Data logging is the quickest way to improve your speed for both the car set up and to improve as a driver. It can lead you directly to where & why you are fast or slow.So what are the sensors needed? What are the essential sensors as a bare minimum?
The essentials (in order of importance);
1) Vehicle Speed sensors;If we were forced to have only one item then that would be vehicle speed. After all that's what the game is all about. It will also allow the analysis software to generate a distance channel (if it is able) which in most instances becomes the x-axis for the graphs if we are to meaningfully interpret the data. While logging speed from a GPS unit is an easy solution but this does have is limitations such as delay, drift & signal drop out. In the picture below we can see that the GPS speed has the braking point 22m later than what actually happened which is due to signal delay.The better solution is to derive vehicle speed from wheel speed sensor/s. Fortunately most vehicles now days have wheel speed sensors fitted for the ABS system that is usually discarded when the vehicle is converted for competition. Ideally we would have all 4 wheels speeds. This allows information on brake locks, wheel spin, differential action plus much more.
The essentials (in order of importance);
1) Vehicle Speed sensors;If we were forced to have only one item then that would be vehicle speed. After all that's what the game is all about. It will also allow the analysis software to generate a distance channel (if it is able) which in most instances becomes the x-axis for the graphs if we are to meaningfully interpret the data. While logging speed from a GPS unit is an easy solution but this does have is limitations such as delay, drift & signal drop out. In the picture below we can see that the GPS speed has the braking point 22m later than what actually happened which is due to signal delay.The better solution is to derive vehicle speed from wheel speed sensor/s. Fortunately most vehicles now days have wheel speed sensors fitted for the ABS system that is usually discarded when the vehicle is converted for competition. Ideally we would have all 4 wheels speeds. This allows information on brake locks, wheel spin, differential action plus much more.
2) Brake Pressure sensors front & rear.These provide the logging system with information on the hydraulic pressure generated in the front & rear circuits of the brake system. This then allows us to evaluate on many levels how well the driver is using the brakes, and there is more time to be had here than most folks give credit.However if the brake system is not set up correctly then the driver has no hope of getting the most from the brakes. Here the brake pressure sensors can help evaluate if there are problems with the brake balance and identify problems with the brake peddle box – which are surprisingly often setup incorrectly.
3) Throttle position sensorAny sensor that gives information on what the driver is up to is worth adding, the throttle is one of the most telling. It is also an easy one to implement as it will always be present from the engine ecu.
4) Lateral G-Force sensorThis provides information on how much cornering force the vehicle is generating at any given moment. The shape of the Lateral G-Force plot also gives valuable insight into how the driver is turning the car into the corner and exiting the corner. Combined with information from other sources such as braking & throttle it builds a picture of how the car is being driven.A side benefit of including Lateral G-Force is that when combined with vehicle speed it allows the analysis software (if it is able) to build a track map for the venue, which then opens a whole new dimension for analysis. Track maps are also able to be generated using GPS data.All Motec dash displays come supplied with a 3-axis G-Force sensor (lateral, longitudinal & vertical) and if the logging in the dash is not activated & the engine ecu is used for the logging then this information can be passed to the likes of a Life Racing ecu via the CAN bus. 5) Longitudinal G-Force sensorThis provides the logging system with information on how much braking or forward acceleration force the vehicle is generating. As mentioned above this is often combined with lateral & vertical G-force in the one sensor. Stand alone sensors are also available if the likes of a Motec dash are not present. Like lateral G-force the shape of the longitudinal G-force plot is a treasure trove of information into how the vehicle is being driven.
6) Engine RPMThis will allow us to see how well the gear ratio/diff ratio selection is working for us as well as how well the driver is keeping the engine on the boil. For data logging systems with good maths functions (like Motec & Life Racing) we can use engine rpm & vehicle speed to simulate alternative gear, diff ratios to predict how improvements may be made. Engine RPM will always be available from the engine ecu.
Not Essential but very useful sensors;
Damper Position sensorsThese measure the position of each damper. The usual convention is to have them reading 0mm with the vehicle at its static ride height, -ve mm’s of displacement when the damper moves in the rebound direction and positive mm’s of displacement when the damper moves in the bump direction. Just by logging these 4 items a whole world of suspension dynamics and aero evaluation is opened up.
Yaw Rate sensorThis supplies the logging system information on the rate the vehicle is rotating. If you were looking down from above the vehicle as it turned into a corner you would see that it rotates to its original direction as it makes its way around the corner – the rate at which it is rotating is what we are measuring. So the yaw rate through a tight corner like a hairpin is much greater than the likes of a kink, even thought the lateral G-force may be the same. This information can then be used for cornering power evaluation and how the driver is driving the car.
Steering Wheel Angle sensorThis sensor is usually attached to the steering column and measures how much from centre the steering wheel is rotated. From this we can also derive the steered angle of the front wheels which then opens up further suspension dynamics evaluation including evaluating how much understeer/oversteer is going on.
The more exotic sensors;If budget permits the list does go on! Laser ride height sensors that measure the chassis position relative to the track, Strain gauge sensors to measure suspension loads & aerodynamic loads, pitot sensors for aerodynamic evaluation.
So that's the sensors – the thing now to realise is that a good data analysis software package worth its salt will truly turbo charge that information.
4) Lateral G-Force sensorThis provides information on how much cornering force the vehicle is generating at any given moment. The shape of the Lateral G-Force plot also gives valuable insight into how the driver is turning the car into the corner and exiting the corner. Combined with information from other sources such as braking & throttle it builds a picture of how the car is being driven.A side benefit of including Lateral G-Force is that when combined with vehicle speed it allows the analysis software (if it is able) to build a track map for the venue, which then opens a whole new dimension for analysis. Track maps are also able to be generated using GPS data.All Motec dash displays come supplied with a 3-axis G-Force sensor (lateral, longitudinal & vertical) and if the logging in the dash is not activated & the engine ecu is used for the logging then this information can be passed to the likes of a Life Racing ecu via the CAN bus. 5) Longitudinal G-Force sensorThis provides the logging system with information on how much braking or forward acceleration force the vehicle is generating. As mentioned above this is often combined with lateral & vertical G-force in the one sensor. Stand alone sensors are also available if the likes of a Motec dash are not present. Like lateral G-force the shape of the longitudinal G-force plot is a treasure trove of information into how the vehicle is being driven.
6) Engine RPMThis will allow us to see how well the gear ratio/diff ratio selection is working for us as well as how well the driver is keeping the engine on the boil. For data logging systems with good maths functions (like Motec & Life Racing) we can use engine rpm & vehicle speed to simulate alternative gear, diff ratios to predict how improvements may be made. Engine RPM will always be available from the engine ecu.
Not Essential but very useful sensors;
Damper Position sensorsThese measure the position of each damper. The usual convention is to have them reading 0mm with the vehicle at its static ride height, -ve mm’s of displacement when the damper moves in the rebound direction and positive mm’s of displacement when the damper moves in the bump direction. Just by logging these 4 items a whole world of suspension dynamics and aero evaluation is opened up.
Yaw Rate sensorThis supplies the logging system information on the rate the vehicle is rotating. If you were looking down from above the vehicle as it turned into a corner you would see that it rotates to its original direction as it makes its way around the corner – the rate at which it is rotating is what we are measuring. So the yaw rate through a tight corner like a hairpin is much greater than the likes of a kink, even thought the lateral G-force may be the same. This information can then be used for cornering power evaluation and how the driver is driving the car.
Steering Wheel Angle sensorThis sensor is usually attached to the steering column and measures how much from centre the steering wheel is rotated. From this we can also derive the steered angle of the front wheels which then opens up further suspension dynamics evaluation including evaluating how much understeer/oversteer is going on.
The more exotic sensors;If budget permits the list does go on! Laser ride height sensors that measure the chassis position relative to the track, Strain gauge sensors to measure suspension loads & aerodynamic loads, pitot sensors for aerodynamic evaluation.
So that's the sensors – the thing now to realise is that a good data analysis software package worth its salt will truly turbo charge that information.