Data Logging Apparatus

The SRF Logger is a tool developed by the Centre for Sustainable Road Freight to log data whilst a vehicle is driving and to transmit data back to a central database in real time. The purpose of this logger is to easily enable high frequency data logging from real-world driving conditions, rather than a simulated environment.

The logger uses a mobile phone running the Android operating system to connect to the truck’s Fleet Management System (FMS) port via a Bluetooth connection. This provides access to a wide variety of signals from the truck’s own management systems. The data available through this port is dependent on vehicle manufacturer and FMS standards, but data summaries for a FMS v3 and SRF Logger equipped vehicle are available in Table 2-1. Note that some signals are sourced from the phone itself, rather than via the FMS port.

Many modern ‘smart’ mobile phones are fitted with GPS receivers and accelerometers. An application on the Android platform uses these sensors, as well as the data received via the Bluetooth connection to collect data. This data is then transmitted over mobile data networks to a central database in the Department of Engineering at the University of Cambridge.

2.1 Data Collection 27 Table 2-1 – SRF Logger Data

Source

Description

Units

FMS Engine fuel use low resolution L

FMS Engine speed RPM

FMS Vehicle distance high resolution m

FMS Engine coolant temperature °C

FMS Wheel-based Vehicle Speed km/h

FMS Clutch pedal switch -

FMS Brake pedal switch -

FMS Cruise control switch -

FMS Accelerator pedal position -

FMS Axle weight for 1st axle kg

FMS Axle weight for 2nd axle kg

FMS Axle weight for 3rd axle kg

FMS Ambient air temperature °C

FMS Fuel rate L/hour

FMS Instantaneous fuel economy km/L

FMS Engine fuel use high resolution L

FMS Engine percent load %

FMS Engine percent torque %

FMS Air pressure in the service brake circuit or reservoir #1 kPa FMS Air pressure in the service brake circuit or reservoir #2 kPa

FMS Diesel exhaust fluid tank level %

FMS Combination vehicle weight kg

FMS Retarder percent torque %

Phone Latitude deg

Phone Longitude deg

Phone Altitude m

Phone Bearing deg

Phone Speed m/s

Phone Longitudinal acceleration m/s2

Phone Lateral acceleration m/s2

28 Analysis of on-road data A diagrammatic representation of the logger and sensors is included in Figure 2-1 and installation of the logger in this setup is straight-forward. The phone is fixed in available space underneath the dashboard on the passenger side of the vehicle. This is to prevent any tampering from the driver. An adapter box is connected to the FMS port, and a FMS splitter is used if the truck is already fitted with telemetry equipment. This box houses the Bluetooth dongle and is also fitted with USB sockets to keep the phone permanently on charge. When installed correctly, the equipment is invisible to the driver. The logger is calibrated for vehicle orientation by experiencing a longitudinal acceleration over five seconds after installation is completed.

The logger is triggered by the vehicle ignition signal and data is transmitted back to the central server over the 4G network in data packets. Data is organised by truck, date and trip number and stored securely.

Figure 2-1 – SRF Logger block diagram

2.1.2. Vehicles

Two phases of data collection were carried out. The initial test phase was completed on a 2015 Euro 6, FMS v3, DAF CF85 - Figure 2-2. Due to the nature of this tractor’s duties, the tractor did not operate with a single trailer or driver. This meant that driving style and ability were variable, along with the physical properties of the vehicle (such as drag coefficients).

In the second, and more significant phase, two trucks were fitted with the SRF Logger. These trucks, with consecutive registration numbers, were identical models and were both 2016 Euro 6, FMS v3, DAF CF85s - Figure 2-3. These trucks are operated as bulk powder transporters and were consistently paired with a single tractor and trailer and had one driver allocated to each, meaning that drag properties and driving styles would be constant for each vehicle.

Phone Measured Vehicle States Vehicle Vehicle Sensors FMS Port Bluetooth Dongle Phone Sensors Phone Secure Database FMS Measured Vehicle States

2.1 Data Collection 29

Figure 2-2 2015 DAF CF85, fitted with SRF Logger during test phase

Figure 2-3 2016 DAF CF85 with bulk powder trailer

The operator’s telematics system identifies Driver 1 as one of the drivers with highest fuel consumption at the depot, and Driver 2 as one of the drivers with low fuel consumption. As bulk powder trucks are weighed on leaving the depot on a weigh bridge, accurate mass information is available for these trucks on departure from their home depot. However, the exact return weight is not known. It is assumed that the return weight of the vehicle will be its empty weight i.e. no powder is returned to depot.

30 Analysis of on-road data 114 days of driving data were collected for Driver 1, and due to logger reliability issues, 44 days of driving data were collected for Driver 2. For both drivers, this is sufficient time to see the variety of routes used and to observe the driver’s style and behaviour. These routes are displayed in Figure 2-4.

Where applicable, in this chapter, journey data is labelled with the following trip ID notation:

YYYY.MM.DD-t

where YYYY is the year, MM the month, DD the day, and t the trip number.

Figure 2-4 – Map illustrating routes used by both phase 2 trucks. Darkness of line indicates the frequency of use (the darker the line, the more frequent its use)

Home depot