News Column

Patent Application Titled "Passive Transformable Wheel and Robot Having the Wheel" Published Online

July 2, 2014



By a News Reporter-Staff News Editor at Defense & Aerospace Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Kim, Yoo Seok (Gwanak-gu, KR); Kim, Hann (Gwanak-gu, KR); Chu, Chong Nam (Gwanak-gu, KR); Jung, Gwang Pil (Gwanak-gu, KR); Cho, Kyu Jin (Gwanak-gu, KR), filed on February 5, 2014, was made available online on June 19, 2014.

The assignee for this patent application is Snu R&db Foundation.

Reporters obtained the following quote from the background information supplied by the inventors: "Typically, small robots having round wheels can run through a narrow clearance and may be efficient in searching a survivor in a place such as a collapsed building or finding an enemy base during a military operation.

"However, a small robot that uses round wheels cannot climb an obstacle taller than the radius of the round wheels.

"As an alternative, legged-wheel robots have been proposed for their better climbing performance. However, such legged-wheel robots have poor driving performance on flat surfaces since their center of mass is vertically changed.

"Thus, there have been proposed robots having transformable wheels which can drive with round wheels on flat surfaces and can climb an obstacle with legged wheels.

"As one background art of the present invention, there is disclosed an exploration-purpose robot that includes a plurality of leg units for supporting a body unit and enabling the robot to walk, each of the leg units including a calf portion, a thigh portion and a plurality of drive joints. The exploration-purpose robot further includes a control unit for operating and controlling the joints of the leg units. The calf portion of each of the leg units is provided with a foot for walking at one longitudinal end thereof. A ball caster for wheel driving is provided at one side of the calf portion. A rotating joint means for selectively operating the foot and the ball caster is provided at the center of the calf portion.

"However, the exploration-purpose robot is merely designed to enhance the moving efficiency by freely selecting a foot's rolling operation and a ball caster's sliding operation depending on the walking environment of the robot. Since the wheel-driving-purpose ball caster used as a moving means exists in the calf portion, the ball caster serving as a wheel cannot passively transforms in conformity with the shape of a terrain. Moreover, the exploration-purpose robot is very complex in configuration. It is therefore difficult to use the exploration-purpose robot in a small robot application.

"As another background art of the present invention, there is disclosed a transformable wheel that can drive on flat surfaces and can climb stairs. The transformable wheel includes: a rim; a plurality of spokes installed inside the rim and fitted at one ends to the rim so that the free ends thereof can protrude outward of the rim; and a gear box. The gear box includes: a rim gear portion for delivering the power of a motor to the rim; a spoke gear portion for delivering the power of the motor to the spokes; and a movable gear portion disposed between the motor, the rim gear portion and the spoke gear portion so as to selectively mesh with the rim gear portion and the spoke gear portion.

"In the transformable wheel cited above, the complex gear box including the motor-operated spoke gear portion for expanding the spokes outward of the rim is mounted to the wheel. Therefore, additional power needs to be used in order to drive the gear box. It is also impossible to automatically expand the spokes to adapt themselves to the terrain features.

"That is to say, the transformable wheel cited above has a complex structure because of the use of a large number of parts, such as a displacing actuator and a rotating actuator, for driving the rim and expanding the spokes. A battery having a large capacity is needed to operate the displacing actuator and the rotating actuator. Therefore, the transformable wheel cited above is not suitable for use in small robots."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "In view of the above, an embodiment of the present invention provides a passively transformable wheel which is not transformed by an actuator but passively transformed by the friction contact with a terrain or a road surface.

"Furthermore, an embodiment of the present invention provides a robot provided with a passively transformable wheel which keeps a round wheel shape when driving on a flat surface and which can be transformed into a legged-wheel shape with a trigger leg and a plurality of passive legs frictionally unfolded when climbing the obstacle. In accordance with an aspect of the present invention, there is provided a passively transformable wheel, which includes: a wheel base including a centrally positioned transmitter rotation shaft, a trigger leg rotation shaft positioned in an outer periphery of the wheel base and one or more passive leg rotation shafts positioned in the outer periphery of the wheel base; a force transmitter rotatably coupled to an end of the transmitter rotation shaft, the force transmitter including a trigger slide and one or more passive leg joints spaced apart from one another; a trigger leg arranged between the wheel base and the force transmitter and rotatably coupled to the trigger leg rotation shaft, the trigger leg including a trigger joint fitted to the trigger slide; and one or more passive legs arranged between the wheel base and the force transmitter so as not to interfere with the trigger leg and rotatably coupled to the passive leg rotation shafts, the passive legs including one or more passive leg slides engaging with the passive leg joints of the force transmitter.

"Further, wherein, when the trigger leg is unfolded by the frictional contact with a road surface, the trigger joint is configured to rotate the force transmitter through the trigger slide of the force transmitter, and upon rotation of the force transmitter, the passive leg joints of the force transmitter are configured to rotate and unfold the passive legs through the passive leg slides of the passive legs.

"Further, each of the trigger leg and the passive legs further includes a grip portion coupled to an inner surface and an outer surface thereof.

"Further, the passive legs include: a first passive leg arranged between the wheel base and the force transmitter so as not to interfere with the trigger leg and rotatably coupled to a first passive leg rotation shaft of the wheel base, the first passive leg provided with a first passive leg slide engaging with a first passive leg joint of the force transmitter; and a second passive leg arranged between the first passive leg and the trigger leg and rotatably coupled to a second passive leg rotation shaft, the second passive leg provided with a second passive leg slide engaging with a second passive leg joint of the force transmitter.

"Further, each of the trigger slide and the passive leg slides includes a first side portion formed of one half portion of an arc corresponding to a moving path of the trigger joint or a moving path of each of the passive leg joints of the force transmitter; and a second side portion formed of the other half portion of the arc.

"Further, the first side portion and the second side portion of each of the trigger slide and the passive leg slides has a curvature identical with a curvature of the arc corresponding to the moving path of the trigger joint or the moving path of each of the passive leg joints of the force transmitter.

"Further, a resilient member for returning the trigger leg and the passive legs unfolded into a legged-wheel shape to an original round shape is coupled to at least one of the trigger leg rotation shaft and the passive leg rotation shafts.

"Further, the trigger leg includes: a link portion linearly extending toward the trigger slide such that the trigger joint is inserted into the trigger slide; a bent portion unitarily formed with the link portion and coupled to the trigger leg rotation shaft of the wheel base; and a support portion extending from the bent portion along a contour line of the passively transformable wheel, the trigger joint protruding from a side surface of the link portion of the trigger leg.

"Further, each of the passive legs includes: a link portion linearly extending toward a base portion of each of the passive leg joints such that each of the passive leg slides of the passive legs engages with each of the passive leg joints of the force transmitter; a bent portion unitarily formed with the link portion and coupled to each of the passive leg rotation shafts of the wheel base; and a support portion extending from the bent portion along a contour line of the passively transformable wheel, each of the passive leg slides formed into a groove or hole shape on a side surface of the link portion of each of the passive legs.

"Further, the trigger leg and the passive legs include flat portions respectively formed at a distal end of the trigger leg, on an outer surface of a support portion of the trigger leg and on an outer surface of a support portion of each of the passive legs.

"In accordance with another aspect of the present invention, there is provided a passively transformable wheel in which a plurality of joints and a plurality of slides are asymmetrically installed in a trigger leg, a plurality of passive legs and a force transmitter, one of the joints is provided in the trigger leg, the remaining joints provided in the force transmitter, one of the slides provided in the force transmitter, and the remaining slides respectively provided in the passive legs,

"wherein, when the trigger leg is unfolded by the frictional contact with a road surface, one of the trigger joints is configured to rotate the force transmitter through the slide of the force transmitter, and upon rotation of the force transmitter, the remaining joints of the force transmitter are configured to rotate and unfold the passive legs through the slides of the passive legs.

"In accordance with further another aspect of the present invention, there is provided a robot provided with the passively transformable wheel, the robot including: a body unit in which a circuit unit for controlling the robot is installed; a frame unit positioned in front of the body unit and provided with a motor unit for driving the passively transformable wheel; and a connecting unit for interconnecting the body unit and the frame unit.

"Further, the robot further includes a shock absorbing unit for absorbing a shock transmitted from the passively transformable wheel toward the body unit.

"Further, the shock absorbing unit includes: a shock absorbing shaft coupled to a support plate of the frame unit; and a shock absorbing member coupled to the shock absorbing shaft so as to resiliently support a wing portion of a motor mount vertically movable along the shock absorbing shaft.

"Further, the connecting unit includes: a hinge bracket installed in a support plate of the frame unit; a hinge projection installed in a plate of the body unit; a connecting shaft for rotatably interconnecting the hinge bracket and the hinge projection; and a stopper for supporting the plate of the body unit so that the support plate and the plate can make rotation within a limited angular extent.

"As set for the above, the passively transformable wheel of the present embodiment has a simple structure in which the trigger leg and the passive legs are frictionally unfolded. It is therefore possible to reduce the number of parts and the manufacturing costs. This helps simplify the manufacturing process and enable mass production.

"The robot provided with the passively transformable wheel is capable of significantly increasing its efficiency when used as swarm robots for performing search and rescue missions. Thus, the robot can be advantageously used as swarm robots through mass production.

"The robot provided with the passively transformable wheel can rapidly drive on a flat surface with its round wheel shape. In a rough terrain where an obstacle exists, the trigger leg and the passive legs are frictionally unfolded, whereby the wheel is transformed into a legged-wheel shape. Thus, the robot capable of passing through a narrow clearance can be efficiently used in searching a survivor in a place such as a collapsed building or finding an enemy base during a military operation.

"The robot provided with the passively transformable wheel is configured such that the motor unit drives the passively transformable wheel and such that the trigger leg and the passive legs are frictionally unfolded. Thus, the robot of the present invention consumes a small amount of power as compared with a conventional robot in which additional actuators are used for driving and unfolding purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

"The above and other objects and features of the present invention will become apparent from the following description of the embodiments given in conjunction with the accompanying drawings.

"FIG. 1 is a perspective view showing a robot provided with a passively transformable wheel according to one embodiment of the present disclosure.

"FIG. 2 is a front view of the passively transformable wheel shown in FIG. 1.

"FIG. 3 is a rear view of the passively transformable wheel shown in FIG. 2.

"FIG. 4 is a view showing a structure in which a joint rotates a slide.

"FIG. 5 is a view showing a structure in which the slide rotates the joint.

"FIG. 6 is a transparent front view showing an arrangement structure of the joints and slides of the trigger leg and the passive legs.

"FIGS. 7A and 7B are graphs plotting the force required for the joint to rotate the slide and the force required for the slide to rotate the joint.

"FIGS. 8A to 8D are views showing the moving path of the joint and the slide identical in curvature with the joint.

"FIG. 9 is view schematically showing the passively transformable wheel that climbs an obstacle.

"FIGS. 10A to 10C are views schematically showing the states of steps 1 and 2 shown in FIG. 9 and a modified example of the passively transformable wheel.

"FIG. 11 is a plan view of the robot provided with the passively transformable wheel shown in FIG. 1.

"FIG. 12 is a view showing a shock absorbing unit shown in FIG. 11.

"FIG. 13 is a view showing a connecting unit shown in FIG. 11."

For more information, see this patent application: Kim, Yoo Seok; Kim, Hann; Chu, Chong Nam; Jung, Gwang Pil; Cho, Kyu Jin. Passive Transformable Wheel and Robot Having the Wheel. Filed February 5, 2014 and posted June 19, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6811&p=137&f=G&l=50&d=PG01&S1=20140612.PD.&OS=PD/20140612&RS=PD/20140612

Keywords for this news article include: Defense, Military, Snu R&db Foundation.

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Source: Defense & Aerospace Week


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