CN102278334A - Hydraulic power system for robot - Google Patents

Abstract

The hydraulic power system of the robot includes the control unit ECU, the starting motor, the engine and the variable pump connected in sequence, the oil inlet of the variable pump is connected with the fuel tank through the coarse filter, and the oil outlet of the variable pump is provided with a first pressure sensor, the oil outlet of the variable displacement pump is provided with a flow sensor in series, and a second pressure sensor is connected in parallel at the oil inlet end of the load, and the first pressure sensor, the second pressure sensor and the flow sensor transmit the collected signals to To the control unit ECU, the control unit ECU monitors the working state of the power system, and at the same time performs closed-loop control on the engine speed and variable pump displacement, so as to realize accurate supply of flow and precise control of system pressure. Further, the oil outlet of the variable displacement pump is provided with an electronically controlled unloading valve, and the oil outlet of the variable displacement pump is connected in parallel with the overflow valve and the accumulator through a one-way check valve. The invention can effectively utilize energy and precisely control the amount of oil supplied.

Description

Robot hydraulic power system

technical field

The invention relates to a hydraulic power system, in particular to a hydraulic power system of a walking robot.

Background technique

The walking bionic robot has the characteristics of high-speed movement under normal flat terrain and strong adaptability under special terrain in the field. Walking robots are mainly oriented to the wild environment. In addition to the normal walking function, there are also specific requirements for carrying payloads and walking mileage during the specific design process. Due to the compact structure, high power density and strong adaptability of hydraulic drive, the application of hydraulic servo drive in this field has great advantages compared with electric drive. In order to meet the various design requirements of the robot: the hydraulic servo mechanism not only requires the hydraulic source to have fast and stable characteristics, but also requires the hydraulic source to have the characteristics of high power density (small size, light weight) and high efficiency. Therefore, developing a highly integrated hydraulic power system to provide a powerful hydraulic source for the robot's walking is a key technology for designing a high-performance walking robot.

Foreign literature on walking robots mainly uses the battery-motor drive system. The quadruped robot structures disclosed in Chinese patent documents ZL200820157956.2, CN101602382A, and ZL03153505.4 also all adopt battery-motor structures. The disadvantage of battery-motor is low power density and poor endurance.

Chinese patent CN 101811304A discloses a hydraulic drive system for a quadruped robot. The power part of the system adopts the structural form of an engine combined with a quantitative pump. In addition, in a robot structure similar to a walking robot, an engine plus a variable pump is also used. The structure changes the output flow of the hydraulic source through the control of the variable pump. The disadvantages of the above two design schemes are as follows:

The first is that the engine drives the quantitative pump to work. The control method of this structure is to achieve different flow outputs by adjusting the engine speed. The disadvantage of this solution is that the range of engine speed changes is small. When the servo mechanism requires a small flow , the pressure of the system can only be reduced by overflow, which causes a waste of energy. When the robot moves at a low speed, the energy consumption is high. At the same time, the wasted energy is converted into heat and needs to be dissipated through the radiator, which increases the heat dissipation of the system. burden.

The second design scheme is to use the engine to drive the variable pump to work. Through the control of the displacement of the variable pump, the adjustment of the system flow is realized, and the adjustment of constant pressure and variable flow is realized. The disadvantage of this solution is that although the flow adjustment is realized by the variable variable pump, when the robot is moving at a low speed, the engine is in a high-speed, low-torque working state, and the fuel cannot be fully burned, resulting in a large fuel consumption of the engine. The working efficiency of the variable displacement pump is also low when the displacement is low, and the energy consumed will also increase the burden on the cooling system to a certain extent.

Contents of the invention

The technical solution of the invention is to overcome the deficiencies of the prior art and provide a robot hydraulic power system. The invention can effectively utilize energy and precisely control the amount of oil supplied.

The technical solution of the present invention is: the robot hydraulic power system, including the control unit ECU, the starting motor, the engine and the variable pump connected in sequence, the oil inlet of the variable pump is connected with the oil tank through the coarse filter, and the outlet of the variable pump A first pressure sensor is provided at the oil port, a flow sensor is provided in series at the oil outlet of the variable displacement pump, and a second pressure sensor is provided in parallel at the oil inlet end of the load, the first pressure sensor, the second pressure sensor And the flow sensor transmits the collected signal to the control unit ECU, the control unit ECU monitors the working state of the power system, and at the same time performs closed-loop control on the engine speed and the displacement of the variable pump to realize the accurate supply of flow.

Further, the oil outlet of the variable displacement pump is connected in parallel with the accumulator through a one-way check valve.

Further, the oil outlet of the variable displacement pump is also connected in parallel with the overflow valve through the one-way check valve.

Further, an electronically controlled unloading valve is provided at the oil outlet of the variable displacement pump.

Preferably, the variable displacement pump is a plunger type variable displacement pump.

The control unit ECU collects the signal of the swash plate inclination sensor of the variable pump, and realizes the closed-loop control of the displacement of the variable pump by controlling the proportional valve of the variable pump.

The control unit ECU collects the signal of the rotational speed sensor of the engine, and realizes the closed-loop control of the rotational speed of the engine by controlling the electronic throttle valve of the engine.

Preferably, the control unit ECU communicates with other systems of the robot through a can bus.

Compared with the prior art, the present invention has the following advantages:

(1) The core components of the power system of the present invention include an engine, a variable displacement pump and a control unit ECU. The starter motor, the engine and the variable displacement pump are connected in sequence. When the power system is started, the starter motor drives the engine to rotate, and the engine drives the variable displacement pump to rotate. A first pressure sensor is provided at the oil port, a flow sensor is connected in series at the oil outlet of the variable displacement pump, and a second pressure sensor is connected in parallel, and the first pressure sensor, the second pressure sensor and the flow sensor will collect The signal of the control unit is transmitted to the control unit ECU, and the control unit ECU monitors the working state of the power system, and through the dual-parameter closed-loop control of the displacement of the variable pump and the speed of the engine, the engine and the engine are reasonably matched during the working process of the power system. The operating point of the variable variable pump achieves the purpose of improving the working efficiency of both; this structural design enables the present invention to improve the working efficiency of the power system and reduce fuel consumption under the premise of ensuring accurate control of the fuel supply.

(2) The oil outlet of the variable displacement pump of the present invention is connected in parallel with the accumulator through a one-way check valve, and the accumulator can supplement the transient flow of the system, improve the dynamic response capability of the power system, and increase the instantaneous flow of the system.

(3) The oil outlet of the variable pump of the present invention is connected in parallel with the overflow valve through the one-way check valve, and the overflow valve plays the role of safety overflow to ensure that the system is below the maximum output pressure.

(4) The present invention adopts the cooperating work of the starting motor and the electric control unloading valve to realize electric starting and quick unloading of the power system. Under the engine idling condition, the unloading valve can effectively reduce the pressure of the oil outlet of the variable pump, which is beneficial to Improve the life of the variable pump.

(5) The present invention adopts an independent control unit ECU to realize intelligent control.

Description of drawings

Fig. 1 is a schematic diagram of the principle of the hydraulic power system of the robot according to the present invention.

Fig. 2 is a functional block diagram of the control unit ECU according to the present invention.

Figure 3 is a working principle diagram of the robot hydraulic power system in the constant current source mode.

Figure 4 is a working principle diagram of the robot hydraulic power system in the constant pressure source mode.

Description of drawing numbers: 1-Starter motor, 2-Engine, 3-Engine electronic throttle, 4-Engine speed sensor, 5-Control unit ECU, 6-Axial piston variable pump, 7-Proportional valve of variable pump , 8-swash plate inclination sensor of variable variable pump, 9-electrically controlled unloading valve, 10-first pressure sensor, 11-one-way check valve, 12-accumulator, 13-flow sensor, 14-second pressure Sensor, 15-fine filter, 16-radiator, 17-oil tank, 18-overflow valve, 19-coarse filter.

Detailed ways

Specific embodiments of the present invention will be described below in conjunction with the accompanying drawings.

As shown in Figure 1, the robot hydraulic power system according to the present invention includes a control unit (ECU) 5, a starter motor 1, an engine 2 and a variable displacement pump 6 connected in sequence, and the oil inlet of the variable displacement pump passes through a coarse filter 19 and The oil tanks 17 are connected, the oil outlet of the variable variable pump is connected in parallel with a first pressure sensor 10, the oil outlet of the variable variable pump is provided with a flow sensor 13 in series, and the load oil supply end is provided with a second pressure sensor 14 in parallel, The first pressure sensor, the second pressure sensor and the flow sensor transmit the collected signals to the control unit ECU, and the control unit ECU monitors the working state of the power system, and at the same time performs closed-loop control on the engine speed and variable pump displacement. Control to realize the precise supply of flow.

The starter motor 1 is directly connected with the engine 2, and when the power system starts, the starter motor 1 drives the engine 2 to rotate. The engine 2 is connected with the variable pump 6 to drive the variable pump 6 to rotate. When the system is started, under the control of the control unit (ECU) 5, the electronically controlled unloading valve is energized and unloaded, and the displacement of the variable pump is adjusted to 0. In this way, the engine can be started under the condition of no load, effectively reducing the resistance torque when the engine starts.

In the embodiment, the engine adopts a gasoline engine (certainly a diesel engine can also be used), and the variable pump adopts a plunger type variable pump (other variable pumps are also OK, but the advantage of using the plunger type variable pump is stable operation, good flow uniformity, and low noise. , high working pressure is conducive to improving the power density of the system. The preferred speed of the engine is not less than 7000r/min, and the preferred speed of the variable pump is not less than 6000r/min. The advantage of using high speed is that it can reduce the volume and weight of the system and improve the system power density.

The engine 2, the variable pump 6 and the control unit 5 are the core components in the power system, and the control unit ECU controls the engine speed and the displacement of the variable pump at the same time to realize the accurate supply of flow. The control unit 5 collects the signal of the speed sensor 4 of the engine, and realizes the closed-loop control of the engine speed by controlling the electronic throttle valve 3 of the engine; The control of 7 realizes the closed-loop control of the displacement of the variable pump.

In order to reduce the outlet pressure of the variable pump when the engine is starting and idling, and increase the life of the variable pump, an electronically controlled unloading valve 9 is connected in parallel at the oil outlet of the variable pump 6 . When the robot starts or stops temporarily, the control unit 5 opens the electronically controlled unloading valve 9 to ensure that the engine 2 starts under no-load conditions. At the same time, the control unit 5 drives the starter motor 1 and supplies fuel to the engine by controlling the electronic throttle valve 3 of the engine, so as to realize the electric start of the robot. When the robot is in a temporary shutdown state, the electronically controlled unloading valve 9 can be opened to reduce the opening of the electronic throttle valve of the engine and reduce the speed of the engine, so that the engine is in a low-speed no-load idle state to save fuel and prolong the life of the variable pump.

The oil outlet of the variable displacement pump 6 is connected in parallel with the overflow valve 18 and the accumulator 12 through the one-way check valve 11. The overflow valve plays the role of safety overflow to ensure that the system is below the maximum output pressure, and the accumulator can The instantaneous flow is supplemented to improve the dynamic response capability of the power system.

The oil return path of the load is connected with radiator 16 and fine filter 15 in series to realize the functions of cooling and cleaning, and ensure that the circulating oil in the oil tank is within the prescribed temperature and cleanliness range.

As shown in Fig. 2, the present embodiment adopts the CAN bus to realize the communication function between the ECU of the power system and other systems of the robot. When the robot is working, the control unit releases the working status and related data of the power system in real time through the CAN transceiver module, and obtains the robot's current gait information, environmental information and motion mode in time, and determines the reasonable Oil supply mode and oil pressure and flow. At the same time, according to the efficiency characteristics of the engine and the variable pump, the two can be matched at the highest efficiency point to achieve the purpose of saving energy on the premise of ensuring the effective oil supply of the hydraulic system.

In this embodiment, the control unit ECU is implemented by a single-chip microcomputer, and the single-chip microcomputer is MC9S12DP256 produced by Freescale. Of course, the ECU can also be implemented using Infineon's SAF-XE164G-72F66L or SAF-XE167FM-72FxxL.

During the working process, the power system realizes the precise control of the flow rate of the robot hydraulic system through the closed-loop control of the engine speed and the displacement of the variable pump. Through the control of the flow rate, two output modes of constant pressure source mode and constant current source mode can be realized.

In the constant current source mode, as shown in Figure 3, it is realized through the closed-loop control of the engine speed and variable pump displacement. Firstly, the ECU determines the required displacement of the variable pump and the engine speed according to the target flow of the system. The displacement of the variable pump is realized by changing the inclination angle of the swash plate of the variable pump. The ECU determines the current of the proportional valve according to the difference between the target inclination angle and the actual inclination angle of the variable pump swash plate, and performs closed-loop control on the variable pump swash plate inclination angle, thereby realizing precise control of the displacement of the variable pump. At the same time, the ECU determines the size of the engine throttle opening according to the difference between the engine target speed and the actual speed, and performs closed-loop control on the throttle opening, thereby realizing precise control of the engine speed.

In the constant flow source mode, the pressure of the system is controlled through the relief valve, and when the pressure is too high, the excess flow will overflow through the relief valve. The advantage of the constant current source mode is that the system has a short response time and can quickly respond to changes in the flow demand of the robot's servo motion mechanism. It is suitable for situations where the robot needs to quickly adjust its posture when the external environment changes suddenly.

In the constant pressure source mode, as shown in Figure 4, the ECU dynamically adjusts the system flow according to the target pressure, and achieves the purpose of controlling the system pressure by adjusting the flow. In the specific adjustment process, firstly, the ECU determines to increase or decrease the flow rate according to the target pressure and the actual pressure value. The change of the flow rate is realized through the closed-loop control of the engine speed and the displacement of the variable pump, and the adjustment process of the flow rate is consistent with the adjustment method in the constant flow source mode.

The advantage of the constant voltage source mode is that it saves energy consumption, has no overflow loss, and is widely applicable to various walking and working states of the robot.

The hydraulic power system of the present invention has the following advantages:

Advantage 1: High efficiency, can effectively reduce the fuel consumption of the robot, and increase the cruising range of adding fuel once.

Advantage 2: Intelligent control, strong adaptability. The working mode of the power system can be flexibly adjusted according to the working state of the robot.

Advantage 3: Fast response, which is beneficial to shorten the response time of the robot and improve the adaptability to emergencies.

Advantage 4: High power density, small size and light weight.

It should be noted that the present invention is applicable to the power system of any robot, especially to the power system of a walking robot.

The content that is not described in detail in the description of the present invention belongs to the well-known technology of those skilled in the art.

The present invention is not limited to the content described in the claims and the above-mentioned embodiments, as long as any invention created according to the conception of the present invention shall belong to the protection scope of the present invention.

Claims (8)

1. robot hydraulic power system, it is characterized in that, comprise control unit ECU (5), the starting electrical machinery of Xiang Lianing (1) successively, motor (2) and variable displacement pump (6), the filler opening of described variable displacement pump links to each other with fuel tank (17) by coarse filtration (19), the oil outlet place of described variable displacement pump is provided with first pressure transducer (10), the oil outlet place series connection of described variable displacement pump is provided with flow transducer (13), fuel feeding end parallel connection in load is provided with second pressure transducer (14), described first pressure transducer, second pressure transducer and flow transducer are transferred to control unit ECU with the signal that collects, described control unit ECU monitors the working state of power system, simultaneously engine speed and variable displacement pump discharge capacity are carried out closed loop control, realize the accurate supply of flow.

2. robot according to claim 1 hydraulic power system is characterized in that, the oil outlet of described variable displacement pump is in parallel with accumulator (12) by one way stop peturn valve (11).

3. robot according to claim 2 hydraulic power system is characterized in that, the oil outlet of described variable displacement pump is also in parallel with relief valve (18) by described one way stop peturn valve (11).

4. robot according to claim 1 hydraulic power system is characterized in that, the oil outlet place of described variable displacement pump is provided with automatically controlled unloading valve (9).

5. robot according to claim 1 hydraulic power system is characterized in that, described variable displacement pump is a plunger type variable capacity pump.

6. robot according to claim 5 hydraulic power system, it is characterized in that, described control unit ECU (5) gathers the signal of the swashplate angle sensor (8) of variable displacement pump, realizes closed loop control to the variable displacement pump discharge capacity by the control to variable displacement pump Proportional valve (7).

7. robot according to claim 1 hydraulic power system, it is characterized in that, described control unit ECU (5) gathers the signal of the speed probe (4) of motor, realizes closed loop control to engine speed by the control to electronic throttle of engine (3).

8. robot according to claim 1 hydraulic power system is characterized in that, described control unit ECU is by other system communication of can bus and robot.

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