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As a part of the driver control group in BMM6 team, the author is going to show his design and present his process and contribution in designing BMM6 throughout the past 7 months in the ECU and Mapping domain. The following report includes all the required specifications for mapping attached with the details of every single part that is connected to the ECU.
ECU stands for electronic control unit. It controls the fuel injection duration and timing and ignition timing at given load and rpm. Also, ECU plays the role of sensors controller and organizer in which it receives signal and data from each sensor and controls via the ECU program. This software is being installed on a microprocessor ships to maintain right engine operation.
The ECU uses closed-loop control, a control scheme that monitors outputs of a system to control the inputs to a system, managing the emissions and fuel economy of the engine (as well as a host of other parameters). Gathering data from dozens of different sensors, the ECU knows everything from the coolant temperature to the amount of oxygen in the exhaust. With this data, it performs millions of calculations each second, including looking up values in tables, calculating the results of long equations to decide on the best spark timing and determining how long the fuel injector is open. The ECU does all of this to ensure the lowest emissions and best mileage (Karim Nice. 2009).
An ECU is basically made up of hardware and software (firmware). The hardware is basically made up of various electronic components on a PCB. The most important of these components is a microcontroller chip along with a Flash memory chip. The software (firmware) is a set of lower-level codes that runs in the microcontroller.
The ECU is characterized by:
· Many analogue and digital I/O lines (low and high power).
· Power device interface/control
· Different communication protocols (CAN, KWP-2000, etc.).
· Large switching matrices for both low and high power signals
· High voltage tests
· Intelligent communication interface adapters
· Automatic fixture recognition and software sequence enable
· Power device simulation (National Instruments. 2009)
Mapping: mapping is the process of adjusting variable and saving these adjustments on the ECU for maximum efficiency taking into account other variables of the engine. Thus, mapping is usually made while running and the engine on the DYNO after connecting all the electronic components. Those connections are dependent on the connectors and the datasheets. While running the engine, the program shows the variables varying while increasing the rpm of the engine and the dyno torque on the other hand.
Engine mapping is done through software that relates all variables together. That software is designed by the ECU manufacturer. Also, the manufacturer usually designs another software for analyzing the received data during mapping. As for our case in BMM6, we are going to reuse Motec M400 (as shown in figure 1) ECU from BMM5. So, Motec manager will be the software for which we are going to perform the engine mapping through. On the other hand, i2 is the name of the software for analyzing the data. M400 controls engines up to four injectors with four ignition outputs.
Figure 1 Motec M400
The software can be downloaded from the MoTeC web site at www.motec.com.au, or is available on CD.
Automobiles in recent years are becoming more electronically controlled in order to improve safety and environmental characteristics, and these control methods are becoming complicated year after year. Because of that, ECU is becoming a must in each car controlling not only the electronic parts, but also the mechanical parts as well. ECU has a lots of works to do in order to organize the timing, functioning and maintaining the engine as a whole functioning as designed to function.
These units are now being linked and interact to control functions such as the immobiliser system, climate control, traction control, fly-by-wire throttle, anti-lock braking, stability control and active suspension & differentials (Taramos , 2008).
Recently, manufacturers started to add microprocessor chips playing the role of a memory for the ECU variables. These "chips" could be removed from the unit, read and then the data could be analysed. This data was not deliberately obscure, however when downloaded it was simply a sequence of numbers and makes very little sense (Taramos , 2008).
Nowadays, the role of the chips inside the ECU is being widen in which micro-processor chips is taking bigger place in controlling process and in which programming that kind of chips is being also more complicated. Modern ECUs can save much more data than the older ones. That is because of the more sensors that are being added to cars year after year.
Douglas Sutton, 1991 .According to projections by the German car industry, the share of electronic components in the cost of production is seen rising from the current 10 percent to around 25 percent by the year 2000. Initially, the development of the data bus is primarily being aimed at expanding and linking the electronic equipment functions.
Bob Sikorsky, 1992. Newer vehicles add a fourth dimension, that of electronic sensors and computer engine controls. Sensors control the timing of the spark and the amount of fuel and air an engine receives. It's not uncommon to find a bad sensor at the bottom of a troublesome start situation.
JIM MOTAVALLI , 2004.Until the late 1970's, a car's fuel-and-air mixture was regulated by the carburetor, a relatively simple device as old as the automobile itself. But today's fuel injection systems are controlled by increasingly powerful onboard computers that regulate combustion efficiency, govern fuel economy and regulate emissions to federal and state standards. In most cases, when setting up a vehicle's computer, carmakers choose conservative settings that will allow the greatest gas mileage and cut down on maintenance problems, but will not always deliver the to-the-limits performance that owners want.
The modified engine control units improve engine performance and drivability thanks to closed loop control. Every engine and vehicle parameter is managed and controlled by three master control units and a satellite control unit. The master control units consist of two Lamborghini LIE engine control units, a Lamborghini GFA (Auxiliary Function Management) control unit and a Lamborghini PMC (Power Motor Control) satellite control unit. The control units are interconnected by a CAN Bus line (gizmag, 2010).
Design and Specifications.
Since we are going to use the Motec M400 ECU that was used in BMM5, our work won't be that difficult in which most of the information and specifications about the ECU are available including the datasheet. Motec M400 is designed for four injector drivers and four ignition outputs and for engines up to four cylinders as shown in Figure2.
Figure 2 Motec M400 Inputs/Outputs (Motec Brochure, 2009)
Variables according to the ECU are divided into two categories; inputs and outputs. Inputs generally represent the data from each sensor. On the other hand, outputs represent signals which have been managed and controlled through the ECU. Data can be read in the middle stage through a PC connected to that ECU via CAN connector.
Starting with the inputs (as shown in figure 3 in the red rectangle), input signals are as mentioned before the signals that are received from sensors. Those sensors are as follows:
The first category of sensors is called the main engine sensors.
The second category of sensors is called the optional sensors.
In fact, there are some other sensors which are not going to be used in BMM6. So, this group of sensors is not mentioned in this report.
Figure 3 ECU Inputs
Crank/Cam Trigger sensor: measures positions and rotational speeds for both; the crankshaft and the camshaft. There are two types of such sensors, magnetic and Hall. Each of them has its own number of connecting wires. Magnetic sensors have 2 wires while Hall sensors have 3 wires (Motec, 2009).
Throttle Position Sensor: These are generally linear or rotary potentiometer that depends on the variation in the resistance of the potentiometer. That variation generates the signal that is being sent to the ECU as an input.
Manifold Pressure Sensor: Pressure sensors work on a differential basis by measuring the difference between the applied pressure and a reference pressure. The reference can either be absolute vacuum pressure or atmospheric (ambient air) pressure. The sensor is therefore said to measure either 'absolute' or 'gauge' pressure (Motec, 2009).
Engine Temperature Sensor: It measures temperature through a thermistor at the end of the sensor itself. So, its mission is to give data to the ECU about the sensed temperature. Afterwards, ECU would manage the air-fuel mixture that is entering to pistons in order to maintain the idling speed for example.
Air Temperature Sensor: It works the same as a coolant sensor. The PCM applies a reference voltage to the sensor (usually 5 volts), then looks at the voltage signal it receives back to calculate air temperature. The return voltage signal will change in proportion to changes in air temperature. Most air temperature sensors are negative temperature coefficient (NTC) thermistors with high electrical resistance when they are cold, but the resistance drops as they heat up. However, some work in the opposite manner. They are positive temperature coefficient (PTC) thermistors that have low resistance when cold, and increase in resistance as they heat up. The changing resistance of the sensor causes a change in the return voltage back to the PCM.
The second category includes optional sensors. Those sensors are also considered as inputs for Motec M400. They are as follows
Lambda Sensor: is a sensor that measures the amount of oxygen in the exhaust of the car. According to that value, ECU plays with rates of fuel/air mixture that is being fed to the engine. So, lambda sensor is a sensor that senses the percentage of oxygen in air being exhausted in the exhaust of the car.
Wheel Speed Sensor: is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup. Special purpose speed sensors Road vehicles Wheel speed sensors are used in.
Exhaust Temperature Sensor: is an air temperature sensor with a thermistor at its end. It is usually situated at the exhaust manifold for sensing the temperature of the exhaust air from the piston.
Oils Temperature Sensor: is the one that senses oil temperature. Usually, such sensors depend on thermistor as a main part for sensing the temperature.
Oil Pressure Sensor: it measures the oil pressure and sends the data back to the ECU which manages the lubrication system of the car.
Fuel Pressure Sensor: is the one that measures the pressure of the fuel and gets the data back to the ECU to control the Fuel pump output.
After receiving signals from the sensors, ECU has to control the causes of that received data which are directly related to the engine itself. Those outputs are categorized as follows:
Ignition System: For m400, Up to four injectors may be driven fully sequentially including very low ohm types (0.5 ohms). The spark timing is controlled by the ECU based on the firing order and created map.
Injection System: The fuel injection is controlled by the timing of injection, duration of the injector nozzle in open state and also the injector pressure. These parameters are controlled by the ECU to obtain required power output from the engine (BMM5 Report. 2009.
Auxiliary Device Control Options: such as Idle Speed, Cam Control, Drive-by-wire, Fuel Pump and Thermo-fans Control are other auxiliary devices that can be controlled via the M400.
Motec M400 Datasheet.
Figure 4 shows the datasheet of the Motec M400.
Figure 4 Motec m400 Datasheet (Motec manual. 2009.)
After connecting the engine to the DYNO after connecting all of its wiring loom components accordingly, the engine is considered to be ready for mapping. Mapping is the process of adjusting engine variables in both; ignition and fueling system. Therefore, it is essential to know every element in the engine. Also, it is essential to know how far those factors can affect the performance while mapping the engine.
Each engine has its own specifications. Our engine is Yamaha YZF-R6 2005. Power train group has provided us with the following specifications about the engine:
600 cm3 (36.61 cu. in)
Forward-inclined parallel 4-cylinder
6-speed with wet multi-plate clutch
Engine Idling Speed
1,250 ~ 1,350 rpm
Liquid Cooled, 4-stroke, DOHC
Bore x Stroke
65.5 x 44.5 mm (2.58 x 1.75 in)
Vacuum pressure at engine idling speed
24 kPa (180 mmHg, 7.0872inHg)
12.4 : 1
Standard compression pressure (at sea level)
1,550 kPa (15.50 kg/cm2,15.50 bar,
220.46 psi) at 400 rpm
Claimed Peak horsepower
117bhp at 13,000rpm
Claimed Peak Torque
49 lbs. Ft (66.43Nm)
Table 1 Engine Specifications.
Mapping process goes through several steps. Those steps are as follows:
That is the most expeditious way to achieve high-accuracy measurements with replaceable or disposable analogue sensors. When the sensor is attached to the measuring instrument, the data is automatically read and used by the instrument's signal processing software/hardware.
Sensor Calibration: since everything has to be so accurate and precise, ECU has to know the threshold of each sensor to start sensing. Thus, four main kinds of sensors have to be calibrated.
Thermal Sensors: most of the temperature sensors are resistive sensors. Each temperature sensor has its own its own specifications. Also, each has its own minimum and maximum values of resistances while sensing that temperature. This information and all other information have to be loaded in the ECU program.
Pressure Sensors: pressure sensors calibration is similar to that applied to the temperature ones. Once the sensor datasheet is available, all of the required data can be loaded.
Lambda Sensor: it is calibrated without loading any data or limits or specifications of the sensor. Data from Lambda sensor can be automatically entered and understood to ECU manage, so for the Lambda Sensor, it is not directly connected to the ECU.
Throttle Position Sensor: it is so simple to calibrate. Simply, through using the sensor's data when the throttle is totally opened. The same thing is repeated when the throttle is totally closed.
After calibration, sensors should be connected to the ECU as inputs through appropriate channels in MoTeC (according to Motec m400 Datasheet). Then, there should be a comparison between what is being read from the ECU to what the sensors ambient conditions are in order to know whether calibration was done appropriately or not.
Not only inputs are prepared in the setup part, but also the outputs require additional considerations for its setup. Firing order in our engine is as 1,2,4,3. Thus, connections for the outputs while mapping have to be done very carefully especially with respect to the ignition system. Moreover, connections for the other outputs should be done according to the datasheet in order not to damage or break engine's parts while mapping. According to Motec m400 Brochure, there are also some outputs that are called auxiliary outputs. Such outputs are used when there are additional non-major sensors introduced to the ECU. For example, Thermo Fan: This output would be used to control the cooling fan to help regulate the engine temperature. It identifies the temperature range for which the fan has to be turned on. Also, a time out value can be entered in. Time out value is the one that allows the fan to be left ON for the set duration after the engine has been shut down. An additional advantage is the fan being in off state initially during engine start, thus eliminating excess load on the battery during engine start. Another example would be Lambda Heater. The Lambda sensor heater will be turned on using this output as soon as the ECU is powered up. The Lambda Sensor heater helps maintain the temperature of the sensor in order to let the sensor to work well from the beginning and provide accurate readings. In fact, that would squeeze mapping period of time and let the team to take data directly from the beginning rather than waiting until sensors warm up and making sure that we are supplying the right temperature conditions.
A dynamometer (Figure 5) or "dyno", is a device for measuring force, moment of force (torque), or power. For example, the power produced by an engine, motor or other rotating prime mover can be calculated by simultaneously measuring torque and rotational speed (rpm). A dynamometer can also be used to determine the torque and power required to operate a driven machine such as a pump or an enigne. In that case, a motoring or driving dynamometer is used. A dynamometer that is designed to be driven is called an absorption or passive dynamometer. A dynamometer that can either drive or absorb is called a universal or active dynamometer (Wikipedia. 2007).
Figure 5 Engine Dynamometer (Schwankeshortblock, 2009)
In fact, Brunel University dyno(as shown in figure 6) is considered to be old. It is known as water brake absorber. It is also called a "hydraulic dynamometer". Water brake absorbers are relatively common, having been manufactured for many years and noted for their high power capability, small package, light weight, and relatively low manufacturing cost as compared to other, quicker reacting "power absorber" types. Their problems are that they can take a relatively long period of time to "stabilize" their load amount and the fact that they require a constant supply of water to the "water brake housing" for cooling.
Other main problem with the available dynamometer in the university is the maximum rpm Brunel dyno can reach. Brunel dyno is called Heenan and Froude DPY 2 Hydrokinetic Dynamometer. It has a maximum rotational speed of around 8000rpm as a maximum speed. Meanwhile, our engine can reach a maximum rotational speed of around 15000rpm. Therefore, it is expected to have some differences in the parameters of the engine while mapping. Those differences are between the designed parameters while mapping and the actual ones. Actually, after some research with some experts about this issue, it has been found that those differences won't affect the vehicle performance on the track. Also, we have been informed that this dyno is being subjected to maintenance regularly in which all of the preceding teams had done their mapping using this dyno before they entered their competition.
Figure 6 Brunel dyno
A chassis dynamometer (as shown in figure 7) measures power delivered to the surface of the "drive roller" by the drive wheels. The vehicle is often parked on the roller or rollers, which the car then turns and the output is measured. Modern chassis dynamometers can do much more than display RPM, horsepower, and torque. With modern electronics and quick reacting, low inertia dyne systems, it is now possible to tune to best power and the smoothest runs, in real-time (Wikipedia. 2007).
In fact, we have been informed that there is an available one, but it is under maintenance for the moment, so it will be available soon.
Figure 7 Chassis Dynamometer (Schwankeshortblock, 2009)
Engine mapping is mainly consisted of several steps which has to be done before going into details in the program and in its details. Those steps are as follows:
Wiring loom should be used to inter connect the engine, ECU and all the other electronic components. That should be done according to the wiring diagram and datasheets.
All injectors and ignition components have to be well connected in order to receive the exact and accurate signal from and to them.
Since E85 fuel will be used it has to be prepared by carefully measure and mixing 15 parts of petrol and 85 parts of ethanol. E85 fuel and the fuel connected to the fuel injectors via the fuel pumps.
The torque readout should be calibrated on the MoTeC software and the torque meter display of the dyno setup. Once the setup is complete the mapping process can be started.
Lambda value (the fuel value) should be adjusted to achieve the lambda value in the Wideband Lambda table. The suggested target lambda values for engines run on petrol for long race where a lot of full throttle is used is 0.87 (MoTeC, 2007). The new fuel value is calculated by checking the difference between the Lambda sensor reading and the value in the Wideband Lambda Table. The engine must be operating near the centre of the site for the calculation to give correct results.
Figure 8 Lambda Mapping (MOtec Manual, 2009)
Fuel mapping is a set of values of the injectors which varies with the throttle position and the speed. Those values are actually pulses that show the period for which injectors keeps opened allowing fuel to be injected to the piston.
Fuel mapping is also related to the amount of air entering through the throttle. Thus, there is a correlation between data coming from the throttle and that going to injectors.
Afterwards, when load is applied on the engine by the dyno, speed varies with the variation of the load at specific throttle positions. An example of such variations would be presented in the following figure that is taken from Motec manual.
Figure 9 Throttle, Engine Speed and Loads Map
Ignition advance is the number of degrees before top-dead-centre (TDC) that a spark occurs. The reason for ignition advance is that the spark to combust the fuel/air mixture needs to be timed so that the point of peak combustion pressure is when the piston is just beyond TDC (Gill, 2009). As the speed of the engine rises, the ignition advance angle needs to increase. This is because the time to combust an unchanging air/fuel mixture is approximately constant. If the ignition advance angle were kept the same, the point of peak combustion pressure would move further and further into the combustion stroke losing more and more power. Therefore the ignition advance needs to be increased to bring the point of peak combustion to just beyond TDC.
Ignition mapping is similar to the fueling mapping before. Motec manager (ECU software) would definitely lead to its mapping. Again, one of it example is shown in figure 10.
Figure 10 Ignition Mapping
Overall Trim Table.
This table is considered as an option for varying some values in the table to enhance the performance. That change is done in the injection width pulse through decreasing or increasing the percentage of the injection pulse. Playing with the percentage of injection would definitely drive to a variation in injection timing. Initially, that would help in which it will ensure that the Table numbers maintain sufficient range and resolution.
There are so many compensation tables which Motec ECU provides. Those various table are mostly related to fuel tables. Thus, compensation tables are listed as follows:
Fuel - Air Temperature Compensation: is the one that relates the variation in the temperature of the air to the fuel injection. Motec manual specifies values for which are shown in the following table.
Table 2 Typical Motec Fuel-Air Temp Compensation
Fuel - Engine Temperature Compensation: it relates engine temperature to the fuel injection. Motec typical values for this kind of compensation tables are shown in the following table.
Table 3 Typical Motec Fuel-Engine Temp Compensation
Fuel - MAP Compensation Table: that relates the increase in percentage of injection to increase of the manifold air pressure. Therefore, fuel must be increased 100% with each 100 kpa increase in air pressure. This value is obtained from motec m400 manual.
Table 4 Typical Motec Fuel-MAP Compensation
Fuel - Cold Start: Start with the typical values that are already stored inside the ECU.
Fuel - Acceleration Enrichment Compensation Table: generally acceleration enrichment is not required above 4000 RPM.
Other Fuel Compensation Tables: Typically all other compensation tables should bet set to zero.
Other compensation tables are related to ignition.
Ignition - Air Temperature Compensation Table: Typically the following table can be used.
Table 5 Typical Motec Ignition-Air Temperature Compensation
Other Ignition Compensation Tables: Typically all other ignition compensation tables should bet set to zero.
Data logger is an instrument that logs in the data coming from the sensors while the vehicle is being driven on the track. It is mostly used for analysing and interpreting the logged data. Thus, it is a memory that saves all the data coming for each sensor in the car for the whole race time.
Motec m400 has its own internal data memory. M400 has an internal memory of 512kB. These data is interpreted via software called i2. Most people interpret it using matlab software. In our case, since Motec is offering i2 for free, interpretation would be simpler than creating our own code in matlab.
In fact, Motec m400 is limited with a number of input sensors. So, additional sensors related to suspension or GPS for example would require a data logger. Actually, suspension group asked for having an additional data logger other than motec one. So, a suggestion came out of having a Net-book data logger. That would be helpful for its shape and weight.
Data Logger Mapping.
Data from the sensors (as shown in figure 11) all over the track are interpreted via Motec i2. This software plots data received from sensors. Also, i2 shows the position of the vehicle on the track through GPS system.
Figure 11 i2 Data Plot.
A traction control system (TCS), also known as Anti-Slip Regulation (ASR), is typically an electro-hydraulic system on production vehicles designed to prevent loss of traction of the driven road wheels, and therefore maintain the control of the vehicle when excessive throttle is applied by the driver and the condition of the road surface (due to varying factors) is unable to cope with the torque applied. Although similar to electronic stability control (ESC) systems, traction control systems do not have the same goal (Wikipedia.2009).
In race cars: Traction control is used as a performance enhancement, allowing maximum traction under acceleration without wheel spin. When accelerating out of turn, it keeps the tires at the optimum slip ratio.
Since the ECU will be reused from BMM, and since the mapping will be done in the university, ECU and mapping won't cost the team anything for this year. In fact, if there is no available ECU , Motec m400 would cost us around 800£. In addition to that, there are some connectors and some instruments for the ECU which costs also around 150 £. So, the overall would be around 1000£.
In fact, it is expected to finish the ECU mapping before assembling the engine on the chassis. Therefore, engine mapping on the dyno should be finished by the end of May just before getting the engine to be assembled. Afterwards, mapping on the chassis dynamometer will be done once the car is ready for running. Since we are going to participate in Silverstone as class 2, there is no need for mapping for that stage. Therefore, chassis mapping can be postponed until after July while preparing for Italy competition.
Finally, it was so beneficial to get introduced to such a tremendous amount of information related to the control of the car. Moreover, playing with variables and interpreting data from sensors were so advantageous.
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