Field of the invention

The present invention relates to a robotic device and to a sensor device for a robotic device. Background of the invention

Robotic devices are used in various applications and environments, for example the automated manufacture of products. Such robotic devices commonly comprise a movable arm to which a tool is attached. In use, the arm and the tool are moved with respect to the product to be manufactured and vice versa.

In this context a problem that needs to be solved is the avoidance of collisions between the robotic device and other objects or human operators.

Known solutions to this problem include stationary sensor devices which are operable to sense the environment of the robotic device. Common sensor devices comprise ultrasound, machine-vision, LIDAR or ToF-sensors. One drawback of this approach is that the robotic device may obstruct the field of vision of the sensors, thereby preventing the reliable detection of potential collisions.

In an alternative approach, torque sensors are attached to the movable parts of the robotic devices to detect collisions by sensing torque variations. Thus, in this approach collisions are not prevented but detected after they have occured. In order to prevent damage, parts of the robotic device are provided with a protective skin or coating. The skin itself can also be arranged to detect collisions.

Also, it is generally known to provide robotic arms with visual sensors to support control and steering of the robotic arm in relation to another object, e.g. a product to be handled by a robotic arm.

The present invention aims to provide a robotic device and a sensor device for a robotic device that provide an improved detection of situations indicative of a potential collision with an object in the vicinity of the robotic device.

Summary of the invention

The present invention is recited in claim 1. Preferred embodiments are recited in the sub-claims. According to one aspect of the present invention there is provided a robotic device comprising: a plurality of sensors distributed over at least a portion of a surface of the robotic device, wherein the sensors are operable to visually detect an object in the vicinity of the robotic device based on a relative movement of the object with respect to the sensors .

The present invention resides in the realisation that by detecting the presence of an object based on its movement relative to the robotic device, it is possible to use low resolution visual sensors. Such sensors can be arranged in clusters and/or evenly distributed on a portion of the peripheral surface of the robotic device, in particular the surface of moving parts of the robotic device, e.g. a movable arm or a portion thereof.

Due to the ability to employ low resolution sensors, it is possible to provide a large number of such sensors at relatively low costs. The sensors may be arranged in clusters. For example, a cluster may include 100 or more such sensors. Also, the sensors may be arranged such as to provide redundancy so that the detection of objects is still possible if some of the sensors fail. Moreover, the processing of the output of the low resolution sensors is of relatively low complexity so that the processing can be performed by a relatively simple and/or low-cost controller. Such controller can be compact and robust so that it may be integrated with the sensors.

The low-resolution sensing of relative movements enabled by the present invention is in contrast to conventional robotic systems that employ complex image recognition systems with high processing overheads and virtually no redundancy.

The surface of the robotic device on which the sensors are arranged may be formed by a section of a cylindrical robotic arm. In this example, the sensors are arranged around the cylindrical outer surface of the arm, for example at the end of the robotic arm to which end a robotic tool is attached.

In one embodiment, the sensors comprise at least first sensors having first sensor characteristics and second sensors having second sensor characteristics different from the first sensor characteristics. For example, the first and second sensors can be optical sensors having different sensitivities in different spectral ranges (e.g. VIS, NIR, MIR) . Alternatively, the first sensors can be optical sensors and the second sensors can be piezo- and/or pyroelectric sensors .

Preferably, the first and second sensors are arranged alternatingly with respect to one another. Thereby, the different sensors can be evenly spread, improving the overall sensitivity .

On one embodiment, the sensors comprise sensors that are both piezoelectric and pyroelectric. Such sensors are known as Pyzoflex® sensors and can be applied by a printing process.

In an embodiment, the plurality of sensors are included in a sensor device comprising an integrated control device to effect an alteration or a termination of a movement of the robotic device in response to a detection of an object in the vicinity of the robotic device. This embodiment enables the implementation of a compact control device that can be used to control the function of the robotic device, in particular to control movements of the robotic device so as to avoid collisions. The control device may be connected to a main controller of the robotic device and may issue control commands to the main controller in order to control movements of the robotic device in response to the detection of an (unwanted) object in the vicinity.

In an embodiment the robotic device comprises a robotic arm including one or more sections, wherein at least one of the sections is movable, wherein the sensors are distributed over at least a portion of the surface of at least one of the sections of the robotic arm. Such robotic device may be employed in the automated robot-aided manufacture of products, for example at assembly lines. The sensors enable a control of the movement of the movable section of the robotic arm and/or other movable devices used in the automated manufacturing process. Such movements may be stopped or altered in response to detecting a potential collision.

In one embodiment the robotic arm comprises a sensor device comprising the plurality of sensors, wherein the sensor device is ring-shaped and arranged at one end of the at least one movable section of the robotic arm. The ring-shaped sensor device enables a round-visibility of the sensors. In one embodiment the end of the movable section comprises a flange, wherein the sensors are integrated in the flange. Such flange may be provided to attach a tool to the robotic arm. By integrating the sensors in the flange it is possible to monitor an area in the vicinity of the tool without requiring additional space for the sensors.

In particular, the sensors may be distributed around the circumference of the flange. Preferably, the sensors are arranged to face radially outward around the circumference of the flange. Accordingly, the sensors have a 360° radial field of vision with respect to the axis of the flange.

In an embodiment, the sensors are arranged in a cluster on the surface of the robotic device. This embodiment enables the monitoring of specific critical areas in the vicinity of the robotic device.

In one embodiment, the sensors are arranged to visually detect the relative movement of an object with respect to the sensors within a range up to approximately 1 meter from the sensors. Accordingly, it is possible to use sensors that operate within this range only, enabling the provision of a high number of relatively low-cost sensors.

The robotic device may be formed by a robotic arm, a mobile robot or a drone. In other words, the present invention can be used in various robotic applications and environments. In each application the sensors may be arranged so as to satisfy application-specific requirements, e.g. a circular arrangement of radially outward-facing sensors to provide round-vision, an arrangement of sensors in clusters to monitor specific delimited areas, etc. According to another aspect of the invention there is provided a sensor device for a robotic device, the sensor device comprising: a support element, in particular collar- or ring-shaped support element, the support element including a plurality of sensors, the support element attachable to a robotic device, in particular to a robotic arm, wherein the sensors are operable to visually detect an object in the vicinity of the robotic device based on a relative movement of the object with respect to the sensors, and wherein the sensors are distributed around the outer surface, in particular the circumference of the support element, and wherein the sensors are arranged to face outwardly around the surface of the support element, in particular radially outward around the outer circumference of the support element .

Such sensor device may be retrofitted to existing robotic devices. For example, the collar- or ring-shaped support element can be attached to a moveable arm of a robotic device, enabling the detection of objects in the vicinity of the robotic device as described above.

In an embodiment, the support element comprises an integrated control device to generate a control signal to effect an alteration or a termination of a movement of a robotic device in response to a detection of an object in the vicinity of the sensors. Accordingly, by retrofitting the sensor device to a robotic device, it is possible not only to add the sensing functionality, but also to add control functionality enabling a control of the movement of the robotic device, e.g. to stop or alter movements of a movable arm or the entire robotic device.

Brief description of the drawings

Exemplary embodiments of the invention are schematically shown in the attached drawings:

Figure 1 schematically illustrates a robotic device in accordance with an embodiment of the present invention.

Figure 2 schematically illustrates an arrangement of a plurality of sensors in accordance with an embodiment of the present invention. Figure 3 schematically illustrates a robotic device in accordance with another embodiment of the present invention.

Figure 4 schematically illustrates a mobile robot in accordance with an embodiment of the present invention.

Figure 5 schematically illustrates a drone in accordance with an embodiment of the present invention.

Description of exemplary embodiments Figure 1 shows a first exemplary embodiment of the invention. A robotic device 1 comprises a robotic arm 2 in a typical six-degree-of-freedom configuration. A tool 4 is attached to the robot flange 7 at the outer (free) end of the arm. The exemplary tool 4 comprises a cylindrical rod-shaped element 5 that attaches to the robot flange 7 and a gripping element 6. In the illustrated embodiment, the robot flange 7 comprises a plurality of sensors (not shown) . The sensors are arranged on the outer cylindrical circumferential surface of the flange 7 and face radially outward.

The robotic device 1 further comprises a base portion 8 that contains a rotary joint, first- 3a, second- 3b and third movable arm portion 3c, rotary joints 9a and 9b, as well as a spherical wrist 9c with its attached robot flange 7. In the illustrated embodiment, each of the arm portions 3a, 3b, 3c is cylindrical, although other shapes are possible.

Figure 2 schematically illustrates a sensor device 20 in accordance with an embodiment of the present invention. The sensor device 20 comprises a support element 21 for supporting a plurality of sensors 22a, 22b. The sensors 22a, 22b are arranged on an outer surface of the support element 21. In particular, the sensors 22a, 22b are distributed evenly over the entire outer surface of the support element 21. The support element 21 may have a circular cross-section, wherein the sensors 22a, 22b face radially outward with respect to the longitudinal axis of the support element 21. In the illustrated embodiment, the support element is cylindrical, although other shapes are possible.

The sensors 22a, 22b are arranged in a facet-like manner on the outer surface of the support element 21. The support element forms a collar that may be arranged around the flange 7 and/or one or more of the arm portions 3a, 3b, 3c (Figure 1)

The sensors 22a, 22b comprise two types of different sensors ("Sensor Pixel - Sensor 1" and "Sensor Pixel - Sensor 2 " ) . The sensors are arranged in alternating fashion so that in each line, a sensor of one type is arranged between two sensors of the other type. Each type may be characterised by predetermined sensor parameters, e.g. sensitivity in a certain spectral region, detection range etc.

In an embodiment, the sensors 22a may be visual sensors of low resolution, while the sensors 22b may be piezo- /pyroelectric sensors, in particular Pyzoflex®-sensors . Preferably, the sensors have detection range up to 1 meter.

The support element 21 may comprise an integrated controller (not shown) operable to process data acquired by the sensors 14 and to generate control signals to control the movement of a robotic device to which the sensor device 20 is attached.

Figure 3 schematically illustrates a robotic device 30 in accordance with another embodiment of the present invention. Except for the arrangement of the sensors, the robotic device 30 is identical to the robotic device 1 of Figure 1. However, in the embodiment of Figure 3, there are three sensor devices 31, 32 and 33 arranged around the movable arm portions 3a, 3b and 3c, respectively. Each of the sensor devices 31, 32, 33 is implemented in a collar- or wristband-type manner, arranged around the respective arm portion. Accordingly, each of the sensor devices 31, 32, 33 comprises a collar- or wristband-shaped support element on which a plurality of sensors is arranged.

Figure 4 schematically illustrates a robotic device 40, as seen from above, in accordance with another embodiment of the present invention. In this embodiment the robotic device 40 is formed by a mobile robot such as a robotic lawn mower or vacuum cleaner on wheels 41. In this embodiment, a plurality of sensors is arranged in clusters 42, 43 and 44 at the two front corners and the rear end of the robotic device 40, respectively .

Figure 5 schematically illustrates a robotic device 50, as seen from above, in accordance with yet another embodiment of the present invention. In this embodiment, the robotic device 50 is formed by a drone. The drone comprises a central element 51 to which four rotor holders 52 are mounted. A rotor flange 53 is mounted at the free and of each of the holders 52. Rotor blades 54 are mounted to each of the rotor flanges 53. Sensor devices 55 and 56 are provided around a portion of the circumference of two of the flanges 53. The sensors face radially outward with respect to the rotation axis of the rotor flanges 53. Another sensor device 57 is provided at one side (the rear) of the central element 51. Each of the sensor devices 55, 56 and 57 comprises a plurality of sensors arranged in respective clusters.

The arrangements of the sensors illustrated in Figures 4 and 5 are exemplary only. Other arrangements are possible, such as an arrangement of clusters of sensors at each of the rotor flanges 53 (Figure 5) or around the entire peripheral surface of the robotic device 40 (Figure 4) . These arrangements too are examples only.