CN101712156B - An Airbag-type Robot Leg Buffer Mechanism with Adjustable Stiffness - Google Patents

Abstract

The utility model provides an adjustable rigidity's gasbag formula robot leg buffer gear, including the connecting block, the gasbag, the leg urceolus, telescopic link and force sensor, the upper end at the leg urceolus is installed to the connecting block, the telescopic link is installed in the leg urceolus, the leg urceolus is stretched out to the lower part of telescopic link, the space between the top is the grease chamber in the upper end piston portion of telescopic link and the leg urceolus, two parts about grease chamber divide into through a baffle, upper portion is provided with the gasbag, the lower part is stored and is had hydraulic oil and link to each other with outside pressure regulation return circuit, be equipped with the damping hole on the baffle, the force sensor who is used for measuring the size and. The invention can adjust the rigidity of the air spring on line according to the ground hardness information detected by the sensing device, reduce the impact force of the ground to the robot, improve the walking stability of the robot in dynamic gait and ensure that the robot walks in the most stable state.

Description

An Airbag-type Robot Leg Buffer Mechanism with Adjustable Stiffness

technical field

The invention relates to a leg buffer mechanism of a hydraulically driven mammal-imitating mobile robot, which belongs to the technical field of multi-legged mobile robots.

Background technique

At present, the relevant technologies of wheeled and tracked mobile robots have been fully developed, and many various mobile robot products have been applied to entertainment, anti-terrorism and explosives, hazardous environment operations, and military fields. Wheeled robots have the advantages of small frictional resistance and fast speed, but they are only suitable for flat ground environments and have poor obstacle-surmounting ability. Tracked robots have strong adaptability to the environment, and can climb over obstacles, climb stairs, and cross trenches, etc., but their transmission efficiency is low. Wheelless, whether it is a wheeled robot or a crawler robot, can only walk on less than half of the land on the earth, while humans and animals can walk anywhere on the land. Therefore, legged mobile robots have stronger environmental adaptability than wheeled and tracked mobile robots.

In the 1960s, bionics (Bionics), which was interpenetrated and combined with life science and engineering technology science, appeared. That is, from this time on, the United States took the lead in the research of bionic robots, and in 1968, Mosher of the General Electric Company of the United States developed the world's first modern four-legged walking robot with control functions. In 1977, Robert McGhee of Ohio State University developed the world's first digital computer-controlled walking bionic robot. Since the 1980s, research institutions in the United States, Japan, Canada, Switzerland, Germany and other countries have begun to study mammal-like legged mobile robots, and many other institutions have studied reptile-like mobile robots.

Quadruped mammalian robot is a multibody system with complex dynamic problems. When walking in a static gait, the robot has three legs to support the ground, which can generally maintain stability; but when walking in a dynamic gait, only two legs support the ground, and the impact force on the ground when the foot hits the ground can easily cause the robot to fall. Therefore, the problem of dynamic walking stability is a difficult problem for quadruped mammalian robot. At present, the main way to solve this problem is to develop new elastic and flexible mechanical systems.

Published in the "Journal of Shanghai Jiao Tong University" in July 1999, the document "A new type of leg structure cushioning characteristics in quadruped walking robots" introduces an elastic walking mechanism, which consists of four groups of parallel elastic elements and a robot leg shell. The four-link mechanism of the frame is composed of four-bar linkages. Its working principle is: when the foot of the walking robot touches the ground, due to the inertia of stepping down, the robot legs drive the compression spring of the lower link to move downward, and the lower link drives the upper link. Swing, because the spring guide rod is connected with the support foot, the upper hinge of the upper link is connected with the stationary end. When the upper and lower connecting rods are in a straight line due to the compression of the spring, the connecting rod mechanism reaches the dead point position, and the lower connecting rod is sucked by the control electromagnet to keep the connecting rod mechanism at the dead point position, thereby absorbing the energy absorbed in the spring. Shock energy is locked in the elastic legs. Then, under a certain gait, the electromagnetic sucker in the elastic leg is controlled to de-energize to release the energy stored in the elastic leg, and assist the robot to lift the leg and swing. This mechanism alleviates the ground impact force when the foot lands to a certain extent, but the structure is complex, and the spring stiffness cannot be adjusted online according to the ground environment with different hardness.

Contents of the invention

The present invention aims at the deficiencies in the leg structure cushioning technology of the existing legged mobile robot, and provides an airbag-type robot leg cushioning mechanism that can adjust the spring stiffness according to the hardness of the ground. Reduce the impact of the ground on the robot and improve the stability of the robot's dynamic walking.

An airbag-type robot leg buffer mechanism with adjustable stiffness of the present invention adopts the following technical solutions:

The robot leg cushioning mechanism includes a connection block, an air bag, a leg outer cylinder, a telescopic rod and a force sensor. The space between the upper piston part of the telescopic rod and the inner top of the outer cylinder of the leg is an oil chamber, which is divided into upper and lower parts by a partition plate, the upper part is provided with an air bag, and the lower part stores hydraulic oil and is connected to the external pressure regulating circuit A damping hole is arranged on the partition, and a force sensor for measuring the magnitude and direction of the contact force between the foot and the ground is installed at the lower end of the telescopic rod.

The pressure regulation circuit includes constant pressure oil source, electro-hydraulic servo valve, hydraulic control check valve and pressure sensor. The constant pressure oil source, electro-hydraulic servo valve and hydraulic control check valve are connected in sequence, and the hydraulic check valve is connected with the lower part of the oil chamber , The pressure sensor is installed between the lower part of the oil chamber and the hydraulic one-way valve to measure the pressure of the hydraulic oil in the oil chamber and transmit it to the robot's control system.

The outer cover of the force sensor is covered with a rubber sleeve, which is used to increase the friction between the foot and the ground, and plays a certain role in buffering and damping.

The buffer mechanism is used as the stub of the leg of the multi-legged robot, and the connecting block is used to connect with other parts of the leg. The telescopic rod can reciprocate and linearly move in the leg outer cylinder, and the friction is reduced through the linear bearing installed between the leg outer cylinder and the telescopic rod. The air bag in the oil chamber is used to absorb the impact force of the ground against the robot to keep the robot stable. The damping hole is used to consume the impact energy of the ground against the robot. The size of the damping hole can be set according to the needs. The storage volume changes the initial pressure of the airbag and adjusts its stiffness.

The invention directly uses the hydraulic oil source of the robot drive system, and the robot control system can adjust the stiffness of the air spring online according to the ground hardness information detected by the sensor device, reducing the impact force of the ground on the robot, and improving the walking performance of the robot in dynamic gait. Stability makes the robot walk in the most stable state. The invention has a simple and compact structure, and can be applied to bionic robots such as bipeds, quadrupeds, hexapods or octapeds driven by hydraulic pressure.

Description of drawings

Fig. 1 is a structural schematic diagram of an airbag-type robot leg cushioning mechanism with adjustable stiffness in the present invention.

Fig. 2 is a schematic diagram of the principle of the pressure regulating circuit in the present invention.

Fig. 3 is a functional block diagram of airbag spring stiffness adjustment according to the present invention.

In the figure: 1. Connecting block, 2. Air bag, 3. Leg outer cylinder, 4. Damping hole, 5. Hydraulic oil connection, 6. Oil chamber, 7. Oil seal, 8. Linear bearing, 9. Bushing, 10. Linear bearing, 11. Through cover, 12. Dust-proof sealing ring, 13. Telescopic rod, 14. Pressure sensor, 15. Rubber sleeve, 16. Pressure sensor, 17. Hydraulic control check valve, 18. Electro-hydraulic servo valve, 19. Constant pressure oil source, 20. Fuel tank.

Detailed ways

The structure of the present invention is shown in Fig. 1, mainly comprises connecting block 1, air bag 2, leg outer tube 3, telescoping rod 13, force sensor 14 and rubber sleeve 15. The present invention is used as the stub of the robot leg, and the connecting block 1 is installed on the upper end of the leg outer cylinder 3 for connecting with other parts of the robot leg. The telescopic rod 13 is positioned and installed in the leg outer cylinder 3 through the linear bearings 8 and 10, and its lower part protrudes from the leg outer cylinder 3. Between the two linear bearings 8 and 10, an axle sleeve 9 for isolation and positioning is provided, and the telescopic rod 13 It can perform reciprocating linear motion relative to the leg outer cylinder 3 . The transparent cover 11 plays a positioning role for the linear bearing 10 , and the embedded dustproof sealing ring 12 prevents dust from entering the linear bearing 10 from the gap between the telescopic rod 13 and the transparent cover 11 . The space between the upper end piston portion of the telescopic rod 13 and the inner top end of the leg outer cylinder 3 is the oil chamber 6 . The middle part of the oil chamber 6 is provided with a transverse baffle, and a damping hole 4 is opened on the baffle. A pre-inflated closed air bag 2 is installed above the partition to buffer the impact of the ground against the robot, and hydraulic oil is stored in the oil chamber 6 . The damping hole 4 increases the resistance of hydraulic oil flowing from one side of the partition to the other, and consumes the impact energy of the ground on the robot. The size of the damping hole 4 is processed as required, and the larger resistance of the damping hole 4 is less, and the energy absorbed by the airbag 2 when the robot lands can be used as a power output when the robot leaves the ground. Since the volume of the oil chamber 6 is constant, when the oil chamber 6 is filled with oil, the air bag 2 is further compressed, the gas pressure in the air bag 2 increases, and the spring stiffness increases accordingly. An oil seal 7 is installed on the piston portion at the upper end of the telescopic rod 13 to seal the hydraulic oil in the oil chamber 6 and keep the pressure in the oil chamber. The hydraulic oil interface 5 is connected with the pressure regulating hydraulic circuit shown in FIG. 2 . The lower end of the telescopic rod 13 is equipped with a force sensor 14, which is used to measure the magnitude and direction of the contact force between the robot foot and the ground, and provides it to the robot control system. The force sensor 14 is covered with a rubber sleeve 15, which is used to increase the friction between the foot and the ground, and plays a certain role in buffering and vibration reduction.

The pressure regulating circuit connected with the oil chamber 6 is shown in Fig. 2 . The constant pressure oil source 19 and the oil tank 20 among the figure all adopt the constant pressure oil source and the oil tank of the robot hydraulic drive system, also can be set separately. A pressure sensor 16 is installed between the oil chamber 6 and the hydraulic one-way valve 17 to measure the pressure of the hydraulic oil in the oil chamber 6 and transmit it to the control system of the robot. The hydraulic control check valve 17 is used to cut off the passage of hydraulic oil from the oil chamber 6 to the electro-hydraulic servo valve 18 to prevent the excessive pressure of the hydraulic oil in the oil chamber 6 from impacting the electro-hydraulic servo valve 18 when the robot lands. However, when the pressure in the oil chamber 6 is actively adjusted, the hydraulic control check valve 17 can communicate in both directions under the control of the electro-hydraulic servo valve 18 . The electro-hydraulic servo valve 18 quickly adjusts the oil volume in the oil chamber 6 according to the hydraulic oil pressure in the oil chamber 6 measured by the pressure sensor 16 and the hydraulic oil pressure corresponding to the spring stiffness of the air bag 2 determined by the hardness of the ground.

The spring stiffness adjustment process of the airbag 2 is shown in FIG. 3 . The spring stiffness of the air bag 2 is related to the gas pressure inside it, and the gas pressure is the same as the pressure of the hydraulic oil in the oil chamber 6 . The adjustment of the hydraulic oil pressure in the oil chamber 6 must be carried out when the legs are in the suspended phase, because the pressure measured by the pressure sensor 16 is the static pressure of the gas in the air bag 2 at this moment. The control system determines the optimal spring stiffness according to the ground information, and compares the gas pressure corresponding to the spring stiffness with the pressure measured by the pressure sensor 16 , and then sends a corresponding current signal to the electro-hydraulic servo valve 18 . The electro-hydraulic servo valve 18 rapidly adjusts the oil volume in the oil chamber 6 according to the current signal until the pressure measured by the pressure sensor 16 is equal to the gas pressure corresponding to the optimal spring stiffness.

Claims (3)

1. the gasbag robot leg buffer mechanism of an adjustable rigidity, comprise contiguous block, air bag, the leg urceolus, expansion link and power sensor, contiguous block is installed in the upper end of leg urceolus, it is characterized in that: expansion link is installed in the leg urceolus, the bottom protruding leg urceolus of expansion link, space between the upper end piston portion of expansion link and the leg urceolus inner top is the grease chamber, the grease chamber is divided into two parts up and down by a dividing plate, top, grease chamber is provided with the closed airbag of inflation in advance, the storage of bottom, grease chamber has hydraulic oil and links to each other with the pressure regulation circuit of outside, dividing plate is provided with damping hole, and the lower end of expansion link is equipped with the power sensor of the size and Orientation that is used for measuring the contact force between foot and the ground; Hydraulic fluid pressure and by the oil mass in the pairing hydraulic fluid pressure rapid adjustment of the spring rate grease chamber of the air bag of ground surface hardness decision in the grease chamber that electrohydraulic servo valve in the pressure regulation circuit is measured according to pressure sensor.

2. the gasbag robot leg buffer mechanism of adjustable rigidity according to claim 1, it is characterized in that: described pressure regulation circuit comprises constant pressure oil source, electrohydraulic servo valve, hydraulic control one-way valve and pressure sensor, constant pressure oil source, electrohydraulic servo valve and hydraulic control one-way valve are connected successively, hydraulic control one-way valve is connected with the bottom, grease chamber, and pressure sensor is installed between bottom, grease chamber and the hydraulic control one-way valve.

3. the gasbag robot leg buffer mechanism of adjustable rigidity according to claim 1 is characterized in that: the outer cup rubber sleeve of described power sensor.

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