3D Image Train Wagon Profiler is an application within the 3D Image Automation suite of automation software applications.
The 3D Image Train Wagon Profiler captures an instantaneous 3D profile of the contents of a train wagon whilst either stationary or moving. The primary application is in determination of the loaded ore profile of train wagons used in the iron ore and coal industries.
Fast image acquisition facilitates the use of 3D imaging for loading control and for capture of the wagon profile at train speeds of up to 100kph.
Each wagon profile is individually archived in real time to a directly linked SQL database. The wagon profile data is immediately available to external applications.
The 3D Image Train Wagon Profiler may also be used for:
- Operator 3D visualisation of the loading process
- Direct control of the loading process
- Determine of spillage
- Loaded wagon volume
- Detection of material hang-up during or after unloading
- Presence of personnel or material in unloaded wagons
- Identification of wagon type from dimensions
Existing Train Wagon Profiling Systems
The majority of wagon loaders are batch or choke feed types:
- Batch Loaders
Batch loaders fill the train wagon by dumping one or more weighed batches of ore into the wagon positioned below a batch hopper. Multiple batches from separate hoppers are often employed in order to provide improved control of the loading rate. - Choke Feed Loaders
Choke feed loaders operate by positioning the discharge chute close to the top of the wagon and filling the wagon up to the chute level. Once the wagon level reaches the discharge chute, then material flow will be choked. The discharge gates are closed as the wagon passes the edge of the discharge chute. The choke feeder loading process is illustrated in Figure 1.
A common problem with both loading systems is that the loading rate is difficult to control due to variation in material flow characteristics at the bin discharge gate. Products that flow freely will fill the wagon too rapidly and splash out of the wagon. In the extreme case, the discharged material may become fluidised and flow freely over the top of the wagon. Other products may bind at the discharge gate and require a large gate opening to release product from the discharge hopper.
Existing wagon loading control systems use various gate sequencing and position modulation schemes in an attempt to overcome the product flow variance. This usually involves a large initial opening to release the product, followed by closing to a pre-set filling position. Fully automatic operation is not achieved and an operator is required to monitor the loading process and alter the loading control setting when problems are noticed.
Current wagon loading control systems also use a loaded wagon profiler to provide feedback of the final load profile to an operator or directly to the wagon loading control system in order to tune the gate sequencing parameters.
A train may be assembled from multiple wagon types, where each wagon type has different dimensions of length, width, height and shape. Wagon loading systems require the wagon type to be identified in order to control the loading process. The wagon type is usually identified via an RFID (Radio-frequency identification device) tag attached to the wagon. The RFID tag is read as the wagon enters the loading facility and used to lookup the wagon details in a wagon database.
Existing wagon profilers employ 2D laser scanners to profile a cross-section of the wagon load and then use the train forward motion to move the cross-section along the wagon to provide the third dimension of the profile. The reliance on train forward motion to provide the third dimension dictates that the positional accuracy of the cross-section along the length of the wagon depends on the accuracy of an externally supplied train speed signal. This introduces considerable latency and places a limitation on the acquisition speed and accuracy of the scanned profile.
Existing wagon loading facilities use the RFID tag wagon type identification as the forward motion and the inaccuracy of train speed measurement limits the use of 2D scanners for the measurement of the wagon dimensions.
Furthermore, existing 2D scanners are not able to measure the load profile in the immediate vicinity of the discharge chute of a train load-out bin. This is due to the flow of product on each side of the laser cross-sectional scan line.
In addition, an important factor for the determination of correct wagon loading is the load profile just inside the leading and trailing edges of a wagon. The beam divergence and vertical orientation of a 2D scanner means that the profile at the leading and trailing edges may lie in the shadow of the wagon edge. This means that actual load profile may be different from that detected by the 2D scanner.
Existing wagon loading control systems use an open loop implied rate control, that is, the loading rate is based on a rate implied from the gate opening and a set of gate control parameters rather than on dynamic measurement of the wagon load.
Existing wagon profilers use 2D laser scanners to profile a cross section of the wagon load and then use the train forward motion to move the cross section along the wagon to provide the third dimension of the profile. The reliance on train forward motion to provide the third dimension dictates that the positional accuracy of the cross section along the length of the wagon depends on the accuracy of an externally supplied train speed signal.
3D Image Train Wagon Profiler – Features
The 3D Image Train Wagon Profiler captures an instantaneous 3D profile of the wagon using one of more 3D Time of Flight cameras.
The 3D Image Train Wagon Profiler captures provides wagon dimension information prior to loading, dynamic measurement of the wagon load during the loading process and an accurate load profile of loaded train wagons.
3D Image Train Wagon Profiler – Description
The Train Wagon 3D Profiler uses multiple 3D Time of Flight cameras to measure the profile of train wagons.
In Time of Flight systems the distance to objects in front of the sensor is measured by analysing the time for a light pulse to travel from an illumination source to the object and back to the sensor. The object in this case is a plan view of the train wagon.
The 3D cameras are mounted above the rail tracks facing down wards. The cameras capture simultaneous plan view 3D images of the wagon below, and the individual camera images are fused together to provide a complete panoramic three dimensional picture of the wagon profile.
The short image capture time provides an instantaneous blur free image, independent of the train speed during loading.
Triggering of the profile capture may be at time intervals, triggered by a remote signal or by the position of the wagon as determined by the leading or trailing edge of the wagon.
The 3D cameras are able to capture the wagon profile at high frame rates to provide a continuously updating 3D visualisation of the wagon profile.
Locating the 3D Time Of Flight cameras along the centre line of the wagon and inside the leading and trailing edges means that the inside surface of the wagon is within the camera field of view. This provides an ideal position to measure the profile level in relation to the top edge of the wagon.
3D Time of Flight cameras positioned to see inside the wagon during the loading process provide the ability to measure the wagon volume fill rate.