At the composting plant, organic waste is processed in an enclosed tunnel composting system following intensive treatment, then transferred to the post-composting hall where it is aerated. Through the fine-processing stage, this is transformed into quality-assured compost for agriculture and horticulture.
Mechanical-biological residual waste treatment poses significant challenges for occupational safety due to dust and odor exposure. Automation is intended to relieve wheel loader operators of the monotonous and physically demanding handling tasks. At the same time, it increases the wheel loader’s utilization rate, as automated operation can take place primarily at night.
The goal of the project is to automate a Liebherr L 544 articulated wheel loader with hydrostatic drive for driverless operation. The wheel loader is designed to perform various transport tasks autonomously, including loading and unloading material onto stockpiles or into metering hoppers.
Sensor technology
- No visible automation infrastructure.
- Sensor fusion: laser scanner, inductive guide wire guidance, ultrasonic distance sensor, position encoder.
- Wheel loader with CAN bus for digital vehicle status information.
Actuators
The wheel loader, which was not originally designed as an FTF, had to be adapted for automated operation. Since the throttle and brakes cannot be controlled electrically, these functions had to be replaced with technical alternatives. The steering, bucket, and lift mechanism are already electrically controlled. The automation was integrated in such a way that the wheel loader can still be operated manually without any changeover time. The hydrostatic drive enables precise speed control.
Escape is impossible—for sure
A safety concept developed in consultation with TÜV and the employers’ liability insurance association protects people during automated operation. The wheel loader can only be started from outside the secured facility. Opening an access gate triggers an emergency stop via radio signal.
A wireless system from GÖTTING KG is used to monitor work processes and vehicle status. The control computer is in constant communication with the vehicle computer, allowing new jobs to be assigned and vehicle data to be displayed. If the wireless connection is lost, an emergency stop is automatically triggered.
Finding Your Way Around the Hall
To navigate within the post-composting hall, the wheel loader uses laser scanners to create a digital map of its surroundings without needing reflective markers on the walls. In the central aisle, inductive guide wires reliably guide the wheel loader through the heavily contaminated environment. The position control system compares the current position with the travel paths stored in the control computer.
Definition of Jobs
Drive commands are issued by the control computer either manually or via the higher-level process computer. Jobs are processed in order of priority. A running job continues up to a defined point before a higher-priority job begins. Once the higher-priority job is complete, the interrupted job automatically resumes.
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