JP2013163457A - Overturn-prevention device for two-wheeled inversion type robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overturn-prevention device for a two-wheeled inversion type robot that when a two-wheeled type robot is stopped, functions as a stand, and when the tilt of the two-wheeled type robot is excessive or a normal inversion control can not be performed, legs can be vertically grounded on a grounding surface and as a result the robot can be stably prevented from being overturned.SOLUTION: An overturn-prevention device is attached to a two-wheeled inversion type robot body for preventing a two-wheeled inversion type robot having a pair of right and left driving wheels from being overturned. The overturn-prevention device includes: a pair of overturn-prevention legs that are attached to at least front and rear of the two-wheeled inversion type robot for preventing the two-wheeled inversion type robot from being overturned; a driving mechanism that makes the overturn-prevention legs drive; and an overturn-prevention control part that controls overturn-prevention operation of the overturn-prevention legs.

Description

  The present invention relates to a fall prevention device that can be attached to a two-wheel inverted robot.

  In recent years, two-wheel inverted robots have been developed extensively. This two-wheel inverted robot usually has an axle in the lower left and right horizontal direction, one drive wheel is disposed at each end of the axle, and a main body for controlling the attitude of the two-wheel inverted robot above the axle It has a configuration including a control unit, a power source unit such as a nickel metal hydride battery or a lithium ion battery, and a body including drive mechanisms such as independent motors for driving the driving wheels.

  In the inversion operation, the inclination of the two-wheel inverted robot is detected by a gyro sensor or the like of the main body control unit, and the driving wheel is driven and inverted so as to correct the inclination by the principle of the inverted pendulum (for example, Patent Documents 1 and 2).

  The two-wheel inverted robot can be moved back and forth by driving the two wheels in the same direction. Further, the traveling direction can be changed by changing the rotational speed of each of the two wheels, and further, the two wheels can be turned by driving in different directions.

  The two-wheel inverted robot having such a configuration and operation has an advantage that the center of gravity can be increased and the ground contact area can be reduced because the dynamic balance is achieved.

Such a conventional inverted robot has the following characteristics.
-The tilt of the body changes with moments due to weight and moments due to acceleration in the front-rear direction.
・ In order to keep the inclination at a constant angle, a constant acceleration in the front-rear direction is necessary to cancel out the moment due to gravity.

  On the other hand, in the conventional two-wheel inverted robot, various proposals have been made such as improving the accuracy of the control function in order to prevent the vehicle from falling.

  However, when traveling on rough terrain or the like, the control function may not be able to cope with unexpected changes in traveling conditions, leading to a fall.

  In addition, since the acceleration and speed of the two-wheel inverted robot are limited by the maximum output of the motor or the like, there may be a case where the inclination of the state becomes excessive, or even when the motor is unexpectedly stopped, etc.

  Furthermore, when the two-wheel inverted robot is stopped, it is necessary to support it using a stand for preventing the main body from falling.

  In order to obtain a stable fall-preventing effect of the two-wheel inverted robot, the present inventors created a prototype of a two-wheel inverted robot fall prevention device as shown in FIG. Repeated.

  The prototype device shown in FIG. 5A is a prototype device provided with a leg having a rotation axis that coincides with the axle of the drive wheel of the two-wheel inverted robot.

It was confirmed that the prototype device having this configuration has the following preferable characteristics.
-The mechanism of the fall prevention device is simple.
-Regardless of the posture of the two-wheel inverted robot, the contact angle of the leg with respect to the floor can be made vertical, and a stable fall prevention effect can be obtained.

However, on the other hand, the following problems were also confirmed in addition to the above preferable features.
-The range of movement of the legs is increased, the legs themselves are increased in size, and they tend to interfere with other parts that are concentrated in the center of the main body of the two-wheel inverted robot, making it difficult to mount the fall prevention device.
・ The torque of the rotating shaft required to drive the legs increases, and a large reduction ratio is required.
-The bending moment applied to the legs increases, making it difficult to secure rigidity to the floor and to reduce the weight of the legs.

  Next, in order to solve the above-mentioned problem, a prototype device including legs having independent rotating shafts at the front and rear as shown in FIG.

  In this prototype device, since the rotation shaft of the leg is provided at a position away from the axle of the drive wheel of the two-wheel inverted robot, the leg can be shortened, it is easy to reduce the weight, and it is easy to mount the fall prevention device. It was confirmed that it has the characteristics.

  However, in the case of this prototype device configuration, the change in the contact angle of the leg corresponding to the change in the posture of the two-wheel inverted robot becomes large, and it is impossible to make contact with the floor perpendicularly, and a stable fall prevention effect is obtained. The problem of not being able to be confirmed was confirmed.

JP 2004-295430 A JP 2008-230548 A

  The present invention solves the conventional problems from the above background, functions as a stand when the two-wheel inverted robot is stopped, and when the tilt of the two-wheel inverted robot becomes excessive, or normal inverted control is performed. It is an object of the present invention to provide a two-wheel inverted robot tipping prevention device for an inverted robot that can ground a leg perpendicular to the grounding surface even when it cannot be performed and can stably prevent tipping.

  The present invention is characterized by the following in order to solve the above problems.

  First, the fall prevention device for a two-wheel inverted robot of the present invention is a fall prevention device attached to the two-wheel inverted robot body in order to prevent the two-wheel inverted robot having a pair of drive wheels on the left and right. A pair of fall prevention legs attached to the front and rear of the two-wheel inverted robot body to prevent the two-wheel inverted robot from overturning, and a drive mechanism for driving the fall prevention legs, A fall prevention control unit for controlling the fall prevention operation of the fall prevention leg, and the fall prevention leg is configured to contact the lower end of the leg when the operation of the two-wheel inverted robot body is stopped. The support leg composed of a columnar body that is in a state of 1 and is lifted upward from the ground contact position during operation and is fixedly held, and one end of the support leg on the two-wheel inverted robot main body side A first arm that is pivotally supported forward or rearward from the axle of the drive wheel, the other end of which is pivotally supported at an appropriate position on the upper side of the support leg, and one end of the two-wheel inverted type A robot body is rotatably supported at a lower portion of the position where the one end of the first arm is attached, and the other end is located at a lower portion of the support leg where the other end of the first arm is attached. The second arm is rotatably supported, and a gear portion for rotational driving is attached to one of the first arm and the second arm on the two-wheel inverted robot body side. The drive mechanism includes a motor that generates a rotational driving force and a driving force transmission unit that transmits the rotational driving force to the gear portion of the first or second arm, and the overturn prevention control. Part of the two-wheel inverted robot The first leg of the fall prevention leg is connected via the drive mechanism so that the support leg is in a first state in which the support leg is grounded when stopped and the support leg is in a second state in which the support leg is lifted upward during operation. Alternatively, when the second arm is rotated and tilted to the maximum tilt angle allowable by the two-wheel inverted robot, the first arm and the second arm are in the second state due to the operation of the first arm and the second arm. The support leg is configured to be perpendicular to the ground plane.

  Second, in the first two-wheel inverted robot tipping prevention device, a third state is set in which the vertical position of the support leg is halfway between the first state and the second state. The transition from the state 3 to the third state was controlled to be performed at a higher speed than the transition from the third state to the second state, and when the third state was reached, the support leg was temporarily stopped. Thereafter, the inversion control of the two-wheel inverted robot is started.

  Third, in either the first or second two-wheel inverted robot tipping prevention device, a caster is provided at each end of the support leg.

  According to the fall prevention device for a two-wheel inverted robot of the present invention, it can function as a stand when the two-wheel inverted robot is stopped, and when the tilt of the two-wheel inverted robot becomes excessive, normal inversion control can be performed. Even when there is not, the leg can be grounded perpendicularly to the ground surface, and it is possible to stably prevent falling.

It is the perspective view which notched and showed the principal part of the state which made the fall prevention leg part function as a stand. It is the perspective view which notched and showed the principal part of the state which made the fall prevention leg part function as a stand. It is the perspective view which cut and showed the principal part of the state which the two-wheel inverted type robot inclined and was supported by the leg part for fall prevention. It is the perspective view which cut and showed the principal part of the state which the two-wheel inverted type robot inclined and was supported by the leg part for fall prevention. (A) is the schematic which shows the two-wheel inverted robot which attached the leg which has a rotating shaft corresponding to the axle of the drive wheel of a two-wheel inverted robot, (b) is a leg which has an independent rotating shaft before and behind. It is the schematic which shows the two-wheel inverted robot which attached the prototype device provided with. It is the graph which showed the change of the contact angle of the leg with respect to the inclination of a two-wheel inverted robot. It is a flowchart which shows the operation | movement from an inverted control stop state to an inverted control state. It is a flowchart which shows operation | movement from an inverted control state to an inverted control stop state.

  Hereinafter, embodiments of the overturn prevention device for a two-wheel inverted robot of the present invention will be described in detail.

  A two-wheel inverted robot (hereinafter simply referred to as a robot) includes an axle in the lower left and right horizontal direction, and one drive wheel is disposed at each end of the axle to control the inverted posture of the robot within the robot body. And a drive mechanism such as an independent motor for driving left and right for driving the drive wheels.

  In the inversion operation, the tilt of the robot is detected by a gyro sensor or the like of the main body control unit, and the driving wheel is driven and controlled to correct the inclination by the principle of the inverted pendulum, thereby realizing the inversion operation.

  The robot can be moved back and forth by driving the left and right drive wheels in the same direction. Further, the traveling direction can be changed by changing the rotational speed of each of the two wheels, and further, the two wheels can be turned by driving in different directions.

  The fall prevention device of the present invention is attached before and after the robot in the traveling direction, and functions as a stand when the robot is stopped and as an auxiliary leg for preventing fall when moving.

  1 to 4 are perspective views showing a part of an essential part of an embodiment of the fall prevention device of the present invention with a part cut away.

  The fall prevention device of the present invention is attached to the front and rear of a robot body, and includes a pair of fall prevention legs for preventing the robot from falling, a drive mechanism for driving the fall prevention legs, and an overturn prevention A fall prevention control unit for controlling the fall prevention operation of the leg.

  1 to 4, a pair of anti-tip legs provided on a pair of opposite sides, an anti-tip control unit, a main body control unit for controlling the posture of the robot, a power supply unit, a driving wheel driving motor, and the like. Is omitted.

  The fall prevention leg portion includes a drive arm 11, a support arm 12, and a support leg 10. Each of these members is formed of a material having strength in order to stably support an expensive robot having a very heavy weight, and the support leg 10 with the most weight load is constituted by a columnar body.

  One end of the drive arm 11 is rotatably supported at a position away from the axle of the drive wheel 30 on the robot body side of the robot body frame 31, and the other end is rotatably supported on the upper side of the support leg 10. Has been. A gear 22 for rotational driving is attached to the shaft support on the robot body side.

  One end of the support arm 12 is rotatably supported by a lower portion of the position where one end of the drive arm 11 of the frame 31 of the robot body is attached, and the other end is attached to the other end of the drive arm 11 of the support leg 10. It is rotatably supported at the lower part of the position.

  As described above, one end of the drive arm 11 and the support arm 12 is rotatably supported at a position away from the axle of the drive wheel 30 of the frame 31 of the robot body, thereby concentrating on the central part of the robot body. Thus, it is possible to attach the fall prevention device without interfering with important parts arranged.

  The driving mechanism includes at least a motor 20 that generates a rotational driving force and a driving force transmission unit 21 that transmits the rotational driving force to the gear 22 of the driving arm 11.

  The motor 20 that generates the rotational driving force is controlled by a fall prevention control unit provided in the robot body, and the fall prevention control unit is controlled by a body control unit that controls the robot body.

  The motor 20 can be used without particular limitation as long as the motor 20 can drive the fall-preventing leg portion in combination with the drive transmission unit 21, and examples thereof include an AC motor, a DC motor, and a stepping motor. . Among these, it is preferable to use a stepping motor in order to control the rotation speed and accurate rotation angle of the motor 20 and to obtain a strong static torque.

  According to the fall prevention device of the present invention having the above configuration, information from the body control unit provided in the robot body is input to the fall prevention control unit, and the drive mechanism operates according to this information and is connected to the drive mechanism. The fall prevention leg can perform a predetermined drive.

  The fall prevention leg of the fall prevention device of the present invention is used when the robot is stopped and when the support leg 10 of the fall prevention leg is grounded when the robot tilts and reaches the maximum tilt angle that the robot can tolerate. Is preferably designed so that the support legs 10 are grounded substantially perpendicular to the floor. 3 and 4 show a state where the robot is tilted and the support leg 10 is in contact with the floor substantially perpendicularly to the floor.

  In addition, as a method of driving the fall prevention leg portion to maintain and fix the robot in a state where the robot tilts and the support leg 10 is in contact with the floor almost perpendicularly to the floor, for example, the stopper 23 shown in FIGS. And a method of fixing one side of the driving arm 11 by contacting the stopper 23 with a driving mechanism, a method of fixing by stationary torque by feedback of position data from a rotary encoder, a position sensor, etc. A method of fixing by an electromagnetic brake due to a short circuit can be used, and these methods can be combined.

  For example, at the time of normal control, a stationary torque based on feedback of position data and an electromagnetic brake are used together. This is because the electromagnetic brake lacks the static torque, and generates a sufficient static torque as well as fine correction of the position by position control as necessary.

  Further, in the event of an emergency such as when all the power is turned off, the operation of the fall prevention leg can be limited by the stopper 23, and at the same time, the robot body can be prevented from tilting and falling.

  As for the maximum tilt angle that the robot can tolerate, from the data obtained in the experiments conducted so far, if the tilt of the robot exceeds ± 20 ° during the inversion control, the inversion control of the robot becomes difficult with a high probability, and the robot falls over. Has been confirmed. Therefore, in the present invention, it is preferable that the maximum inclination angle allowed by the robot is set to ± 20 °, and the robot is set so that the support leg contacts the floor perpendicularly to the floor at an angle of ± 20 °.

  By setting the leg for preventing the fall so that the robot contacts the support leg 10 perpendicularly with respect to the floor at an angle of ± 20 °, the swing width before and after the robot inversion control, and the support leg 10 and It becomes possible to secure the maximum clearance from the floor.

  As a specific design of the fall prevention leg that satisfies the above conditions, for example, the radius of the drive wheel 30 is 260 mm, and the mounting position of the frame 31 of the robot body of the drive arm 11 and the support arm 12 is the drive wheel 30. The design may be 260 mm from the center, the mounting interval is 100 mm, the length of the drive arm 11 and the support arm 12 is 150 mm, and the mounting interval of the support leg 10 of the drive arm 11 and the support arm 12 is 140 mm. it can. According to this design, the support leg 10 can be grounded perpendicularly to the floor when the robot body is inclined ± 20 °.

  In addition, said design is a design about one Embodiment, This invention is not limited to this.

  The angle of contact of the support leg 10 with respect to the tilt angle of the robot equipped with the above-described design overturn prevention device, and the tilt of the robot equipped with the prototype device including the legs having independent rotation axes shown in FIG. The contact angle of the leg with respect to was measured. The result is shown in the graph of FIG.

  From this result, it can be seen that, in the robot equipped with the fall prevention device of the present invention having the above design, the support leg 10 is in contact with the floor substantially perpendicularly over the inclination of 70 to 110 degrees. .

  On the other hand, in the robot shown in FIG. 5B provided with legs having independent rotation axes at the front and rear, the contact angle of the legs with respect to the floor greatly changes with respect to the change in the tilt of the robot. Recognize.

  From these results, it was confirmed that in the robot equipped with the fall prevention device of the present invention having the above design, the support leg of the fall prevention leg portion is always stably grounded according to the change in the tilt of the robot. .

  In the fall prevention device of the present invention, it is preferable to provide a free caster at the tip of the support leg 10 of the fall prevention leg. By providing a universal caster at the tip of the support leg 10, it is possible to support the robot while maintaining the moving state of the robot even when the robot body is tilted and the support leg 10 is grounded when the robot moves. .

  In the fall prevention device of the present invention, the fall prevention control unit that receives information from the main body control unit provided in the robot body drives the motor 20, thereby driving the fall prevention leg under specific conditions. is there.

  In the following, a flow diagram is used for an embodiment of the fall prevention device of the present invention 1) operation from the inverted control stop state of the robot to the inverted control state and 2) operation from the inverted control state of the robot to the inverted control stopped state. Will be described in detail. In the following embodiments, the description will be made on the assumption that the floor is a horizontal plane and the pair of front and rear fall prevention legs of the robot simultaneously perform the same operation.

  FIG. 7 is a flowchart showing the operation of the overturning prevention leg from the inversion control stop state to the inversion control state of the robot.

  First, the initial state is a state in which the inversion control of the robot is stopped, and a state in which the fall prevention leg is in contact with the floor vertically as a stand.

  In response to this state, when an inversion control start command (S10) from the user is input to the main body control unit, the main body control unit outputs the inversion control start command to the overturn prevention control unit before starting the inversion control. The fall prevention control unit drives the motor to perform the first leg raising operation (S11) of the fall prevention leg.

  This first leg raising operation (S11) is an operation for slightly raising the movable leg of the fall prevention leg from the floor at a high speed, up to a position where the support leg comes in contact with the floor perpendicularly with an inclination of ± 7 °. This is an operation of lifting the fall prevention leg, and for example, lifting about 50 mm in height from the floor is considered.

  This inclination of ± 7 ° is an angle obtained by experiments conducted so far. At angles smaller than ± 7 °, the front and rear support legs may come into contact with the floor and hinder the control of the robot's inversion. Yes, at an angle greater than ± 7 °, when the inversion control is started with the robot body tilted, the movement of the drive wheel increases and decreases, and the robot can come into contact with people, objects, and buildings near the robot. It is not preferable because of its properties.

  Information indicating that the first leg raising operation is completed (S12) is output from the fall prevention control unit to the main body control unit, thereby starting the inversion control of the robot (S13). In addition, it is possible to minimize the change in the state of the robot by setting a short time from the output of the information indicating that the first leg raising operation is completed until the inversion control is started. At this point, the robot is not movable.

  Next, based on the information (S14) indicating that the inverted control started from the main body control unit is started, the fall prevention control unit drives the motor to perform the second leg raising operation (S15) of the fall prevention leg unit. Make it.

  This second leg raising operation (S15) is an operation of pulling up the fall-preventing leg at a slow speed to a position where the support leg is in contact with the floor perpendicularly when the robot has an angle of ± 20 °. is there.

  Information indicating that the second leg raising operation is completed (S16) is output from the fall prevention control unit to the main body control unit, and in response to this, the main body control unit sets the robot in a movable state (S17).

  As described above, the robot is stopped and the fall prevention leg can function as a stand by exchanging information between the main body control unit and the fall prevention control unit and the operation of the fall prevention device. Transition to a new state.

  Next, the operation of the overturn prevention device from the transition from the inverted control state of the robot to the inverted control stop state will be described with reference to the flowchart shown in FIG.

  First, the robot is in an invertible control and movable state. In response to this state, when an inverted control stop command (S20) is input from the user to the main body control unit, the main body control unit stops moving the robot (S21) and (S22), and then inverts the inverted control stop command. Output to prevention control unit. The fall prevention control unit drives the motor to perform the first leg lowering operation of the fall prevention leg (S23).

  This first leg lowering operation (S23) is an operation for slowly lowering the support leg of the fall prevention leg part to a position slightly raised from the floor, and the support leg is perpendicular to the floor with a tilt of ± 7 °. This is an operation of lowering the fall-preventing leg portion to a position in contact with the. At this time, the inverted control is being performed.

  Information indicating that the first leg lowering operation has been completed (S24) is output from the fall prevention control unit to the main body control unit, and the main body control unit receiving the information stops the inversion control of the robot (S25).

  Next, when the information indicating that the inversion control has been stopped (S26) sent from the main body control unit is output to the overturn prevention control unit, the overturn prevention control unit drives the motor to change the number of the fall prevention leg unit. A two-leg lowering operation (S27) is performed.

  The second leg lowering operation (S27) is performed at a high speed so that the support leg of the fall prevention leg is in contact with the floor vertically, and the robot is supported by the fall prevention leg as a stand. (S28).

  In addition, it is possible to minimize the change in the state of the robot by shortening the time from the stop of the robot inversion control (S25) to the completion of the second leg lowering operation (S28).

  From the state in which the robot can be inverted and moved by exchanging information between the main body controller and the anti-tip controller and the operation of the anti-tip device as described above, the inversion control is stopped and the anti-tip leg is placed on the stand. Can be transferred to a supported state.

  In addition, as a method of driving and maintaining the driving arm in each of the above states at a specific speed, for example, a value of the rotary encoder of the motor is set in advance, and the driving mechanism is controlled according to this value. By doing so, a specific driving can be performed.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

  For example, in the embodiment of the fall prevention device of the present invention shown in FIGS. 1 to 4, in order to reliably support the robot body, the support legs are configured to have two left and right support legs, but sufficient strength is ensured. One design can be used as long as possible, or three or more configurations can be adopted.

  In the above embodiment, the drive arm is up and the support arm is down. However, this may be reversed, that is, the support arm is up and the drive arm is down. .

  In the above embodiment, it is assumed that the pair of front and rear anti-falling legs are operated in the same manner at the same time. However, the operation timing of the front and rear anti-falling legs is adjusted to perform different operations. It can also be.

  Furthermore, it can also be used as a jack by lowering the fall prevention leg to a position lower than the grounding part of the drive wheel. By using the fall-preventing leg as a jack and lifting the robot body upward, it is possible to easily replace the drive wheels, maintain the power supply device for the drive wheels installed under the robot, and the like.

DESCRIPTION OF SYMBOLS 10 Support leg 11 Drive arm 12 Support arm 20 Motor 21 Drive force transmission part 22 Gear 23 Stopper 30 Drive wheel 31 Frame

Claims (3)

An overturn prevention device attached to the two-wheel inverted robot body in order to prevent the two-wheel inverted robot having a pair of drive wheels on the left and right from falling.
At least a pair of fall prevention legs attached to the front and rear of the two-wheel inverted robot body to prevent the two-wheel inverted robot from falling, a drive mechanism for driving the fall prevention legs, and the fall A fall prevention control unit for controlling the fall prevention operation of the prevention leg,
The fall prevention leg is in a first state where the lower end of the leg is grounded when the operation of the two-wheel inverted robot main body is stopped, and in a second state where the leg is lifted upward from the ground position and fixedly held during operation. A support leg composed of a columnar body, and one end of which is rotatably supported forward or rearward from the axle of the drive wheel on the two-wheel inverted robot body side, and the other end of the support leg. A first arm that is pivotally supported at an appropriate position on the upper side, and one end of which is pivotally supported at a lower portion of the position where one end of the first arm of the two-wheel inverted robot body is attached, and the other end Is composed of a second arm rotatably supported at a lower portion of the position where the other end of the first arm of the support leg is attached, and one of the first arm and the second arm On the other hand, the two-wheel inverted type Bot body side, a gear portion for driving the rotation is mounted,
The drive mechanism includes a motor that generates a rotational driving force, and a driving force transmission unit that transmits the rotational driving force to the gear portion of the first or second arm.
The overturn prevention control unit is configured so that the support leg is in a first state where the support leg is grounded when the two-wheel inverted robot is stopped, and is in a second state where the support leg is lifted upward during the operation. When the first or second arm of the fall prevention leg is rotated through a mechanism and tilted to a maximum tilt angle allowable for the two-wheel inverted robot, the first arm and the second arm An overturn prevention device for a two-wheel inverted robot, wherein the support leg in the second state is configured to be perpendicular to the ground plane by the movement of the arm.   A third state in which the vertical position of the support leg is in the middle of the first state and the second state is set, and the transition from the first state to the third state is the second state to the second state. Control to be performed at a higher speed than the transition to the state, and when the third state is reached, the support leg is once stopped, and then the inverted control of the two-wheel inverted robot is started. The overturn prevention device for a two-wheel inverted robot according to claim 1.   The fall prevention device for a two-wheel inverted robot according to claim 1 or 2, wherein a caster is provided at each end of the support leg.

Images