EMBEDDED SHOES

Embedded-technology developers have identified their next frontier, and it starts at your feet.

VectraSense Technologies Inc. (Beverly, Mass.) has designed a smart shoe, that will let shoes exchange information so people can communicate via their footwear. Adidas (Portland, Ore.) produced microprocessor-equipped running shoes, that can adapt to a runner's size, speed and fatigue level.

And at the Massachusetts Institute of Technology, researchers developed shoes that do everything from providing gait therapy to generating power for wearable electronics.

For now, experts say smart shoes may be no more than a niche — but with some 12 billion feet in the total available market, it's a niche with potential. What's more, they say, the advent of Microprocessors in shoes could signal a broader trend.

Adidas engineers say adding embedded intelligence to a running shoe solves a longstanding problem: Ever since running gained widespread popularity during the 1970s, shoe manufacturers have been searching for a way to create an "adaptable shoe" that could provide the appropriate level of cushioning, whether the wearer weighed 90 pounds or 200.

"People in the industry have dreamed about it, and they've been waiting for that magic material they could put under the heel that would automatically become harder or softer as needed."

Adidas engineers said that they considered a number of possibilities — including magnetic rheological fluids, piezoelectrics and shaped memory alloys — but that each posed power and other problems. So the team decided long years ago to endow a running shoe with electronic intelligence so it could "decide" on its own when to alter the cushioning level.




The version of the Adidas shoe incorporates a microcontroller, tiny electric motor, lead screw, magnet, sensor, lithium coin cell battery and metal cushioning element, as well as in-house software algorithms. The design places a Hall-effect sensor atop the soft cushioning in the shoe's midsole and a magnet below that cushion. When a runner's foot strikes the pavement and compresses the cushion, the Hall-effect sensor notes the compression of the cushion by measuring the change in distance between itself and the magnet. It then sends that information to an 8-bit PIC16F88 microcontroller, from Microchip Technology Inc. (Chandler, Ariz.), which "decides" whether the runner needs a change in cushioning.

If so, the controller activates a 6,000-rpm, 3-volt electric motor from Mabuchi Motor America Corp. (Troy, Mich.) that turns the lead screw. As the screw turns, it then shortens or lengthens an elliptical, metallic cushioning element beneath the heel. When the element lengthens, the shoe's cushioning grows softer; when it shortens, cushioning becomes firmer.

With the MCU operating at 20 MHz and sampling the sensor at 1,000 times per second, the unit can change the shoe's cushioning in less time than it takes for a human knee-jerk reaction, according to Adidas.

The company said that its engineers struggled with a multitude of sticky technical issues, including durability and software creation, before settling on the final design. To maintain durability, they ultimately used a flexible printed-circuit board, which starts at the heel and wraps around the side to the shoe's "upper."

"We didn't want to rely on connectors, because they tend to be the weakest link in a circuit," DiBenedetto said. "With a flexible printed circuit, we could do it all in one piece and have the most affordable system possible." The company said it expects the new shoe to sell for around $250.

Because no shoe manufacturer had ever done real-time studies of sole compression, Adidas' engineers researched the subject in-house by studying runners and building a database of their findings. The data was then tapped to build the software algorithm on which the shoe bases its decision-making process.

By "watching" the compression data, DiBenedetto said, the microcontroller can determine the runner's size and speed, as well as the characteristics of the running surface. It can even detect fatigue, he said, and adjust the cushioning accordingly to guard against injury.

Adidas engineers said creation of the software algorithms was among the most complex challenges, in part because the design team consisted of mechanical engineers who had scant programming experience. Thus the team went back to school, signing up for a course in programming Microchip's PIC16F88 MCU.

"We didn't have much choice," DiBenedetto said. "We flew to Chicago, took classes and started writing code."

Big business

Adidas isn't the only company adding intelligence to shoes. VectraSense Technologies has been producing smart shoes for long years. Its first effort, called the ThinkShoe and introduced in 2001, combined a Motorola microcontroller with an integrated air pressure system to maintain optimal cushioning. Now it's hinting its shoes will "talk" while you walk.

And MIT's Media Lab has developed a series of intelligent shoes, the most recent being a student PhD project, completed two weeks ago, that tucks a wearable sensor package in a shoe. The sensor, together with software algorithms and other associated electronics, serves as part of a physical-therapy system to help patients manage chronic disorders that can affect gait.

The Media Lab has developed other forms of electronic footwear, including a shoe that lets wearers produce musical streams by moving their feet, as well as microelectronics-based systems that let walkers generate power for wearable subsystems. There are no plans at present to commercialize the developments. "We're all looking at these kinds of systems," said Joe Paradiso, an associate professor at the lab. "People won't buy a technology unless it really helps them run."

Analyst Enderle considers the rise of wearable computing inevitable, citing the development of thermally regulating intelligent outerwear and garments that embed antennas to strengthen cell phone signals. As for intelligent shoes, "People could end up wearing them as day shoes, just to show off," he said. "It could fade away from the legitimate running-shoe category pretty quickly." Still,"If ring tones can become a billion-dollar business, wearable computing will be at least as big."

GPS EMBEDDED SNEAKERS

Miami based Isaac Daniel’s Compass Global 1000(TM)pushes the limits of how technology can function in footwear with GPS tracking abilities.

The GPS technology, embedded into seven different men’s and women’s sneaker models with 19 color combinations, are outfitted with a microcomputer with satellite tracking communication that, in the event of a perceived crisis by the wearer, can activate a Covert Alarm Locator. The alarm generates an emergency signal to the company’s ID Conex monitoring station, pinpointing the shoes’ location anywhere on the earth’s surface. The whereabouts of the wearer are then communicated to law enforcement authorities.



The need for Daniel’s line of Quantum Satellite Technology across a broad range of demographic groups has been proven. The company is currently in negotiations to market the Compass Global sneaker — and in the future, boots and shoes — to various military outfits, caretakers of those suffering from Alzheimer’s disease, and parents who want the ability to keep track of their young children. The need for this type of sneaker has already been recognized by the public and the press with feature stories in The New York Post, Women’s Wear Daily, and Fitness and Footwear Plus magazines.



Created by inventor and designer, Isaac Daniel, the Compass Global 1000(TM) is, says Daniel, “a ground-breaking product that is set to change people’s minds about how sneakers can be worn and their purpose in our lives. The Compass Global 1000(TM) is a sneaker for new realities in the new millennium.”

EMBEDDED SYSTEMS

An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions. It is usually embedded as part of a complete device including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal computer, can do many different tasks depending on programming.

Since the system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product, or increasing the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.



Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.

In general, "embedded system" is not an exactly defined term, as many systems have some element of programmability. For example, Handheld computers share some elements with embedded systems - such as the operating systems and microprocessors which power them - but are not truly embedded systems, because they allow different applications to be loaded and peripherals to be connected.

APPLICATIONS OF EMBEDDED SYSTEMS

1.) Audio like mp3 players and telephone switches for interactive voice response systems



2.)Avionics, such as inertial guidance systems, flight control hardware/software and other integrated systems in aircraft and missiles



3.)Cellular telephones and telephone switches



4.)Electric or Electronic Motor controller for Brushless DC motors, Induction motors and DC Motors



5.)Engine controllers and antilock brake controllers for automobiles



6.)Home automation products, such as thermostats, air conditioners, sprinklers, and security monitoring systems



7.)Handheld calculators



8.)Household appliances, including microwave ovens, washing machines, television sets, DVD players and recorders



9.)Medical equipment



10.)Personal digital assistant



11.)Videogame consoles



12.)Computer peripherals such as routers and printers



13.)Industrial controllers for remote machine operation



14.)Digital musical instruments (digital synthesizers and digital pianos).



15.)Security applications such as DVR and video server.



CHARACTERISTICS OF EMBEDDED SYSTEMS

1) Embedded systems are designed to do some specific task, rather than be a general-purpose computer for multiple tasks. Some also have real-time performance constraints that must be met, for reason such as safety and usability; others may have low or no performance requirements, allowing the system hardware to be simplified to reduce costs.

2) Embedded systems are not always separate devices. Most often they are physically built-in to the devices they control.

3) The software written for embedded systems is often called firmware, and is stored in read-only memory or Flash memory chips rather than a disk drive. It often runs with limited computer hardware resources: small or no keyboard, screen, and little memory.



User interfaces

Embedded systems range from no user interface at all - dedicated only to one task - to full user interfaces similar to desktop operating systems in devices such as PDAs.

Simple systems

Simple embedded devices use buttons, LEDs, and small character- or digit-only displays, often with a simple menu system.

Complex Systems

A full graphical screen, with touch sensing or screen-edge buttons provides flexibility while minimising space used: the meaning of the buttons can change with the screen, and selection involves the natural behavior of pointing at what's desired.

Handheld systems often have a screen with a "joystick button" for a pointing device.

The rise of the World Wide Web has given embedded designers another quite different option: providing a web page interface over a network connection. This avoids the cost of a sophisticated display, yet provides complex input and display capabilities when needed, on another computer. This is successful for remote, permanently installed equipment. In particular, routers take advantage of this ability.

CPU platform

Embedded processors can be broken into two distinct categories: microprocessors (μP) and microcontrollers (μC). Microcontrollers have built-in peripherals on the chip, reducing size of the system.

There are many different CPU architectures used in embedded designs such as ARM, MIPS, Coldfire/68k, PowerPC, x86, PIC, 8051, Atmel AVR, Renesas H8, SH, V850, FR-V, M32R, Z80, Z8, etc. This in contrast to the desktop computer market, which is currently limited to just a few competing architectures.



PC/104 and PC/104+ are a typical base for small, low-volume embedded and ruggedized system design. These often use DOS, Linux, NetBSD, or an embedded real-time operating system such as MicroC/OS-II, QNX or VxWorks.


(PC/104 SYSTEM DESIGN)

A common configuration for very-high-volume embedded systems is the system on a chip (SoC), an application-specific integrated circuit (ASIC), for which the CPU core was purchased and added as part of the chip design. A related scheme is to use a field-programmable gate array (FPGA), and program it with all the logic, including the CPU.


(SOC EMBEDDED DESIGN)


(ASIC DESIGN FLOW)



Peripherals

Embedded Systems talk with the outside world via peripherals, such as:

1.)Serial Communication Interfaces (SCI): RS-232, RS-422, RS-485 etc


(RS232 CABLE)


(RS422 CABLE)

2.)Synchronous Serial Communication Interface: I2C, JTAG, SPI, SSC and ESSI


(I2C INTERFACE)

3.)Universal Serial Bus (USB)



4.)Networks: Ethernet, Controller Area Network, LonWorks, etc





5.)Timers: PLL(s), Capture/Compare and Time Processing Units

6.)Discrete IO: aka General Purpose Input/Output (GPIO)



7.)Analog to Digital/Digital to Analog (ADC/DAC)



Tools

As for other software, embedded system designers use compilers, assemblers, and debuggers to develop embedded system software. However, they may also use some more specific tools:

1.)In circuit debuggers or emulators.
2.)Utilities to add a checksum or CRC to a program, so the embedded system can check if the program is valid.
3.)For systems using digital signal processing, developers may use a math workbench such as MATLAB, Simulink, MathCad, or Mathematica to simulate the mathematics. They might also use libraries for both the host and target which eliminates developing DSP routines as done in DSPnano RTOS and Unison Operating System.
4.)Custom compilers and linkers may be used to improve optimisation for the particular hardware.
5.)An embedded system may have its own special language or design tool, or add enhancements to an existing language.
6.)Another alternative is to add a Real-time operating system or Embedded operating system, which may have DSP capabilities like DSPnano RTOS.

Software tools can come from several sources:

1.)Software companies that specialize in the embedded market
2.)Ported from the GNU software development tools
3.)Sometimes, development tools for a personal computer can be used if the embedded processor is a close relative to a common PC processor

As the complexity of embedded systems grows, higher level tools and operating systems are migrating into machinery where it makes sense. For example, cellphones, personal digital assistants and other consumer computers often need significant software that is purchased or provided by a person other than the manufacturer of the electronics. In these systems, an open programming environment such as Linux, NetBSD, OSGi or Embedded Java is required so that the third-party software provider can sell to a large market.

Debugging

Embedded Debugging may be performed at different levels, depending on the facilities available. From simplest to most sophisticated they can be roughly grouped into the following areas:

1.)External debugging using logging or serial port output to trace operation using either a monitor in flash or using a debug server like the Remedy Debugger which even works for heterogeneous multicore systems.
2.)An in-circuit debugger (ICD), a hardware device that connects to the microprocessor via a JTAG or NEXUS interface. This allows the operation of the microprocessor to be controlled externally, but is typically restricted to specific debugging capabilities in the processor.
3.)An in-circuit emulator replaces the microprocessor with a simulated equivalent, providing full control over all aspects of the microprocessor.
4.)A complete emulator provides a simulation of all aspects of the hardware, allowing all of it to be controlled and modified, and allowing debugging on a normal PC.

Unless restricted to external debugging, the programmer can typically load and run software through the tools, view the code running in the processor, and start or stop its operation. The view of the code may be as assembly code or source-code.

Reliability

Embedded systems often reside in machines that are expected to run continuously for years without errors, and in some cases recover by themselves if an error occurs. Therefore the software is usually developed and tested more carefully than that for personal computers, and unreliable mechanical moving parts such as disk drives, switches or buttons are avoided.

Recovery from errors may be achieved with techniques such as a watchdog timer that resets the computer unless the software periodically notifies the watchdog.

Specific reliability issues may include:

1.)The system cannot safely be shut down for repair, or it is too inaccessible to repair. Solutions may involve subsystems with redundant spares that can be switched over to, or software "limp modes" that provide partial function. Examples include space systems, undersea cables, navigational beacons, bore-hole systems, and automobiles.
2.)The system must be kept running for safety reasons. "Limp modes" are less tolerable. Often backups are selected by an operator. Examples include aircraft navigation, reactor control systems, safety-critical chemical factory controls, train signals, engines on single-engine aircraft.
3.)The system will lose large amounts of money when shut down: Telephone switches, factory controls, bridge and elevator controls, funds transfer and market making, automated sales and service.

High vs Low Volume

For high volume systems such as portable music players or mobile phones, minimizing cost is usually the primary design consideration. Engineers typically select hardware that is just “good enough” to implement the necessary functions.

For low-volume or prototype embedded systems, general purpose computers may be adapted by limiting the programs or by replacing the operating system with a real-time operating system.



Embedded software architectures

There are several different types of software architecture in common use.

Simple control loop

In this design, the software simply has a loop. The loop calls subroutines, each of which manages a part of the hardware or software.

Interrupt controlled system

Some embedded systems are predominantly interrupt controlled. This means that tasks performed by the system are triggered by different kinds of events. An interrupt could be generated for example by a timer in a predefined frequency, or by a serial port controller receiving a byte.

These kinds of systems are used if event handlers need low latency and the event handlers are short and simple.

Usually these kinds of systems run a simple task in a main loop also, but this task is not very sensitive to unexpected delays. The tasks performed in the interrupt handlers should be kept short to keep the interrupt latency to a minimum.

Sometimes longer tasks are added to a queue structure in the interrupt handler to be processed in the main loop later. This method brings the system close to a multitasking kernel with discrete processes.

Cooperative multitasking

A nonpreemptive multitasking system is very similar to the simple control loop scheme, except that the loop is hidden in an API. The programmer defines a series of tasks, and each task gets its own environment to "run" in. Then, when a task is idle, it calls an idle routine (usually called "pause", "wait", "yield", "nop" (Stands for no operation), etc.).

The advantages and disadvantages are very similar to the control loop, except that adding new software is easier, by simply writing a new task, or adding to the queue-interpreter.

Preemptive multitasking or multi-threading

In this type of system, a low-level piece of code switches between tasks or threads based on a timer. This is the level at which the system is generally considered to have an "operating system", and introduces all the complexities of managing multiple tasks or threads running seemingly at the same time.

Any piece of task or thread code can damage the data of another task or thread; they must be precisely separated. Access to shared data must be controlled by some synchronization strategy, such as message queues, semaphores or a non-blocking synchronization scheme.

Because of these complexities, it is common for organizations to buy a real-time operating system, allowing the application programmers to concentrate on device functionality rather than operating system services.

Microkernels and exokernels

A microkernel is a logical step up from a real-time OS. The usual arrangement is that the operating system kernel allocates memory and switches the CPU to different threads of execution. User mode processes implement major functions such as file systems, network interfaces, etc.



In general, microkernels succeed when the task switching and intertask communication is fast, and fail when they are slow.

Exokernels communicate efficiently by normal subroutine calls. The hardware, and all the software in the system are available to, and extensible by application programmers.

Monolithic kernels

In this case, a relatively large kernel with sophisticated capabilities is adapted to suit an embedded environment. This gives programmers an environment similar to a desktop operating system like Linux or Microsoft Windows, and is therefore very productive for development; on the downside, it requires considerably more hardware resources, is often more expensive, and because of the complexity of these kernels can be less predictable and reliable.



Common examples of embedded monolithic kernels are Embedded Linux and Windows CE.

Despite the increased cost in hardware, this type of embedded system is increasing in popularity, especially on the more powerful embedded devices such as Wireless Routers and GPS Navigation Systems. Here are some of the reasons:

1.)Ports to common embedded chip sets are available.
2.)They permit re-use of publicly available code for Device Drivers, Web Servers, Firewalls, and other code.
3.)Development systems can start out with broad feature-sets, and then the distribution can be configured to exclude unneeded functionality, and save the expense of the memory that it would consume.
4.)Many engineers believe that running application code in user mode is more reliable, easier to debug and that therefore the development process is easier and the code more portable.
5.)Many embedded systems lack the tight real time requirements of a control system. A system such as Embedded Linux has fast enough response for many applications.
6.)Features requiring faster response than can be guaranteed can often be placed in hardware.
7.)Many RTOS systems have a per-unit cost. When used on a product that is or will become a commodity, that cost is significant.

Exotic custom operating systems

A small fraction of embedded systems require safe, timely, reliable or efficient behavior unobtainable with the one of the above architectures. In this case an organization builds a system to suit. In some cases, the system may be partitioned into a "mechanism controller" using special techniques, and a "display controller" with a conventional operating system. A communication system passes data between the two.