As portable computing devices become increasingly smaller and lightweight, fewer customized hardware based computing solutions are incorporated directly into the device. This is especially true for tablet PCs that traditionally incorporate usb or serial I/O to expand the built-in capabilities of the device. The typical expansion solutions that exist for tablet PCs plug into one of these usb/serial expansion ports and may be coupled by cable to an electronic module that provides additional functionality to the tablet. While the usb/serial interface can provide practically all customized functionality, tablet I/O mechanical connections including proprietary, usb type A, and usb type B connectors have poor mechanical characteristics with little or no strain relief and may be easily dislodged during portable operation. When a customized tablet computing solution is achieved by adding the electronic module at the end of a cable, the elegance and efficiency of the tablet PCs mobility and form factor are compromised. Many expansion devices intended for mobile computing are coupled to the tablet PC using a cradle or sled approach to enhance the mobility, mechanical rigidity, and electrical connection to the tablet PC. These cradle and sled attachments tend to be bulky, and do not maintain the elegant weight and size profiles of the original tablet PC. Expansion bays to add functionality currently exist in some rugged tablet PCs and stylus PCs however they are generally internal pockets with limited access or are located on the back or edge of the PC behind cover plates. The rugged tablet PCs, available with expansion bays, are constructed with housings and components that can be exposed to environments where mechanical stresses to the unit and exposure to various wet and dusty conditions will not harm the PC. Portable Tablet based modular data acquisition systems are needed for this type of environment.
The human interface device on these mobile platforms has also evolved from traditional keyboards and mouse to stylus touchscreens, multi-touch gesture based touchscreens, voice recognition, and hand gesture analysis. Portable Tablet based modular data acquisition systems are needed using advanced human interface devices.
Today's mobile platforms are highly energy efficient. Some rugged tablet PCs have a second hot swappable battery so that the tablet PC can run in a mobile untethered mode indefinitely. When the tablet PC is used for data acquisition some sensors attached to it require very low power to operate. It would be ideal to use the tablet PC's power instead of requiring additional power sources. Portable Tablet based modular data acquisition systems that provide power to sensors through the data acquisition module and through the data acquisition carrier are needed.
Some of the hardware functionality desired on a tablet-based platform is the ability to make measurements including process monitoring, electrical measurements, mechanical measurements, chemical analysis and various measurements of physical phenomena. The tablet PC could process these measurements to perform complex data analysis, perform data logging and to control electrical and mechanical equipment. This functionally is all well known in the art collectively as data acquisition systems. There are many manufacturers of data acquisition systems and each may provide a fixed or modular system to make measurements. A modular system has the ability to select an electronic module suitable for the type of measurement desired and interchange it in a chassis when that measurement configuration is desired. One such company that makes modular data acquisition systems is National Instruments based out of Austin, Tex. National Instruments has several versions of modular data acquisition systems where the system has a sensor attached to a carrier attached to a computer. The commercialized version of the technology tends to be designed for desktop use where very complex combinations of measurements are possible. The mobile version of modular data acquisition as illustrated on National Instruments website, NI.com, has a data acquisition chassis tethered at the end of a cable to a laptop. With the popularity of tablet PCs, it would be nice to take this data acquisition technology and migrate it from a desktop platform to a fully mobile platform. To do this, the most compact form of a National Instruments data acquisition chassis can be adapted to attach to the tablet PC. Their most compact system is comprised of 50 different measurement modules capable of hundreds of different types of measurements that can be inserted into several different chassis comprising 1, 4, or 8 slots. These chassis then connect to a computer via usb, Ethernet, wifi or integrated controller forming a complete data acquisition system. The National Instruments system is called cDaq or CompactDaq and is protected by a dozen US patents. A majority of these patents detail specific elements of the system such as programmable elements, defining interfaces, configuring measurements, module design, and protocols between modules, carriers and computers. Just a few describe an overall system architecture however like all technological evolutions the reduction to practice often requires additional elements and novel methods to commercialize them.
What is needed is a single slot data acquisition chassis attached to a rugged tablet PC that accepts attachably detachable expansion modules to create a rugged tablet PC based modular data acquisition system.