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| RoadRobot - Fully Automtic Road Paver |
| Applicable type of work: |
Asphalt pavement |
Official price: |
Classification:
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Work
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| Purpose of the development: |
Fully automatic road paver
Improvment of quality
Reduction of costs |
Lease and rental: |
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| Level of practical use: |
Working in practical job |
Development company: |
Joseph Vögele AG |
| Information |
Company name:
Address:
Phone:
Fax:
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Joseph Vögele AG
Design Dept.
Neckarauer Str. 168-228
D-68146 Mannheim, Germany
+49-621-8105-262
+49-621-8105-467
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1. Application
Today, road pavers show a high level of automation. On this machinery regulating systems are already provided for conveyance and spreading of the asphalt, for direction of motion and paving speed as well as for surface accuracy of the pavement.
2. Outline
In view of increasingly growing requirements made on quality and in view of increasing costs, automation of only individual functions will not do to satisfy future needs. It is rather to link the entirety of operating functions to form an overall system. The result is a fully automated road paver, in other words a robot. The newly developed paver "RoadRobot" provides this:
- automated reception of asphalt
- automatic control of asphalt conveyance
- automatic control of asphalt spreading
- automatic steering control with mechanical sensor and automatic control of paving speed
- automatically controlled start/stop of all paving functions of the RoadRobot
The paver operator does not have to direct his attention to controlling reception of the asphalt or steering the road paver, i.e. to jobs he usually has to do, but can fully concentrate his skills on the screed for assuring a high paving qulity.
3. Characteristics and effects
- Disel-Electric Drive System
A systematic study of automated pavement construction shows that full automation of a conventional road paver cannot be achived in an economical way. Only with the development of a road paver with disel-electric drive system, it was possible to create a basis for automation under economical conditions.
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As power source of this new road paver serves a 55 kVA three-phase A.C. generator driven by a disel engine rated at 61 kW.
The 380 V three-phase output voltage supplied by the synchronous generator has a frequency of 37 or 60 Hz and is made available to the three-phase asynchronous motors operating at constant speed as well as to the system for screed heating. The components such as supply unit, central electronic unit and inverter modules are accomodated in a control cabinet located at the rear of the road paver.
Output voltage of the supply unit is linked to the inverter modules via intermediary circuit. To these inverter modules are connected the variable-speed drive units for traction, conveyors, augers, tamper and vibrators.
Optimum matching of power unit output to the various operating functions of the drives for rotary movements is achived by frequency converters.
The electrical/digital actuator level created in this way admits to integrate process automation in an economical way, without a need for additional conversion.
The improvments achived by this drive system in terms of efficiency on the one hand and the better matching of electric drive output for paving functions on the other, permitted to reduce power of the dieesel engine by 50% without a decrease in paving performance.
Especially when it was about designing a low-noise road paver, electric drives proved advantageous. Noise levels at the screed, while paving could be reduced from formerly 93 dB(A) to 81 dB(A).
Furthermore, the quantity of hydralic oil which has to be carried along with the paver, could be cut from formerly 380 litres to now 20 litres.
- Reception of Asphalt
Reception of asphalt is a process which is constantly repeated. For the RoadRobot this process has been fully automated.
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Sensors located at the front of the driver's cabin pick up the distance to the feed vehicle and measure the height of asphalt on the conveyors. A symbolic display informs the lorry driver about what steps to perform for correct discharge.
A paving start or paving stop is initiated as a function of the quantity of asphalt in the material hopper of the RoadRobot. This ensures that provided a correct nadling of the control system for conveyors and augers, a constant head of asphalt in front of the screed is guaranteed, both when starting paving, when paving and when stopping paving.
- Automtic Steering Control
Steering a road paver precisely along a guide line such as, for example, a curb will very soon make excessive demands on the paver operator due to the monotonous nature of the job on the one hand, and the high degree of concentration required on the other. This risks to produce mistakes in steering. Only automatic steering control allows precise steering along a given reference line.
Automatic steering control used on the RoadRobot is based on mechanical referencing from a guide line such as a curb, for example. The accuracy achived was +/- 2 mm.
A second type of travel control system was installed on top of the cabin of the RoadRobot operated according to the principle of a laser-based navigation system. This steering system is applied when no reference or other line is available from which referencing can be carried out.
The laser beam of the laser unit scans, like radar, the area around the RoadRobot, and the laser unit calculates the angle btween the RoadRobot and the reflection elements positioned in place.
The more reflexes are identified, the higher will be the accuracy of positioning. The highest possible accuracy achived with this system was around +/- 20 mm.
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4. Features of the robotization and automation
By automation of asphalt and steering as well as integration into the overall system of the RoadRobot, automation of the entire paving process has been completed.
The paver operator very often is a specialist with great skill. While paving, he need no longer concentrate on the paver, but is available for monitoring the functions of the screed.
Robotization of the road paver in an economical way by use of the disel-electric drive system showed that substantial progress has been made not only as far as automation of operating functions of the road paver is concerned, but also in terms of environment protection by reduction of noise levels and exhaust emission.
5. Work execution record
Within the scope of an European Research Project entitled ESPRIT, in which partners from 5 European countries participated, the basis of a fully automated road paver (RoadRobot) has been investigated and the result was presented at the German Road Museum at Germersheim on June 28th, 1996, as well as on a job site of the company Teerbau located nearby.
Demonstration of the RoadRobot on site has shown that the fully automated road paver with diesel-electric drive system and also the semi-automated one are developments oriented towards the future.
6. Usage conditions
The RoadRobot is the first road paver worldwide capable of navigating and steering itself. All functions necessary for road pavement construction from asphalt spreading through to levelling, profiling and compacting are computer controlled.
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The fully automatic road paver RoadRobot in operation |
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