The invention relates to a mobile spherical robot according to the preamble of claim 1.

The invention also relates to a method for determining the position of the spherical robot.

In the present context, the term 'mobile robot' is used to refer to a vehicle which is mobile without an operator riding the robot and is programmable to perform predetermined tasks. However, the inventive concept covers the idea of a passenger riding the vehicle.

In the prior art, mobile robots are currently implemented such that their mobility is based on a number of wheels, robot legs, an air cushion, or other conventional means of moving.

US Patent Specification 4,733,737 discloses mechanics for implementing the mobility of a spherical vehicle. However, the publication does not inspect the details of the vehicle shell structure, nor the control method which renders automatic control possible.

The goal of the invention is to eliminate the drawbacks of the above-described prior art and to provide an entirely novel type of spherical robot as well as a method for determining the position thereof.

The invention is based on the concept of the spherical robot comprising active elements utilized for controlling the robot. The active elements can also be used for gathering information as well as for communication between the spherical robot and an internal or external control unit thereof.

In more detail, the spherical robot according to the invention is characterized by what is stated in the characterizing part of claim 1.

The method according to the invention is characterized by what is stated in the characterizing part of claim 11.

The invention provides considerable benefits.

By means of sensors located in or on the shell structure the position of the robot can be determined with great accuracy. The transparent shell structure makes it possible to film the surroundings straight through the shell structure. Correspondingly, data communication modules mounted in or on the shell structure make it possible to select a shell structure material which is impenetrable to electromagnetic radiation, thus protecting the internal electronics of the robot against interference radiation. Using evenly positioned sensors, the concentration gradient of, e.g., a substance in gaseous state can be determined while the robot is in motion.

The spherical form provides for a mechanically steady structure and the construction of a liquid- and gasproof and electromagnetically impenetrable capsule. What is more, the spherical form sets no limits for changes in the advancing direction of the machine. Lastly, the robot can impossibly fall over.

A spherical robot equipped with an intelligent shell structure is an excellent home robot, as it is durable and people are more likely to accept an object with the psychologically cheerful form of a ball in their homes. The primary applications of such a robot comprise a dust- removing device and a radio-controlled toy. Other applications include environmental monitoring chiefly in the context of security- and surveillance-related tasks

(gas leaks; temperature, e.g. the presence of a human being) .

In the following, the invention in described in greater detail with reference to exemplifying embodiments in accordance with the annexed figures.

Fig. la is a sectional view of the spherical robot according to the invention.

Fig. lb is a bottom view of the spherical robot of Fig. la

Fig. 2 illustrates the spherical robot shell construction according to the invention.

The main principle of the spherical robot according to the invention is that the mass within the light ball-shaped capsule rotates the capsule shell. Energy is transmitted from the internal mechanics by the intermediation of one or several wheels to the external shell. The wheel or wheel structure may also be turned in relation to the internal mechanics and the outer capsule shell. In the internal mechanics, the mass centre is arranged as low as possible. Thus, no problems are posed by heavy batteries. The benefit provided by the wheel implementation lies in its simplicity which reduces manufacturing costs, and in addition, the construction makes it possible for the robot to turn without advancing into any direction.

Figs, la and lb illustrate the following parts:

1 wheel ring

2 drive wheel

3 gearing 4 drive wheel turning motor

5 drive wheel shaft

6 mounting unit for turning motor 4

7 toothed gearwheel for turning the drive wheel

8 drive wheel motor

9 motor slip rings

10 supporting framework for supporting bar 11 supporting bar

12 spring

13 ball mounted in bearing

14 toothed gear for drive wheel

15 twist wheel 16 drive wheel mounting

17 toothed gearwheel for turning drive wheel

18 turning gearing

19 bottom plate

20 turning bearing 21 shell

30 batteries

35 control means

The material of the wheel ring 1 is such that sufficient friction is attained between the shell 21 and the wheel 2. The drive wheel 2 rotates and thereby makes the ball move into the direction opposite to the direction of rotation of the drive wheel. The motion of the ball is based on the continuous moment caused by the imbalance of the centre of mass of the internal structure of the ball, this being the result of the rotative movement of the drive wheel 2. The ball robot can be steered to different directions by turning the drive wheel 2. The gearing 3 transmits the energy required for turning the drive wheel 2. The motor 4 turns the drive wheel for redirecting the robot. The shaft 5 transmits the energy required for turning the drive wheel 2. The motor 4 is fixed to the bottom plate 19 by means of fixing devices 6. The energy of the motor 4 is transmitted by means of the gearwheel 7 for turning the drive wheel 2. The motor 8 rotates the drive wheel 2. The slip rings 9 transmit the required energy from the batteries 30 to the motor. The support bar 11 is mounted on the bottom plate 19

by means of a supporting framework 10. The supporting bar 11 is necessary for providing a second supporting point for the internal mechanics in the upper part of the sphere. Two supporting points make sure that the internal mechanism does not fall over within the sphere. The ball 13 carried by a spring 12 is pressed against the shell 21 of the sphere. The ball 13 mounted in a bearing acts as a supporting point for the upper end of the supporting bar 11. The twist wheel 15 transmits motor 8 power for rotating the drive wheel 2. The toothed gear 14 transmits power for rotating the drive wheel 2. The motor 8 is fixed to the bottom plate 19 with a mounting 16. The toothed gear 17 and the gearing 18 are used to transmit turning motor 4 power for turning the drive wheel 2. Most of the components of the robot are fixed to the bottom plate 19. The drive wheel 2 is mounted on the bottom plate 19 using a bearing 20 in order to provide for the turning of the wheel 2. The shell 21 encapsulates the entire internal structure. Several batteries 30 are mounted in the lower parts of the internal mechanism with as small a spacing as possible, thus obtaining as low a centre of gravity as possible. The control unit 35 is used to control the engines 4 and 8. The control unit 35 may be coupled to the external control processor of the robot directly through the radio-frequency penetrable shell 21, or alternatively, via the intelligent shell depicted in Fig. 2, whereby the latter shell, if need be, can be constructed such that it is impenetrable to radio frequency waves. Automatic control can be implemented, e.g., by means of a microprocessor which carries out the controlling in a programmed manner utilizing sensors intended for positioning and for monitoring the surroundings. Communication between the operator and the robot takes place through the shell or, as a separate implementation, via a communication link between the shell and the internal structure. In the latter case the operator communicates with an intelligent shell which in turn communicates with the internal structure.

Where the monitoring sensors are placed inside the spherical robot instead of on the shell, the shell must be designed penetrable to the variable measured by the sensors. In the case of a camera, this means transparency on the wavelength used (infrared, visible light, or ultraviolet) . In the case of gas sensors, the shell must be gas permeable.

Where the sensors are placed on the shell, a communication link is required between the sensors and the control unit of the robot.

Fig. 2 shows the parts of an intelligent spherical shell according to the invention. The circles in the figure stand for the different parts of the spherical shell. The different parts are connected to each other by galvanic coupling analogously to the implementation of the corresponding electronics on a conventional circuit card.

40 sensor (e.g. temperature, pressure or gas)

41 battery or accumulator (for satisfying the demand for power of the electronic components)

42 microprocessor (for processing the measurement data) 43 communication module between the shell and the internal parts (infrared- or ultrasound-based or electromagnetic) 44 communication with the external world (e.g., with a control room) 45 weights for balancing the shell

The active components of the shell structure according to the invention comprise, among others, different kinds of sensors, processors, or communication units. The shell may be provided with an access door through which things can be entered into a transportation case inside the sphere, or through which a robot hand attached to the internal

mechanism may emerge. The passive components comprise, for instance, studs on the shell, a friction surface, batteries, and weights relating to the balancing of the shell. Communication between the shell and the internal mechanism may be implemented by conventional means using infrared light, ultrasound or electromagnetic radiation. If the communication is to take place through the shell, the shell structure should be designed penetrable to the wavelength used.

A concrete embodiment is exemplified by a gas leak inspection robot where the robot shell is provided with evenly spaced gas sensors. In the case of a gas leak the sensors closest to the gas leak measure greater gas concentrations, whereby information is provided as to what direction the gas leak is located in.

The intelligent shell structure makes it possible to transmit data from the spherical shell to the internal mechanics of the spherical robot and from the internal mechanics to the spherical shell. This is useful if the spherical shell constitutes an electromagnetic screen but it is desirable to prevent electromagnetic communication from inside the sphere toward the exterior world. Communication between the shell and the internal mechanics is also necessary where it is desirable to move to a direction on the basis of measurements performed by the shell structure, for instance, closer to a detected gas leak. If sensors are evenly spaced on the surface of the sphere, measuring accuracy is improved and it becomes possible to, e.g., sense the direction of an emission source.

The movement of the ball can be followed by measuring which part of the sphere faces the ground, whereby even the past path of the sphere can be traced by calculation. Thus, with the right placing of sensors on the shell, the shell will

provide a kind of distance gauge. The positioning of the robot can be implemented, e.g., by means of a dead reckoning-type positioning method combining information concerning the travelling direction of the internal part and the distance already covered. The travelling direction of the internal part in relation to the given coordinate system is measured by means of a gyro intended for measuring rotations of the vertical axis. The distance travelled can be measured either on the basis of the distance covered by the internal wheels against the spherical shell or by means of sensors mounted on the shell and being receptive to ground contact. The latter way eliminates the error margin which is due to sliding between the internal wheels and the shell. An alternative, or parallel, implementation of positioning comprises using external beacon systems, as is the case with other mobile robots.

The sensors can be used to measure the closeness and shapes of obstacles to movement as well as variables affecting the environment. Measurement results gathered by the sensors may be processed by means of processors mounted on the shell, if any, or alternatively, they may be sent directly in an unprocessed state to the internal processor for processing. Thus, the processor capacity required for controlling the robot can be placed either inside the robot or on the shell, or it can be divided between the two. In the two latter cases a communication link between the internal part and the shell is necessary. Thus, with sufficient processor capacity, the intelligent shell can directly control the internal actuators.

An intelligent shell will prove useful in all applications where information is gathered by measurements performed outside the robot. Such applications include, e.g., gas leak surveillance robots, burglary detection robots, ore prospecting robots, and minesweeping robots. The robot

according to the invention is better suited for use in minesweeping that prior art robots designed for this purpose, because the capsule can be constructed strong enough to withstand explosion.

Mobility in different types of settings is provided by changing the structure of the outer shell. A soft terrain requires some kind of patterning whereas a smooth, anti¬ skid surface is the best alternative for indoor use, and icy conditions necessitate the use of studs.

When the spherical robot has proved useful on a smaller scale, it can be developed further for use as a vehicle for pleasure rides or as passenger transportation means.

When a gas- or watertight shell structure is applied, charging current can be fed to the batteries, e.g., inductively.

More than two support points 2 and 13 may naturally be arranged between the shell 21 and the internal part.

Instead of toothed gears, bands, toothed belts, chains, variators, or other suitable transmission means may be used to transmit power from the motors to the spherical shell.

The shell may be constructed of a transparent materal, whereby a camera inside the capsule may be used to observe phenomena outside the capsule.

The spherical shell may be constructed of various materials and several layers whereby the space between the layers may be used for mounting sensors or additional structures.

In one embodiment of the invention, the actuators may be placed in or on the capsule shell. Hereby the mobility of the robot can be realized by means of, e.g., pumps and

mercury containers evenly placed on the shell. In this embodiment, the above-described internal part becomes redundant.