阅读说明：本技术 一种带表面微织构的变接触面积结构自供能滑觉传感器 (Self-powered sliding sensor with surface microtexture and contact area-variable structure ) 是由 程广贵 顾伟光 丁建宁 张忠强 于 2020-05-27 设计创作，主要内容包括：本发明属于传感器领域,具体涉及一种基于摩擦发电技术的带表面微织构的变接触面积结构自供能滑觉传感器装置。所述自供能滑觉传感器包括底座,位于所述底座上的多级表面支承结构,所述多级表面支承结构与所述底座之间通过弹性柱体联接,所述弹性柱体上设置有弹簧,所述多级表面支承结构上表面设有摩擦发电装置,底座两侧表面上也设有摩擦发电装置；能够将待测物体的滑动转化为电能,并以电信号形式输出。(The invention belongs to the field of sensors, and particularly relates to a self-powered sliding sensor device with a surface microtexture and a variable contact area structure based on a friction power generation technology. The self-powered sliding sensor comprises a base and a multi-stage surface supporting structure positioned on the base, wherein the multi-stage surface supporting structure is connected with the base through an elastic cylinder, a spring is arranged on the elastic cylinder, a friction power generation device is arranged on the upper surface of the multi-stage surface supporting structure, and friction power generation devices are also arranged on the surfaces of the two sides of the base; the sliding of the object to be measured can be converted into electric energy and output in the form of electric signals.)

1. The self-powered sliding sensor with the surface microtexture and the variable contact area structure is used for detecting the sliding of an object to be detected and is characterized by comprising a base and a multi-stage surface supporting structure positioned on the base, wherein the multi-stage surface supporting structure is connected with the base through an elastic cylinder, the elastic cylinder is provided with a spring, the upper surface of the multi-stage surface supporting structure is provided with a friction power generation device, and the surfaces of the two sides of the base are also provided with the friction power generation device; the self-powered sliding sensor can convert the sliding of an object to be detected into electric energy and output the electric energy in the form of an electric signal.

2. The self-powered sliding sensor with the surface microtextured variable contact area structure as claimed in claim 1, wherein the multi-stage surface supporting structures are symmetrically distributed along the central line of the base in a step shape, and the heights of the multi-stage surface supporting structures decrease in sequence, and at least 3 surface supporting structures are included to form the 3-stage surface supporting structures with the two side surfaces of the base.

3. The self-powered sliding sensor with the surface microtextured variable contact area structure of claim 1, wherein the friction generating device comprises an electrode layer and a friction layer arranged on the upper surface of the multi-stage surface supporting structure and the two side surfaces of the base; if the material of the object to be detected is a metal conductive material with weaker electron binding capacity, the electrode layer is made of the metal conductive material with weaker electron binding capacity, and the friction layer is made of a non-metal insulating material with stronger electron binding capacity; if the object material to be detected is a non-metal insulating material with strong electron binding capacity, the electrode layer is simultaneously used as a friction layer, a metal conductive material with weak electron binding capacity is selected, and a shielding layer is arranged on the bottom surface of the multistage surface supporting structure.

4. The self-powered sliding sensor with the surface microtextured variable contact area structure as claimed in claim 3, wherein the metal conductive material is Cu, Al or an alloy thereof, and the non-metal insulating material is PTFE or PVDF material.

5. The self-powered slip sensor with the surface microtextured variable contact area structure of claim 1, further comprising electrical signal measuring devices, wherein the electrical signal measuring devices are respectively connected with the electrode layer and a reference ground, and the electrical signal measuring devices obtain a potential difference signal between the electrode layer and the reference ground; the electric signal measuring device is integrated inside the base.

6. The self-powered sliding sensor with the surface microtexture variable contact area structure as claimed in claim 1, wherein when an object to be measured slides, friction occurs between the object to be measured and the friction layer, the contact area changes, the electrode layer can generate electronic exchange with a reference ground through a grounding wire so as to balance potential change on the electrode, when sliding starts, namely static friction is changed into dynamic friction between the object to be measured and the friction layer, tangential deformation of the elastic cylinder arranged under the multistage surface supporting structure is changed rapidly and repeatedly, so that potential difference between the electrode layer and the reference ground fluctuates, and high-frequency components are generated in an output electric signal of the sliding sensor; the method comprises the steps of collecting and processing signals output by a self-powered sliding sensor by adopting a discrete wavelet transform technology, extracting high-frequency components in electric signals, setting a detail coefficient critical value obtained after discrete wavelet transform when sliding occurs as a threshold value after filtering clutter interference, and judging whether an object initially slides or not by comparing the relationship between the detail coefficient and the threshold value in practical application.

7. The self-powered sliding sensor with the surface microtexture variable contact area structure as claimed in claim 1, wherein when the self-powered sliding sensor is applied to a clamping device, if an object to be measured stops sliding, a certain control period can be set according to the requirement on the sensitivity of the clamping device, and the higher the sensitivity requirement is, the shorter the control period is; when the sign of sliding occurs, the control system detects the signal output by the sliding sensor, rapidly increases the normal force for clamping the measured object and continues to detect the output signal of the sliding sensor until the detail coefficient is lower than the threshold value.

8. The self-powered sliding sensor with the surface microtexture and the variable contact area structure as claimed in claim 1, wherein when the self-powered sliding sensor with the multi-level surface structure is applied to the clamping device, when the applied normal force is larger than a certain value, the upper level step sinks to the same surface as the lower level step, the step sinks to increase the contact area of the sensor and the object to be tested, the potential difference generated between the electrode layer and the reference ground when the object to be tested slides is increased, the range of the clamping normal force interval can be identified according to the change amplitude of the voltage signal in unit time, and the increased clamping force in the control period is adjusted according to the range of the clamping normal force; the normal force added in the control period in different clamping force intervals is different, and when the working area is positioned on the surface of the lower level of the multistage surface structure, the size and the interval range of the clamping force are larger, the normal force added each time is larger, and therefore the working range of the slip sensor can be effectively improved.

9. The self-powered sliding sensor with the surface microtexture variable contact area structure as claimed in claim 1, wherein the fingerprint of a finger is copied on the surface of the friction layer of the sensor by a transfer printing method, and the touch sensitivity of the sensor is further improved by the surface microtexture; when a slip occurs in a certain direction, the presence of the microtexture can increase the electrical output value in the direction, and thus, the effect of enhancing the output is achieved.

Technical Field

The invention belongs to the field of sensors, and particularly relates to a self-powered sliding sensor device with a variable contact area structure based on a friction power generation technology.

Background

The slip sensor is a sensor for detecting the degree of slip between the robot and a gripping object, and has wide application prospects in the fields of agricultural picking robots, rehabilitation medicine, life detection, emergency rescue and disaster relief and the like; if the flexible clamping device is applied to the field of automatic picking of fruits and vegetables, the clamping force can be flexibly adjusted according to the sizes of the fruits and vegetables, and flexible nondestructive picking is realized; the device is applied to the fields of bionic hands, artificial limbs and the like, and can realize the soft grabbing function of fragile objects by further connecting with electromyographic signals; the currently commonly used slide sensors comprise PVDF piezoelectric film sensors, piezoelectric ceramic bimorph sensors, array type touch sensors, piezoresistor sensors and the like; the PVDF piezoelectric film sensor has low sensitivity to force, and charges generated by PVDF are easily subjected to electromagnetic interference in the transmission process; the piezoelectric ceramic bimorph sensor is sensitive to noise interference, and when the sliding speed is low, a sliding signal is not easy to detect; the array type touch sensor has high requirements on resolution and scanning rate in the sensing process, and has a complex structure and more lines; when the piezoresistor sensor is used as a slip sensor, the change of positive pressure and the slip signal are not easy to distinguish; more importantly, the sensors all need external energy supply and have high manufacturing cost; the invention provides a self-powered sliding sensor with a variable contact area structure based on the working principle of a friction nano generator, which can realize the sliding detection of a detected object and the judgment of a range interval of a normal force.

Disclosure of Invention

The invention aims to solve the technical problem of providing an electrostatic self-powered sliding sense sensor with a multi-stage surface structure, which can be used for detecting sliding sense, does not need to provide extra energy, can convert the sliding of an object to be detected into electric energy and output the electric energy in the form of an electric signal, and has the characteristics of high precision, easiness in processing, simplicity and convenience in operation and the like.

The technical scheme adopted by the invention for solving the technical problems is as follows: the self-powered sliding sensor with the variable contact area structure is used for detecting the sliding of an object to be detected; the self-powered sliding sensor comprises a base and a multi-stage surface supporting structure positioned on the base, wherein the multi-stage surface supporting structure is connected with the base through an elastic cylinder, a spring is arranged on the elastic cylinder, a friction power generation device is arranged on the upper surface of the multi-stage surface supporting structure, and friction power generation devices are also arranged on the surfaces of the two sides of the base; the sliding of the object to be measured can be converted into electric energy and output in the form of electric signals.

The multistage surface supporting structures are symmetrically distributed along the central line of the base in a step shape on two sides, the heights of the multistage surface supporting structures sequentially decrease, the multistage surface supporting structures at least comprise 3 surface supporting structures, and the surface supporting structures and the surfaces on two sides of the base form 3 stages of surface supporting structures.

Further, the friction generating device includes an electrode layer and a friction layer provided on an upper surface of the multi-stage surface support structure and both side surfaces of the base. If the material of the object to be detected is a metal conductive material with weaker electron-binding capacity, the electrode layer is made of a metal conductive material with weaker electron-binding capacity, such as Cu, Al or an alloy thereof, and the friction layer is made of a non-metal insulating material with stronger electron-binding capacity, such as PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride) and the like; if the object material to be detected is a non-metal insulating material with strong electron-binding capacity, the electrode layer is simultaneously used as a friction layer, and a metal conductive material with weak electron-binding capacity, such as Cu, Al or an alloy thereof, is selected. The surface of the friction layer is provided with the fingerprint surface microtexture which is used for enhancing the electrical output performance of the friction power generation device and further improving the sensitivity of the self-powered sliding sensor. The bottom surface of the multi-stage surface supporting structure is provided with a shielding layer.

Furthermore, when the object to be measured slides, friction is generated between the object to be measured and the friction layer, the contact area changes, the electrode layer and the reference ground are subjected to electronic exchange through the grounding wire so as to balance potential change on the electrode, when sliding starts, namely the object to be measured and the friction layer are rotated from static friction to dynamic friction, the tangential deformation of the elastic cylinder arranged under the multi-stage surface supporting structure is rapidly and repeatedly changed, so that the potential difference between the electrode layer and the reference ground fluctuates, and high-frequency components are generated in the output electric signals of the sliding sensor.

Further, the slip sensation sensor further comprises electric signal measuring devices, the electric signal measuring devices are respectively connected with the electrode layer and the reference ground, and the electric signal measuring devices obtain potential difference signals between the electrode layer and the reference ground.

Further, the electrical signal measuring device is integrated inside the base.

Furthermore, a discrete wavelet transform technology is adopted to collect and process signals output by the self-powered sliding sensor, high-frequency components in the electric signals are extracted, after clutter interference is filtered, a detail coefficient critical value obtained after discrete wavelet transform when sliding occurs is set as a threshold value, and in practical application, whether the object initially slides is judged by comparing the relationship between the detail coefficient and the threshold value.

Further, when the invention is applied to the clamping device, if the object to be measured stops slipping, a certain control period can be set according to the requirement on the sensitivity of the clamping device, and the higher the sensitivity requirement is, the shorter the setting of the control period is. When the sign of sliding occurs, the control system detects the signal output by the sliding sensor, rapidly increases the normal force for clamping the measured object and continues to detect the output signal of the sliding sensor until the detail coefficient is lower than the threshold value.

Further, the present invention adopts a multi-step surface structure, which is applied to a clamping device, when a normal force applied is greater than a certain value, an upper step is sunk to the same surface as a lower step. The contact area of the sensor and the measured object is increased due to the stepped sinking, the potential difference generated between the electrode layer and the reference ground is increased when the measured object slides, the range of the clamping normal force can be identified according to the change amplitude of the voltage signal in unit time, and the increased clamping force in the control period is adjusted according to the range of the clamping normal force.

Further, the normal force added in the control period in different clamping force intervals is different, and when the working area is on the surface of the lower level of the multi-level surface structure, the size and the interval range of the clamping force are larger, and the normal force added in each time is also larger. Therefore, the working range of the slip sensor can be effectively enlarged.

The invention has the beneficial effects that: the invention can convert the sliding of the detected object on the sensor surface into electric signals according to the mechanical energy-electric energy conversion characteristic, the data is output by the signal processing and output device in the device, the high-frequency component in the signals is extracted by adopting a discrete wavelet transform method, and whether the detected object slides or not can be judged by comparing the relation between the detail coefficient and the set threshold value. Compared with other slip sensation detection devices, the electrostatic self-powered slip sensation sensor with the multi-stage surface structure has the advantages of simple structure, wide application range, high measurement precision, high output voltage, large working range, no need of additionally providing a power supply and the like.

Drawings

Fig. 1(a) - (c) are state diagrams of a self-powered sliding sensor with a variable contact area structure under different load intervals, wherein fig. 1(a) is a schematic structural diagram of the self-powered sliding sensor with the variable contact area structure under an unloaded state, and fig. 1(b) and (c) are schematic diagrams of multi-stage surface depression when the self-powered sliding sensor with the variable contact area structure is subjected to a certain load;

FIG. 2 is a fingerprint microtexture topography of the friction layer surface;

FIGS. 3(a) - (b) are schematic diagrams of the operation of the friction power generating device of the present invention;

fig. 4 is a schematic diagram of a rectifier circuit of the present invention.

Reference numbers in the figures: 1. friction layer 2, electrode layer 3, multi-stage surface supporting structure 4, elastic cylinder 5, spring 6 and base.

Detailed description of the invention

The following detailed description of specific embodiments of the present invention is provided in connection with the accompanying drawings.

Referring to fig. 1(a), the invention provides a self-powered sliding sensor with a variable contact area structure, which is used for detecting the sliding of an object to be detected, and comprises a base 6 and a multi-stage surface supporting structure 3, wherein the multi-stage surface supporting structure 3 is symmetrically distributed along the central line of the base in a step shape towards two sides, and forms a 3-stage surface supporting structure with the surface of the base 6. The multistage surface supporting structure 3 is connected with the base 6 by using an elastic cylinder 4, the elastic cylinder 4 is provided with a spring 5, the upper surface of the multistage surface supporting structure 3 and two sides of the surface of the base 6 are provided with a friction layer 1 and an electrode layer 2, wherein the electrode layer 2 is made of a metal conductive material with weak electron binding capacity, such as Cu, Al or an alloy thereof; the material of the friction layer 1 is selected according to the electrical property of the object to be detected, if the material of the object to be detected is a metal conductive material with weak electron binding capacity, the friction layer 1 is made of a non-metal insulating material with strong electron binding capacity, such as PTFE, PVDF and other materials; if the object material to be measured is a non-metal insulating material with strong electron binding capability, the electrode layer 2 is used as a friction layer at the same time. The surface of the friction layer 1 is provided with a surface microtexture, and the principle is that a finger fingerprint is copied on the surface of the friction layer by a transfer printing method to form a microstructure, so that the electrical output performance of the friction power generation device is enhanced, and the sensitivity of the self-powered sliding sensor is improved. The bottom surface of the multi-stage surface support structure is provided with a shielding layer (not shown).

Referring to fig. 3(a) - (b), when the measured object is loaded, the surface of the slide sensor is completely contacted with the surface of the measured object, and the two opposite surfaces generate equal amounts of heterogeneous charges due to the electric effect of the contact. When the object to be measured is stressed to generate displacement, the contact area between the two surfaces which slide relatively changes, the charges generated by the friction layer cannot be completely neutralized, and charge exchange can be generated between the electrode layer 2 and the reference ground according to the electrostatic induction principle so as to balance potential change. Therefore, when the friction layer of the present invention starts to displace, i.e. the friction layer changes from static friction to dynamic friction, the deformation amount of the elastic cylinder 4 under the multi-stage surface supporting structure 3 in the tangential direction changes rapidly and repeatedly, so that the contact area between the friction layer 1 and the object to be measured changes at a high frequency, and therefore the potential difference between the reference ground and the electrode layer 2 fluctuates rapidly and repeatedly, and high-frequency components appear on the output signal. Therefore, the high-frequency component in the output signal is extracted by adopting a discrete wavelet transformation method, and whether the object to be measured slides or not can be judged and feedback is generated according to the occurrence or non-occurrence of the high-frequency component.

In the embodiment, when the object to be measured slips, the corresponding slip signal is subjected to short-time fourier transform processing, and then a high-frequency component appears in the slip signal, so that the slip can be detected by detecting the high-frequency component. In the invention, a discrete wavelet transformation method is adopted to detect the instantaneous high-frequency component of a signal, the signal outputs a detail coefficient (from a high-pass filter) and an approximate coefficient (from a low-pass filter) after discrete wavelet transformation, and the detail coefficient is used for representing a slip sensation signal and carrying out grabbing force adjustment control on an end effector. Firstly, after clutter influence is filtered, a critical value of a detail coefficient when sliding occurs is set as a threshold value, in a set control period, if the detail coefficient of discrete wavelet transform of a signal is larger than the threshold value, sliding is considered to occur, if sliding of a measured object is to be stopped, normal clamping force on the measured object is increased, and output signals are continuously detected until the detail coefficient is smaller than the threshold value, namely, the measured object cannot slide further.

In this embodiment, the sliding sensor support surface has a multi-stage structure, and when the sliding sensor support surface is applied to the clamping device, when the normal force is greater than a certain value, the first stage will sink to the same plane as the second stage, and so on, and the elastic coefficient of the spring 5 is changed to adjust the working range of each stage. The contact area of the slip sensor and the measured object is increased due to the step subsidence, the change amplitude of the potential difference between the electrode layer and the reference ground is increased, and the range of the interval where the normal force is located can be judged according to the change of the change amplitude of the output voltage in unit time. The normal force applied to the object to be measured is larger when the lower-level supporting surface detects the sliding, the interval range is larger, and the normal force increased every time in the corresponding control period is larger. Therefore, the structure can effectively improve the working range of the slip sensor.

In summary, the slip of the detected object can be recognized by combining the voltage output signal of the friction power generation device. Therefore, the grabbing force of the mechanical arm can be adjusted in real time, and the purpose of grabbing the object by using the minimum grabbing force is achieved. The invention has the advantages of simple structure, wide application range, high measurement precision, high output voltage, large working range, no need of additionally providing a power supply and the like, and can be applied to the fields of nondestructive picking of vegetables and fruits by the mechanical arm, soft grabbing of bionic hands and artificial limbs and the like.