What is an Occupant Detection System (ODS)? How Does an ODS Work?

Stanley Subaru answers these questions with this week's Technical Schmecnical Lesson.

Federal Motor Vehicle Safety Standards require the use of an Occupant Detection System (ODS). This system is designed to determine if a person is seated in the front passenger seat*, and, more importantly, if the person is of adequate size to be protected in the event of the deployment of the front passenger seat airbag (SRS) in a moderate to severe frontal collision.

Most Occupant Detection Systems measure the weight of the front seat passenger, to determine if the front passenger seat airbag should deploy.

All 2012 and 2013 Impreza and 2013 BRZ models use a new type of Occupant Detection System called Electrostatic Capacitance Sensor ODS. This system does not use weight to determine whether to turn the Occupant Detection System ON and OFF. 

The Electrostatic Capacitance represents a material's capability of storing an electrical charge.  Have you ever been shocked when walking across a carpeted floor and touching a doorknob? This demonstrates your ability to store an electrical charge in your body.

When anyone is seated or when anything is placed on the front passenger seat, there is a change to that capacitance value.  This change in capacitance value is what the Electrostatic Capacitance Sensor ODS uses to determine whether the front passenger seat airbag (SRS) will be ON or OFF.

Everything that is placed on the seat will affect a change in capacitance value.  The system can determine whether to change the OFF status of an airbag to ON depending on what is on the passenger seat which in turn causes a change in capacitance value. 

Some examples:

>A proper sized passenger will change the OFF status of an airbag to ON.

>Platic, metals and other substances, even if at a heavy weight, will not change the OFF status of an airbag.

>A false electrical charge, for example, those caused by laptops that are processing data, cellphones that are on, or even an electric device connected to a car charger can cause the airbag status to switch ON.

>When water or anything with high moisture content is spilled on the front passenger seat cushion, the airbag is designed to remain OFF until the seat cushion is dry.  This will also be the case if the passenger has moisture on their clothing, such as rain-soaked pants or rain gear.  In each of these situations, the airbag status may remain OFF even if a passenger is seated.

The Electrostatic Capacitance Sensor ODS on 2012 and 2013 Impreza and 2013 BRZ models uses a low level electrical charge to determine what is on the front passenger seat.  This low level charge will NOT result in an electrical shock.

Passengers are advised NOT to sit in the front passenger seat if the seat cushion is wet or if their clothing is wet.  The best way to ensure proper operation is to keep everything off the front seat except a passenger. 

Remember, anything not belted in can be a projectile in the event of a crash and could increase injuries.

For more detailed information, please read and understand the Owner's Manual.

*Passengers seated in the front of the vehicle must meet all State and Federal Regulations according to the Federal Motor Vehicle Safety Standard 208. Never install a child seat or booster seat in the front of the vehicle. See Owner Manual for more details.

Categories: Technical Schmecnical