KR20120048410A - Pitch-balancing walking multi-ped robot - Google Patents

Abstract

PURPOSE: A pitch-balancing legged robot is provided to prevent a pitch-over by reducing a longitudinal displacement of center of gravity in an acceleration and deceleration. CONSTITUTION: A pitch-balancing legged robot comprises a body(10), a plurality of legs(20), an acceleration sensor(30), a MCU(Micro Process Unit)(40), and a compensation unit(50). The plurality of legs is symmetrically arranged in the center part of the body, thereby supporting the body. The acceleration sensor measures an acceleration generated in a movement of the body. The MCU circulates a gravity center displacement value by using the measured acceleration. The compensation unit reduces a gravity center displacement by compensating the circulated gravity center displacement value.

Description

Pitch balancing leg robot {PITCH-BALANCING WALKING MULTI-PED ROBOT}

The present invention relates to a leg-type robot, and more particularly, to a pitch balancing leg-type robot for reducing the center of gravity movement during acceleration and deceleration to improve the maximum speed during driving.

Robots have been developed for industrial use and as part of factory automation, or have been used to collect or collect information on behalf of humans in extreme environments that humans cannot tolerate. This field of robotics has been developed in recent years as it is used in the cutting-edge space development industry, and recently, until a human-friendly home robot was developed. A representative example of such a human-friendly home robot is a cleaning robot.

One of the robots, the cleaning robot, is a device that inhales dust or foreign substances while driving itself in a certain cleaning area such as a house or office. Such a cleaning robot is provided with a driving means including a right wheel and a left wheel motor for transmitting a driving force to a wheel for driving the cleaning robot as well as a vacuum cleaner that sucks dust or foreign matter. As the wheel is rotated by the rotation of the right wheel and the left wheel motor, the cleaning robot can travel.

On the other hand, there is a quadruped robot that runs the robot using four legs in addition to the method of traveling using wheels, such as a cleaning robot. This quadruped robot travels according to the forward and backward driving of the bridge.

However, in such a mobile system such as a vehicle or a mobile robot, longitudinal weight deflection is generated by acceleration and deceleration. The angular displacement in the pitch direction is generated from the center of gravity due to the center of gravity shift due to this amount of tilt. If the value of the center of gravity shift value exceeds a certain value, a pitch-over (overturning in the pitch direction) occurs. Physically, when a pitch-over occurs, the front row (in case of rapid acceleration) or the rear row of legs or wheels (in case of sudden deceleration) can be heard.

In a typical vehicle, the geometric aspect ratio, H / L (where L is the distance between the front and rear wheels, H is the distance between the center of gravity and the ground; the proportional relationship between the weight deflection due to inertia generated during acceleration and deceleration) Has a small value, and the amount of pull generated is small, and since the suspension device is mounted between Unsprung Mass and Sprung Mass separately, the amount of pitch generated by its own motion such as the amount of pull during high-speed driving on flat ground is also attenuated. Becomes smaller. In addition, such a suspension system contributes to the stable running of the vehicle body in which the center of gravity is located even when there is an inclined road having a pitch value or irregularities on the ground.

On the other hand, in the case of the leg-type robot, which is not easy to apply the suspension system, it is necessary to consider the weight deflection caused by the acceleration and deceleration during the concept design and the complementary stage, and the center of gravity movement resulting from it.

An object of the present invention for solving the above problems is to reduce the longitudinal weight shift generated during acceleration and deceleration, not only to prevent the pitch-over, but also to increase the maximum forward speed under the same weight and the same driving conditions. It is to provide a legged robot that can.

A feature of the present invention for solving the above problems is a robot having a plurality of legs, the body; A plurality of legs positioned below the body and symmetrically positioned at the center of the body to support the body; An acceleration sensor measuring acceleration generated when the body moves; A microprocessor that calculates the center of gravity movement value of the robot using the measured acceleration; And a compensating unit for reducing the center of gravity movement by compensating for the center of gravity movement value calculated by the microprocessor.

Here, the plurality of legs is preferably four legs, the shape of the body, it is preferable that the moment of inertia of the shape having the same weight is the maximum.

The compensator may include a body having a constant weight capable of moving and an actuator for moving the body, and the actuator may be a pneumatic cylinder or a motor, and the movement calculated by the microprocessor. It is preferable to move the body by the direction opposite to the movement direction of the weight center by using a tooth distance of the compensation value to reduce the movement of the center of gravity.

According to the present invention, by providing a structural shape for reducing the longitudinal weight movement generated during acceleration and deceleration and a compensation device, not only the prevention of the pitch-over, but also the maximum traveling speed under the same weight and the same driving conditions ( Maximum Forwarding Speed) can be increased.

In addition, there is an advantage that the device can be easily configured as a simple structure to lower the manufacturing cost.

1 is a view showing a schematic diagram of a pitch balancing leg robot according to the present invention,
FIG. 2 is a schematic diagram illustrating a lost gait example due to a weight pull backward and a generated pitch in an acceleration situation of a legged robot; FIG.
3 is a view for explaining the coordinate reference applied to the leg-shaped robot according to the present invention,
4 is a graph illustrating an example in which pitch-over occurs when the motor angular velocity is applied at 75 rpm in the same simulation environment.
5 is a view showing the effect of adding the weight of the front (front) to compensate for the amount of weight generated during acceleration;
6 is a view showing a free body of the static state of the wheeled platform,
7 is a diagram showing a free object diagram when acceleration is generated;
8 is a view showing a free body diagram for calculating the pitch,

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

1 is a diagram showing a schematic diagram of a pitch balancing leg robot according to the present invention. As shown in Figure 1, the leg-shaped robot of the present invention, a robot having a plurality of legs, the body (10); A plurality of legs 20 positioned below the body and symmetrically positioned at the center of the body to support the body; An acceleration sensor 30 that measures acceleration generated when the body moves; A micro processor unit (MCU) for calculating the center of gravity movement value of the robot using the measured acceleration; And a compensator 50 for reducing the center of gravity movement by compensating for the center of gravity movement value calculated by the micro processor unit (MCU).

As such, the present invention proposes a robot having a pitch balancing device for preventing the generation of pitch-over (overturning in the pitch direction) generated when the robot accelerates or decelerates and inducing a stable running.

First of all, for the quantitative examination of Lost Gait due to weight deflection (not centered on the ground, it does not reach the ground and does not contribute to the generation of traction force by air), and the Pitch-Over case and the amount of deflection, In the following, the Lost Gait case and the Pitch-Over case caused by the backside of the weight generated during acceleration will be described, and the pitch balancing leg robot according to the present invention for solving such a problem will be described in detail.

FIG. 2 is a simulation diagram illustrating a lost gait example due to weight deflection and generated pitch angular displacement in an acceleration situation of a legged robot. FIG.

As shown in FIG. 2, the dynamic simulation condition simulated a driving situation in which the acceleration is performed at a stationary state (step 1) for a group 4 robot equipped with an actuator only in the hip joint. The lower five figures of FIG. 2 show only five frames having the same time interval (steps 1 to 5). As shown in FIG. 2, the front body is lifted by the weight being moved backwards, and the front row legs do not come into contact with the ground (step 3 and step 5), and as a result, they do not contribute to the generation of the traction. That is, it reaches the state which is easy to overturn. At this time, the angular velocity of the motors mounted on each hip joint was applied at 20 rpm. In this case, no pitch-over (overturned in the pitch direction) occurred.

3 is a view for explaining the coordinate reference applied to the leg-shaped robot according to the present invention. As shown in Fig. 3, the front and rear of the robot, that is, the vertical axis is referred to as the X axis, the horizontal axis is referred to as the Y axis, and the vertical axis is referred to as the Z axis. The rotation about the Z axis is called Yaw. Hereinafter will be described based on the axis and the rotation direction illustrated in FIG.

4 is a graph illustrating an example in which pitch-over occurs when the motor angular velocity is applied at 75 rpm in the same simulation environment. It can be seen that the pitch-over occurred under the condition that the acceleration was greater than that of FIG. 2, and that the pitch angular displacement rapidly changed from -180 deg to 180 deg, that is, physically flipped at 0.9 seconds. Therefore, it is possible to compensate for this by simply increasing the front weight at the design stage for the amount of weight backward generated during acceleration.

5 is a view showing the effect of adding the weight of the front (front) to compensate for the amount of weight caused during acceleration. As shown in Figure 5, it can be seen that there is an effect of increasing the running speed and motion stability obtained by increasing the weight in front.

In FIG. 5, the solid red line represents the behavior of the initial concept model, the green dotted line represents the behavior of the complementary model in which 0.5 kg is added to the front part and the blue dashed line is 1 kg. As a result, it can be seen that by adding weight to the front part, the amount of pitch generated during acceleration is reduced and the forwarding speed (Vx) is improved.

This indicates that, under the same driving environment and energy conditions, the speed increase effect due to the increase in the traction obtained by reducing the lost gait by reducing the pitch due to the acceleration is greater than the speed decrease effect due to the weight increase.

However, the simple compensation method considering only the acceleration as described above (the method of moving the center of gravity forward by adding weight in front) has the effect of compensating for the amount of weight deflection that is moved backward during acceleration, Since the weight pull amount in the front is greater and may cause an adverse effect of flipping around the front, the addition of simple weight does not solve the above-described pitch-over problem, and reduces the pitch amount by adding and moving the weight. It is the key.

6 is a view showing a free body of the static state of the wheeled platform. As shown in Fig. 6, the free object diagram is applicable to the leg-mounted robot in which the actuator is mounted only on the hip joint illustrated in the present invention.

In the following description, the amount of weight deflection for the wheeled platform is explained for clarity. Equation 1 is derived from the force equilibrium and the moment equilibrium conditions at point A.

Where R _{AS is} the static vertical load (reaction force) at point A in the static state.

7 is a diagram illustrating a free object diagram when acceleration is generated. That is, when acceleration occurs in the x direction, it is a free-body diagram showing the reaction force, that is, the inertia force due to the acceleration acting on the center of gravity. As shown in Fig. 7, [Equation 2] and [Equation 3] are derived through the moment parallel conditions at points A and B.

8 is a diagram illustrating a free body diagram for calculating a pitch. The center of gravity shift is shown in [Equation 4]. To calculate the center of gravity movement amount (△ x) of the virtual here, it was equivalent to the R and R _{A_D B _D} calculated earlier in the static state as shown in Fig. 8 on the basis.

As a result, it can be seen that when the acceleration of a _x , the center of gravity movement (weighting) occurs. Here, as shown in FIG. 8, if the limit is set so that the center of gravity movement does not exceed the rear wheel, the limit value (a _{x_MAX} ) that the system can give in the state of H / L ratio is determined and a _x is determined as a requirement. The limit of the H / L ratio to be considered {H / L} _MAX is given by the following Equations 5 and 6, respectively.

In the case of a vehicle, the H / L is designed in consideration of the longitudinal acceleration that an ordinary driver can generate by stepping on the accelerator pedal, so that the front wheel or the rear wheel is not lifted in most acceleration and deceleration environments, and a pitch is generated. Even if the suspension is attenuated.

On the other hand, it is difficult to mount the suspension system, and additional mechanisms need to be supplemented for the high speed driving performance that is required for the legged robots having less freedom for H / L selection. Accordingly, the present invention proposes a leg-shaped robot provided with the above-described center of gravity movement (weighting) or reducing or pitch balancing device.

That is, as proposed in FIG. 1, the body having the correction mass m is initially disposed in the center of gravity, and formed into a structure for moving the correction body to compensate for the center of gravity movement value generated during acceleration through the actuator on the left and right sides. do. At this time, the displacement to move the correction body is as shown in [Equation 7].

Based on this value, it is possible to calculate the command value of the actuator that generates the displacement of the correction body. That is, when the longitudinal acceleration of the platform a _x is measured, the displacement amount of the correction body is calculated to reduce or compensate the center of gravity movement.

That is, as shown in FIG. 1, the body of the robot is calculated by using Equation 4, and the body is moved by using Equation 7 again using the calculated center of gravity value. Compensation value for reducing the center of gravity movement, which should be the displacement amount, is sent to the actuator 53 of the compensation unit.

When the body having a constant weight by the operation of the actuator 53 is moved in the opposite direction of the center of gravity movement direction by the displacement amount, the movement of the center of gravity of the robot as a whole can be reduced to achieve pitch balancing.

Here, the actuator 53 may be any device that can drive the transfer of the object precisely and quickly, such as a hydraulic cylinder or a motor. In addition, the acceleration sensor 30 for measuring the acceleration a _x that appears when the robot accelerates and decelerates is preferably a three-axis acceleration sensor.

The acceleration sensor 30 is a sensor that measures the acceleration of an object and converts it into an electrical signal. In the present invention, a three-axis acceleration sensor is preferably used. This is a 3-axis accelerometer that can measure all three axes for more precise measurement, since the direction of acceleration can be arbitrarily formed in the vertical direction or diagonal direction. Is preferably.

9 is a view showing the structural shape of the leg-shaped robot with pitch balancing as another embodiment according to the present invention.

Minimizing the longitudinal weight deflection (or center of gravity shift) generated during acceleration and deceleration at the design dimension selection stage is the primary task. It is preferable that it is a shape which lowers L.

In the exemplary embodiment of the present invention illustrated in FIG. 9, the relationship between the moments causing the pitch angular acceleration due to the movement of the center of gravity generated by acceleration is represented by Equation (8).

Therefore, the moment of inertia due to the center of gravity movement, there is a way to increase the moment of inertia J _c to minimize the pitch (θ (t); integral Pitch angular acceleration twice), to the position away from the center of gravity It is preferable to arrange the weight so as to increase the weight. That is, it is the same as the shape illustrated in FIG.

In the case of a vehicle, there is a limitation in selecting a body shape such as a boarding space and an engine position. Therefore, the center of gravity movement can be reduced by the design of the H / L and the suspension system. Since the freedom of selection is high, it can be said that it is advantageous for the selection of the body shape which increases the pitch inertia matrix as shown in FIG.

Such a shape is a method for selecting a body shape to increase Inertia in the pitch direction, and has a shape that increases in weight away from the center of gravity in a body having the same weight. This has the effect of minimizing the pitch angular displacement at the center of gravity due to weight deflection by maximizing pitch inertia under the same weight and the same acceleration / deceleration environment.

 Finally, even with the H / L ratio design and the increase of the pitch inertia of the body, it is difficult to satisfy the required high-speed driving capability (ie, space constraints, aerodynamic air drag, etc.). If any), as described above, through the mechanical addition as shown in Fig. 1, the pitch reduction effect can be obtained.

Thus, if the present invention provides, in the leg-shaped robot, by measuring and calculating the longitudinal weight pull amount generated during acceleration and deceleration, by providing a structural shape and a compensation device for reducing this, by reducing the center of gravity movement and pitch In addition to the prevention of over, the maximum forwarding speed can be increased under the same weight and the same driving conditions.

While the invention has been shown and described with respect to the specific embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Anyone with it will know easily.

Claims (6)

In a robot having a plurality of legs,
Body;
A plurality of legs positioned below the body and symmetrically positioned at the center of the body to support the body;
An acceleration sensor measuring acceleration generated when the body moves;
A microprocessor that calculates the center of gravity movement value of the robot using the measured acceleration; And
And a compensating unit for compensating the center of gravity movement value calculated by the microprocessor to reduce the center of gravity movement.
The method of claim 1,
Pitch balancing leg robot, characterized in that the plurality of legs are four legs.
The method of claim 1,
The shape of the body,
Pitch balancing leg robot, characterized in that the maximum moment of inertia of the shape having the same weight.
4. The method according to any one of claims 1 to 3,
The compensation unit,
A body having a constant weight that can be moved,
Pitch balancing leg robot, characterized in that it comprises an actuator for moving the body.
The method of claim 4, wherein
And said actuator is a pneumatic cylinder or a motor.
The method of claim 4, wherein
Movement of the body,
And moving the body in a direction opposite to the movement direction of the center of gravity by the distance of the compensation value for reducing the movement of the center of gravity by using the movement value calculated by the microprocessor.

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