What is Rugged

As the portable computer market evolves, an ever growing number of vendors claim to have "ruggedized" computers. As such how can decision makers tell how rugged a computer really is?

Truly rugged computing devices are engineered, inside and out, to operate in a range of hostile environments. Their design encompasses the external housing, internal components, special coatings, and seals among others allowing them to function correctly in operating environments ranging from challenging to extreme.
Mobile Workers that are required to operate outside of a controlled office environment are ideal candidates for a rugged Tablet PC.

Customers have to rely on a product’s specifications and warranty statements to evaluate the amount of ruggedisation included in the product’s design. Since specifications vary from product to product a number of ratings and standards established by various government agencies and industry associations such as the Military Standards for Environmental Testing (MIL-STD-810F) are available to help even out the evaluation process and provide a better assessment of a product’s ruggedisation.

Because certain ratings, standards and test methods are subject to interpretation closer scrutiny of a vendor’s claims is recommended. To clearly understand a device’s ability to perform where it will be used it is important to obtain detailed testing information (validated by an independent body) and warranty statements from the manufacturer to verify a product’s ability to operate in those environments.

Splash Down

Military Standards for Environmental Testing

Published by the U.S Department of Defense the MIL-STD-810F specification is a series of guidelines and test methods for determining the effects of natural and induced environments on equipment used in military or commercial applications. Below is a summary of the key standards and tests that determine a product's level of ruggedisation and ability to operate in harsh environments. UUT is the anacronym for Unit Under Test.

Drop
Truly rugged products should have a correlating drop specification that defines that device's ability to withstand the shock of a fall to a non-yielding surface. This is 4' to concrete, while operating, on all corners, sides and edges which is the typical standard for proper testing and is what users typically encounter. If this distance and surface are not clearly stated, or are less than below, in a product's specification then said product's drop specification should be questioned.

Characteristic	Requirement	Test Method	Unit Status
Transit Shock	48 in drop, concrete, all surfaces, edges and corners (26 drops)	MIL-STD-810F Method 516.5	Test must be conducted while the UUT is operating. Permanent loss of function is not acceptable.

Shock
Truly rugged products should have correlating mechanical and crash shock specifications that define the device's ability to withstand the shock of an impact (repetitive) or collison (particulary if mounted in a vehicle). These types of shocks affect the computer's performance while operating and are conditions that users commonly encounter in the field. If the mechanical and/or crash shock specifications are not clearly stated, or are less than below, in a product's specification then said product's shock specification should be questioned.

Characteristic	Requirement	Test Method	Unit Status
Mechanical Shock	20g, 11ms, Terminal Sawtooth, Operating 40g, 11ms, Terminal Sawtooth, Non-Operating	MIL-STD-810F Method 516.5	Test must be conducted while the UUT is operating. Loss of critical function is not acceptable.
Crash Shock	75g, 11ms, Terminal Sawtooth	MIL-STD-810F Method 516.5	Test conducted while the UUT is non-operating in the vehicle mount. Loose, protruding or hazardous parts are not acceptable.

Vibration
Truly rugged products should have correlating vibration specifications that define the device's ability to withstand the constant effects of vibration (particulary if mounted and operated in a vehicle). Recurring vibration affects the computer's performance while operating and is one of the leading conditions resulting in system failure. If the vibration specifications are not clearly stated, or are less than below, in a product's specification then said product's vibration specification should be questioned.

Characteristic	Requirement	Test Method	Unit Status
Vibration (Integrity)	Minimum Integrity Test 0.04g^2/Hz, 20Hz – 1000Hz -6dB/octive 1000Hz – 2000Hz Figure 514.5C-17	MIL-STD-810F Method 514.5	Test must be conducted while the UUT is operating. Temporary, intermittent or permanent loss of function is not acceptable.
Vibration (Vehicle)	Composite Wheeled Vehicle Figure 514.5C-3	MIL-STD-810F Method 514.5	Test must be conducted while the UUT is operating. Temporary loss of function is acceptable only if recovery is automatic and does not require user intervention.

Enclosure
Truly rugged products should have correlating enclosure class specifications that define the device's ability to withstand the effects of contaminants such dust and moisture and other detrimental conditions such as solar radiation and salt fog. Taken together these specifications allow a product to properly function in a variety of harsh environments and protect the internal components from damage. If the enclosure specifications are not clearly stated, or are less (or omitted) than below, in a product's specification then said product's enclosure class specification should be questioned.

Characteristic	Requirement	Test Method	Unit Status
Relative Humidity	0% to 95% (+3/-5%) non-condensing, 23º C to 60ºC, 10 cycles of 48 Hr.	MIL-STD-810F Method 507.4	Test must be conducted while the UUT is operating. Ingress of moisture is not acceptable.
Solar Radiation	1120 W/m2 (355 Btu/ft2/hr) UVB @ 50oC, 7x24 ;hr cycles	MIL-STD-810F Method 505.4	Test conducted while the UUT is non-operating. Fading or degradation of material composition is not acceptable.
Rain	Blowing Rain 4"/Hr, 40mph Wind	MIL-STD-810F Method 506.4 Procedure I	Test must be conducted while the UUT is operating. Ingress of moisture is not acceptable.
Rain	Drip Proof 7 gal/ft2/hr	MIL-STD-810F Method 506.4 Procedure III (Drip)	Test must be conducted while the UUT is operating. Ingress of moisture is not acceptable.
Sand & Dust	Particle Size <149 mm, 10 ± 7 g/m3 particle density 1.5 m/s to 8.9 m/s Wind Speed	MIL-STD-810F Method 510.4 Procedure I (Blowing Dust)	Test must be conducted while the UUT is operating. Ingress of sand or dust is not acceptable.
Salt Fog	5% saline for 48 hr (12 hr. wet, 12 hr. dry, 2 cycles)	MIL-STD-810F Method 509.4	Test must be conducted while the UUT is operating. Fading or degradation of material composition is not acceptable. Ingress of moisture is not acceptable.
Contamination by Fluids	Detergents, brake fluid, aromatic hydrocarbons	Verified by Analysis	Test conducted while the UUT is non-operating. Fading or degradation of material composition is not acceptable.
(1) Immersion	Immerse system to 30 cm in water - Wait for 30 minutes, verify no bubbles from unit	MIL-STD-810F Method 512.4 Procedure 1	Test must be conducted while the UUT is operating. Temporary, intermittent or permanent loss of function is not acceptable.

Temperature
Truly rugged products should have correlating operating and storage temperature specifications that define the device's ability to withstand the effects of extreme temperature environments, especially when the device is used outside or mounted in a vehicle. If the temperature specifications are not clearly stated, or are less than below, in a product's specification then said product's temperature specification should be questioned.

Characteristic	Requirement	Test Method	Unit Status
Operating Temperature	-20º C to +60º C	MIL-STD-810F Methods 501.4, 502.4	Test must be conducted while the UUT is operating. Temporary, intermittent or permanent loss of function not acceptable.
Storage Temperature	-40ºC to +75ºC	MIL-STD-810F Methods 501.4, 502.4	Test conducted while the UUT is non-operating. Permanent loss of function not acceptable.
Thermal Shock	> 1.5º C < 5º C / min -20º C to +60º C	Verified during temperature cycle testing above	Test must be conducted while the UUT is operating. Temporary, intermittent or permanent loss of function not acceptable.

Summary
To truly understand a computer's "ruggedness" decision makers need to understand both the specification definitions and how the vendor determined a particular product's specifications. Understanding a computer's ruggedization specifications is critical when purchasing a ruggedized device. To aid in a real world application of these specifications the table below is presented:

Test	Real World Event
Drop	· The navigator drops the computer from chest height (when holding the device in the crook of the arm) while processing data. · The operator accidentally drops the computer while moving between port & starboard rails
Shock	· The computer sustains unexpected force when mounted in a yacht and that yacht is involved in a collision or the computer is struck when in operation.
Vibration	· The computer is constantly shaken from the low level vibration associated with engine noise while mounted in yacht · The computer is exposed to vibration extremes as part of everyday use i.e. bumpy water
Sand, Dust and Moisture	· The computer is used to complete mission critical tasks in varying environments that include rain or dust
Temperature	· The computer is used by operators in all kind of variable temperature environments for instance it may be left sitting mounted in a yacht with hot summer sun beating in while the operator is on deck. It must function immediately when the operator returns to the chart table. · The computer is used in frigid temperatures and must be ready to function when needed by the operator.
Thermal Shock	· On a summer day the computer is moved from an air conditioned cabin on to deck and then moved back to the cabin.

Military Standards for Environmental Testing

Drop

Shock

Vibration

Sand, Dust and Moisture

Temperature

Thermal Shock