WO2006073248A1

WO2006073248A1 - A non-contact close obstacle detection device for a cleaning robot

Info

Publication number: WO2006073248A1
Application number: PCT/KR2005/004654
Authority: WO
Inventors: Kyung Chul Shin; Shin Kim; No Soo Lee; You Shin Kim; Jae Young Lee
Original assignee: Yujin Robotics Co., Ltd.
Priority date: 2005-01-03
Filing date: 2005-12-29
Publication date: 2006-07-13
Also published as: KR100588059B1

Abstract

Provided is a non-contact obstacle detection device for a cleaning robot for driving a plurality of IR sensors using a single oscillator, driver, amplifier and filter through a time division method. The non-contact obstacle detection circuit for a cleaning robot, which senses an obstacle to operate while avoiding a collision with the obstacle and includes n IR sensors (n is a natural number), comprises: a transmission controller 10 for controlling the n IR sensors using a time division method such that the n IR sensors sequentially output infrared rays; a reception controller 12 operated in cooperation with the transmission controller 10 to sense the sequentially output infrared rays to detect whether or not an obstacle exists; and a sensor 14 for outputting infrared rays to sequentially sense the obstacle using n sensor driving signals for the n sensors and sequentially reading infrared rays from the n sensors using n-shifted signal to sense whether or not the obstacle exists. The transmission controller 10 comprises: a counter 102 for dividing a clock signal having a predetermined frequency and counting a first phase signal Phase A that is the divided pulse signal to output n count signals; a decoder 104 for decoding the count signals output from the counter 102 into n signals and outputting n sensor operation control signals; a logic AND 106 for performing a logic product (logic- AND) operation for the n sensor operation control signals output from the decoder 104 and the clock signal to output the n sensor driving signals at the rising edge of the first phase signal; and a reception control signal generator 108 for generating a load signal RCLK for loading data in a shift register 124 based on the first phase signal Phase A and the count signals and generating a shift signal SRCLK for a shift command of the shift register 124 based on a second phase signal Phase B whose phase is delayed such that the first and second phase signals have a phase difference therebetween. The reception controller 12 comprises: a latch 122 for latching the first phase signal Phase A and a sensor driving signal IR&lowbar;SIG; and the shift register 124 for reading a latched signal, loading the latched signal using the load signal RCLK, reading data at the rising edge of the second phase signal Phase B using the shift signal SRCLK and shifting the data by n at the falling edge of the first phase signal Phase A.

Description

A NON-CONTACT CLOSE OBSTACLE DETECTION DEVICE

FOR A CLEANING ROBOT

Technical Field

[1] The present invention relates to a non-contact close obstacle detection device for a cleaning robot carrying out cleaning along a predetermined route, and more particularly, a non-contact close obstacle detection device for a cleaning robot, which drives a plurality of IR sensors using a single oscillator, a driver, an amplifier and a filter through a time division method.

[2]

Background Art

[3] Cleaning robots are developed and put on the market recently, which are constructed by combining a cleaner with a sensing technique and operated by various algorithms. A conventional cleaning robot transmits ultrasonic signals used in submarines to detect an obstacle placed on a route and operates while avoiding a collision with the obstacle. Another cleaning robot evades a collision with an obstacle by sensing the obstacle using an infrared (IR) sensor.

[4] Obstacle sensing capability is very important to a moving robot. The moving robot must have capability of sensing an obstacle in order to avoid a collision and recognize the position thereof. To sense an obstacle, various kinds of sensors are used.

[5] There are various obstacle sensors. Among these, a non-contact close obstacle sensor that senses a close obstacle placed in less than several cm is most basic and serves as the last safety valve. Non-contact sensors for sensing a close obstacle include an ultrasonic sensor, an IR sensor, a laser sensor, a PSD sensor, a magnetic capacity sensor, hall sensor, a camera and so on, which have their own characteristics and merits and demerits. Most of these sensors have a narrow sensing region so that they use a plurality of sensors. Using a plurality of sensors is costly because most of the sensors are expensive. However, this is inevitable for the stability of a robot. Among the aforementioned sensors, the IR sensor is most inexpensive and simply constructed so that most of moving robots use the IR sensor as a close obstacle sensor.

[6] The IR sensor includes a transmitter for transmitting an IR signal and a receiver for receiving a reflected IR signal and judges whether an obstacle exists according to whether there is light reflected by the obstacle. In general, the transmitter frequency- modulates a signal such that the signal does not interfere with external light and includes an oscillator and a driver, as shown in FIG. 1. Furthermore, the transmitter includes a very large amplifier and a narrow-band filter to receive a small signal from the receiver.

[7] The IR sensor has a very narrow operating range because of characteristic of infrared rays. Thus, when a moving robot uses the IR sensor, a large number of IR sensors should be set in the robot. This requires a large number of oscillators, drivers, amplifiers and filters constituting transmitters and receivers of the IR sensors, resulting in an increase in the cost of the moving robot.

[8]

Disclosure of Invention Technical Problem

[9] Accordingly, the present invention has been made to solve the aforementioned problem occurring in the prior art, and it is an object of the present invention to provide a non-contact close obstacle detection device for a cleaning robot, which drives a plurality of IR sensors using a single oscillator, a driver, an amplifier and a filter through a time division method.

[10]

[H]

Technical Solution

[12] To accomplish the above object, according to an aspect of the present invention, there is provided a non-contact obstacle detection device for a cleaning robot, which senses an obstacle to operate while avoiding a collision with the obstacle and includes n IR sensors (n is a natural number), comprising: a transmission controller 10 for controlling the n IR sensors using a time division method such that the n IR sensors sequentially output infrared rays; a reception controller 12 operated in cooperation with the transmission controller 10 to sense the sequentially output infrared rays to detect whether or not an obstacle exists; and a sensor 14 for outputting infrared rays to sequentially sense the obstacle using n sensor driving signals for the n sensors and sequentially reading infrared rays from the n sensors using n-shifted signal to sense whether or not the obstacle exists.

[13] The transmission controller 10 comprises: a counter 102 for dividing a clock signal having a predetermined frequency and counting a first phase signal Phase A that is the divided pulse signal to output n count signals; a decoder 104 for decoding the count signals output from the counter 102 into n signals and outputting n sensor operation control signals; a logic AND 106 for performing a logic product (logic- AND) operation for the n sensor operation control signals output from the decoder 104 and the clock signal to output the n sensor driving signals at the rising edge of the first phase signal; and a reception control signal generator 108 for generating a load signal RCLK for loading data in a shift register 124 based on the first phase signal Phase A and the count signals and generating a shift signal SRCLK for a shift command of the shift register 124 based on a second phase signal Phase B whose phase is delayed such that the first and second phase signals have a phase difference therebetween.

[14] The reception controller 12 comprises: a latch 122 for latching the first phase signal Phase A and a sensor driving signal IR_SIG; and the shift register 124 for reading a latched signal, loading the latched signal using the load signal RCLK, reading data at the rising edge of the second phase signal Phase B using the shift signal SRCLK and shifting the data by n at the falling edge of the first phase signal Phase A.

[15] The sensor includes a light-emitting diode for outputting infrared rays to sequentially sense an obstacle using the n sensor driving signals for the n sensors, and a light-receiving transistor disposed oriented such that a receiving angle has a predetermined angle to a radiating angle of the infrared rays output from the light-emitting diode.

[16] Preferably, the first phase signal Phase A is used to transmit infrared rays, the second phase signal Phase B is used to receive infrared rays, and the first phase signal Phase A is counted by the counter 102 and indexed.

[17]

Advantageous Effects

[18] The non-contact obstacle detection device for a cleaning robot according to the present invention can drive a plurality of IR sensors using one driver without using an oscillator or an amplifier for each IR sensor. Accordingly, the cost of components of the IR sensors and consumption power required for driving the IR sensors can be reduced. Furthermore, an operation of tuning an amplifier is performed only once, and thus the manufacturing process of the detection device can be simplified and productivity can be remarkably improved.

[19]

Brief Description of the Drawings

[20] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[21] FIG. 1 is a block diagram of a non-contact obstacle detection device for a cleaning robot according to an embodiment of the present invention;

[22] FIG. 2 is a circuit diagram of a transmission controller 10 of FIG. 1 according to an embodiment of the present invention;

[23] FIG. 3 is a circuit diagram of a reception controller 12 of FIG. 1 according to an embodiment of the present invention;

[24] FIGS. 4 and 5 are waveform diagrams for explaining the operation of the circuit of FIG. 2;

[25] FIG. 6 is a circuit diagram of a circuit that can be added to block external light according to an embodiment of the present invention; and

[26] FIG. 7 is a circuit diagram of a receiving circuit of a sensor 14 according to an embodiment of the present invention.

[27]

Best Mode for Carrying Out the Invention

[28] The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings.

[29] FIG. 1 is a block diagram of a non-contact obstacle detection device for a cleaning robot according to an embodiment of the present invention and FIG. 2 is a circuit diagram of a transmission controller 10 of FIG. 1 according to an embodiment of the present invention. FIG. 3 is a circuit diagram of a reception controller 12 of FIG. 1 according to an embodiment of the present invention and FIGS. 4 and 5 are waveform diagrams for explaining the operation of the circuit of FIG. 2.

[30] Referring to FIGS. 1 and 2, the non-contact obstacle detection device for a cleaning robot according to the present invention senses an obstacle to operate while evading a collision with the obstacle. The non-contact obstacle detection device for a cleaning robot has n IR sensors (n is a natural number).

[31] The non-contact obstacle detection device includes a transmission controller 10 for controlling the n IR sensors using a time division method such that the n IR sensors sequentially output infrared rays, a reception controller 12 operated in cooperation with the transmission controller 10 to sense the sequentially output infrared rays to detect whether or not an obstacle exists, and a sensor 14 for outputting infrared rays to sequentially sense the obstacle using n sensor driving signals for the n sensors and sequentially reading infrared rays from the n sensors using an n-shifted signal to sense whether or not the obstacle exists,

[32] In this embodiment, n is 8, a counter which will be explained later is an octal counter, a decoder which will be explained later is a 3:8 decoder and a shift register which will be explained later is an 8-shift register. The non-contact obstacle detection device uses a clock signal such that the clock signal oscillates at a predetermined frequency to transmit infrared rays in order to prevent disturbance of sunlight.

[33] The transmission controller 10 includes a counter 102, and a decoder 104. The counter 102 divides a clock signal having a predetermined frequency and counts a first phase signal Phase A that is the divided pulse signal to output n count signals. That is, the first phase signal Phase A is used to transmit infrared rays and a second phase signal Phase B is used to receive infrared rays. The first phase signal Phase A is counted by the counter 102 and the counting order is indexed to decide the order of operating sensors. The decoder 104 decodes the count signals output from the counter 102 into n signals to output n sensor operation control signals.

[34] A logic AND 106 logic- ANDs the n sensor operation control signals output from the decoder 104 and the clock signal and sequentially outputs the n sensor driving signals at the rising edge (A) of the first phase signal. That is, the logic AND 106 ANDs the first phase signal Phase A and the clock signal to output a burst signal (or firing signal) used as an input of a driver to actually transmit infrared rays.

[35] A reception control signal generator 108 generates a load signal RCLK for loading data in a shift register 124 based on the first phase signal Phase A and the count signals and generates a shift signal SRCLK for a shift command of the shift register 124 based on the second phase signal Phase B whose phase is delayed such that it has a phase difference of 90 from the first phase signal Phase A. The second phase signal Phase B can be easily formed by inputting the first phase signal Phase A to a flip-flop (not shown).

[36] A latch 122 of the reception controller 12 latches the first phase signal Phase A and a sensor driving signal IR_SIG. A shift register 124 receives a latched signal. The shift register 124 loads the latched signal using the load signal, reads data at the rising edge (B) of the second phase signal Phase B and shifts the data by n at the falling edge (C) of the first phase signal A.

[37] That is, the burst signal or firing signal for light emission of the IR sensor is composed of 8 clock pulses of a clock signal. The number of clock pulses constituting the clock signal is determined by sensitivity of an amplifier. In the case that the amplifier performs measurement with the threshold of the amplitude of a signal, the number of clock pulses of the burst signal will be determined by a time constant of a charging condenser and a clock frequency. The first and second phase signals Phase A and Phase B, which are control signals for time division, respectively generate 8 pulses while the burst signal is output. Here, the burst signal is generated by the counter 102 (202) and decoder 104 (204) for each sensor at the rising edge and falling edge of the first and second phase signals Phase A and Phase B and the shift register 124 (224) carries out its shifting operation such that 8 sensors are operated in time division.

[38] The decoder is operated using the counted value at the rising edge (A) of the first phase signal Phase A to output the firing signal to a desired IR sensor, and the shift register reads data at the rising edge (B) of the second phase signal Phase B and shifts the data at the falling edge (C) of the first phase signal Phase A. When the value of a D-latch for reading a signal input at the falling edge (D) of the second phase signal Phase B is cleared and overflow of 8 counters occurs, information of all the sensors has been obtained and thus data is sent to a buffer. [39] The sensor 14 includes a light-emitting diode (not shown) for outputting infrared rays to sequentially sense an obstacle using the n sensor driving signals for the n sensors and a light-receiving transistor (not shown) disposed oriented such that a receiving angle has a predetermined angle to a radiating angle of the infrared rays output from the light-emitting diode. Preferably, the sensor is constructed such that the light-emitting diode and the light-receiving diode are arranged in parallel and they have an angle therebetween because a sensible length is considerably varied with characteristic of a reflector. The sensible length is varied with the angle and the distance between two sensors. For example, when the angle is 40 and the distance is 9mm, maximum 5cm can be sensed though there is a deviation according to the material of the reflector. To remove the deviation, the setting depth of each sensor is increased.

[40] FIG. 6 is a circuit diagram of a circuit that can be added to block external light according to an embodiment of the present invention. When there is severe interference due to external light such as sunlight so that a reflected signal is not detected and a DC component caused by disturbance is saturated so that it is not sensed, a desired signal can be obtained and the DC component can be removed using the circuit of FIG. 6. Because the desired signal does not include the DC component, a primary amplifier can be constructed only using a resistor without setting a condenser in a feedback stage. Although a secondary amplifier having the same structure as the primary amplifier can be placed behind the primary amplifier, the present invention uses LM567 such that it can serve as a narrow band filter and an amplifier. When LM567 is used, a clock signal can be generated without using a separate oscillating circuit, as shown in FIG. 7. FIG. 7 is a circuit diagram of a receiving circuit of the sensor 14 according to an embodiment of the present invention. An input current approximately proportional to the quantity of light can be obtained using photo- transistors of an input part. Photo-diodes can replace the photo-transistors. Here, a voltage proportional to the quantity of light can be obtained through resistors connected to the emitters of the transistors Tr.l, Tr2,..., Tr.n at the rising edge A of the first phase signal Phase A. The quantity of light includes the quantity of modulated light corresponding to an actual signal source and the quantity of light caused by disturbance, and thus only a desired signal can be obtained at the rising edge B of the second phase signal Phase B through a DC block.

[41] As described above, the non-contact obstacle detection device for a cleaning robot according to the present invention can drive a plurality of IR sensors using a single driving circuit without using an oscillator or an amplifier for each IR sensor. Furthermore, circuits used for time division are constructed of simple logic gates and thus they can be easily constructed using EPLD or programmable FPGA (Field-Programmable Gate Array). Most of circuits recently developed can be easily integrated because they use these ICs. Moreover, the present invention can reduce the cost of components of the detection device and decrease consumption power required for driving sensors by the number of the sensors. Furthermore, an operation of tuning an amplifier can be performed only once and thus the manufacturing process can be simplified.

[42] While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

Claims

[1] A non-contact obstacle detection device for a cleaning robot, which senses an obstacle to operate while avoiding a collision with the obstacle and includes n infrared ray (IR) sensors (n is a natural number), comprising: a transmission controller 10 for controlling the n IR sensors using a time division method such that the n IR sensors sequentially output infrared rays; a reception controller 12 operated in cooperation with the transmission controller 10 to sense the sequentially output infrared rays to detect whether or not an obstacle exists; and a sensor 14 for outputting infrared rays to sequentially sense the obstacle using n sensor driving signals for the n sensors and sequentially reading infrared rays from the n sensors using n-shifted signal to sense whether or not the obstacle exists, wherein the transmission controller 10 comprises: a counter 102 for dividing a clock signal having a predetermined frequency and counting a first phase signal Phase A that is the divided pulse signal to output n count signals; a decoder 104 for decoding the count signals output from the counter 102 into n signals and outputting n sensor operation control signals; a logic AND 106 for performing a logic product (logic AND) operation for the n sensor operation control signals output from the decoder 104 and the clock signal to output the n sensor driving signals at the rising edge of the first phase signal; and a reception control signal generator 108 for generating a load signal RCLK for loading data in a shift register 124 based on the first phase signal Phase A and the count signals and generating a shift signal SRCLK for a shift command of the shift register 124 based on a second phase signal Phase B whose phase is delayed such that the first and second phase signals have a phase difference therebetween, and the reception controller 12 comprises: a latch 122 for latching the first phase signal Phase A and a sensor driving signal IR_SIG; and the shift register 124 for reading a latched signal, loading the latched signal using the load signal RCLK, reading data at the rising edge of the second phase signal Phase B using the shift signal SRCLK and shifting the data by n at the falling edge of the first phase signal Phase A.

[2] The non-contact obstacle detection device for a cleaning robot as claimed in claim 1, wherein the sensor comprises: a light-emitting diode for outputting infrared rays to sequentially sense an obstacle using the n sensor driving signals for the n sensors; and a light-receiving transistor disposed oriented such that a receiving angle has a predetermined angle to a radiating angle of the infrared rays output from the light-emitting diode. [3] The non-contact obstacle detection device for a cleaning robot as claimed in claim 1, wherein the first phase signal Phase A is used to transmit infrared rays, the second phase signal Phase B is used to receive infrared rays, and the first phase signal Phase A is counted by the counter 102 and indexed.