Sensor architecture allows real-time auto emissions monitoring, Pt. 1

As opposed to current periodic emission-control system testing—sensors, MCUs, and memory come together in an updated approach to real-time exhaust monitoring for improved pollution control.


"Green" is the buzzword these days. Globally, various organizations are striving to make their processes as eco-friendly as possible, with the automotive industry one of the leaders in this endeavor.

Vehicle-emissions are being strictly monitored and emission-norms being revised regularly to ensure a "greener" and pollution-free environment. However, present vehicle pollution-checking is still dependent on old mechanisms of manual-regular-checking of the auto-exhaust. The exhausts are sensed and analyzed by a machine and a pollution certificate is issued.

This article highlights inherent limitations of this traditional approach and proposes a real-time exhaust monitoring solution to enforce better pollution control for a greener future."

The challenges of emission pollution control
Probably, pollution is one of the biggest problems which humankind is facing today and the worst part is that the pollution has reached such a level that we have ourselves stuck in a vicious cycle of this evil and auto emission is one of the biggest contributors. Automobiles used worldwide produce vast amount of harmful exhausts including carbon dioxide, carbon monoxide, nitrogen oxides (NO_X), and un-burned hydrocarbons. All these add to greenhouse gases and are significant contributors to global warming.

Taming this devil has become one of the biggest challenges for the governments worldwide. Adoption of cleaner fuels like compressed natural gas and commercial development of hydrogen-based automobiles is one of the priorities for many agencies. However, before we can reach such a long-term, fool-proof solution, probably the easiest and the cheapest solution is to keep the pollution emissions of the current automobiles in check.

In every country, the emission norms are regulated by the respective pollution control regulatory body. Vehicles are checked for their emissions and if exhaust is within the specified limit, a certificate might be issued for the vehicle, which may come with an expiry date. However, this system has its own loopholes—the system only checks for the emissions on the date of the test, not in between the two test dates. Also, the data is not under load conditions, which might change according to the age and condition of the vehicle. Besides, many factors like engine-tuning, adulteration of fuel, etc might increase the pollution temporarily and may move it to an unacceptable level.

Instead, we can have some mechanism in place which would signal the real-time pollution level data of the vehicle to the owner/driver and also, if required, to the monitoring and controlling authority (via wireless communication). This way, we can implement a rather strict pollution check regime.

In such a case, there might not be any need for regular pollution checks and issuance of vehicle fitness certificates. The authority may take appropriate action against repetitively defaulting vehicle/owners. This would ensure better upkeep of the vehicles and as a result, good upkeep of the environment! The rest of this article deals with the technical implementation of the above mentioned system/regime.

Proposed solution architecture
The basic blocks required for above mentioned real-time monitoring mechanism include: Profiling of the exhaust gases, conversion of this data into digital form, storing and processing the data, display of the result, and transmission of the data. Each of these blocks works together to generate the desired results. The micro-level architecture of the proposed solution is shown below. Discussion of the operation of the above mentioned blocks follows.


Profiling the exhaust gases
An array of sensors can be used to sense the amount of various components of the exhaust. These sensors would be giving real-time information of the exhaust components such as carbon monoxide, nitrous oxide, etc. The sensors can give either digital output or analog output.

If sensors with digital outputs are used, then they can be interfaced with some timer module of the MCU (microcontroller) to quantify the output. In case the sensors are of the analog output type, then the next mentioned block (converter, next page) would be used to make the output usable by the MCU.

Another alternative could be to use the data from the engine control and management unit (ECMU). This information could serve to replace the network of sensors. However, this method may suffer from relative inaccuracy because sensors directly sense the exhaust, and thus are able to give more accurate results as compared to the ECMU data. But again, that statement is based upon the assumption that the array would give fairly accurate results and the fact that the array would be sitting right at the exhaust, sensing the real-time information.