sensor-switch, such as a key on a touchpad, which
haptic drivers support ERMs, LRAs and piezo
accepts the external input stimulus and sends
actuators that can be used for applications
a signal to the system microcontroller (MCU). In
ranging from hand-held consumer electronics
addition to its other processing functions, the
to industrial robots, from intelligent building
MCU generates an output waveform, which a
management to the latest automobiles.
driver amplifies to the appropriate voltage and
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Creating haptic effects
2 Generate
The touch event triggers the
processor to generate a
waveform.
MCU/Apps
Processor
Analog/
Digital
Driver
Touch Event
Actuator
1 The touch screen
Touch
3 Vibrate
The waveform
controller sends a
trigger signal to the
processor when a
press is detected.
Actuator
Vibration
Touch Screen & Capacitive Buttons
causes the actuator
to move in a
specific direction or
pattern to create a
vibration.
Figure 3. The process for creating haptic effects.
Unlike traditional motor drivers, these devices are
Integrated diagnostics simplify design and aid
designed specifically for driving haptic actuators,
in rapid testing for manufacture. TI’s advanced
simplifying the design process by eliminating
manufacturing process technologies keep power
unnecessary functions and their software controls.
requirements for its haptic drivers to the minimum
All parts needed for haptic driving are already
needed for full functionality.
integrated, including the high-voltages required
TI offers reference designs for smartphones,
for piezo actuators (Figure 4). Any type of touch
computer mice, touchscreens, refrigerator
input can be used, making the drivers extremely
control panels, watches, HMI, handheld barcode
versatile in new haptic applications.
scanners, industrial mobile computing, and other
Essential features for haptic effects are designed
applications. The company also collaborates with
into the drivers to improve performance and
its extensive network of third parties to deliver
simplify design. Among these features are
additional system design and integration support.
automatic closed-loop feedback to improve
Because of TI’s uniquely wide-ranging product line,
response from ERMs and LRAs, automatic
it provides other major system components such
calibration that detects and configures the closed-
as ultra-low power MCUs, analog front-ends and
loop feedback coefficients for every actuator, and
power management devices, simplifying the IC
auto-resonance detection to sense the resonant
selection process for developers. In addition, TI’s
frequency of LRAs. Ready-made waveform effects
ongoing research efforts mean that it will be well-
such as clicks, buzzes and ramps come with the
positioned to support new developments in haptic
drivers, and the developer can create custom
technology, such as polymer-based actuators and
waveforms to make software prototyping easy.
haptic effects based on electrical stimulus.
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DRV8662
High-Voltage
Driver
150-250Vp
Force Sense or
Capacitive Touch
Sensor
Key 1
Actuator
I2C
Key 2
MSP430™
Microcontroller
Key 3
Key 4
GND
Use switches to multiplex the actuators
Figure 4. A system block diagram showing multiple actuators.
Staying in touch
As we rely more and more on touchpads, flat control panels and other electronic user interfaces, increasingly
we will need tactile feedback to help us understand what systems are doing. Haptic technology not only
makes our experiences more satisfying, it also helps improve control, extends functionality and enhances
safety for system users, while helping manufacturers to differentiate their products. As an industry leader in
developing innovative IC technology that enables haptics, TI offers highly integrated, easy-to-use, low power
solutions for introducing tactile simulation in a wide range of applications. No matter where the future of
electronics leads us, TI haptic advancements will help us keep in touch with our systems.
For more information visit:
TI Haptic reference designs: www.ti.com/corp-inn-innind-mc-lp2
TI’s Haptic website: www.ti.com/corp-inn-innind-mc-tidesigns
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