Acumine Collision Avoidance Safety System ( 4CAST )
A proximity system is defined as a system to detect the presence of other nearby haul trucks, light vehicles or personnel. This system can be used for collision avoidance, and is most useful in adverse environmental conditions such as dust, fog and rain and under operator fatigue.
There are two types of proximity / collision avoidance systems; active systems where specially fitted vehicles communicate through some kind of network, and passive detection systems where each vehicle must use sensors to try and detect other vehicles such as radars.
Another important aspect is the reporting action to the operator. An intelligent proximity / collision avoidance system is expected to evaluate the actual threat situation and to provide assistance with the driving task or appropriate level of warning to the operator. Unnecessary / False alarms needs to be avoided at all cost since the operator will eventually stop using the safety system. That is one of the reason why approaches based on only passive sensors had not been very successful in this application.
Acumine has been working for the last 5 years developing robust safety system. A successful implementation of a safety system must include a comprehensive combination of sensing and intelligence to be able to determine not only that there are resources in proximity but to know what these resources are doing. That is to know their position, velocity and direction of travel. This is essential to evaluate the actual threat of collision to generate an appropriate level of warning or to provide assistance to the driver to perform a maneuver.
Acumine has developed the technology to deploy high integrity systems that can be adapted to many different mine scenarios. The system includes different type of complementary sensors, operator interfaces with voice and Graphic capabilities and the patent pending Acumine context switching technology to avoid unnecessary alarms. The system monitoring facilities can also be included with the optional Base Station- Server computers that can be used to monitor and design the mine safety operation. All these technologies together form the most comprehensive safety system available today for mining applications.
The importance of providing situation awareness is shown with the example below. This was taken during normal operation at a mine in Australia. In this case the operator does not have visibility of the vehicle in front. By having a brief look at the interface the operator can see that there is a truck (HV in front), is too close to the truck and is overspeeding (Icon). He/she can also see that the truck is approaching an intersection (area in blue).
Acumine Operator Interface
The Primary detection System uses mesh wireless network with GPS sensors. Each resource broadcast its information with and adaptive sampling time and receive the position of all other agents in proximity. The system can detect other resources at ranges up to 500 meters, depending on line of sight conditions. The mesh network can also enable the detection of resources not in line of sight through retransmission from another resource. The figure shows that the 3 trucks and 2 light vehicles are all aware of each other position although they are not all in direct contact.
With the mesh network approach each resource can communicate with other resources even if not direct line of sight
Each agent has full information of position, velocity and heading of all the agents in the area. For example, a truck will know the area it is operating in (crusher, Haul road, loader) and complete information of all agents in his proximity, e.g.: two trucks in front moving in same direction at given speed and a stationary grader at a certain distance. This information is used for the implementing of different warning depending on the actual threat. The level and type of warnings is determined with the information provided by mine managers and the operators as their input and acceptance is essential for the successful implementation of the system. The figure shows a truck with information about 3 agents running in same direction outside the second warning area. Different actions on both resources can be programmed when the inside a given area.
The truck in front is aware of identity, position, speed and direction of travel of other vehicles in proximity.
The primary proximity system addresses many of the risk scenarios currently occurring in most mine operation. Nevertheless an additional level of integrity would provide more functionality and address more risk situations
The Close Proximity sub-system developed is based on range sensors that can detect the presence of an active tag in proximity. The Figure shows a practical implementation of this approach in a haul truck with an on board sensor in front and another at back. Other sensors can be added for extended coverage such us underneath the truck if required. Light vehicles have a single sensor. This approach is also used to implement the personnel proximity hardware but based on low power devices with optimized software to extend the sensor autonomy. With this option the mine personnel can be made part of the proximity network and will provide warning to haul trucks when people are in proximity.
Detection of resources in close proximity
Acumine has developed various personnel proximity nodes based on range / GPS and range only devices. One of the key features of the personnel nodes is autonomy. The system is designed to operate without charging the batteries for periods between 7 - 30 days depending on the models and sensing capabilities.
High Integrity Proximity Detection
For an active detection system, it is important that there is redundancy in the system. This is essential when there is a failure in one of the active systems since there will be a backup system to detect nearby vehicles. Two active detection systems are used in the Acumine proximity system. The first is based on a high bandwidth, long range system using 2.4GHz wireless mesh networks and autonomous GPS. The second is based on a 430 MHz network system that provides low bandwitdh data transfer capabilities and range and identification information.
The monitoring of the operation of the system is performed at the base station/s usually located in the crusher. The positions and events relating to each truck and its proximity to other resources is then downloaded to the base station. The information downloaded to the base station is then transferred to a server and becomes available to the mine database system. This information will be used for integrity and monitoring purposes.
The Base Station collects the information from the trucks and make it available to the mine database.
The Base Station / server computers are not strictly necessary for the operation of the proximity system. Nevertheless, these components are essential to monitor, design and improve the safety operation in a mine site. The next Figure shows an example of the implementation of mine safety / monitoring and design with the actual Acumine technology. The trucks are retrofitted with operator interfaces to provide different levels of warning according to the situation around the truck. The proximity events and alarms are logged by each truck and then downloaded when close to the base station. Further off-line processing is then done to provide feedback to the managers and to the drivers. This information can also be used to detect dangerous areas in the mine and to provide different rules for different areas. This is what is referred to as “Context Switching”.
The system provides reactive information to the truck driver and feedback to the mine manager for post-analysis when the logged data from the truck is downloaded to the base station
Graphical and Voice Interface
The operator interface is the unit responsible of processing all the information obtained by the different proximity sub-systems, evaluates the threat situations and generate the appropriate actions/alarms depending of the agreed reporting capabilities. The Inference engine becomes an essential part of the proximity system to prevent false alarms since in many normal cases (loading, etc) there will be many conditions that can potentially generate alarms.
The operator Interface Module evaluates the threat and generates appropriate action
It is the responsibility of the inference engine to analyse and understand the situation and report only the most vital information to the operator. The reporting could be a combination of sound and/or voice command in cases of extreme risk or it can be graphic aids. Acumine has implemented a variety of operator interfaces that can be adapted to different mine operations. The basic system incorporates an interface with alphanumeric display and voice capabilities as shown below
Acumine Graphical / Voice Interface
Various Implementation of Haulcheck and Collision Avoidance have been installed in various mines isuch asa Alcoa, Brockman, Grasberg and Quarries such as Bracalba.
Haul trucks retrofitted with the Proximity Technology in Brockman
Acumine has an active research program in the area of Safety that is funded by Acumine, industry, CRC Mining and R&D Grants.
The current Hardware version of the Collision Avoidance hardware includes a wide range of interface capabilities to interact with many of the facilities available in the resources. The system has Ethernet, CAN bus, serial and a number of Digital and Analog Input Outputs and can integrate all the navigation sensors presents in the machine such as encoders, gyros etc. It also include the close proximity hardware and a full 6 degree inertial system. This hardware capabilities give the essential platform to incorporate the expertise of ACFR in developing high integrity industrial systems.
Acumine Collision Avoidance Signal Processor PSP V1.1
|Requisites||Power||12- 24V 1 Amp|
|Logging Capabilities||Events||Current date and time; Vehicle identification; Vehicle position speed, orientation; Other vehicle position, velocity and orientation in proximity, Alarms events generated. Optional other truck information.|
GPS information broadcasted with 801.11b Mesh network
Range information with RFID devices at 433 Mhz