DE102004041938A1 - Stacking device e.g. reach stacker, for gripping e.g. container, has sensors for recording area of unknown layout of loads, preferably containers, and computer-aided image identification system for processing sensor data - Google Patents

Abstract

The device (12) has a vehicle undercarriage (13), where a hinged telescopic arm has a load lifting tool that is mounted on the undercarriage. Sensors are provided on the stacking device for recording the area of unknown layout of loads, preferably containers. A computer-aided image identification system is provided for processing sensor data. The device serves as sensors cameras, laser scanners and/or radar scanners. An independent claim is also included for a method for gripping and stacking loads e.g. containers using a stacking device.

Description

The Invention relates to a stacker, in particular a reachstacker, and a method for gripping and Stacking loads, preferably containers, with this stacker.

Reach Stacker are rubber-tired vehicles with diesel engines and driver's cab. They are capable of loads, especially containers, trailers, sheet metal coils, general cargo, etc., to transport and stack. Previously known reachstackers are arranged with a telescopic arm as a load-carrying means Container spreader equipped, d. H. a raising and lowering of the spreader takes place only over the Telescopic arm. You can Handle and stack containers in a row in a row and one above the other.

When operating a Reachstackers, it is usually time-consuming to grasp containers which are not directly within the field of vision of the operator, since the spreader must be positioned with an accuracy of a few centimeters over the container so that it can pick up the container. In the 1 is shown an arrangement of containers, the area below the dashed line can not be viewed by the operator. When gripping the left overhead container, only the position of the spreader can be estimated from the position of the boom. If the longitudinal orientation of this container is not exactly perpendicular to the boom, then under certain circumstances the container can not be picked up at all.

Become Containers stacked, encounter the driver similar problems. The container must as possible be approached with exact position. An inaccurate oblique placement can lead to the jamming of neighboring containers, so that these can not be raised anymore.

task The invention is therefore a generic stacking device, preferably a Reachstacker, such that the gripping and stacking of Containers for simplifies the operator.

According to the invention this Task by a stacker according to claim 1 solved. In this case, at the stacking device, especially the reachstacker, which consists of a vehicle chassis and one on this pivotally mounted telescopic boom with a load receiving means, sensors for detecting an area from a non-known arrangement of loads, preferably containers, intended. Furthermore, a computerized image recognition system for processing the sensor data.

preferred Embodiments of the stacking device according to the invention result arising from the subordinate claims to the main claim. Here are particularly preferred methods for gripping and stacking Containers with the stacking device according to the invention.

More particularly, the invention relates to stackers for gripping and stacking loads, such as containers, having at least three degrees of freedom. Such devices usually have as load handling means a Contai neraufnahmegerät (so-called spreader), a chassis and a boom. The boom-mounted container-receiving device can be rotated about an axis β (t), translationally moved T (t) and telescoped l (t). The boom includes a drive to vary boom length l (t) and pitch angle Θ (t). With the help of the chassis, which has a steering and a propulsion, the position and orientation of the stacking device v (t) can be varied.

Around To transport a container from the site to the destination, the stacker must handle the container Approach to exact position. Should a container be stacked at the destination this must be done flush with Target container happen. According to the invention, these tasks are included stack devices with a computerized Procedure solved. It can be selected from two modes. In the first mode maneuvered the computer algorithm automatically routes the stacker to the target object. In the second mode, the computer unit directs with optical or acoustic Signals the operator to the target object.

• – Erfassen der Sensordaten
• – Abschätzen der dreidimensionalen Lage und Orientierung von Umweltmerkmalen der Lasten schon während des Verfahrens des Stapelgerätes,
• – Rekonstruktion der Lastkonturen aus den zuvor gewonnenen Schätzdaten,
• – Erstellen eines Containerumweltmodells,
• – Auswahl der Last.

Based on 5 For example, the overall structure of the method for gripping and stacking containers according to the invention can be described. Here is the overall structure of the inventive method for gripping and stacking loads, preferably containers, shown. The method according to the invention comprises the following steps:

• - Acquire the sensor data
• Estimating the three-dimensional position and orientation of environmental features of the loads already during the process of the stacking device,
• Reconstruction of the load contours from the previously obtained estimated data,
• - create a container environment model,
• - Selection of the load.

Of particular importance in the process according to the invention is that of the sensor elements installed in the vehicle data is fused by a state observer. These fused sensor data S (t) serve the state observer to estimate the three-dimensional position and orientation of environmental features M (t) such as container corners, edges and surface segments. It is essential that this detection algorithm is carried out permanently, that is, even during the manual travel to the destination container. From the determined data, container contours C (t) are reconstructed and used to successively build up the three-dimensional model of the container scenario U. Typically, the model includes only portions of the entire stacking scenario and includes multiple containers. On the basis of plausibility conditions, the destination container Z is selected from this.

at The choice of fully automatic operation is calculated by the module for path planning from the three-dimensional position of the container as well as from the distance and the orientation of the recording device (or container bottom of the container to be stacked) according to the invention a time-indexed trajectory for each joint variable. An axis controller ensures a stabilized implementation of the nominal path.

Becomes semi-automatic operation selected, calculated the module for path planning from the three-dimensional position of the destination container as well as from the distance and the orientation of the recording device (or Container bottom of the container to be stacked) optical or Acoustic signals to guide the driver to the destination.

Further Features, details and advantages of the invention will become apparent explained in more detail in an embodiment shown in the drawing. It demonstrate:

1 : a reachstacker while picking up a container to clarify the problem,

2 Fig. 1 is a schematic representation of a reachstacker according to an embodiment of the present invention during picking up a container from a container stack;

3 : a schematic representation of a reachstacker,

4 : A top view of a container spreader, as it is used as a lifting device in a reachstacker of the present invention and

5 : A diagrammatic representation of the overall structure of the inventive method.

1 shows an arrangement of containers 10 and a reachstacker 12 with which the containers are to be handled. The area below the dashed line 13 can not be viewed by the operator. Without special measures can therefore when gripping the left uppermost container, as shown here in the figure, the position of the spreader only based on the position of the boom 14 the reachstacker 12 to be appreciated.

In the 3 is a reachstacker 12 shown a vehicle chassis 13 has, in the usual and not shown here, a diesel engine is arranged as a drive motor. The Reachstacker shown here has a rear rubber-tyred pair of wheels 16 and two front pairs of wheels 18 on. The front pairs of wheels sit on the drive axles, while the rear pair of wheels sits on a longitudinal axis. At the vehicle chassis 13 is a telescopic boom can be raised and lowered 20 arranged. The telescopic boom 20 is curved in itself in the embodiment shown here, in particular from the 1 seen.

The telescopic boom 20 is about a single appropriately sized rocker cylinder 22 raised and lowered. At the top of the telescopic boom 20 is a load-bearing means in the embodiment shown here, a spreader 24 articulated, by means of which as a load, for example, a container 10 can be included. On the vehicle chassis 13 is also a driver's cab side 28 arranged.

4 shows a plan view of the load-receiving means in the form of the spreader 24 , In the 3 and 4 For example, the degrees of freedom of movement used by the control device are specified. So can the spreader 24 around the axis 26 are rotated by the angle β (t), are translationally moved in the direction T (t) and, accordingly, when the length of the boom is changed 20 telescoped around the boom length l (t). The boom itself includes a drive to change the boom length l (t). About the cylinder 22 the angle of elevation Θ (t) is varied. With the help of the chassis, which has a steering and a propulsion, the position and orientation of the stacking device v (t) can be varied.

In the 2 is an inventive Reachstacker 12 shown in which a first CCD camera 30 and a second CCD camera 32 for surveying the containers located in the near field of the spreader.

in the The following will focus on how the individual modules work received.

At the Device mounted Sensor elements such as cameras, laser scanners or radar scanners capture permanently an area from an unknown array of containers. The image data of the camera system are subjected to a digital image preparation, so that from it image information such as container corners, edges or Stabilization struts can be detected. It exists in principle also the possibility the corner fittings to detect the container using pattern recognition methods. The two-dimensional image information becomes a three-dimensional image in the next step Assigned position and orientation and transformed into the target coordinate system. It is necessary, the relative distance of the extracted Identify characteristics of the camera system. For this, depending on the system configuration, three different measuring principles in a suitable combination used:

stereo camera

The Image characteristics of the two camera images are assigned and the spatial Position of the features calculated by the triangulation method.

Single camera using the perspective imaging ratio

The Width of the container is a standard size. Because the optical properties the camera are known the characteristics associated with the transverse and cover side of the container are, by means of the perspective reproduction ratio be measured three-dimensionally.

camera system with laser scanner

At the Device additionally attached to the camera system one or more laser scanners, the three-dimensional measurement data deliver in the form of a point cloud. At least one laser scanner is like that aligned so that at least one measuring beam parallel to the optical Axis runs. Because the scanners are mounted at a certain distance from the camera system are the three-dimensional measuring points of the laser sensors transferred by means of a coordinate transformation in the camera coordinate system, so that the corresponding pixels are given a three-dimensional position can be. additionally These data are used to form container surface segments to detect.

The relative location and orientation of the environmental features M (t) change during movement of the stacker. For this reason, a condition observer is used for the faster estimation of the environmental conditions, which fuses the data of the different sensors and uses odometry. The joint variables x ⁽ⁱ⁾ (t) of the device are detected and made available to the observer after a transformation into the corresponding sensor coordinate system (vector O (t)).

The feature information M (t) is the basis for the reconstruction of container contours C (t). First, the measured edges and surface segments are awarded vertical and horizontal planes. Then the intersection is calculated, which consists of straight lines or points. Points are interpreted as possible container corners and straight lines are interpreted as candidates for container edges. In addition, the environmental features M (t) are selected, which can be used to describe the Kontor (container corners and edges). On the basis of geometric plausibility conditions, parts of the container account are reconstructed from this information. It is helpful to consider the reconstructed contours already present in the container environment model U.

The reconstructed subregions of the container contours C (t) are used to generate a three-dimensional container environmental model U. In doing so, the model reflects the container scenarios detected during a manual or automatic journey by successively supplementing the contour information. It is also trying to complement non-reconstructed contours so that the container in size and position can be described in three dimensions. The location and orientation of the containers that are not in the immediate gauge space of the sensors are estimated using the reconstructed neighboring containers. The advantage of this method is that the scenario of the container arrangement is known even before the actual positioning. As a result, difficult to view loading situations can be reconstructed or estimated using the container environment model. In addition, the environmental model offers a safety function, since incorrectly detected container characteristics can be excluded with the help of a plausibility check. Another advantage of the environmental model is that the position information of the three-dimensional detected container can also be used when sensors fail or their optical detection range in the target approximation z. B. is restricted by obstacles.

Since the container environment model U usually comprises several containers, the destination container Z must be selected therefrom. This can be done by the modeled container scenario is displayed on a touch screen and the device operator selects the destination container. Furthermore, the destination container can also ge automatically be chosen. To do this, the operator independently drives the target area. As is always known by the odometry and a corresponding transformation in the gripper coordinate system, where the spreader is in the container environmental model, the target container is then selected when a certain distance from the target container to the spreader (or container bottom when stacking) is exceeded.

The destination coordinates of the container to be stacked or to be gripped are the basis for the path planner. It can be between a fully automatic operation in which the device automatically leads the spreader to the detected target object, and a semi-automatic operation in which the operator performs the positioning manually, be selected. In the semi-automatic operating mode, the operator is navigated to the destination with visual or audible instructions. In gripping operations, in semi-automatic operation, the path planner determines the relative three-dimensional distance and orientation offset from the spreader to the destination container on the basis of the destination coordinate Z and the current joint variable x (t). When stacking, the path planner calculates in semi-automatic operation the distance from the bottom of the container to be stacked to the destination container. The geometric data of the container to be stacked is determined from the last gripping operation. It is essential in semi-automatic operation that the operator autonomously controls the device according to his ideas and continuously receives directional instructions to the destination container. If the operator selects automatic operation, the device automatically moves to the destination container. Considering whether to stack or record, the path planner generates a time-indexed trajectory for each degree of freedom of the device. If the device has more kinematic degrees of freedom than the working space, the calculation of the target joint angles of the drives is not clear. These additional degrees of freedom are exploited in order to optimize the web according to specifiable quality criteria. A possible quality criterion ensures a time-optimized course of the desired trajectory, with geometric constraints from the environmental model U and drive-related secondary conditions, such as the maximum drive dynamics and kinematic restrictions, being taken into account. The generated desired trajectory of the drive joints x ⁽ⁱ⁾ _soll (t) is converted with a nonlinear axis controller according to the method of the "inverse torque method".

Claims (10)

Stacker, in particular Reachstacker, consisting of a vehicle chassis and a telescopic boom pivotally mounted thereon with a load-receiving means, characterized by arranged on the stacking device Sensors for detecting a region from a known arrangement of loads, preferably containers, and a computer-controlled Image recognition system for processing the sensor data. stacker according to claim 1, characterized in that as sensors cameras, Laser scanner and / or radar scanner serve. stacker according to claim 1 or 2, characterized in that optical and / or Acoustic signalers are provided. Method for gripping and stacking loads, preferably Containers, with a stacking device behind one of the preceding claims with the following steps: - To capture the sensor data, - estimating the three - dimensional position and orientation of environmental features of the Loads already during the method of the stacker, - reconstruction the load contours from the previously obtained estimation data, - Create a container environmental model, - Selection of the load. Method according to claim 4, characterized in that the existence fully automatic and semi-automatic operation for gripping and stacking loads, preferably containers, is selectable. Method according to claim 5, characterized in that that at fully automatic operation, the desired path is determined and that the stacking device accordingly is controlled. Method according to claim 5, characterized in that that at fully automatic operation, the desired path is determined and that the stacking device means a control along the desired path is moved. Method according to claim 6 or 7, characterized that at fully automatic operation over a railway planning module from the three-dimensional position of the container as well as the distance and the orientation of the lifting device or the container bottom of the container to be stacked a time-indexed Trajectory for each joint variable is formed. Method according to claim 8, characterized in that that about one Axis controller is a stabilized implementation of the desired path. A method according to claim 9, characterized in that in semi-automatic operation via a path planning module from the three-dimensional position of the target container and the distance and the Orientation of the lifting device or the container bottom of the container to be stacked optical and / or acoustic signals are generated to navigate the operator to the destination.