Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
2002-03-01
2003-03-11
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S245000, C700S258000, C318S568120, C318S587000, C701S023000, C701S300000, C901S001000, C901S046000, C901S047000, C706S905000, C180S167000
Reexamination Certificate
active
06532404
ABSTRACT:
The present invention relates to an autonomous mobile robot, preferably a robot for cleaning, and a system of control of a robot able to guide it towards a fixed station and/or able to adapt its behavior to the local degree of dirtiness and/or comprising a rotary brush and able to release the robot after the blocking of the aforementioned brush.
The invention relates more particularly to a system of guidance of the path of an autonomous mobile robot, including its positioning with respect to, and the approach towards, a fixed station of recharge in energy or discharge of elements collected by the robot. It will be, most frequently but not exclusively, a robot for cleaning the ground, which is provided with rechargeable batteries, for example a robotic vacuum cleaner. However it can also be a robot for spreading a substance or a monitoring robot.
An autonomous mobile robot, for example supplied with batteries, presents a limited autonomy. If one wants to obtain a continuous operation, the robot must be able to recharge its batteries at regular intervals of time. Other functions can also require the regular access to a fixed point for example the unloading of a bag of dust (robot-like vacuum cleaner) or re-supplying in fuel (thermal engine) or in a product to be spread.
A solution to this problem has already been disclosed (see EP-A-0744093), where in the mobile machine, sensitive to the gradient of an electromagnetic field, repositions itself automatically to the vertical of a coil traversed by a AC current.
In the case of surfaces comprising disturbing elements for the electromagnetic field (steel reinforcement of concrete for example), the above system operates with difficulty.
It can then be preferable to associate with the fixed station an infra-red radiation source (transmitting LED) allowing the mobile machine to locate the station remotely.
U.S. Pat. No. 4,679,152 discloses an autonomous mobile robot able to automatically return to a recharging station when the level of charge of a battery decrease below a predetermined threshold. The recharging station and the mobile robot are provided with a infra-read beam transmitter and a system of detection connected to a microcomputer. The robot and the recharging station may thus communicate in a bi-directional way. There is provided a search program with an opto-acoustic system which may involve a random moving of the robot on the work surface. Such system is complicated and appears to be poorly efficient when a very accurate positioning of the robot relative to the recharging station is required for the recharging operation. The purpose of the present invention is to overcome this drawback by providing, according to the simplest embodiment, a system using a narrow beam emitted by the recharging station, detectable by a directional sensor located on the chassis at the center of rotation of the robot.
According to a first aspect of the invention, a relatively narrow beam, varying for example between 2 and 10° preferably approximately 5°, emerges from the fixed station. The corresponding transmitter and the associated station are preferably oriented so that the beam extends over a maximum length of the work surface of the robot. The mobile robot, provided with a system of directional detection of infra-red emission, is moving substantially in a random way on this surface, crosses and detects the narrow beam in statistically periodic manner.
According to a preferred embodiment, if some duration of work is exceeded, e.g. 15 to 45 minutes, whatever the state of load of the battery, the robot will return towards the fixed station for a cycle of recharge or refill as soon as it crosses an infra-red beam of a given intensity. If it is near the station after the above-mentioned duration of work, it will join it and will thus start a reload. This process avoids the operation of seeking the beam when the state of the battery decreases below a predetermined level. The narrowness of the beam allows a precise final positioning relative to the fixed station, and thus allows, for example, a recharging operation by induction or more simply by physical contact of conductors.
As the working time increases, the algorithm of the microprocessor performs so that the threshold of intensity of the infra-red beam to be detected by the mobile robot decrease in a linear way or by increment, in order to initiate the return step.
The stage of return can cause the discontinuance of all the functions of the robot which are not essential in order to find the station of recharge or refill.
According to another embodiment of the invention, the system of guidance and of positioning is based upon at least two beams of different directionality property emerging from the fixed station, the beam(s) less directional being used for the approach towards the fixed station, while the more directional beam is used for the ultimate stage of precise positioning of the robot relative to this fixed station. This alternative allows the guidance of the robot in a more complex environment (e.g. an apartment with several rooms, with several doors).
The transmitter of the less directional beam is located at a level of the fixed station so that its influence decreases at the ultimate stage of approach and of positioning of the robot. It can be manually directed as desired and located at the end of an overhanging arm above the front part of the fixed station itself.
In the phase of positioning, the transmitter will thus be advantageously located above the robot, the beam emitted being then out of the detection plane of the sensors of the robot. The latter, by a movement of rotation around its center, is then able to determine a final position of recharge, for example with physical contact, while basing itself on the signal of the transmitter of stronger directionality located in the detection plane of the sensors of the robot. The power of the beams can be different, the most powerful beam being generally but not necessarily the least directional beam.
The robot includes a directional system of detection of infra-red emission, for example comprising at least two directional sensors for which intensities of signals are compared, in a known way, by a microcomputer to control a rotation towards the source of emission. These sensors are preferentially located on the chassis at the center of the robot, oriented in the direction of movement of the robot. Possibly, one or several other sensors may be provided, for example on the lateral sides or on the rear side, advantageously having directional detection system substantially opposed to that of the central sensors. Advantageously also, the beams to be recognized by the sensors of the robot will be modulated in order to avoid any background noise.
According to this aspect of the invention, there is proposed a system of location and positioning relative to a fixed station for an autonomous mobile robot moving in a room characterized in that the fixed station emits two modulated infra-red beams, primarily in the plane of the rooms, one of the beams being appreciably more directional than the other. The least directional transmitter beam allows the location and the approach of the fixed station by the mobile robot provided with directional sensors sensitive to these beams. The signals of the sensors are treated by one microcomputer controlling the advance of the mobile robot, the transmitter of weaker directionality being located on the fixed station at a position perpendicular to the mobile robot when the latter joins its desired position in the fixed station, the more directional beam is then able to be detected in a more sensitive way by the aforementioned sensors, precise positioning being carried out by rotation of the machine about a vertical axis according to an algorithm based on the detection of the narrow beam.
According to an alternative one proposes a system of location and of positioning at a fixed station for a mobile autonomous robot moving in a room characterized in that the fixed station emits at least three infra-red modulate
Cuchlinski Jr. William A.
Marc McDieunel
Morgan & Lewis & Bockius, LLP
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