By Neville Judd, Communications Director
Backing into a loading position is a perennial challenge for truck operators. “Spotting” right the first time saves time, money, and keeps everything running smoothly. Getting it wrong means the shovel operator must ask the truck operator to reposition, which typically takes about 40 seconds; that’s an additional 40 seconds every other truck must wait.
The direct cost of inaccurate reversing operations can be as high as $5,000 per shovel, per day. Reverse guidance technology from Hexagon Mining helps to minimize or eliminate re-spotting by guiding truck operators. It is also an important step towards a solution eyed by mining companies for years.
Several mining companies have deployed and experimented with autonomous haulage in recent years. However, the adoption rate has been less than one percent of the global haulage population. Why? Mining is a risk-averse industry. Current autonomous haulage systems are all-or-nothing technologies. Aware of the risk of impact to their planned production profile, potential customers have no way to become comfortable with autonomous haulage.
Human assist products solve many of the technical problems that stand in the way of full-scale autonomous haulage. Better yet, they can be implemented with little risk. Hexagon Mining’s autonomous strategy is to develop these building-block applications that can later be integrated into an autonomous haulage solution.
The advent of disruptive technology
To date, the application space has been hindered by an accepted industry price point for haulage equipment that precludes the use of RTK (Real-Time Kinematic) positioning. However, precision positioning will become inexpensive and ubiquitous, as the automotive industry requires (and develops) decimeter positioning accuracy, even in GNSS (Global Navigation Satellite System) challenged environments. The introduction of high-precision positioning systems on mining haulage equipment will disrupt competitors and create significant opportunities for applications that require this positioning accuracy. Reverse guidance is one such application.
The benefits of reverse guidance
Reverse guidance offers significant operational and safety benefits to mining operators. By providing a truck operator with the precise position of the truck in relation to the shovel, the operator can position themselves in the loading location more quickly. By calculating a path and providing a truck operator with guidance along that path, machine damage due to hard cornering and inadvertent contact with the shovel and/or related infrastructure is eliminated, not to mention any associated injuries. By providing guidance to the truck operator, repositioning events can be minimized or eliminated.
There are ancillary benefits, too. Centered loading in trucks leads to longer tire life and lowered suspension maintenance. Off-centered distribution of weight directly affects tire wear and suspension components.
Counting the cost of repositioning
The direct cost of inaccurate reversing operations can be as high as $5,000 per shovel, per day comprising the following:
- Opportunity cost: During the time the shovel spends waiting for the truck to reposition, the shovel is unable to load material
- Direct operating cost: Both the shovel and the truck cost money to operate. The time spent repositioning has a quantifiable cost, but no economic process value.
- Ancillary equipment cost: When reversing to a crusher or hopper facility, an angled approach or inaccurate stopping location causes material spillage in front of the facility. This spillage is frequent enough that the location is allocated support equipment such as a wheel dozer.
How reverse guidance works
Hexagon Mining’s Reverse Guidance system calculates the optimum reversing path for a truck to follow when backing into a shovel pit to be loaded, or when backing to a hopper to unload.
- When an equipped truck enters a shovel pit or dumping area, the low-precision GNSS receivers will change to a high-precision mode that allows for centimeter accuracy.
- When the transmission is shifted to reverse, a path will be planned to a spot location, avoiding mapped objects.
- Using this path, an optimal steering angle will be calculated and the operator will be prompted to adjust steering angle to this value through light bars attached to the mirrors and through an audible prompt.
- As the operator reverses the truck, the truck’s position and orientation will be compared to the calculated path. The operator will receive prompts if corrections are necessary.
- Distance to the stopping point will be indicated through audible prompts.
- When the spot is reached, a continuous audible prompt is issued.
Reverse Guidance hardware
Hexagon Mining’s Reverse Guidance system comprises the following components:
- Embedded Novatel dual receiver and antennas
- Computing unit rugged PC with internal WiFi
- Steering wheel encoder
- LED indicators designed to mount on the reversing mirrors of a haul truck – available from Machine Control
- Speaker for audible indications