WO2003103375A1

WO2003103375A1 - Self-propelled device with a sensor constituted of a hall effect transducer and an adjustable operational part

Info

Publication number: WO2003103375A1
Application number: PCT/SE2003/000918
Authority: WO
Inventors: Per-Olof Zakrisson; Lars-Erik Sundberg
Original assignee: Electrolux AB
Current assignee: Electrolux AB
Priority date: 2002-06-07
Filing date: 2003-06-03
Publication date: 2003-12-18
Anticipated expiration: 2004-12-07
Also published as: AU2003244285A1; WO2003103375A8; SE0201741D0

Abstract

The present invention relates to a self-propelling device, preferably a self-propelling lawn-mowing robot comprising at least a control and navigational control system that in conjunction with outer influence on the device, for instance collision with an object, at least by information from one or several sensors (41) placed in or on the device, controls the movements of the device across a surface area. The device is designed so that at least a first part of the device moves in relation to the device's remaining parts in conjunction with the outer influence. The device is so designed that the first part of the device moves in relation to the device's remaining parts in conjunction with outer influence. The self-propelling robot comprises a sensor (41) that detects the movements of the first part without being in contact with the first part.

Description

Case P-10092

Applicant: Aktiebolaget Electrolux, Stockholm

SELF-PROPELLED DEVICE WITH .A SENSOR CONSTITUTED OF A HALL .EFFECT TRANSDUCER AND AN ADJUSTABLE OPERATIONAL PART ^■

TECHNICAL FIELD

The present invention relates to a self-propelling device, preferably a self-propelling lawn-mowing robot. The device comprises at least a control and operational system which, in conjunction with outer influence on the device, for example impact with an object, at least by information from one or several sensors positioned in or on the device, controls the movements of the device across a surface area. The device is designed so that at least a first part of the device moves in relation to other parts of the device in conjunction with outer influence.

TECHNICAL BACKGROUND

The thought to develop fully automatic working implements is old. Such working implements can for instance relate to robots for lawn mowing. In spite of this fact, such products have reached the market only in recent years. The robotic lawnmower is an example hereof. It mows an area by moving across the area and orients itself according to a certain pattern within the area to be worked on.

Control loops are arranged for the robot to stay within a limited area. These are positioned to mark the limit that the robot may not pass. Such loops can comprise electric conductors, which transmit signals to be sensed by the robot. The robot's control and navigational control system receives the signals transmitted by the loop and processes them in order to control the robot's movement pattern in a specified way. The robot can possibly also receive control signals from the loop that activate certain functions of the robot and can possibly also transmit signals. The loops can, besides facilitating the robot's movement pattern, assist in directing the robot towards for instance a charging station. The robot's control and navigational control system then directs the robot along a loop towards the station. To avoid problems for the robot when colliding with an object, further sensors, connected to the control and navigational control system, are placed in the robot. These sensors can for instance comprise an ultrasonic system or similar, which transmits signals and receives them after having been reflected against the object. The movements of the robot can in such a way be control to avoid collisions with the object. An alternative possibility is that the robot is equipped with collision sensors, which detect collisions between the robot and the object. Other types of sensors for detection of outer influence of the robot are also conceivable.

The design of these sensors has always played a significant role in achieving a well- functioning robot. Normally, outer influence takes place from the front by means of the robot colliding with an object. Therefore the robot's front part could principally be equipped with a switch, connected to the control and navigational control system, which senses the collision. However, in order to also detect other influences such as collisions at an angle or from the side or that somebody decides to lift the device, a technical solution comprising one or many movable parts in relation to the other part of the robot is preferably used. That implies that the movable parts, which are the parts of the robot that first come into contact with the object in the collision or sense a lifting movement, can move in relation to other parts. In order to sense these movements, electric switches are normally used.

The problem with sensing by means of switches is that the movable part often is limited to movements in certain directions so that certain collisions are detected by the robot's control and navigational control system. Consequently the robot's possibilities to operate are limited. Besides, in certain environments, the operation of the switches can deteriorate due to contact point wear of the switches or due to humidity, etc. Another problem with this technical solution is that the cost for the sensing system tends to become high. It is therefore preferable to design a collision sensing system without these problems.

SUMMARY OF THE INVENTION

The device is so designed that the first part of the device moves in relation to the other parts of the device in conjunction with outer influence. The self-propelling robot comprises a sensor that senses the movements of the first part without being in direct contact with the first part. DESCRIPTION OF FIGURES

The invention is described in more detail in conjunction with the preferred embodiments and with reference to the enclosed drawings.

Fig. 1 shows a perspective view of a robot in accordance with the invention.

Fig. 2 shows a perspective view of the second part of the robot in accordance with fig. 1.

Fig. 3 shows a perspective view of the rotating and the adjusting part of the robot according to fig. 1.

Fig. 4 shows a perspective view of the cover of the adjusting part in accordance with fig. 3.

Fig. 5 shows a perspective view of the outer adjustment part of the adjusting part in accordance with fig. 3.

Fig. 6 shows a perspective view of the inner adjustment part of the adjusting part in accordance with fig. 3.

Fig. 7 shows a perspective view of the locking spring of the adjusting part in accordance with fig. 3.

Fig. 8 shows a perspective view of a part of the second part in accordance with fig. 2.

Fig. 9 shows a perspective view of a part of the wheel front of the part in accordance with fig. 8.

Fig. 10 shows a perspective view of the upper part of the robot in accordance with fig. 1.

Fig. 11 shows a perspective view of the collision part in accordance with fig. 10. Fig. 12 shows a perspective view of a pillar as part of the collision part in accordance with fig. 11.

Fig. 13 shows a perspective view of the lifting part in accordance with fig.2.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

The figures show a preferred embodiment of a robot in accordance with the invention. The preferred embodiment shall not be interpreted as a limitation of the invention but rather has the aim of concretely illustrate a type of robot in which the invention can be applied. This is to further illustrate the thought behind the invention.

Fig.l shows a lawn-mowing robot. The robot has two bigger rear wheels 1, which propels the robot forwards. Observe that the upper part of the robot is not shown in the figure. The upper part relates to the cover or the shell, which covers the entire robot in fig. 1. The shell is mounted on the collision parts 2 and an upper movable part (not shown). The collision parts, as a significant part of the invention, are described below in closer detail with reference to fig. 10-12. The upper part will thereby be able to move freely in all directions parallel in relation to the robot when colliding with an object. That embodies the thought of the invention. Apart from the collision parts the robot also comprises an adjusting part 3, whose cover is shown in the figure. The adjusting part having a rotating part is described below in further detail with reference to fig. 3-7. The figure also shows a cavity 4 for the robot's control and navigational control system, which controls the lawn-mowing robot's rear wheels and the rotating part, i.e. its cutting blades. The system is also connected to the sensors described in further detail in conjunction with fig. 10-13. The system as such is not described in further detail in this patent application.

In fig. 2 the robot has been opened by means of lifting off a covering part 5. The figure is primarily intended for showing the positioning of the adjusting part 3 and a lifting part 6. The lifting part is described below in further detail with reference to fig. 13. Also shown are one of the motors 7 with shaft, which drive the rear wheels 1, and the control and navigational control system 8, that directs the robot. Fig. 3-7 show the rotating part and the adjusting part in closer detail. These parts constitute a part of the robot and complement the new robot system, which the collision parts facilitate.

At the top of fig. 3 and in fig. 4 a cover 9 is shown, which can also be seen in fig. 1. It co-operates with an aperture 10 in the cover part 5. There are clips 11 on the cover, which facilitate the cover to be snapped onto the outer adjusting part 12 via groove 13, see fig. 5. The grooves and clips are shaped so that the cover can be snapped on in one way only. The reason is that the scaling as shown in fig. 1 shall correspond to the rotating parts height above the ground.

The outer adjusting part's 12 outer side 14 is profiled in order to co-operate with a stop lug 15 and a locking spring 16, see fig. 7. The reason is that the rotation of the outer adjusting part shall be guided and that it shall be impossible to rotate the outer adjusting part 12 too far. The locking spring is mounted on a lower part of the chassis 17, with which also the outer adjusting part co-operates. There are also inner threads 18 in the outer adjusting part. These have a steep pitch and co-operate with threads 24 of an outer adjusting part 19. The shape of the threads facilitates the whole intended adjustment range to be achieved in one turn. A motor 20 driving a rotating part 21, i.e. the cutting blades, is placed in the inner adjusting part. The motor is placed at an aperture 22 in the lower adjusting part so that the motor shaft protrudes underneath. The inner part also comprises an aperture 23 for motor cables. The space between the inner part and the lower chassis is sealed with a flexible rubber bellow in order to seal and protect the motor and parts of the rotating part.

The adjusting part 3 for the adjustment of the cutting height of the cutting blades functions as per below. The operator rotates the cover 9 according to the scaling as shown in fig. 1. Thereby also the outer part 12 rotates between the two extreme positions limited by the locking spring 16. By means of co-operation between the outer and the inner part's 19 threads, the cutting blade's height above the ground, and thereby the cutting height, is controlled by the rotation of maximum one turn.

Fig. 9 shows a part of the lower chassis 17. Both motors 7 can be seen. Since one of the rear wheels 1 has been taken off, one wheel front 25, 27 appears, see fig. 8. The intention with this is to facilitate two alternative mountings of the motor, motor shaft, gear arrangement (not shown) and wheel shaft 26. The wheel front comprises a part of the robot and complements the new robot system that are facilitated by the sensors. By placing the wheel front rotated 180 degrees in relation to the one shown in fig.l, all these parts are displaced downwards. Thereby simple means to achieve different cutting height adjustments for the robot during production is created. Four outer holes 28 are used to fasten the front to the chassis and four inner holes 29 to fasten the motor and the gear to the front.

Fig. 10 shows the cover part 5, see fig. 1. The cover part comprises the essential parts of the intended invention. The figure illustrates the lower side of the cover 9 and the cavity

4. Besides, significant parts of the two collision parts 2 are shown. These comprise one of the parts which facilitate sensing of outer influence on the robot, preferably by sensing collisions. These are clearer illustrated in the exploded view in fig. 11. The figure shows a part 30 of the cover or upper part, which is mounted on top of the robot in a movable manner. A rubber element 31 is mounted on the part 30 in a fix or detachable way. The main part of the of the collision part comprises a pillar 32 (see fig.

12), whose upper end 33 is connected (possibly in a detachable way) to the rubber element, preferably by means of the end perforating a part of the element. The pillar is flexibly mounted to the cover part 5 by means of a fastening ring 34 (upper part) and a rubber gaiter 34 (lower part). The gaiter, fastened to the cover part by means of the fastening part, is co-operating with the pillar whereby sealing and fixing of the pillar to the gaiter are achieved.

The collision parts 2 also comprise a deflection limiter 35 through which the pillar 32 extends. It prevents the pillar from moving too much in any direction. A part 36, that co-operates with the limiter 35, is conically shaped in order to stop the limitation from being too abrupt. The pillar's lower end 37 is shaped so that it can hold a permanent magnet 38. A holder 39 is designed into the cover part 5. The assembled pillar will move in the holder. A circuit board 40 with a Hall effect transducer 41 is placed in its bottom.

The collision parts 2 function as follows. When the robot collides with an object, the cover, and consequently the upper part 30, which constitutes the part of the robot that senses the collision, will move in relation to the remaining parts of the robot. Since the upper part is suspended in the two collision parts and a front collision pillar (not shown), these will be forced to follow the movement. At the same time as the upper part's movement is dampened by the collision parts, the lower ends 33 and 37 of the collision parts move in separate directions. The movements of the lower part 37 and the permanent magnet 38 are detected by the Hall effect transducer, which is connected to the control and navigational control system. The control and operational system 8 thereby detects collisions against objects and can take measures to direct the robot in relation to the object.

A lifting part is shown in fig. 13, see also fig. 2. The lifting part constitutes another possible way of sensing outer influence of the robot, preferably if it is lifted or passing across hollows etc. Instead of a cover as the second part, a wheel suspension for the robot's both front wheels 46 is used. The suspension includes a wheel spindle 47, which is arranged at the wheel in a rotating manner in order to function as a wheel shaft as well as being arranged in a rotating and sliding manner in a transmission device 42 at the lower chassis 17 of the robot. A permanent magnet 43 is arranged at the other end of the wheel spindle. A circuit board 44 and Hall effect transducer 45 are arranged in the chassis.

The lifting parts function as follows. When lifting the robot, at least one of the front wheels, suspended in the transmission device 42, will be forced downwards by gravity. The same happens if the wheel, when the robot is moving, passes over a hollow and falls downwards. Since the wheel spindle 47 is arranged in a sliding manner in the transmission device, the permanent magnet 43 will move away from the Hall effect sensor 45 until the spindle comes to a stop. The stop (not shown) prevents the spindle from sliding out of the transmission device. The control and navigational control system 8 (connected to the Hall effect transducer) thereby detects movements and directs the object in relation to the hollow. An alternative way can be that the system chooses to stop the rotation of the cutting blade disc, back away from the object or turn.

Further preferred embodiments are included in the intended thought of invention as specified in the patent claims. The invention is consequently not limited to what is described above and shown in the drawings of the preferred embodiments, but can be used within all areas where an improved detection of outer influence on the robot is requested.

Claims

1. Self-propelling device comprising at least a control and navigational control system (8) that in conjunction with outer influence on the device, at least by information from one or several sensors (41, 45) placed in or on the device, controls the movements of the device across a surface area, whereby at least a first part (2, 47) of the device moves in relation to the remaining parts of the device in conjunction with outer influence, characterised in that the sensor (41, 45) detects movements of the first part (2, 47) without being in direct contact with this first part (2, 47).

2. Self-propelling device according to patent claim 1 characterised in that the sensor (41, 45) constitutes a Hall effect transducer, whereby a permanent magnet (38, 43) is arranged at the first part (2, 47).

3. Self-propelling device according to any of the previous patent claims, characterised in that the first part (2, 47) constitutes a collision part (2) that is arranged at the upper continuous part (30) on the device, which suspends at least one of the device's outer sides, whereby the movements of the collision part (2) is influenced by a force against the upper continuous part (30), whereby the applied force moves the upper part (30) mainly in parallel relative to a second part (5) of the device.

4. Self-propelling device according to patent claim 3 characterised in that at least one collision part (2) comprises an elongated sub-shaft (32) directed from the upper continuous part (30), the sub-shaft (32) has a first end arranged at the upper continuous part, whereby the shaft between the ends is at least flexibly arranged at the second part (5) of the device.

5. Self-propelling device according to patent claim 4 characterised in that the collision part (2) is flexibly arranged at the first part by means of a first rubber part (31) and arranged at the second part in a flexible and retracting manner by means of a second rubber part (34).

6. Self-propelling device according to any of the patent claims 4 - 5 characterised in that the elongated sub-shaft's (32) other end is directed towards the sensor (41) and carries a permanent magnet (38).

7. Self-propelling device according to any of the previous patent claims, characterised in that at least the first part (2, 47) constitutes a lifting part (46, 47) that comprises a wheel (46) and a wheel spindle (47) arranged at the wheel (46) intended to suspend the device, whereby, during outer influence of the device, the lifting part (46, 47) is brought into movement by the gravitational force, the movement showing a direction partly corresponding to that of the gravitational force.

8. Self-propelling device according to patent claim 7 characterised in that the wheel spindle (47) is in one piece and constitutes or is attached to the wheel shaft and is arranged at the device's second part (17, 42) in a rotating and between two end positions sliding manner.

9. Self-propelling device according to any of the patent claims 7 - 8 characterised in that one end of the wheel spindle (47), opposite the end nearest to the wheel (46), is directed towards the sensor (45) and carries a permanent magnet (43).

10. Self-propelling device according to any of the previous patent claims, characterised in that the device comprises an operational part (3, 21) with a rotating part (21) suspended by an adjusting part (3), the adjusting part (3) constituting an outer adjusting part (12), arranged at a second part (5) of the device in a rotating manner, and an inner adjusting part (19) with threads (24) which co-operate with threads (18) on the outer adjusting part (12), whereby the rotating part (21) is arranged at the inner adjusting part (19) so that the rotating part's (21) distance to the surface is controlled by making the outer adjusting part (12) rotate.

11. Self-propelling device according to patent claim 10 characterised in that the outer adjusting part's (12) threads (18) have a pitch and design that facilitate distance control by turning the outer adjusting part (12) maximum one full turn.

12. Self-propelling device according to any of the patent claims 10 - 11 characterised in that the inner adjusting part has an inner space and co-operates with a device (46) by which the space is kept essentially free from particles penetrating from outside, whereby a motor (20), which drives the rotating part (21), is placed in the space.

13. Self-propelling device according to any of the previous patent claims, characterised in that at least one of the wheel shafts is mounted in bearings at a wheel front (25, 27) designed so that the position of the shaft can be changed by rotating the wheel front (25, 27) in relation to the device.

14. Self-propelling device according to any of the previous patent claims, characterised in that the device constitutes an automatic lawn-mowing robot that comprises a control and navigational control system (8) and an operational system (3, 21) for mowing a lawn surface.

15. Suspension part for suspension of the first part of a device in relation to a second part of the device, characterised in that when the suspension part is arranged at the first part (30) and the first part is influenced by a force, the first part (30) moves essentially parallel in relation to the second part (5) of the device.

16. Suspension part according to patent claim 15 characterised in that the suspension part comprises an elongated sub-shaft (32) directed from the first part (30), the sub-part (32) having a first end arranged at the first part (30), whereby the shaft between the ends is at least flexibly arranged at the second part (5) of the device.

17. Suspension part according to patent claim 16 characterised in that the suspension part is flexibly arranged at the first part by means of a first rubber part (31) and arranged at the second part in a retracting manner by means of a second rubber part (34).

18. Suspension part according to any of the patent claims 16 - 17 characterised in that the elongated sub-shaft's (32) second end carries a permanent magnet (38).