Macro-micro composite platform vibration isolation system and control method thereof

Abstract

The present application relates to a kind of macro-micro composite platform vibration isolation system and its control method, the system includes the motion state detection module being arranged at the bottom of micro-motion platform, active actuator and position sensor being arranged in macro-motion platform, wherein, macro-motion platform is installed on passive vibration isolation pedestal, passive vibration isolation pedestal is provided with passive vibration isolation unit, passive vibration isolation unit includes parallel elastic element and damping element.The method includes: by applying adjustable excitation signal, the motion state of motion state detection module output is combined, and macro-micro composite platform motion equation is constructed;Then according to macro-micro composite platform motion equation, closed-loop active vibration isolation control law is constructed, the displacement of macro-motion platform is controlled, and vibration isolation effect is realized.Compared with prior art, the present application can effectively realize the isolation of high-frequency environmental disturbance and low-frequency environmental disturbance.

Description

Technical Field

[0001] This invention relates to the field of vibration isolation technology for motion platforms, and in particular to a macro-micro composite platform vibration isolation system and its control method. Background Technology

[0002] Macro-micro composite motion mechanism is a mechanism with high precision and wide range of motion capabilities. It consists of two levels of structures: macro motion and micro motion. The macro motion structure is responsible for the wide range of motion, while the micro motion structure is responsible for high-precision fine adjustment. It is currently widely used in surgical robots, precision machining and other fields, and can achieve high-precision, high-speed and high-reliability motion control.

[0003] In practical applications, due to the high accuracy of robot target positioning and the influence of on-site environmental factors such as ground and wind turbines, vibration excitation is usually introduced into the system. In order to achieve micron-level motion accuracy, vibration isolation elements are often added to improve the system robustness. However, active vibration isolation is easily constrained by various technologies and equipment. The first constraint is the controller. The frequency range of micro-vibration interference is mainly 0Hz to 200Hz. According to the Nyquist sampling theorem, theoretically, the sampling frequency of the controller needs to be more than twice the highest control frequency, and in engineering practice, it needs to be 5 to 10 times. Therefore, the controller needs to have sufficient signal acquisition bandwidth and system computing power to ensure vibration identification within a single sampling time. The second factor is the actuator and sensor. The actuator requirements include control output linearity, power, frequency range, size, mass, heat dissipation, and working duration. The sensor needs to have high low-frequency vibration sensitivity, long-term stable operation, and insensitivity to temperature radiation. Measuring micro-vibration interference places high demands on sensor performance. Since the magnitude of low-frequency vibration signals is small, in order to ensure a sufficiently high signal-to-noise ratio for the test signal, the noise in the low-frequency region must be much smaller than the test signal. The third factor is the control algorithm. Stable and effective control methods have always been a challenge and a key focus of active control.

[0004] It can be said that existing macro-micro composite platforms are unable to effectively and reliably isolate high-frequency and low-frequency environmental disturbances when dealing with vibration isolation problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a macro-micro composite platform vibration isolation system and its control method. By combining active vibration isolation of macro motion with passive vibration isolation in parallel, the system can isolate high-frequency and low-frequency environmental disturbances.

[0006] The objective of this invention can be achieved through the following technical solution: a macro-micro composite platform vibration isolation system, comprising a motion state detection module disposed at the bottom of the micro motion platform, an active actuator and a position sensor disposed on the macro motion platform, wherein the macro motion platform is mounted on a passive vibration isolation base, and a passive vibration isolation unit is disposed on the passive vibration isolation base, wherein the passive vibration isolation unit comprises a parallel elastic element and a damping element.

[0007] Furthermore, the micro-motion platform and the macro-motion platform are connected by a flexible connection.

[0008] Furthermore, the motion state detection module includes an accelerometer sensor and a multi-dimensional force sensor.

[0009] A vibration isolation control method for a macro-micro composite platform includes the following steps:

[0010] S1. Apply an adjustable excitation signal and combine it with the motion state output by the motion state detection module to construct the motion equation of the macro-micro composite platform;

[0011] S2. Based on the motion equation of the macro-micro composite platform, a closed-loop active vibration isolation control law is constructed to control the displacement of the macro motion platform and achieve vibration isolation effect.

[0012] Furthermore, the adjustable excitation signal applied in step S1 is specifically the low-frequency disturbance F(t) generated by the macro-micro composite platform during its motion.

[0013] Furthermore, the motion equations of the macro-micro composite platform in step S1 are specifically as follows:

[0014]

[0015] Where m is the mass of the micro-motion platform, k is the elastic element, b is the damping element, x is the absolute displacement of the macro-micro motion platform base, ζ is the controllable basic displacement of the active actuator, and x-ζ is the relative displacement of the macro-micro motion platform base.

[0016] Furthermore, the controllable basic displacement of the active actuator is specifically as follows:

[0017] ζ(t)=-W x (x(t))

[0018] That is, the controllable basic displacement ζ(t) of the active actuator is derived from the absolute displacement x(t).

[0019] Furthermore, step S2 specifically involves performing a Laplace transform on the motion equations of the macro-micro composite platform and constructing a closed-loop active vibration isolation control law accordingly.

[0020] Furthermore, the transfer function of the closed-loop active vibration isolation control law is specifically as follows:

[0021]

[0022] Among them, W x / F (s) is the transfer function of the absolute displacement x of the macro motion platform base and the disturbance force F.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] I. This invention utilizes a motion state detection module at the bottom of a micro-motion platform to detect the motion state of the coupled system; an active actuator and position sensor on a macro-motion platform for basic displacement control; and the macro-motion platform mounted on a passive vibration isolation base, which is equipped with parallel elastic and damping elements for passive vibration isolation. Thus, by combining active vibration isolation with passive vibration isolation, not only can active vibration isolation against high-frequency environmental disturbances be achieved, but also isolation against low-frequency environmental disturbances.

[0025] Second, this invention applies an adjustable excitation signal and constructs a closed-loop active vibration isolation control law based on the absolute displacement of the macro platform base and environmental disturbance forces. It is invariant to the disturbance excitation generated by the movement of the macro and micro motion platforms, and can actively adjust the excitation using the macro motion platform to compensate for the influence of environmental disturbances. Combined with position sensors, it realizes closed-loop vibration detection and control, ensuring effective active vibration isolation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0027] Figure 2 This is a schematic diagram of micro-motion vibration isolation;

[0028] Figure 3 This is a block diagram of a closed-loop active vibration isolation control system.

[0029] The markings in the diagram are as follows: 1. Micro-motion platform, 2. Macro-motion platform, 3. Passive vibration isolation base, 11. Accelerometer sensor, 12. Multi-dimensional force sensor. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] Example

[0032] like Figure 1As shown, a macro-micro composite platform vibration isolation system includes a motion state detection module disposed at the bottom of the micro motion platform 1, an active actuator and a position sensor disposed on the macro motion platform 2, the macro motion platform 2 is mounted on a passive vibration isolation base 3, and a passive vibration isolation unit is disposed on the passive vibration isolation base 3, the passive vibration isolation unit 3 including a parallel elastic element and a damping element.

[0033] The micro-motion platform 1 and the macro-motion platform 2 are connected by a flexible connection, and the motion state detection module includes an accelerometer sensor 11 and a multi-dimensional force sensor 12.

[0034] Applying the above system to practice, a vibration isolation control method for a macro-micro composite platform includes the following steps:

[0035] S1. Apply an adjustable excitation signal and combine it with the motion state output by the motion state detection module to construct the motion equation of the macro-micro composite platform;

[0036] S2. Based on the motion equation of the macro-micro composite platform, a closed-loop active vibration isolation control law is constructed to control the displacement of the macro motion platform and achieve vibration isolation effect.

[0037] This embodiment applies the above-mentioned technical solution, and through modeling passive vibration isolation and closed-loop active vibration isolation, compares and analyzes to select the optimal solution to achieve micron-level motion accuracy. First, multimodal environmental and body motion excitation analysis is performed, and the rigid connection between the robot base and the ground interaction surface, as well as the macro-micro system connection surface, is changed from a rigid connection to a flexible connection. Then, passive vibration isolation is achieved by introducing additional mass elements, elastic elements, and damping elements. In addition, based on passive vibration isolation, an active adjustable excitation is connected in parallel to compensate for the influence of environmental disturbances. Combined with position sensors, vibration closed-loop detection and control are realized to achieve active vibration isolation.

[0038] Specifically, a protection scheme based on the motion state signal of the isolated object is adopted for micro-motion vibration isolation. Taking micro-motion vibration isolation as an example (e.g.) Figure 2 As shown in the diagram, the excitation signal is the low-frequency disturbance F(t) generated by the macro-micro coupled system during motion. The motion state of the coupled system is detected by a fixed accelerometer sensor and a multi-dimensional force sensor at the bottom m of the micro-motion platform. An active actuator is set at the end of the macro-motion platform to control the basic displacement ζ(t) (the macro-motion platform is equipped with a position sensor for displacement detection). The passive module consists of an elastic element k and a damping element b connected in parallel.

[0039] For a macro-micro motion platform with overall mass m, its motion can be described by a differential equation:

[0040]

[0041] Where x(t) and x-ζ are the absolute and relative displacements of the macro-micro motion platform base. From the system dynamic parameters, it can be seen that the controllable basic displacement ζ(t) of the active actuator can be constructed from the absolute displacement x(t):

[0042] ζ(t)=-W x (x(t))(2)

[0043] Substituting into equation (1) and performing a Laplace transform, we get:

[0044] [ms 2 +(bs+k)(1+W x (s))]x=F(3)

[0045] Construct according to equation (3) as follows Figure 3 The control block diagram shown indicates that the transfer function between the absolute displacement x of the macro-motion platform base and the disturbance force F can be expressed as:

[0046]

[0047] Compared to purely passive vibration isolation, the effective coefficient of closed-loop active vibration isolation is:

[0048]

[0049] Therefore, based on equation (4), an active vibration isolation system with invariance to the disturbance excitation generated by the motion of the macro-micro motion platform can be constructed. However, for the vibration isolation of the micro-system's motion base, factors such as the spatial vibration excitation decomposition caused by its attitude change and the projection of gravity onto the base's normal direction need to be considered, and the dynamic equations need to be reconstructed. In practical applications, based on the completion of the prototype construction of the motion control system of the brain electrode implantation surgical robot system, a three-dimensional laser interferometer can be used to measure the amplitude of the guide needle's end motion in various directions in space, thereby further calculating and analyzing the system's vibration isolation efficiency.

[0050] In summary, this technical solution, within a macro-micro composite motion system, utilizes the macro motion platform to actively adjust excitation, thereby compensating for the impact of environmental disturbances. Combined with position sensors, it achieves closed-loop vibration detection and control, thus realizing active vibration isolation. This effectively reduces environmental interference during the precise operation of the micro motion platform in the macro-micro composite motion mechanism. Based on the absolute displacement of the macro platform base and the environmental dynamics, this technical solution constructs an active vibration isolation dynamic equation that remains invariant to the disturbance excitation generated by the macro-micro motion platform, effectively isolating high-frequency environmental disturbances. Furthermore, by incorporating a passive vibration isolation unit in parallel with the macro-motion active vibration isolation, this technical solution effectively isolates low-frequency environmental disturbances.

Claims

1. A macro-micro hybrid platform vibration isolation control method, applied to a macro-micro hybrid platform vibration isolation system, characterized in that, The macro-micro compound platform vibration isolation system comprises a motion state detection module arranged at the bottom of a micro-motion platform (1), an active actuator and a position sensor arranged on a macro-motion platform (2), the macro-motion platform (2) is installed on a passive vibration isolation base (3), the passive vibration isolation base (3) is provided with a passive vibration isolation unit, and the passive vibration isolation unit comprises parallel elastic elements and damping elements; The control method of the macro-micro compound platform vibration isolation system comprises the following steps: S1, an adjustable excitation signal is applied, and a motion state output by the motion state detection module is combined to construct a macro-micro compound platform motion equation; S2, according to the macro-micro compound platform motion equation, a closed-loop active vibration isolation control law is constructed to control the displacement of the macro-motion platform, and the vibration isolation effect is realized.

2. The macro-micro hybrid platform vibration isolation control method of claim 1, wherein, The micro-motion platform (1) and the macro-motion platform (2) are connected in a flexible manner.

3. The macro-micro hybrid platform vibration isolation control method of claim 1, wherein The motion state detection module comprises an accelerometer sensor (11) and a multi-dimensional force sensor (12).

4. The macro-micro hybrid platform vibration isolation control method of claim 1, wherein The adjustable excitation signal applied in the step S1 is specifically a low-frequency disturbance generated by the macro-micro composite platform during movement .

5. The macro-micro hybrid platform vibration isolation control method of claim 4, wherein, The macro-micro compound platform motion equation in the step S1 is specifically as follows: wherein, is the micro-motion platform mass, k is the elastic element, b is the damping element, is the absolute displacement of the macro-micro-motion platform base, is the controllable base displacement of the active actuator, is the relative displacement of the macro-micro-motion platform base.

6. The macro-micro hybrid platform vibration isolation control method of claim 5, wherein, The controllable basic displacement of the active actuator is specifically as follows: The controllable basic displacement of the active actuator from the absolute displacement is constructed.

7. The macro-micro hybrid platform vibration isolation control method of claim 6, wherein, The step S2 is specifically by performing Laplace transformation on the macro-micro compound platform motion equation, and accordingly constructing a closed-loop active vibration isolation control law.

8. The macro-micro hybrid platform vibration isolation control method of claim 7, wherein, The transfer function of the closed-loop active vibration isolation control law is specifically as follows: wherein, absolute displacement of the macro-motion platform base transfer function of the disturbance force transfer function of the disturbance force

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