Abstract:
A state detecting method applied to a mobile device includes: arranging a depth sensor at the bottom of the mobile device, obtaining a detection signal of the depth sensor, and determining if the mobile device is in a lifted state, a tilted state, or an edge-bordering state, based on the numerical value of the detection signal of the depth sensor. The lifted state is associated with the mobile device without contacting with a support surface. The tilted status is associated with one end of the mobile device contacting the support surface and the other end of the mobile device without contacting the support surface. The edge-bordering state is associated with the mobile device located at the edge of the support surface. Accordingly, when the mobile device is in any of the aforementioned states, an appropriate response can be implemented.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 103142261 filed in Taiwan, R.O.C. on Apr. 12, 2014, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     Technical Field 
     The instant disclosure relates to a robot, in particular, to a robot with state-detection ability, a mobile device, and a state detecting method. 
     Related Art 
     With the advancement in technology, robots are being widely used in today&#39;s modern day life. Some examples include robotic arms, security robots, broom-sweeping robots, etc. Robots can perform precise operations, repeat routine tasks, and help humans with basic chores such as broom-sweeping robots. One type of broom-sweeping robots is self-propelled robot vacuum. This robot vacuum is applicable for home cleaning. When people are sleeping at night or out for work during the day, the robot vacuum can move around the house and clean up dusts, particles, etc. Hence, the residents are saved from cleaning the house room-by-room tediously. 
     The self-guided robots are often deployed with obstacle detectors. For instance, an infrared emitter emits infrared in a forward direction. When the infrared is reflected by a forwardly standing obstacle and received by the infrared receiver equipped on the robot, the robot can determine whether an obstacle exists in the path. However, aside from detecting obstacles to prevent from hitting the robots, the robots may stick or flip over due to uneven ground geometry or steep slopes, thus causing work interruption. Another issue is if a child is present, the child may be curious enough to lift up the robot. If the robot is not stopped from its operation in time, the situation could cause injury to the child. 
     SUMMARY 
     In light of above, the instant disclosure provides a state detection method applicable for mobile devices, such as robots, cellular phones, electric charging stations, and other movable devices. First, the mobile device is furnished with a depth sensor on an inner side thereof. After a depth sensing signal is obtained, based on the numerical value of the signal, the mobile device is determined to be in a lifted state, a tilted state, or an edge-bordering state. The lifted state is defined as without touching the support surface. The tilted state is defined as one end touching the support surface, while another end is without touching the support surface. The edge-bordering state is defined as being at the edge of the support surface. Therefore, when the mobile device is in any of the above-mentioned states, a response procedure can be implemented. 
     In one embodiment, the response procedure implements immediate or gradual change of the motion for the mobile device (such as non-linear or linear stop, turnaround, linear or non-linear back up, etc). The response procedure prevents the mobile device from continuing its original motion or remaining in the original state. In another embodiment, the response procedure issues a warning. The warning could be sent out continuously until it is lifted or lifted automatically after a time duration. The warning reminds the user to make the mobile device exiting any of the above-mentioned states. 
     In yet another embodiment, the response procedure makes the mobile device to return to the original position or starting location. Alternatively, the mobile device is made to return to a previous state. After the mobile device has reached the previous state, the mobile device can change its current state proactively or passively. 
     In some embodiments, based on at least one depth sensing signal, the moving direction of the mobile device and its travelled distance can be obtained via the state detection method. The obtained data is further used to retrieve the travelling path of the mobile device. Therefore, based on the travelling path, the mobile device can be returned to its original position or starting location. 
     In further yet another embodiment, a multiplicity of depth sensors is employed. When the signal changes of all sensors surpass a first threshold value, the mobile device is determined to be in the lifted state. If the signal changes of some sensors surpass a second threshold value, while the sensor signals of all other sensors do not change, the mobile device is determined to be in the tilted state. Meanwhile, if the signal changes of some sensors surpass a third threshold value, while the sensor signals of all other sensors do not change, the mobile device is determined to be in the edge-bordering state. 
     In one embodiment, the state detection method further includes disposing a shield in front of the depth sensor, along with detecting the sensor signal. When the numerical value of the sensor signal is zero, the mobile device is determined to be in a collision state. 
     The instant disclosure also provides a robot. The robot comprises a main body, a moving unit, at least one depth sensor, and a control module. The moving unit and the depth sensor are arranged on one side of the main body. The control module is electrically connected to the moving unit and the depth sensor. Based on the numerical value of the sensor signal, the control module determines whether the robot is in the lifted state, the tilted state, or the edge-bordering state. The lifted state is defined as the robot not touching a support surface. The tilted state is defined as one end of the robot touching the support surface, while another end thereof is not touching the support surface. The edge-bordering state is defined as the robot being adjacent to the edge of the support surface. Therefore, when the robot is in any of the above-mentioned states, the afore-mentioned response procedure can be implemented. 
     The instant disclosure further provides a mobile device. The mobile device comprises a main body, at least one depth sensor, and a control module. The depth sensor is arranged on one side of the main body, and the control module is electrically connected to the depth sensor. Based on the numerical value of the sensor signal, the control module determines whether the mobile device is in the lifted state, the tilted state, or the edge-bordering state. The lifted state is defined as the mobile device without touching a support surface. The tilted state is defined as one end of the mobile device touching the support surface, while another end thereof does not touch the support surface. The edge-bordering state is defined as the mobile device being adjacent to the edge of the support surface. 
     Based on the above, the state detection method, the robot, and the mobile device disclosed by the instant disclosure utilize the depth sensor to identify the state (lifted, tilted, collision, or edge-bearing) of the robot or the mobile device. None of the other instruments are needed. When any of the four above-mentioned states is identified, the appropriate response procedure is triggered to restrict the motion of the robot/mobile device, or to change the internal state or procedure of the system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a robot for a first embodiment of the instant disclosure. 
         FIG. 2  is a schematic view of a depth sensor for the first embodiment of the instant disclosure. 
         FIG. 3  is a block diagram of the robot in  FIG. 1 . 
         FIG. 4  is a schematic view showing the lifted state for the first embodiment of the instant disclosure. 
         FIG. 5  is a schematic view showing the tilted state for the first embodiment of the instant disclosure. 
         FIG. 6  is a schematic view showing the edge-bordering state for the first embodiment of the instant disclosure. 
         FIG. 7  is a flow chart of a state detection method for the first embodiment of the instant disclosure. 
         FIG. 8  is another schematic view of the depth sensor in  FIG. 2 . 
         FIG. 9  is a schematic view of a mobile device for the first embodiment of the instant disclosure. 
         FIG. 10  is a top view of the robot for a second embodiment of the instant disclosure. 
         FIG. 11  is a flow chart for the state detection method for the second embodiment of the instant disclosure. 
         FIG. 12  is another flow chart for the state detection method for the second embodiment of the instant disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 , which shows a perspective view of a robot  100  for a first embodiment of the instant disclosure. The robot  100  comprises a main body  110 , a moving unit  120 , and at least one depth sensor  130 . For the present embodiment, the robot  100  is for broom-sweeping purpose. The main body  110  includes a casing  111 , a vacuum opening  112  formed on the casing  111 , a brush  113 , and a vacuum unit  114  (as shown in  FIG. 3 ). In other embodiments, the robot  100  may serve other purposes with the main body  110  having the casing  111 , but including other accessories (e.g. video camera, robotic arm, etc.). The selection of accessories is based on desired capabilities of the robot, which does not necessarily need to have aforementioned vacuum opening  112 , brush  113 , and the vacuum unit  114 . 
     As shown in  FIG. 1 , the vacuum opening  112  and the brush  113  are formed and disposed, respectively, on the bottom portion of the casing  111 . The vacuum unit  114  is disposed internally of the casing  111 . The vacuum unit  114  may include a motor, a dust bag, a filter, etc. The moving unit  120  is disposed on the bottom portion of the main body  110 . The depth sensor  130  is arranged on one side of the casing  111  (the depth sensor  130  is disposed internally of the casing  111  but adjacent to the bottom portion thereof and partially exposed from the bottom portion thereof). Detection away from the robot  100  is made by the depth sensor  130 . The moving unit  120  includes a swivel wheel  121 , a pair of fixed wheels  122 , and a drive motor (not shown). The depth sensor  130  can be an infrared sensor, an ultrasonic sensor, a static sensor, or other non-contact type distance sensor. 
     Please refer to  FIG. 2 , which shows the depth sensor  130 . For the present embodiment, the depth sensor  130  is an infrared sensor, which includes a cover  131 , an emitter  132 , and a receiver  133 . The cover  131  is formed with a pair of light-permitting openings  134  corresponding to the emitter  132  and the receiver  133 . One of the light-permitting openings  134  allows the emitter  132  to output infrared externally of the cover  131 . The other light-permitting opening  134  allows the reflected infrared to be received by the receiver  133  internally of the cover  131 . 
     As shown in  FIG. 2 , one end of the receiver  133  adjacent to one of the light-permitting holes  134  is bent toward the emitter  132 . Such configuration maximizes the receiving area and the angle for the receiver  133  to receive reflected infrared. 
       FIG. 2  further illustrates a protrusion  135  formed between the light-permitting openings  134  on the cover  131 . In particular, the protrusion  135  extends from a surface flushed with the light-permitting openings  134 . The protrusion  135  serves to isolate the emitter  132  and the receiver  133  from each other, so as to prevent the receiver  133  from receiving emitted infrared directly without reflection. The isolation allows the light-permitting openings  134  to be radially maximized, in order to increase the luminous flux off the emitter  132  and reflected influx to the receiver  133 . The above configuration enhances detection precision and flexibility. 
     Now please refer to  FIG. 3 , which shows a block diagram for the robot  100  further having a control module  140 . The control module  140  can be a processor of embedded type. The control module  140  electrically connects the moving unit  120  and the depth sensor  130 . Based on the numerical value of the detection signal of the receiver  133  (i.e., electrical signal generated by the optical-electrical conversion of the reflected infrared), the control module  140  determines whether the robot  100  is in the lifted state, the tilted state, or the edge-bordering state. Particularly, the numerical value and the distance between the depth sensor  130  and a support surface  200  ( FIGS. 4-6 ) are negatively correlated for determining the state of the robot  100 .  FIGS. 4-6  are discussed in details below to describe the three states of the robot  100 . 
       FIG. 4  shows the lifted state for the robot  100 , in which the robot  100  is lifted from the support surface  200 . The support surface  200  may be a ground surface, a table surface, etc. The lifted state means not one part of the robot  100  is in touch with the support surface  200 . For example, when a child lifts up the robot  100 , the robot  100  is suspended off the support surface  200 . 
     Please refer to  FIG. 5 , which shows the tilted state of the robot  100  with one end thereof suspended off the support surface  200 . However, another end of the robot  100  is in contact with the support surface  200 . In particular, the right side of the robot  100  is suspended off the support surface  200 , while the left side thereof touches the support surface  200 . 
     The edge-bordering state is shown in  FIG. 6 , as can be seen when the robot  100  is at the edge of the support surface  200 . For instance, the robot  100  moves to the edge of a step. 
     Next,  FIG. 7  shows a flow chart for a state detection method for the first embodiment of the instant disclosure. This method is performed by the aforementioned control module  140 . First, at least one depth sensor  130  is disposed on one side of the mobile device (step S 710 ). The mobile device may be a self-propelled device like a robot. For the present embodiment, the mobile device is the robot  100 . In other cases, the mobile devices may be mobile phones or other portable devices. 
     In step S 720 , the control module  140  obtains a detection signal of the depth sensor  130 . 
     In step S 730 , based on the numerical value of the detection signal, the control module  140  determines whether the mobile device is in the lifted state, the tilted state, or the edge-bordering state. If the mobile device is in any of the above-mentioned states, the method will proceed to step S 740 , which will implement a response procedure. If not, the method will return to step S 720  for continuing detection by the depth sensor  130 . The response procedure referred herein may include any of the following features. First, the mobile device is put into a different motion, such as powering off or switch to standby mode, to stop the current motion of the mobile device, so the child would not be injured by the continuous motion of the mobile device. Other attribute is reducing power consumption by the mobile device. The mobile device can also be instructed to turn around from its original direction or trek backward, in order to change its current motion or exit from its current state. Secondly, the response procedure can issue a warning, to alert the user to get the mobile device out of its current state. The third option is to make the mobile device return to its original location or previous state, so the mobile device can exit from any of the abovementioned states. The response procedure is executed by the control module  140  based on switching between different software operations like interrupting, polling, threading, etc. 
     In  FIG. 8 , another schematic view of the depth sensor  130  is shown. This depth sensor  130  differs from the one in  FIG. 2  by having a shield  136 . The shield  136  is connected to the cover  131  by a flexible member (e.g., spring). The shield  136  is disposed in front of the receiver  133 . When the robot  100  is hit on the bottom portion thereof, the shield  136  would be displaced toward the receiver  133 , so as to block the light from entering the light-permitting opening  134  corresponding to the receiver  133 . As suggested by the description, the shield  136  provides covering and blocking functions. Thus, when a collision occurs, the numerical value of the detection signal of the depth sensor  130  would be zero or close to zero. Once the collision state has been detected, any of the aforementioned response procedures can be carried out accordingly. For the present scenario, the protrusion  135  also serves to block and limit the movement of the shield  136 . 
     In other embodiment, the shield  136  can be arranged in front of the emitter  132 . When a collision occurs, the shield  136  would block the infrared output by the emitter  132 . 
     For another embodiment, the depth sensor  130  further includes an on/off switch (not shown), which is disposed between the cover  131  and the shield  136 . The purpose is that when the shield  136  is displaced toward the cover  131 , the shield  136  would actuate the switch. By connecting electrically to the switch, when the control module  140  receives the triggering signal of the switch, a collision state is determined to have occurred. 
       FIG. 9  shows a mobile device  300  for the first embodiment of the instant disclosure. For the present scenario, the mobile device  300  is a cellular phone, with the depth sensor  130  shown in  FIG. 8  being disposed on the back surface thereof. Under the collision state (i.e., the back surface of the cellular phone is facing toward and disposed on the support surface), the aforementioned first response procedure is implemented. In other words, the cellular phone is powered off or put in standby mode, so as to save power consumption. 
     Please refer back to  FIG. 3 . The robot  100  can further include a warning module  150  electrically connected to the control module  140 . The warning module  150  can issue a warning to execute the aforementioned second response procedure. Also, for different types of warning, the warning module  150  can be made up by different parts. For example, if the warning is provided in audio mode, the warning module  150  can be a speaker or a buzzer. When the warning is provided in lighting mode, the warning module  150  can be an indicator light or a display. Alternatively, if the warning is in a message form, the warning module  150  may be a mobile communication module or a wireless internet module. Thus, a warning message can be sent to a designated device (e.g., cell phone or computer) of the user. The warning may last for a period of time before terminating automatically. Another option may be the warning would be on continuously until being terminated by the user. For example, the robot  100  has a disarm button (not shown) for pressing by the user to terminate the warning. 
     In some embodiments, if the third type response procedure is employed, and based on the detection signal provided by the depth sensor  130 , the state detection method can covert the detection signal into an image. The before and after images are then compared to identify the moving direction of and distance traveled by the mobile device. By using the obtained data, the travelling path of the mobile device can be stored. Accordingly, the robot  100  can further have a storage module  160 , such as a memory unit, memory card, hard disk, etc. As illustrated in  FIG. 3 , the storage module  160  is electrically connected to the control module  140 . When the mobile device intends to return to its original location, the control module  140  can read the travelling path saved in the storage module  160 . Based on the recorded travelling path, the control module  140  can guide the moving unit  120  in trekking back to the original location. For the present scenario, the original location is an electric charging station or a starting location. 
     In another embodiment, after the robot  100  has returned to its previous state, the robot  100  can change its state again proactively or passively, such as moving toward another direction. 
     For a second embodiment of the robot  100  for the instant disclosure, please refer to  FIG. 10 , which shows a top view of the robot  100 . The present embodiment differs from the first embodiment in that the robot  100  has three depth sensors  130  substantially evenly distributed on the bottom portion thereof. More detailed description of the embodiment having a multiplicity of depth sensors  130  is provided below. 
     Please refer to  FIG. 11 , which shows a first flow chart of the state detection method for the second embodiment. The detection process is carried out while the robot  100  is in motion. In step S 910 , the robot  100  starts to move. Then, the control module  140  determines if any of the three depth sensors  130  does not indicate the presence of the support surface  200  (step S 920 ). If at least one depth sensor  130  does not detect the support surface  200 , the method proceeds to step S 940 . In step S 940 , the control module  140  determines whether a predetermined time period has passed with the support surface  200  going undetected. If yes, the robot  100  is determined to be in lifted or tilted state and its current motion must be stopped (step S 950 ). If no, the state detection process returns to step S 910 . Please note, step S 930  is between step S 920  and step S 940 . Step S 930  is for the robot  100  to avoid any obstacle if encountered upon. 
       FIG. 12  shows a second flow chart for the state detection method for the second embodiment of the instant disclosure. Unlike the first flow chart, the present detection process is implemented while the robot  100  is still. For step S 960 , the control module  140  determines if any of the three depth sensors  130  does not detect the presence of the support surface  200 . If at least one of the depth sensors  130  does not detect the support surface  200 , the robot  100  is determined to be in the lifted state or the tilted state, and the detection process must proceed to step S 970 . In step S 970 , the robot  100  is stopped from its current operation. 
     The determination of whether any depth sensor  130  has detected the presence of the support surface  200  is based on if the changes of numerical value for the detection signals surpass a threshold value. For example, if the robot  100  is in the lifted or the tilted state, at least one depth sensor  130  would not be able to receive reflected infrared. A resulting change in the numerical value of the detection signal would be over the threshold value. Thus, when the changes in magnitude of detection signals for all depth sensors  130  surpass a first threshold value, the robot  100  is determined to be in the lifted state. When the changes in magnitude of detection signals for some depth sensors  130  surpass a second threshold value, with the detection signals for the rest of the depth sensors  130  do not change, the robot  100  is determined to be in the tilted state. When the changes in magnitude of detection signals for some depth sensors  130  surpass a third threshold value greater than the second threshold value, with the detection signals for the rest of the depth sensors  130  remain constant, the robot  100  is determined to be in the edge-bordering state. 
     Based on the above, the instant disclosure provides a state detection method, a robot  100 , and a mobile device  300 . At least one depth sensor  130  is employed to identify if the robot  100  or the mobile device  300  is in the lifted state, the tilted state, the collision state, or the edge-bordering state. No complex sensing instruments are needed to achieve the above purpose. After any of the four abovementioned states has been identified, the appropriate response procedure is implemented, in order to limit the motion or adjust the internal state or procedure of the system for the robot  100  or the mobile device  300 . 
     While the present invention has been described by the way of example and in terms of the preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.