GB2358003A

GB2358003A - Robotics

Info

Publication number: GB2358003A
Application number: GB9929094A
Authority: GB
Inventors: Alan Frank Thomas Winfield; Robert Derek Channon
Original assignee: University of Bristol; University of The West of England
Current assignee: University of Bristol; University of The West of England
Priority date: 1999-12-09
Filing date: 1999-12-09
Publication date: 2001-07-11
Also published as: AU2193001A; GB9929094D0; WO2001041976A1

Description

2358003 ROBOTICS

Field of the Invention

The invention relates to robotics, and in particular, to robots for use in conducting experiments relating to distributed mobile robotics.

Background of the Invention

It is well known for robots to be controlled by wireless communication means. It is also known for multiple robots to operate in distributed wireless systems, in which a plurality of robots interact with is one another. Such a system is sometimes referred to as a distributed mobile robotics system.

When developing a distributed mobile robotics system, for example in a laboratory, it is desirable to conduct large scale experiments in collective robotics, so that features such as swarming and self-organisation can be investigated. Ideally, such experiments should be conducted using about fifty robots, or more.

However, laboratory experiments are limited by the physical size of the robots themselves. Existing robots which are capable of operating in a wireless local area network (LAN) are approximately 30cm (twelve inches) in diameter. This means that laboratory experiments are constrained to a relatively small population of robots, being typically between twelve to fifteen for even a large sized laboratory. Carrying out experiments with greater numbers of robots, for example fifty, would require extremely large laboratories, which would therefore be impractical.

HL73953 2- To allow experiments to be carried out with large populations of robots, each robot must be made as small as possible. Although miniature robots themselves are known, the physical constraints placed on available processing space means that known miniature robots do not have wireless networking capabilities, and are generally not intelligent enough to take part in experiments relating to distributed mobile robotics.

The miniaturisation of a robot is constrained by a number of factors. For example, a robot requires a plurality of wheels to enable it to move from one location to another. Some form of steering mechanism is also needed to enable the direction of the robot to is be controlled. A robot also requires some form of power source, such as a battery, for supplying power to the drive mechanism of the robot. All these elements act against the miniaturisation process.

For example, ideally the size of the battery should be as small as possible. However, reducing the size of the battery also reduces its capacity, which means that it must be replaced, or recharged more often.

The aim of the present invention is to provide a miniature robot which is physically small enough to allow large scale distributed mobile robotic experiments to be conducted in a laboratory environment, yet having the processing capabilities which allow it to function in a wireless distributed mobile robotics system, and without having the disadvantages mentioned above.

The robot of the present invention is also suited HL73953 for many other applications which require miniature robots.

Summary of the Invention

According to a f irst aspect of the invention, there is provided a robot as def ined in the claims hereof.

According to another aspect of the invention, there is provided a development system for conducting distributed mobile robotic experiments.

According to yet another aspect of the invention, there is provided a method of conducting distributed mobile robotic experiments.

is Brief Description of the drawings

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: - Figure 1 shows a robot according to a preferred embodiment of the present invention; Figure 2 shows a underside view of the robot of Figure 1.

Detailed description of a ipreferred embodiment of the present invention.

Figure 1 shows a miniature robot 1 according to a preferred embodiment of the present invention. The robot 1 comprises a chassis 3, which houses a vertically mounted control box 5. The control box 5 contains the control electronics required for controlling the operation of the robot 1.

The underside of the chassis 3 houses two drive wheels 7, each drive wheel having an associated HL73953 motor/gearbox assembly 9, as shown in Figure 2. The chassis 3 also houses a set of brushes 11, which act to stabilise the robot, and maintain it in its upright position.

Figure 2 shows an underside view of the robot of Figure 1. Each wheel 7 is driven by a respective motor/gearbox assembly 9. The provision of an independent motor/gearbox assembly 9 for each wheel 7 enables the direction of the robot 1 to be controlled.

A plurality of batteries 13 are provided for powering the motors 9, and are preferably evenly distributed in the chassis 3 so that the robot 1 is is evenly balanced.

The brushes 11 mounted in chassis 3 are sufficiently stiff so as to maintain the robot 1 in its upright position, yet sufficiently flexible horizontally to allow the robot 1 to turn under the power of the wheels 7, with negligible resistance from the brushes 11. In this way, the need for castors or trailing wheels associated with conventional robots is avoided. The horizontal flexibility of the brushes also allows acceleration and braking of the robot.

In Figure 2, the robot is shown having two pairs of brushes 11, each pair being located on opposite sides of the axis of the wheels, and also being equally spaced from the axis.

However, the arrangement of the brushes 11, or other supports, can be chosen to suit any particular application. For example, the front of the robot may have a different arrangement to that of the back of the HL73953 robot. A number of different variables may be considered when choosing the arrangement of the supports. These include the actual number of supports, the horizontal and vertical stiffness of the individual supports and the position of the supports in location to the axis of the wheels.

For example, a plurality of supports, each having a relatively low stiffness, may be chosen as an alternative to a smaller number of supports, each having a higher stiffness.

Also, the choice of stiffness can vary depending on distance between the support and the axis of the wheels. The further the support is located away from the axis, the greater the vertical stiffness needed to support the robot, but the lower the horizontal stiffness needed to produce the required turning moment.

All these factors enable the arrangement of supports to be chosen to suit the particular application, or acceleration/braking requirements, turning requirements, and so on. Examples include a robot having two supports on one side, and a single support on the other. In such an embodiment, the stiffness of each support can vary, such that the single support may have a stiffness which is equivalent to the combined stiffness of the pair of supports located on the opposite side.

Moreover, in Figure 2, the brushes 11 are made from an electrically conductive material, which allows the brushes 11 to collect DC power from a powered floor, as will be described below. For example, the HL73953 brushes can advantageously be formed from individual bristles made of a copper alloy or copper coated steel.

The number of bristles must be chosen to give the vertical stiffness required to support the weight of the robot, while allowing sufficient horizontal flexibility as described above.

The powered floor can advantageously consist of conducting strips, alternately connected to positive and negative voltage sides of a DC power supply. By choosing strip widths which are suitable for the dimensions c-l' the robot, and by providinq a diode bridge in the robot, power can be collected by the conducting brushes 11, regardless of the orientation of is the robot.

To prevent the brushes from electrically shorting, the chassis 3 is made from an insulating material, for example Delrin', which is a machinable, nylon-like insulating material. This aspect of the invention avoids the need for the batteries 13 to be replaced, or removed for recharging, which is a major advantage in a highly populated distributed mobile robotics system.

The control electronics within the control box 5 contains a complete PC compatible micro controller, sufficiently powered to run an operating system such as Linux. The control electronics controls the power management, motor drive electronics and wireless communications. The Linux operating system includes full TCP/IP networking, including Telnet, FTP and Web servers, which enable the robot 1 to operate as a node on a wireless IP network. It is therefore possible for the robot 1 to be controlled remotely f rom any PC or workstation with Internet connectivity.

EM73953 The robot 1 may have a miniature magnet mounted within the inside walls of each drive wheel 7, having a corresponding Hall-effect sensor set into the chassis 3, close to the drive wheels 7, thereby enabling the control electronics to count drive wheel revolutions for closed loop or speed control. Alternatively, each motor 9 may be a stepped motor, the robot being controlled by stepping each motor through a predetermined number of revolutions.

The chassis 3 is preferably made as a single-piece machined chassis, with insets for the motor/gearbox assemblies 9, brushes 11 and batteries 13. The chassis 3 is preferably circular, and the miniaturisation is techniques described above enable the diameter to be made less than 6cm.

The miniature robot described above allows large scale experiments to be conducted in collective robotics to enable, for example, swarming or self organisation to be studied.

Although the preferred embodiment has been shown to have a plurality of batteries 13, it will be readily understood by a person skilled in the art that the invention may equally be used with just one battery 13.

Further, although the preferred embodiment has been shown to have four brushes 11, it will be readily understood by a person skilled in the art that the invention may equally be used with just one pair of conductive brushes. Indeed, if the robot is to be supplied with electrical power only from its battery or batteries, and is not pick up power from a powered floor, the wheels 7 can be mounted on an offset axle, HL73953 and only one brush or other supporting member need be used.

Furthermore although the robots have been described mainly for use in conducting experiments in distributed mobile robotics, the robots may also used be used in other applications. For example, the brushes 11 may have inbuilt strain gauges to allow the robot to sense surface textures, cracks or flaws, allowing the robot 1 to be used in applications such as surface inspection, particularly in situations where larger robots are unable to access.

HL73953

Claims

1. A robot comprising; a chassis; a pair of wheels, each wheel being independently driven; first and second motors for independently driving the respective wheels; control means for controlling the operation of the robot; and at least one support member for supporting the robot in its upright position.

is

2. A robot as claimed in claim 1, wherein the support member is sufficiently rigid so as to maintain the robot in its upright position, yet sufficiently flexible to allow the robot to be driven.

3. A robot as claimed in any one of the preceding claims, wherein the chassis is made from an insulating material.

4. A robot as claimed in claim 3, comprising a plurality of electrically conductive support members, the support members being in contact, when in use, with a powered floor.

5. A robot as claimed in any one of the preceding claims, having a plurality of support members.

6. A robot as claimed in claim 5, wherein the plurality of support members are evenly HL73953 -10distributed around a circular path on the chassis.

7. A robot as claimed in claim 5, wherein the stiffness of each support member is related to the number of support members provided.

8. A robot as claimed in claim 5 or 7, wherein the stiffness of each support member is related to the position of the support member with respect to an axis of the wheels.

9. A robot as claimed in any one of claims 4-8, wherein the robot is powered by the powered floor via the conductive support member or members.

is

10. A robot as claimed in any one of claims 4-8, wherein the robot is powered by at least one battery, the battery being charged by the powered floor via the conductive support member or members.

11. A robot as claimed in any preceding claim, wherein the chassis is a single piece machined chassis.

12. A robot as claimed in claim 11, wherein the chassis body is circular, having a diameter less than 6cm.

13 A robot as claimed in any one of the preceding claims, wherein the chassis is made from a machinable insulating material, for example Delrin'.

14. A robot as claimed in any one of the HL73953 preceding claims, wherein the pair of wheels are mounted along the same axis.

is. A robot as claimed in claim 14, wherein the axis of the wheels is centrally located in the chassis, and at least one support member is provided on either side of said axis for supporting the robot in the upright position.

16. A robot as claimed in claim 14, having two support members positioned either side of the central axis.

17. A robot as claimed in claim 14, having two is support members positioned on one side of the central axis and one support member positioned on the other side of the central axis, the stiffness of the one support member being equal to the combined stiffness of the other two support members.

18. A robot as claimed in claim 14, wherein the axis of the wheels is located in the chassis away from the centre of gravity, and at least one support member is provided on the opposite side of the centre of gravity, for supporting the robot in the upright position.

19. A robot as claimed in any preceding claim, further comprising a magnet provided in each wheel, and a corresponding Hall effect sensor provided in the chassis.

20. A robot as claimed in any one of the preceding claims, wherein each support member has ILL73953 -12a sensor.

21. A robot as claimed in claim 20, wherein the sensor is a strain gauge for sensing surface texture.

22. A robot, comprising; a chassis; a pair of wheels, for contact with a support surface; first and second motors, for independently driving the respective wheels; control means for controlling the operation of the robot; and is a plurality of electrically conductive support members, mounted on the chassis for contact with said support surface to support the robot in an upright position.

23. A development system for conducting experiments in distributed mobile robotics, the system comprising a plurality of robots as defined in claim 22, and further comprising a powered floor for powering the plurality of robots.

24. A development system as claimed in claim 23, having in excess of fifty robots.

25. A robot, comprising; a single pair of wheels; at least one support member, the support member and the wheels together supporting the robot on a support surface; first and second motors for independently driving the respective wheels; HL73953 control means for controlling the operation of the robot; and a wireless transceiver, for communicating with a remote control device.

26. A method of conducting an experiment in distributed mobile robotics, the method comprising providing a plurality of robots as defined in claim 25, wherein each robot forms a node in a wireless network.

27. A method as claimed in claim 26, the method further comprising the step of powering each robot from a powered floor.

28. A method of conducting an experiment in distributed mobile robotics, the method comprising providing a plurality of robots as claimed in claim 1, wherein each robot forms a node in a wireless network, and wherein each robot is powered by a powered floor.

29. A method as claimed in any one of claims 26 28, wherein each robot is controlled using TCP/IP communications protocol.

30. A method as claimed in claim 29, wherein each robot may be controlled from any workstation or PC with Internet connectivity.

31. A robot comprising; a chassis machined as a single piece; a pair of wheels housed in said chassis along the same general axis, each wheel being independently driven; HL73953 first and second motors for independently driving the respective wheels; control means for controlling the operation of the first and second motors; and at least one support member extending downward from said chassis, for supporting the robot in its upright position.

EL73953