Sensor-assisted robot gripper system according to the tentacle principle

The invention relates to a device and a method for handling devices, in particular for self- and remote-controlled robot for detecting, gripping and holding objects with not known in detail shape. Nature. Position and spatial position, wherein the gripping operation is carried out by a looping of the object and by nestling of gripper parts of the multi-membered gripper mechanism to article parts. The kinematics of the gripper mechanism is characterized by a high number of kinematic axis degrees of freedom, which allows an initiated by actuators flexible adaptation of the gripper shape to the shape of the object. Here are sensors on the gripper surface, for example in the vicinity of the joints of the gripper mechanism for detecting contact forces in the contact and wrapping of the object to be gripped. The sensor signals are amplified, digitized and fed to an arithmetic unit, for example digital computers, where, after digital processing, they serve in a control algorithm for controlling the actuators of the multi-unit gripper mechanism. For the control algorithm linear and non-linear methods, but advantageously known elements such as neural networks and fuzzy algorithms are used.

The method for control-technical evaluation of the sensor signals in the arithmetic unit and the control and control of the gripper motors allow a gripping operation without prior knowledge of the exact item position, object position, object shape and object condition by the sensor signals themselves are used to the location and design characteristics of the object during the gripping process to investigate. The gripping reaction is triggered by the device-technical simulation of a conditional reflex, wherein the information present in the sensor signals by location and time of the object contact and, for example, the size of the received contact forces information for optimizing the gripping process in terms of gripping position, gripping speed and gripping force is used. In this respect, reference is made to the preambles of claims 1 to 7.

Gripper systems are known which have, for example, gripping tongs-like devices, vacuum suction systems or mold-forming mating surfaces for detecting the article.

DE 4 109 724 A, for example, a gripping tool for receiving disorderly lying in containers workpieces is described, soft is equipped in an alternative embodiment with tentacles made of limp and longitudinally elastic hose. These tentacles are passively carried by the gripping tool and not articulated moves. It can therefore be effected by regulated actuators flexible adaptation of the gripper shape to the shape of the object, as is the case with the device according to the invention.

Furthermore, US Pat. No. 4,723,353 A discloses interchangeable multifunctional end effector tools equipped with suction cups, which, however, are not supported by a multi-link mechanism as in the device according to the invention, which has a high number of kinematic axes compared to the number of spatial degrees of freedom. Degrees of freedom. It can be caused by a control technology realized gripping reflex by the presented device no looping of the workpiece.

FR 2 354 861 A describes a multi-element gripper mechanism. Its elements are not moved as in the device according to the invention in the sense of a sensor-monitored, control technology realized gripping reflex.

Also known from SU 1 240 578 A are staple-shaped grippers with multi-element fingers, which facilitate gripping in hollow workpieces. In contrast to the device according to the invention, these multi-element fingers are not moved in the sense of a sensor-monitored gripping reflex realized by control technology.

EP 402 849 A describes robotic manipulators whose motion progression is controlled by means of fuzzy algorithms. There, the rule-based elements of the fuzzy control are used to circumvent the inverse kinematic problem, and not as in the inventive method to achieve a control technology replicated gripping reflex.

Various embodiments of fuzzy logic circuits are also known. For example, US 5 046 019 A and GB 2 252 426 A. In the first example, defuzzification is accomplished by neural networks. In the second example, an arithmetic unit consisting of a Fuzzv controller calculates the membership function according to the control value of the route by means of inference, and determines the control variable from the membership function. In contrast to the method according to the invention, these regulators do not serve to achieve a gripping reflex, and therefore do not suggest the subject invention.

The prior methods and apparatus require positioning of the gripper system taking into account at least approximately agreement with the object position and position, the position and attitude of the object being at least approximately known

AT 401 633 B must. The number of kinematic axis degrees of freedom of the known gripper systems is in the order of the spatial degrees of freedom or less, so that initiated by actuators flexible gestaltmäßige adaptation of the outer shape of the gripper system to the object shape is not possible.

Also known are gripper systems that are equipped with tactile sensors to gain information for controlling the gripper actuators by contact and force information from the interaction with the object. However, the sensors are used, for example, only the detection of the contact forces and the sliding behavior between the gripper and the object, the sensor signals are not used for equipment simulation of a conditional gripping reflex, as is the case with the inventive method.

The invention is therefore based on the object an apparatus and method for handling equipment, especially for self- or remote-controlled robots, which detects and grips objects with a shape that is not known in detail, Nature, Position and spatial position allows, wherein the Greitvorgang itself is initiated and controlled by sensors on the gripper system surface and a connected calculator, that a device-technically imitated gripping reflex is effected.

The device according to the invention is characterized by the following features:

Device for handling equipment, in particular for self- and remote-controlled robot for detecting, gripping and holding objects with not known in detail shape, nature, position and spatial position, characterized in that the gripping operation by a looping of the article and by nestling of gripper parts of the multi-membered , In the sense of an artificial gripping reflex regulated gripper mechanism is performed on the object or parts of the object to be gripped.

The kinematics of the gripper mechanism has a high number of kinematic axis degrees of freedom relative to the number of spatial degrees of freedom to allow looping of the article and article parts and nestling against the article surface. A high number of sensors compared to the number of spatial degrees of freedom measure the contact with the object surface via methods known per se, such as, for example, acceleration measurement, force measurement and structure-borne sound measurement. The sensor signals are fed to a calculator after preparation and digitization. The actuation of the actuators is effected by control signals, which are obtained by processing an executed in the arithmetic unit algorithm from the sensor signals.

The method according to the invention for detecting and gripping objects with a gripping reflex simulated by apparatus is characterized by the following method steps:

The control algorithm executed to control the gripping operation causes, according to a stepwise search method involving the sensor information with known optimization criteria, a looping of the article or article parts, as well as a clinging of the gripper mechanism (1,2,3,4,5 and 7) to the object surface. Thus, a device-technically imitated gripping reflex is exercised. The process steps are in detail:

- The gripper system is offset by means of its actuators in a neutral starting position.

By sweeping the space in which the object to be gripped is located, the gripping process is initiated by the first contact between the object and the gripper sensors (gripping reflex simulated by the apparatus)

In a variant of the method according to the invention, space-sweeping movements of the gripper members cause random further object sensor contacts, the spatial coordinates of the object point being stored with each touch in order to later serve as auxiliary information for approximating the position of the object space. The coordinates of the points of contact can be determined from the known position of the gripper members with the help of the arithmetic unit.

- The gripper members are, controlled by the calculator, moved in the direction in which increases the number of sensor touches. This process is carried out in the form of a step-by-step search method with optimization criteria known per se, and causes the article to be looped around and clinging to the object surface. The search method is supported by previously determined item helper points.

- The search process is aborted if the object is in the grip of the gripper system. This condition is determined by the calculator from the sensor signals.

For the control algorithm known per se linear or non-linear methods are used, but advantageously elements such as neural networks and fuzzy algorithms.

Advantageous embodiments and further developments of the device according to the invention and the method according to the invention for detecting, holding and gripping objects are described with reference to FIG

AT 401 633 B

Drawings explained. The basic principle of the device according to the invention with reference to four advantageous embodiments for detecting, gripping and holding objects, Figure 2 shows an embodiment of the device according to the invention with identification of an exemplary sensor arrangement and Figure 3 is a block diagram for Processing of the sensor signals in an arithmetic unit and for controlling the actuators.

The exemplary embodiments of the device according to the invention illustrated in FIGS. 1 (a) to (d) serve to illustrate the mode of operation of the devices and of the method according to the invention. The base (5) of the gripper mechanism is fixed, for example, in the working space, or mounted on a robot. The gripper mechanism composed of the links (7) by means of joints (JO, J1, J2, 1, 2, 3 and 4) is moved by actuators (19) which in the exemplary embodiments in the region of the joints (JO, J1, J2, FIG. 1, 2, 3 and 4) are located. In FIG. 2, for example, three current angles of the mechanism are designated phi, a1 and b1. By driving the actuators (19), which are located for example in the region of the joints (1, 2, 3 and 4), these angles can be changed. The sensors (11), which are also located in the region of the joints and on the surface of the mechanism, serve to detect an object contact. The elements of the device according to the invention for processing the sensor and actuator signals are shown in FIG. These are: (11) sensors, (12) signal amplifiers and filters, (13) analog-to-digital converters, (14) multiplexers, (15) calculator, (16) demultiplexers, (17) digital-to-analogue converters, (18) filters, Amplifier and actuator control and (19) actuators. The actuators (19) operate according to known methods, for example electromechanically, piezoelectrically, as a DC or AC motor or hydraulically.