The present technology relates to mobile robots, mobile robot control methods, and programs, and more particularly to mobile robots and the like that prevent the scattering of scattered objects such as water, sand, mud, or snow accompanied by movement.
Conventionally, mobile robots such as legged mobile robots have been proposed. When the mobile robot moves outdoors, if there are scattered objects such as water, sand, mud, or snow on the road surface, the scattered objects may be scattered to hit people or other objects.
For example, PTL 1 discloses a walking robot device that switches gaits (trotting, crawling) based on the gradient, unevenness, wetness, and the like of the road surface ahead. However, PTL 1 does not mention how to prevent the scattering of scattered objects such as water, sand, mud, or snow when there are such scattered objects on the road surface.
[PTL 1]
An object of the present technology is to prevent the scattering of scattered objects such as water, sand, mud, or snow accompanied by movement.
A concept of the present technology is represented by a mobile robot, including: a constraint information acquisition unit that acquires scattering prevention constraint information based on road surface information; and a control unit that controls movement based on the scattering prevention constraint information.
In the present technology, the acquisition unit acquires the scattering prevention constraint information based on the road surface information. For example, the road surface information may include road surface type information. In this case, for example, the road surface information may further include road surface depth information. The control unit controls the movement based on the scattering prevention constraint information.
For example, a road surface information acquisition unit that acquires the road surface information may be further provided. By providing the road surface information acquisition unit in this way, it is possible to acquire the road surface information in real time. In this case, for example, a vibration detection unit that detects vibration information may be further provided, and the road surface information acquisition unit may acquire road surface information based on the vibration information. Here, the vibration detection unit may be configured using, for example, a vibration sensor, a force sensor, or a microphone.
For example, a vibration application unit that applies vibration to the road surface may be further provided. By providing the vibration application unit in this way, it is possible to acquire road surface information satisfactorily based on the vibration information. In this case, for example, the mobile robot may be a legged mobile robot, and the vibration application unit may apply vibration to the road surface by vibrating joints of a leg. In this case, for example, the vibration application unit may use a vibrator to apply vibration to the road surface.
In this case, for example, the vibration application unit may change an amplitude or frequency of the applied vibration based on the acquired road surface information. In this way, it is possible to improve the accuracy of road surface information recognized based on the vibration information.
For example, the mobile robot may be a legged mobile robot, and the control unit may control leg movement. In this case, for example, the scattering prevention constraint information may include information on at least one of a leg tip speed constraint when landing on a floor, a leg tip speed constraint when leaving the floor, a leg tip attitude angle constraint when landing on the floor, a leg tip attitude angle constraint when leaving the floor, and a leg raising height constraint of a swing leg.
As described above, in the present technology, the movement is controlled based on the scattering prevention constraint information acquired based on the road surface information. Therefore, it is possible to prevent the scattering of scattered objects such as water, sand, mud, or snow accompanied by movement.
Modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described hereinafter. The descriptions will be given in the following order.
“Appearance of Legged Mobile Robot”
The joint 105 connects the main body 101 and the leg 102. The joint 106 connects the legs 102 and 103. The joint 107 connects the leg 103 and the foot 104. Each joint has an actuator (motor) and an encoder for detecting the position of the actuator. A vibration sensor is mounted on the foot 104.
Each leg preferably has three or more degrees of freedom. In addition, each leg can dynamically change the angle during the leg tip movement when landing on and leaving the floor, and dynamically change the leg raising height. Moreover, each leg can apply vibration to the ground surface by vibrating the joint of the ground leg (support leg) when grounded.
“Control System Configuration of Legged Mobile Robot”
The road surface information acquisition device 201 estimates road surface information (information on a road surface type and a road surface depth) based on the vibration information obtained by the vibration sensor mounted on the foot 104, and calculates the amplitude and frequency of the vibration applied to the road surface.
The road surface information acquisition device 201 has a sensor input unit 211, a vibration time series storage unit 212, a road surface depth estimation unit 213, a road surface type estimation unit 214, and an applied vibration calculation unit 215. The sensor input unit 211 inputs vibration information (frequency and amplitude) obtained by the vibration sensor mounted on the foot 104. The vibration time series storage unit 212 samples the vibration information (frequency and amplitude) input to the sensor input unit 211 at high speed, and stores sampling values for a certain past period as a vibration time series.
The road surface depth estimation unit 213 estimates the road surface depth based on the vibration time series stored in the vibration time series storage unit 212. In this case, based on the vibration time series related to the vibration information obtained by the vibration sensor mounted on the foot 104 of the swing leg (the leg on the side away from the road surface), the road surface depth is estimated from a difference between a leg tip height when the leg tip of the swing leg plunges into a liquid surface and a leg tip height when the leg tip of the swing leg contacts the road surface.
The road surface type estimation unit 214 estimates the road surface type based on the vibration time series stored in the vibration time series storage unit 212 and the road surface depth estimated by the road surface depth estimation unit 213. In this case, the road surface type is estimated based on the vibration time series related to the vibration information obtained by the vibration sensor mounted on the foot 104 of the support leg (the leg on the side of the road surface) and the road surface depth estimated by the estimation unit 213.
The flowchart in
When it is determined that there was no water splashing sound when landing on the floor, the road surface type estimation unit 214 determines in step ST3 whether the attenuation at the time of vibration application is large, that is, whether the attenuation factor is greater than a threshold attenuation factor α. When the attenuation is small, the road surface type estimation unit 214 estimates that the road surface is hard in step ST4. On the other hand, when the attenuation is large, the road surface type estimation unit 214 estimates that the road surface is sand in step ST5.
When it is determined in step ST2 that there is a water splashing sound at the time of landing on the floor, the road surface type estimation unit 214 determines in step ST4 whether the attenuation when the vibration is applied is large, that is, whether the attenuation factor is greater than a threshold attenuation factor β. When the attenuation is large, the road surface type estimation unit 214 estimates that the road surface is a shallow puddle in step ST7. On the other hand, when the attenuation is small, the road surface type estimation unit 214 estimates that the road surface is mud in step ST8.
When it is determined in step ST1 that the road surface depth is equal to or greater than the threshold, the road surface type estimation unit 214 determines in step ST9 whether the attenuation at the time of vibration application is large, that is, whether the attenuation factor is greater than a threshold attenuation factor γ. When the attenuation is large, the road surface type estimation unit 214 estimates that the road surface is a deep puddle in step ST11. On the other hand, when the attenuation is small, the road surface type estimation unit 214 estimates that the road surface is a pile of snow in step ST11.
Returning to
The scattering prevention constraint calculation device 202 calculates scattering prevention constraints (constraint parameters) based on the road surface depth and road surface type estimated by the road surface information acquisition device 201. The scattering prevention constraints include a leg tip speed constraint when landing on the floor, a leg tip speed constraint when leaving the floor, a leg tip attitude angle constraint when landing on the floor, a leg tip attitude angle constraint when leaving the floor, and a leg raising height constraint of swing legs. It should be noted that it is not necessary to include all of these constraints, and at least any one of these constraints should be included.
Also, for example, when the road surface is sand, the constraint parameters are calculated such that the leg tip speed when landing on the floor is “land slowly and lower vertically”, the leg tip attitude angle when landing on the floor is “land from the heel”, the leg tip speed when leaving the floor is “raise vertically and do not kick sand”, the leg tip attitude angle when leaving the floor is “raise horizontally”, and the leg raising height is “normal”.
Also, for example, when the road surface is a shallow puddle, the constraint parameters are calculated such that the leg tip speed when landing on the floor is “land slowly and lower vertically”, the leg tip attitude angle when landing on the floor is “land from the heel”, the leg tip speed when leaving the floor is “raise vertically”, the leg tip attitude angle when leaving the floor is “raise horizontally”, and the leg raising height is “normal”.
Also, for example, when the road surface is a deep puddle, the constraint parameters are calculated such that the leg tip speed when landing on the floor is “land slowly and lower vertically”, the leg tip attitude angle when landing on the floor is “land from the heel and land flat”, the leg tip speed when leaving the floor is “normal”, the leg tip attitude angle when leaving the floor is “normal”, and the leg raising height is “raise the foot above the depth of the water”.
For example, when the road surface is mud, the constraint parameters are calculated such that the leg tip speed when landing on the floor is “land very slowly and lower vertically”, the leg tip attitude angle when landing on the floor is “land from the heel”, the leg tip speed when leaving the floor is “raise vertically”, the leg tip attitude angle when leaving the floor is “raise horizontally”, and the leg raising height is “normal”.
Also, for example, when the road surface is a pile of snow, the constraint parameters are calculated such that the leg tip speed when landing on the floor is “lower vertically”, the leg tip attitude angle when landing on the floor is “land flat”, the leg tip speed when leaving the floor is “normal”, the leg tip attitude angle when leaving is “normal”, and the leg raising height is “raise the foot above the depth of the snow”.
Returning to
“Control System Processing Flow”
Each leg of the bipedal mobile robot 100 moves in a desired direction by switching between a support phase and a swing phase. The flowchart of
The control flow for the support leg, that is, the leg in the support phase will be described with reference to the flowchart of
Next, in step ST23, the amplitude and frequency of the vibration to be applied to the road surface are calculated based on the estimated road surface type and the vibration time series obtained from the vibration information of the vibration sensor of the support leg. Next, in step ST24, control of the support leg, that is, control of the position of the leg for walking, and control of vibrating the leg (joint) in order to apply vibration of the calculated amplitude and frequency to the road surface are performed.
Next, in step ST25, it is determined whether the support leg should be shifted to the swing leg. In this case, when the tip of the swing leg comes into contact with the road surface, it is determined that the support leg is shifted to the swing leg. When it is determined that the support leg will not be shifted to the swing leg, the processing returns to step ST21, and the same processing as described above is repeated. On the other hand, when it is determined that the support leg is shifted to the swing leg, the leg shifts to the swing phase in step ST26. In other words, the leg that has been the support leg until now becomes the swing leg, and the control flow for the swing leg, that is, the leg in the swing phase is applied.
The control flow for the swing leg, that is, the leg in the swing phase will be described with reference to the flowchart of
Next, in step ST32, the information on leg tip activation (leg tip speed, leg tip attitude angle, and leg raise height) is updated based on the calculated scattering prevention constraints. For example, when the hard road surface changes to a shallow puddle, the scattering prevention constraints are updated from those of the hard road surface to those of the shallow puddle (see
Next, in step ST33, control of the swing leg, that is, control of the position of the leg for walking is performed. In this case, the leg tip activation is controlled so that the updated leg tip activation described above is performed. For example, when the leg tip activation is updated to one corresponding to a shallow puddle, the leg tip speed when landing on the floor is controlled to satisfy “land slowly and lower vertically”, and the leg tip attitude angle when landing on the floor is controlled to satisfy “land from the heel”.
Further, for example, when the leg tip activation is updated to one corresponding to a shallow puddle, the leg tip speed when leaving the floor is controlled to satisfy “raise vertically”, and the leg tip attitude angle when leaving the floor is controlled to satisfy “raise horizontally”. Further, for example, when the leg tip activation is updated to one corresponding to a shallow puddle, the leg raising height after leaving the floor is controlled to satisfy “normal”.
Next, in step ST34, vibration information is acquired from the vibration sensor mounted on the foot 104 of the swing leg. Next, in step ST35, vibration information (frequency and amplitude) is sampled at high speed, and sampled values for a certain past period are stored as a vibration time series.
Next, in step ST36, it is determined whether the tip of the swing leg has plunged into a liquid surface based on the vibration time series obtained from the vibration information of the vibration sensor of the swing leg. When it is determined that it has plunged into the liquid surface, the leg tip height at the time of plunging into the liquid surface is stored in step ST37, and then the processing proceeds to step ST38. If it is determined that it has not plunged into the liquid surface, the processing immediately proceeds to step ST38.
Next, in step ST38, based on the vibration time series obtained from the vibration information of the vibration sensor of the swing leg, it is determined whether the tip of the swing leg has come into contact with the road surface. When it is determined that the leg tip is not in contact with the road surface, the processing returns to step ST31 and repeats the same processes as described above. On the other hand, when it is determined that the leg tip has come into contact with the road surface, the leg shifts to the support phase in step ST39. In other words, the leg that has been the swing leg until now becomes the support leg, and the control flow for the support leg, that is, the leg in the support phase is applied.
The road surface depth is estimated based on the difference between the leg tip height when the tip of the swing leg has plunged into the liquid surface and the leg tip height when the tip of the swing leg comes into contact with the road surface.
As shown in the flowchart of
The arrow in
As described above, in the bipedal mobile robot 100 shown in
The bipedal mobile robot 100 shown in
In the bipedal mobile robot 100 shown in
In the above-described embodiment, an example of using road surface information (information on road surface type and road surface depth) obtained in real time based on vibration information obtained by the vibration sensor mounted on the foot 104 is shown. However, it is conceivable that road surface information corresponding to the movement path of the bipedal mobile robot 100 is provided in advance and used.
In the above-described embodiment, an example in which vibration information is detected by the vibration sensor mounted on the foot 104 is shown, but instead of the vibration sensor, a force sensor or a microphone may be used to detect vibration information.
A bipedal mobile robot 100A in
In the above-described embodiment, an example of acquiring road surface information based on vibration information detected by a vibration sensor has been shown, but road surface information can also be acquired based on other sensor information such as an image sensor.
A bipedal mobile robot 100B shown in
In the above-described embodiment, an example in which vibration is imparted (applied) to the road surface by vibrating the joints has been shown, but it is also conceivable to impart vibration to the road surface with other configurations. A bipedal mobile robot 100C of
In the above-described embodiment, an example of a bipedal mobile robot is shown, but the present technology can be similarly applied to a legged mobile robot other than a bipedal mobile robot.
The control system configuration and processing flow of this quadruped mobile robot 100D are the same as those of the bipedal mobile robot 100 shown in
In the above embodiments, an example of a legged mobile robot is shown, but the present technology can be similarly applied to a mobile robot that moves using other moving parts such as wheels instead of legs.
Although preferred embodiments of the present disclosure have been described in detail with reference to the accompanying drawings as described above, the technical scope of the present disclosure is not limited to such examples. It is apparent that those having ordinary knowledge in the technical field of the present disclosure could conceive various modified examples or changed examples within the scope of the technical ideas set forth in the claims, and it should be understood that these also naturally fall within the technical scope of the present disclosure.
Further, the effects described in the present specification are merely explanatory or exemplary and are not intended as limiting. That is, the techniques according to the present disclosure may exhibit other effects apparent to those skilled in the art from the description herein, in addition to or in place of the above effects.
In addition, the present technology can also adopt the following configurations.
(1) A mobile robot including: a constraint information acquisition unit that acquires scattering prevention constraint information based on road surface information; and a control unit that controls movement based on the scattering prevention constraint information.
(2) The mobile robot according to (1), further including: a road surface information acquisition unit that acquires the road surface information.
(3) The mobile robot according to (2), further including: a vibration detection unit that detects vibration information, wherein the road surface information acquisition unit acquires the road surface information based on the vibration information.
(4) The mobile robot according to (3), wherein the vibration detection unit is configured using a vibration sensor, a force sensor, or a microphone.
(5) The mobile robot according to (3) or (4), wherein further including: a vibration application unit that applies vibration to the road surface.
(6) The mobile robot according to (5), wherein the mobile robot is a legged mobile robot, and the vibration application unit applies vibration to the road surface by vibrating joints of a leg.
(7) The mobile robot according to (5), wherein the vibration application unit uses a vibrator to apply vibration to the road surface.
(8) The mobile robot according to any one of (5) to (7), wherein the vibration application unit changes an amplitude or frequency of the applied vibration based on the acquired road surface information.
(9) The mobile robot according to any one of (1) to (8), wherein the road surface information includes road surface type information.
(10) The mobile robot according to (9), wherein the road surface information further includes road surface depth information.
(11) The mobile robot according to any one of (1) to (10), wherein the mobile robot is a legged mobile robot, and the control unit controls leg movement.
(12) The mobile robot according to (11), wherein the scattering prevention constraint information includes information on at least one of a leg tip speed constraint when landing on a floor, a leg tip speed constraint when leaving the floor, a leg tip attitude angle constraint when landing on the floor, a leg tip attitude angle constraint when leaving the floor, and a leg raising height constraint of a swing leg.
(13) A mobile robot control method including: a procedure of acquiring scattering prevention constraint information based on road surface information; and a procedure of controlling movement based on the scattering prevention constraint information.
(14) A program causing a computer to function as:
an acquisition means for acquiring scattering prevention constraint information based on road surface information; and
a control means for controlling movement of a mobile robot based on the scattering prevention constraint information.
Number | Date | Country | Kind |
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2020-104712 | Jun 2020 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/022806 | 6/16/2021 | WO |