CN114770601B - Foot type robot motion experiment table - Google Patents

Abstract

A legged robotic motion laboratory bench comprising: a base (3); a pavement simulation platform (1) which comprises a running belt arranged on a base platform; a displacement measuring device (2) which is arranged on the base platform and measures the displacement of the robot on the running belt; and the control system is used for controlling the speed of the running belt according to the displacement of the robot on the running belt measured by the displacement sensor of the displacement measuring device in real time, and provides an experimental condition for exploring the deviation between an experimental actual result and an expected result under the condition of different road equivalent speeds.

Description

Legged Robot Motion Experiment Bench

technical field

The invention belongs to the field of intelligent robot testing technology and equipment, in particular to a footed bionic robot motion test bench.

Background technique

In recent years, footed bionic robots have developed rapidly. As a discipline integrating machinery, electronics, computers, control science, measurement and control technology, and artificial intelligence, its wide range of disciplines and high degree of technology integration have attracted many scholars and scientific research. Favored by institutions and technology companies, it is one of the hottest research fields at the moment.

Jumping is the way most animals achieve fast walking and crossing obstacles, and it is also the expected goal of bionic design of legged robots. The jumping experiment is an indispensable and important process to evaluate the robustness of the legged robot's stability control algorithm and the structure design. Generally, the robot is placed on a treadmill for experiments, and the experimenter controls the speed of the treadmill to realize the cyclic reset process of the robot position. However, this method is difficult to ensure accurate and timely speed regulation, and the robot has the risk of falling from the treadmill. Not as a proven solution.

Contents of the invention

The purpose of the present invention is to provide an experimental platform and experimental method for the legged robot jumping experiment, to solve the deviation of the expected experimental effect caused by the difficulty in continuing the current robot jumping experiment process, and the manpower consumed by frequent resetting of the robot during the experiment , and the problems caused by other factors that may affect the experimental results, and provide experimental conditions for exploring the deviation between the actual experimental results and the expected results under different road equivalent speeds.

According to an aspect of the embodiments of the present invention, there is provided a legged robot motion test bench, comprising:

base;

A road surface simulation platform, which includes a running belt installed on the base;

a displacement measuring device installed on the base platform to measure the displacement of the robot on the running belt; and

A control system configured to perform the following steps when the robot performs a jumping experiment:

Real-time measurement of the displacement D of the robot on the running belt by the displacement sensor of the displacement measuring device;

Calculate the real-time absolute velocity v _a of the robot in the horizontal direction during the jumping experiment according to the displacement

v _a = -Δy·f = (D _k+1 -D _k )f

In the formula, _Dk and _Dk+1 are two adjacent return values of the displacement sensor, and f is the frequency of the displacement sensor;

Find the real-time real speed v _r of the robot, v _r = v _a -v _b , where v _b is the speed of the running belt;

Continuously correct the speed of the running belt according to the following formula: v′ _b =v _r +Δv, where Δv is the speed compensation item, determined by the following formula: Δv=KΔD, where K is the structure of the test bench and the expected response The proportional coefficient related to the effect, ΔD=DD _m , where v _r and Δv are values calculated in real time, and D _m is the effective distance value when the robot is synchronized with the moving speed of the running belt.

In some examples, before the robot performs the jumping experiment, the robot is started and made to walk on the running belt at a constant speed, starting from the robot walking, the real-time absolute velocity v _a of the robot in the horizontal direction is obtained, and the maximum value is The robot tests the speed v _ae , and adjusts the belt speed v _b of the running belt to v _b =-v _ae .

In some examples, the running belt is at rest when the robot walk begins, and is not activated until a time ΔT has elapsed, where ΔT is determined by:

L is the effective length of the running belt.

In some examples, the displacement measuring device includes a guide rail and a slider, the guide rail is vertically fixed on the center line of the running belt arrangement direction of the base platform, and the plurality of sliders are arranged on the guide rail, One displacement sensor is arranged on each slider.

In some examples, an attitude sensor is mounted on the robot that stops the running belt when the robot detects that the robot is at risk of falling.

The invention simulates the running road surface, and can adjust the speed through the running belt to realize the test requirements including but not limited to the continuous jumping experiment of the legged robot, breaking through the limitation of the space of the actual experimental site. On the premise of not interfering with the jumping action process of the legged robot, the invention ensures certain safety in the experiment process. The present invention is guided by the realization of the test function to achieve the purpose of the continuous jumping experiment of the legged robot. Its practical application value also has room for function expansion.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings of the embodiments will be briefly introduced below.

1 to 3 are schematic diagrams of a legged robot motion experiment platform provided by an embodiment of the present invention.

Fig. 4 is a schematic diagram of the coordinate system of the legged robot motion experiment platform provided by an embodiment of the present invention.

Fig. 5 is a truth table of the signal of the displacement sensor of the legged robot motion test bench provided by an embodiment of the present invention.

Fig. 6 is a flow chart of displacement signal processing provided by an embodiment of the present invention.

Fig. 7 is a flow chart of obtaining the horizontal speed of a robot on a running belt according to an embodiment of the present invention.

Fig. 8 is a flow chart of the initial speed synchronization process between the robot and the test bench provided by an embodiment of the present invention.

Fig. 9 is a control flow chart of the test bench for the robot reset process provided by an embodiment of the present invention.

Detailed ways

1 to 3 show a legged robot motion test bench, which includes a base 3 , a road surface simulation platform 1 and a robot displacement measuring device 2 installed on the base 3 . The base 3 has a supporting foot cup 18 at the bottom. The road simulation platform 1 includes a running belt 10 , a running board 11 and a driving system for driving the running belt 10 . The running board 11 is arranged between the running belts 10 and is fixed on the base 3 by the running board connector 12 . The transmission system includes a motor 5 and a first roller 4 and a second roller 8 positioned at both ends of the running belt 10 to tension it. The two rollers 4 and 8 are parallel to each other, and are fixed on the bottom platform 3 by the roller connector 13 . The second cylinder 8 is connected with a pulley, and the motor 5 shaft is connected with a small pulley 6, and two pulleys are connected by a transmission belt 7 to form a belt drive.

As shown in FIG. 3 , the robot displacement measuring device 2 includes a guide rail 14 , a slider 15 and a displacement sensor 16 . The guide rail 14 is vertically fixed on the center line of the arrangement direction of the running belt 10 of the bottom platform 3 by the guide rail connector 17 . A plurality of sliders 15 are arranged on the guide rail 14 , and can be moved, adjusted and fixed on the guide rail 14 . A displacement sensor 16 is arranged on each slider 15 .

The control of the legged robot motion test bench is described in detail below.

1) Turn on the test bench, place the test robot 19 on the back of the middle of the running belt 10 of the test bench, and keep an appropriate distance from the displacement sensor 16 . Taking the geometric center of the surface of the running belt 10 as the origin of the coordinate system of the test bench, establish the coordinate system of the test bench as shown in Fig. 4 . Taking the center of mass of the test robot as the reference point of the robot position, then in the coordinate system of the test bench, the coordinate range of the center of mass of the test robot correctly placed is:

(X _C ,L/4,Z _C )～(X _C ,L/2,Z _C )

Wherein L is the effective length of the running belt 10 of the test bench.

2) During the whole process of the experiment, the displacement is measured in real time by the displacement sensor 16 configured on the test bench. Take three displacement sensors as an example, but not limited thereto. Specifically, the three displacement sensors work at the same time and feed back the displacement signals of the three robots, which are respectively d ₁ , d ₂ , and d ₃ from top to bottom, and their values are the distances from the sensors to the body of the test robot. Obviously, if the distance d _i :

d _i ≥ L (i=1,2,3)

At this time, the sensor is out of focus, that is, the reflection point is not on the fuselage, it is invalid to record A _i =0, otherwise it is valid to record A _i =1, and A _i is a logical quantity representing whether d _i is valid. All possible values of the three logical quantities are shown in Figure 5, record the logical quantity B=A ₁ +A ₂ +A ₃ , and B=1 means that the displacement signal at this time can accurately represent the test robot in the coordinate system Y of the test bench Coordinate changes in the axial direction, and B=0 means that the test robot has not been placed on the test bench at this time or has fallen down.

When B=1, record D as the effective distance from the fuselage to the sensor, if a single signal is valid, let D=di, if multiple signals are valid, take the average value, specifically:

The real-time displacement measurement signal processing flow of the test robot is shown in Figure 6. During the whole experiment, the displacement sensor 16 is always in the working state and continuously returns the distance measurement value.

When the test robot is placed on the test bench for the first time, it does not move, that is, the ground displacement is zero. Specifically, when the difference between two adjacent return values of the displacement sensor 16 is D _k+1 -D _k ≤ 0.001f, it can be determined that the test robot itself is not moving at this time, where f is the frequency of the displacement signal returned by the displacement sensor, where During the test bench motor 5 standby does not rotate.

3) During the test, the test robot is first started and walks on the test bench at a low speed (<0.5m/s) at a constant speed. At this time, it is obvious that D _k+1 -D _k >0.001f is established, by The real-time absolute speed of the test robot in the horizontal direction can be obtained by two adjacent return values of the displacement sensor:

v _a = -Δy·f = (D _k+1 -D _k )f

In the formula, _Dk and _Dk+1 are two adjacent effective distances returned by the sensor and processed by the signal; f is the frequency of the displacement sensor.

From the start of the test robot walking, the two adjacent effective distances are constantly different, and the test robot speed is calculated, and the maximum value is taken as the test robot test speed, which is recorded as v _ae , as shown in Figure 7.

Referring to Fig. 8, to realize the speed synchronization between the test robot and the running belt, that is, the ground displacement of the test robot is zero, then: v _b = -v _ae should be established, where v _b is the belt speed of the test bench.

According to the belt speed v _b of the test bench, the output speed of the motor when the speed of the test bench and the test robot is synchronized can be obtained:

In the formula, D _G is the outer diameter of the second drum 8 of the test bench; i is the transmission ratio of the belt transmission formed by the small pulley 6 on the motor 5 shaft and the pulley on the second drum 8 . Because the rotation speed of the stepping motor 5 is proportional to the frequency of the input electric pulse, the output speed of the motor 5 can obtain the frequency _f of the electric pulse that should be input as:

Where β is the stepping angle of the stepping motor. So far, the synchronization between the test robot and the running belt speed can be realized by sending the electric pulse signal to the stepping motor from the obtained electric pulse frequency f _e that should be input. At this time, the ground displacement of the test robot is approximately zero, and the The coordinates (X _c , Y ₀ , Z _c ) of the robot’s center of mass in the coordinate system of the test bench are recorded as the experimental origin E ₀ , where Y ₀ =L/2-D _m , and D _m is when the test robot is synchronized with the speed of the running belt. The effective distance value of is also the maximum value in the process.

In addition, in order to make the speed of the test robot calculated by the return value accurate and reliable, the motor of the test bench does not start when the test robot starts to walk, that is, the running belt is stationary, but starts after ΔT time. ΔT is determined by the following formula:

4) During the test, when the test robot is in the walking state and has been synchronized with the speed of the running belt, v _a ≈ 0 should be established at this time, and the jumping experiment process can be started. Let the test robot jump while moving. When the test robot is in the air, the effective distance D from the robot body to the sensor is fed back by the displacement sensor of the test bench. From the method of obtaining the real-time speed of the robot in 3), similarly, the jump test can be obtained. The real-time absolute velocity v _a of the robot in the horizontal direction during the process, and the real-time real velocity of the test robot at this time is: v _r = _va -v _b , when v _b =0, v _r = _va holds true.

When v _a ≠ 0, that is, v _r ≠ -v _b is established, there is a relative motion trend between the test robot and the test bench. Specifically, if v _r >-v _b , the test robot tends to lean forward relative to the test bench. If v _b remains unchanged, the test robot will fall forward to the test bench; if v _r <-v _b , at this time, the test robot has a tendency to move backward relative to the test bench under the action of the running belt. If v _b remains unchanged, the test robot will fall backwards to the test bench under the action of the running belt; if v _r ≈-v _b , then At this time, the test robot and the test platform have no relative motion trend, and the ground displacement of the test robot is approximately zero. However, if v _b remains unchanged, the test robot will fall forward to the test platform during the subsequent jumping process.

Referring to Figure 9, in consideration of the protection of the test robot and the reliability of the experimental process, it should be ensured that the take-off position of the test robot is always at the origin of the experiment during the jump experiment. To achieve this goal, the belt speed should be continuously corrected according to the following formula:

v′ _b ＝v _r +Δv

In the formula, Δv is the speed compensation item, which is determined by the following formula:

Δv=KΔD

Among them, K is a proportional coefficient related to the structure of the test bench and the expected recovery effect, which can be 0.6-0.8; and ΔD=DD _m . It is worth noting that v _r and Δv in the formula are values calculated in real time.

Specifically, when ΔD>0, that is, D>D _m , there is Δv>0, at this time v _a =v _r +v′ _b <0, at this time the test robot will approach positively along the y-axis under the action of the running belt The origin of the experiment; as ΔD gradually decreases, and when ΔD<0, that is, D<D _m , there is Δv<0, at this time v _a =v _r +v′ _b >0, and the test robot will be on the running belt Under the action, it is close to the origin of the experiment along the negative direction of the y-axis. According to the obtained _v'b and then according to the steps in 2), the corresponding motor output shaft speed and the electric pulse frequency to be input can be obtained at this time.

Furthermore, if ΔD=0 holds true, then Δv=0, that is, v′ _b =v _r , v _a =0, at this time the test robot is at the same speed as the running belt again, and the ground displacement is zero. Considering that the actual test situation cannot strictly guarantee the establishment of ΔD=0, when |DD _m |≤0.01 is established, it is judged that the test robot has returned to the original point of the experiment at this time, and if Δv=0, then v′ _b =v When _r is established, the test robot is synchronized with the speed of the running belt. At this time, press 3) to carry out the next experiment.

5) During the entire process from when the test robot is placed on the test bench to the end of the experiment, the attitude sensor 20 installed on the test robot always feeds back real-time attitude data. When the angular displacement of any axis fed back by the IMU exceeds the set threshold, such as 45 °, it can be judged that the posture of the test robot is abnormal and there is a risk of falling, and the motor of the test bench stops immediately to protect the test robot.

6) The purpose of the process of making the test robot walk at a certain speed and synchronize with the belt speed described in step 3) is to make the test robot and the test bench pre-check whether there are faults or not. It is also feasible to place the test robot as the origin of the experiment and perform jumping experiments according to step 4). The presence or absence of the speed synchronization process before the jump experiment described in step 3) should not be construed as a limitation to the present invention.

Claims (7)

1. A legged robotic motion laboratory bench, comprising:

a base table;

a pavement simulating platform including a running belt mounted on the base;

a displacement measuring device installed on the base platform for measuring the displacement of the robot on the running belt; and

a control system configured to perform the following steps when the robot is conducting a jump experiment:

measuring the displacement D of the robot on the running belt in real time through a displacement sensor of the displacement measuring device;

solving the horizontal direction reality of the robot in the jumping experiment process according to the displacementTime absolute velocity v _a

v _a ＝-Δy·f＝(D _k+1 -D _k )f

In the formula, D _k And D _k+1 F is the frequency of the displacement sensor;

calculating real-time real speed v of robot _r ，v _r ＝v _a -v _b In the formula v _b Taking the speed for the running belt;

continuously correcting the running belt speed according to the following formula: v' _b ＝v _r + Δ v, where Δ v is a velocity compensation term, determined by: Δ v = K Δ D, where K is a scaling factor related to the bench structure and the expected recovery effect, Δ D = D-D _m In the formula v _r And Δ v are both values calculated in real time, D _m And the effective distance value is the effective distance value when the robot and the running belt move synchronously.

2. The legged robot motion laboratory table according to claim 1, wherein K is 0.6 to 0.8.

3. The legged robot motion laboratory bench of claim 1, wherein before the robot performs the jump experiment, the robot is started and made to walk on the running belt at a constant speed, and the horizontal real-time absolute velocity v of the robot is obtained from the start of walking of the robot _a Taking the maximum value as the test speed v of the robot _ae The belt speed v of the running belt _b Is adjusted to v _b ＝-v _ae 。

4. The legged robot motion laboratory bench of claim 3, wherein the running belt is stationary at the beginning of robot walking and is activated after a time Δ T has elapsed, Δ T being determined by the following equation:

l is the effective length of the running belt.

5. The legged robot movement laboratory table according to any one of claims 1 to 4, characterized in that the displacement sensor has a plurality of sensors.

6. The legged robot motion laboratory table according to claim 5, wherein the displacement measuring device comprises a guide rail and a slider, the guide rail is perpendicularly fixed on a center line of the running belt arrangement direction of the base table, the plurality of sliders are disposed on the guide rail, and one displacement sensor is disposed on each slider.

7. The legged robot motion laboratory bench of claim 1, characterized in that the robot is equipped with an attitude sensor that detects the robot falling risk and makes the running belt still.

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