CN107843390B - Flexible force sensor curvature influence testing device and method - Google Patents
Flexible force sensor curvature influence testing device and method Download PDFInfo
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- CN107843390B CN107843390B CN201710841370.1A CN201710841370A CN107843390B CN 107843390 B CN107843390 B CN 107843390B CN 201710841370 A CN201710841370 A CN 201710841370A CN 107843390 B CN107843390 B CN 107843390B
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- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
Abstract
The invention relates to a device and a method for testing influence of curvature of a flexible force sensor. The device comprises a support and a flexible force sensor to be measured, wherein the support is supported with a horizontal shaft, the horizontal shaft is circumferentially sleeved with a curved surface cylinder and a circumferential loading arm, and the circumferential loading arm is fixedly connected with the curved surface cylinder; the curved cylinder is provided with a curved cylinder main body; the bracket is also provided with a longitudinal through hole, a radial loading rod is arranged in the longitudinal through hole, the upper end of the radial loading rod is a load bearing end for bearing external radial load, and the lower end of the radial loading rod is provided with an arc surface; the flexible force sensor is positioned between the lower end of the radial loading rod and the curved surface cylinder main body; and the signal output end of the flexible force sensor is connected with external data acquisition equipment. The invention can test the output data performance of the flexible force sensor under different curvatures and under different external radial loads or different circumferential shear loads, and can obtain the specific influence degree.
Description
Technical Field
The invention relates to a device and a method for testing influence of curvature of a flexible force sensor, and belongs to the technical field of sensor calibration.
Background
To the applicant's knowledge, the measurement of the force between the contact interfaces is usually carried out indirectly by means of a measurement of the pressure, which is usually expressed as the force applied per unit area with respect to the surface of the object, so that a good control of the contact surface is of particular importance in order to achieve an effective measurement of the contact force, and this is even more important in view of the complexity of the contact of the person with the outside. With the development of sensor technology and the increase of the requirements of related applications and the explosive growth of applications in the field of human motion detection, on one hand, the performance of sensors represented by flexible force sensors is continuously enhanced, and on the other hand, the requirements on the sensitivity of the sensors are higher and higher.
For haptic feedback needs, the measurement of contact force information is mostly implemented using flexible force sensors (Stassi, et., 2014) that provide an electrical signal output (voltage or current) proportional to the measured pressure; key specifications required for flexible force sensors in terms of sensor performance include linearity, hysteresis, temperature sensitivity, sensing size and pressure range, etc. (Almassri, et al, 2015; Stassi, et al, 2014); flexible force sensors can be classified into capacitive sensors, resistive sensors, piezoelectric sensors, and piezoresistive sensors (Majumder, et al, 2017) according to the sensing material.
The capacitive sensor consists of a suspended structure plate capacitor, and under the action of external force, the distance between the plates or electrode areas is shortened, so that the capacitance change between the two electrodes is generated. The capacitive touch pressure sensing technology is one of the most sensitive technologies for detecting small deflection change, and has the characteristics of high spatial resolution, good frequency response, low power consumption, wide dynamic range and the like. The commercialized human motion recognition system based on the sensor comprises an EMED sole pressure system and a PEDAR insole system of Novel corporation of Germany.
Resistive sensors are typically constructed of a conductive polymer force sensitive resistor, which changes when pressure is applied, decreasing the resistance between the two electrodes and increasing the current. Commercial human motion recognition systems based on the sensor include the mathscan pressure system and the F-scan insole system of Tekscan corporation of America.
Piezoelectric transducers are transducers that convert an applied stress or force into a voltage and are considered to be smart materials due to the properties of their piezoelectric materials as sensors and actuators (Almassri, et al, 2015). The piezoelectric sensor has the characteristics of mechanical flexibility, high piezoelectric coefficient, fixed size, light weight, stable work and the like. When force is applied, the piezoelectric material also has high sensitivity when high voltage is output, and the sensitivity can reach 130 pC/N. Piezoelectric sensors are passive sensors with high reliability and are suitable for a variety of applications. However, since the voltage output is reduced with the passage of time and the internal resistance is too large, the advantage of measuring static force is not obvious, and the method is only suitable for detecting dynamic force; the main piezoelectric materials are quartz ceramics (PZT), polyvinylidene fluoride (PVDF), etc., where quartz ceramics are mainly used for dynamic tactile sensing and polyvinylidene fluoride is more suitable for tactile pressure applications. Since the piezoelectric device has a high impedance and is susceptible to excessive electrical interference, resulting in an unacceptable signal-to-noise ratio, an ultra-thin input impedance is essential in designing the circuit of the piezoelectric sensor. Commercial human motion recognition systems based on this sensor include the american Measurement Specialties system and the american pizotronics PCB system.
The piezoresistive sensor is made of a piezoelectric material based on a semiconductor material, the piezoelectric material deforms under the influence of stress, the resistivity changes along with the deformation, and generally, the resistivity of the sensor is high when no external force acts on the sensor, and the resistivity of the sensor is reduced when the external force acts on the sensor. The piezoresistive sensor has the advantages of low cost, high sensitivity, relatively simple structure, low long-term stability, low noise, high accuracy, high reliability, mature technology and the like, but can only measure the pressure of one fixed point. They can be customized in a variety of shapes and sizes and can be used in many applications, particularly for detecting contact forces between two surfaces of an object. Flexi-Force sensors from Tekscan, USA, and Parotec sensors from Paromerd, Germany are typical.
These flexible force sensors are capable of sensing touch and adapting to different shapes, and in addition to the high integration required to simulate human skin, their main drawback is that the hysteretic sensing response under special conditions affects the repeatability of the measurement, so that the characteristics of these sensors are further studied for high precision measurement applications (Stassi, et al, 2014; Wong, 2012); furthermore, deficiencies in measurement can also be compensated for by effective signal extraction (Aroca, et al, 2013).
At present, the development trend of human motion information acquisition technology indicates that the real-time and on-site measurement of daily life parameters must adapt to the rapidly changing and scientifically complex living environment (Razak, et al, 2012). In order to realize uninterrupted acting force information measurement of people contacting with the outside and faithfully reflect daily human body activities in real life, the flexible force sensor which can realize movability, no attachment sense and contact surface measurement is adopted to be an effective measure in fully integrating the target environment.
In the early 90 s of the last century, Zhu et al developed a system for measuring plantar pressure distribution in shoes using 7 force sensitive resistance sensors (FSRs) to distinguish pressure characteristics between unsynchronized states (Zhu, et al, 1991). Subsequently, similar studies began to increase. In 2011, Feng and the like design a human body recognition system adopting dynamic plantar pressure based on a Flexi-Force flexible Force sensor, and the system compares the pressure information of key points at different positions and uses a Support Vector Machine (SVM) classification algorithm to perform gait recognition, so that the system can achieve the recognition accuracy of 96% (Feng, et al, 2011). Salpavaara et al, chose javelin sports to design a capacitive sensor-based system for monitoring the timing of the lower limbs of a throwing athlete (Salpavaara, et al, 2009). These studies have confirmed that the flexible force sensor can be well adapted to real-time acquisition of plantar pressure information, and can measure contact force information of the foot and the ground to obtain key information such as gait.
As another source of information on human contact with the outside, researchers have recently come to pay attention to the real-time acquisition of information on hand contact force. Rogers et al developed a low cost system that uses a compatible MRI force-sensitive resistor (FSR) to evaluate performance during the task of finger sequencing, and also provides information on finger coordination, including the time interval between sequences, the interval between taps, and the tap duration (Rogers, et al, 2010). Komi et al devised a golf glove system based on a Flexi-Force flexible Force sensor to measure grip characteristics in a golf swing (Komi, et al, 2007). Aroca et al, integrated Flexi-Force flexible Force sensors, etc. designed a wearable picked fruit rating system for analyzing and measuring attributes of fruit via a glove-type system (Aroca, et al, 2013).
All the above studies are wireless system applications, aiming at avoiding the obstruction of the device to the human body movement as much as possible, and the research uses the commercialized flexible force sensor.
In order to measure the interface pressure between the contacting object and the skin, the sensor should, in addition to being small, thin, flexible and sensitive to low pressures, also take into account the influence of the curvature of the skin surface (Ferguson-Pell, et al, 2000). For example, in a hand-grasping function test, on one hand, the sensor cannot influence the characteristics of an operation object and the action of an operator, so the sensor must be effectively designed and integrated to reflect the real exertion condition; on the other hand, a force sensor used in an apparatus typified by a grip dynamometer can measure only a force in one direction, has poor spatial resolution, and is also affected by sensor rigidity, and it is difficult to apply a plurality of sensors to a surface clamped by a curved surface, and therefore a flexible force sensor becomes an optimum means for contact force measurement under curved surface contact conditions (Komi, et al, 2007).
In a study of Ferguson-Pell et al using Flexi-Force sensors for small Force measurements, it was found that the radius of curvature of the surface increases from 8.0mm to 51.7mm, the pre-load on the sensor decreases with increasing radius, and the sensitivity of the sensor decreases significantly below a radius of 32.5mm (Ferguson-Pell, et al, 2000). Komi et al selected four different surfaces (plane and curved surface with diameter of 30, 25 and 20 mm) and tested 0 to full scale for Tekscan 9811, Flexi-Force and QTC sensors, and the zero load output by the sensors is loaded externally, which shows that the pretightening Force is lower than 1.5N, and the results show that the curvature change has little influence on the Force measurement of Tekscan 9811 (-1.0% -5.2%) and Flexi-Force (0.95% -2.9%), but has larger influence on the measurement of QTC sensors (Komi, et al, 2007). The existing researches research researches the curvature change response characteristics of the sensor, and the defects exist under the influence of experimental conditions, the Ferguson-Pell experiment uses ABS series water pipes sold in the market, the curve change adjustment has no linear characteristic, and the experiment loading is small; while Komi et al only selected 3 curvature conditions in the experiment, the study of the curvature change response characteristics of the sensor requires special experimental conditions and further experiments.
Through search, the device comprises a positioning transmission component and a control component electrically connected with the positioning transmission component, wherein the positioning transmission component comprises a calibrated working platform and a pressure head testing component, and the pressure head testing component is connected with a force measuring sensor through a Z-direction linear stepping motor telescopic head.
The device comprises a three-coordinate guide rail robot, a three-dimensional force loading mechanism, an array platform and a control part electrically connected with the array platform, wherein the three-dimensional force loading mechanism is arranged on the three-dimensional guide rail robot; the three-coordinate guide rail robot comprises an X-axis guide rail, a Y-axis guide rail and a Z-axis guide rail, wherein grating rulers with position detection functions are installed on the X-axis guide rail, the Y-axis guide rail and the Z-axis guide rail. The three-dimensional force loading mechanism is installed at the lower end of the Z-axis guide rail through a parallel mechanism installing flange and comprises a parallel mechanism and a three-dimensional force detection part, and the three-dimensional force detection part is installed at the operation tail end of the parallel mechanism.
However, the above technical solutions cannot calibrate the influence of curvature change on the flexible force sensor, and it is necessary to develop a device capable of meeting the requirement.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the device and the method for testing the curvature influence of the flexible force sensor can test the influence caused by curvature change.
The technical scheme for solving the technical problems of the invention is as follows:
a curvature influence testing device of a flexible force sensor comprises a support and the flexible force sensor to be tested, and is characterized in that the support supports a horizontal shaft, a curved surface cylinder and a circumferential loading arm are circumferentially sleeved on the horizontal shaft, and the circumferential loading arm is fixedly connected with one end of the curved surface cylinder; the curved cylinder is provided with a cylindrical curved cylinder main body, and the circumferential loading arm extends along the radial direction of the curved cylinder main body; the central axis of the curved surface cylinder main body is superposed with the central axis of the horizontal shaft, and the circumferential loading arms are symmetrically distributed on two sides of the central axis of the horizontal shaft; the support is also provided with a longitudinal through hole positioned right above the curved surface cylinder, a radial loading rod is arranged in the longitudinal through hole, the central axis of the radial loading rod is vertically intersected with the central axis of the curved surface cylinder main body, the upper end of the radial loading rod is a load bearing end for bearing external radial load, the lower end of the radial loading rod is provided with a cambered surface, the cambered surface is a part of a cylinder, the central axis of the cylinder is superposed with the central axis of the curved surface cylinder main body, and the radius difference between the cylinder and the curved surface cylinder main body is the thickness of the flexible force sensor; the flexible force sensor is positioned between the lower end of the radial loading rod and the curved surface cylinder main body, and the center of the flexible force sensor is superposed with the central axis of the radial loading rod; the device also comprises at least one weight with a hook, and the tail end of the circumferential loading arm is provided with a protrusion or a hanging hole for hooking the weight; and the signal output end of the flexible force sensor is connected with external data acquisition equipment.
By adopting the structure, the radial loading rod presses the flexible force sensor on the surface of the curved cylinder main body and enables the flexible force sensor and the curved cylinder main body to be jointed, so that the flexible force sensor has curvature as a whole; and then testing is carried out, and the influence result of the curvature on the flexible force sensor can be obtained.
Preferably, the curved cylinder and the circumferential loading arm respectively form a revolute pair with axial constraint with a horizontal shaft; the radial loading rod and the longitudinal through hole form a longitudinal moving pair with horizontal constraint; the support and the horizontal shaft form a rotating pair with axial restraint. With this preferred structure, the test accuracy can be further ensured.
Preferably, the device has: adjusting the extension direction of the circumferential loading arm to be the horizontal direction, loading external radial load on a load bearing end of the radial loading rod, and under the action of the lower end of the radial loading rod, fitting the flexible force sensor with the surface of the curved cylinder main body in a first test state; and on the basis of the first test state, hanging a preset weight in a second test state of the tail end of the circumferential loading arm; when the device is in a first test state or a second test state, output data of the flexible force sensor are collected through external data collection equipment. This allows a more comprehensive test of the influence of curvature on the flexible force sensor.
Preferably, the circumferential loading arm is sheet-shaped and integrally formed, the circumferential loading arm is formed by symmetrically and fixedly connecting two trapezoidal sheet-shaped pieces, the long bottom edges of the two trapezoidal sheet-shaped pieces are connected with each other, the joint is in arc transition, and the short bottom edges of the two trapezoidal sheet-shaped pieces are arc-shaped and respectively form the tail ends of the circumferential loading arm; the plane on which the circumferential loading arm is positioned is vertical to the horizontal axis. With this preferred structure, the device can be kept in a more stable state during testing.
Preferably, the curved surface cylinder is further provided with a connecting platform, the connecting platform is a cylinder and coaxial with the curved surface cylinder main body, the radius of the connecting platform is smaller than that of the curved surface cylinder main body, one end of the connecting platform is fixedly connected with the circumferential loading arm through a bolt, and the other end of the connecting platform and the curved surface cylinder main body are integrally formed. The preferred structure can be adopted to ensure that the connection between the curved surface cylinder and the circumferential loading arm is more stable.
Preferably, the curved surface cylinders are in a group, and the curved surface cylinder main bodies of the curved surface cylinders have different radiuses; the radial loading rods are in one group and correspond to the curved surface cylinders one to one. Therefore, during specific testing, the curved surface cylinders with different radiuses can be selected to test the output data of the flexible force sensor under different curvatures; meanwhile, the corresponding radial loading rod can ensure that the flexible force sensor is attached to the curved surface cylinder main body, so that the accuracy of a test result is ensured.
Preferably, the bracket is composed of a top piece, a bottom piece, a first side piece and a second side piece which are respectively in block shapes, and the first side piece is parallel to the second side piece; the bottom ends of the first side edge piece and the second side edge piece are fixedly connected with the bottom piece respectively, and the top ends of the first side edge piece and the second side edge piece are fixedly connected with the top piece respectively; the first side piece and the second side piece are respectively provided with a through hole, and bearings for supporting the horizontal shaft are respectively arranged in the through holes.
Preferably, the source of the external radial load carried by the load carrying end of the radial load bar is an external weight or an external pressure device.
The present invention also provides:
the testing method adopting the flexible force sensor curvature influence testing device is characterized by comprising the following steps of:
firstly, fixedly connecting a curved surface cylinder and a circumferential loading arm, sleeving the curved surface cylinder and the circumferential loading arm on a horizontal shaft, and supporting the horizontal shaft on a support; adjusting the extension direction of the circumferential loading arm to be a horizontal direction; arranging a flexible force sensor to be tested on the surface of the curved-surface cylinder main body, penetrating a radial loading rod through a longitudinal through hole of a support and pressing the radial loading rod on the flexible force sensor, so that the flexible force sensor is attached to the surface of the curved-surface cylinder main body, and the center of the flexible force sensor is overlapped with the central axis of the radial loading rod;
secondly, continuously increasing the radius of the curved cylinder to a preset maximum radius by a fixed increment under the condition of fixed external radial load, or continuously increasing the circumferential shear load to a preset maximum circumferential shear load by a fixed increment under the condition of fixed external radial load and fixed curved cylinder radius, or continuously increasing the external radial load of the load bearing end of the radial loading rod to a preset maximum external radial load by a fixed increment under the condition of fixed curved cylinder radius by a preset method; meanwhile, acquiring output data of the flexible force sensor;
thirdly, judging the influence degree of curvature change on the flexible force sensor according to the radius of the curved surface cylinder and the output data of the corresponding flexible force sensor; or judging the influence degree of the circumferential shearing load on the flexible force sensor under the fixed curvature according to the circumferential load and the output data of the corresponding flexible force sensor; and (5) finishing the test.
By adopting the testing method, the influence degree of the flexible force sensor to be tested under different curvatures and under different external radial loads or different circumferential shear loads can be smoothly obtained.
Preferably, in the second step, the predetermined method is: the radius of the curved surface cylinder is increased continuously by fixed increment by replacing the curved surface cylinders with different radii; the method comprises the following steps that weights with different weights are loaded at the tail end of a circumferential loading arm, so that the circumferential shearing load is increased continuously in a fixed increment; the external radial load is increased continuously in fixed increments by loading different weights of external radial loads at the load bearing ends of the radial load levers.
The testing device and the testing method can test the output data performance of the flexible force sensor under different curvatures and under different external radial loads or different circumferential shear loads, thereby obtaining the specific influence degree.
Drawings
Fig. 1 and fig. 2 are schematic structural diagrams of a testing device in an embodiment of the invention at different angles.
Fig. 3 and 4 are schematic diagrams of test results in the test case of the present invention, respectively.
Detailed Description
The invention is described in further detail below with reference to embodiments and with reference to the drawings. The invention is not limited to the examples given.
Examples
As shown in fig. 1 and 2, the device for testing influence of curvature of a flexible force sensor in the embodiment includes a support 01 and a flexible force sensor (not shown) to be tested, wherein the support 01 supports a horizontal shaft 02, a curved cylinder 03 and a circumferential loading arm 04 are circumferentially sleeved on the horizontal shaft 02, and the circumferential loading arm 04 is fixedly connected with one end of the curved cylinder 03; the curved cylinder 03 is provided with a cylindrical curved cylinder main body 05, and the circumferential loading arm 04 extends along the radial direction of the curved cylinder main body 05; the central axis of the curved cylinder main body 05 is superposed with the central axis of the horizontal shaft 02, and the circumferential loading arms 04 are symmetrically distributed on two sides of the central axis of the horizontal shaft 02; the bracket 01 is also provided with a longitudinal through hole positioned right above the curved surface cylinder 03, a radial loading rod 06 is arranged in the longitudinal through hole, the central axis of the radial loading rod 06 is vertically intersected with the central axis of the curved surface cylinder main body 05, the upper end of the radial loading rod 06 is a load bearing end for bearing external radial load, the lower end of the radial loading rod 06 is provided with an arc surface, the arc surface is a part of a cylinder, the central axis of the cylinder is superposed with the central axis of the curved surface cylinder main body 05, and the difference between the radii of the cylinder and the curved surface cylinder main body 05 is the thickness of the flexible force sensor; the flexible force sensor is positioned between the lower end of the radial loading rod 06 and the curved surface cylinder main body 05, and the center of the flexible force sensor is superposed with the central axis of the radial loading rod 06; the device also comprises at least one weight 07 with a hook, and the tail end of the circumferential loading arm 04 is provided with a protrusion or a hanging hole for hooking the weight 07; and the signal output end of the flexible force sensor is connected with external data acquisition equipment.
The curved surface cylinder 03, the circumferential loading arm 04 and the horizontal shaft 02 form a rotating pair with axial constraint respectively; the radial loading rod 06 and the longitudinal through hole form a longitudinal moving pair with horizontal constraint; the bracket 01 and the horizontal shaft 02 form a rotating pair with axial restraint.
The device of the embodiment comprises: adjusting the extension direction of the circumferential loading arm 04 to be a horizontal direction, loading external radial load on a load bearing end of the radial loading rod 06, and under the action of the lower end of the radial loading rod 06, fitting the flexible force sensor with the surface of the curved cylinder main body 05 in a first test state; and a second test state in which a predetermined weight 07 is hung at the end of the circumferential loading arm 04 on the basis of the first test state; when the device is in a first test state or a second test state, output data of the flexible force sensor are collected through external data collection equipment.
The circumferential loading arm 04 is sheet-shaped and integrally formed, the circumferential loading arm 04 is formed by symmetrically and fixedly connecting two trapezoidal sheet-shaped pieces, the long bottom edges of the two trapezoidal sheet-shaped pieces are connected with each other, the joint is in arc transition, and the short bottom edges of the two trapezoidal sheet-shaped pieces are arc-shaped and respectively form the tail end of the circumferential loading arm 04; the plane of the circumferential loading arm 04 is perpendicular to the horizontal axis 02.
The curved surface cylinder 03 is further provided with a connecting platform 08, the connecting platform 08 is cylindrical and coaxial with the curved surface cylinder main body 05, the radius of the connecting platform 08 is smaller than that of the curved surface cylinder main body 05, one end of the connecting platform 08 is fixedly connected with the circumferential loading arm 04 through a bolt, and the other end of the connecting platform 08 and the curved surface cylinder main body 05 are integrally formed.
Specifically, the curved surface cylinders 03 are grouped, and the curved surface cylinder main bodies 05 of the curved surface cylinders 03 have different radiuses; the radial loading rods 06 are in one group, and the radial loading rods 06 correspond to the curved surface cylinders 03 one by one.
The bracket 01 is composed of a top piece 09, a bottom piece 10, a first side piece 11 and a second side piece 12 which are respectively in block shapes, wherein the first side piece 11 is parallel to the second side piece 12; the bottom ends of the first side member 11 and the second side member 12 are fixedly connected with the bottom member 10, and the top ends of the first side member 11 and the second side member 12 are fixedly connected with the top member 09; the first side member 11 and the second side member 12 have through holes, and bearings for supporting the horizontal shaft 02 are provided in the through holes, respectively.
The source of the external radial load 13 carried by the load carrying end of the radial load bar 06 is an external weight or external pressure device (e.g., a material tester).
The test method adopting the device comprises the following steps:
firstly, fixedly connecting a curved surface cylinder 03 with a circumferential loading arm 04, sleeving the curved surface cylinder and the circumferential loading arm 04 on a horizontal shaft 02, and supporting the horizontal shaft 02 on a support 01; adjusting the extension direction of the circumferential loading arm 04 to be a horizontal direction; arranging a flexible force sensor to be tested on the surface of the curved surface cylinder main body 05, penetrating the radial loading rod 06 through the longitudinal through hole of the bracket 01 and pressing the flexible force sensor on the flexible force sensor, so that the flexible force sensor is attached to the surface of the curved surface cylinder main body 05, and the center of the flexible force sensor is superposed with the central axis of the radial loading rod 06;
secondly, continuously increasing the radius of the curved surface cylinder 03 to a preset maximum radius in a fixed increment under the condition of fixing the external radial load 13 by a preset method, or continuously increasing the circumferential shear load to a preset maximum circumferential shear load in a fixed increment under the conditions of fixing the external radial load 13 and fixing the radius of the curved surface cylinder 03, or continuously increasing the external radial load 13 of the load bearing end of the radial loading rod 06 to a preset maximum external radial load 13 in a fixed increment under the condition of fixing the radius of the curved surface cylinder 03; meanwhile, acquiring output data of the flexible force sensor;
the predetermined method comprises the following steps: by replacing the curved surface cylinder 03 with different radiuses, the radius of the curved surface cylinder 03 is increased continuously by fixed increment; the method comprises the following steps that weights 07 with different weights are loaded at the tail end of a circumferential loading arm 04, so that the circumferential shearing load is increased continuously in a fixed increment; the external radial load 13 is continuously increased in fixed increments by loading different weights of the external radial load 13 at the load bearing end of the radial loading rod 06;
thirdly, judging the influence degree of curvature change on the flexible force sensor according to the radius of the curved surface cylinder 03 and the output data of the corresponding flexible force sensor; or judging the influence degree of the circumferential shearing load on the flexible force sensor under the fixed curvature according to the circumferential load and the output data of the corresponding flexible force sensor; and (5) finishing the test.
Test cases
By adopting the device and the method of the embodiment, 10 curved surface cylinders 03 are adopted, the minimum radius is 10mm, the maximum radius is 55mm, and the fixed increment is 5 mm; correspondingly, 10 radial loading rods 06 are arranged and correspond to the curved surface cylinders 03 one by one; the thickness of the flexible force sensor is 2 mm; the deadweight of the radial loading rods 06 is 0.5kg respectively; the symmetrical torque of the circumferential loading arm 04 is less than 0.0001Nm, and the moment arm of the bearing point is 10 cm; no vibration interference is required in the test process, and the device is placed on a horizontal table top.
The flexible force sensor output Signal was collected using National Instruments Signal Express 2013 software and USB6009 data acquisition card (National Instruments Corporation, Austin, TX, USA) at a sampling frequency of 1000 Hz.
The test results are as follows:
1. influence of variation in radius of curved cylinder 03 under fixed external radial load 13
The flexible force sensor is placed on a plane, the weight loaded on the flexible force sensor is equal to the pressure of the radial loading rod 06, and the output data of the flexible force sensor is collected and used as non-curvature data.
The curved surface cylinder 03 with different radiuses is replaced, and the radius is increased by 5mm from the curved surface cylinder 03 with the radius of 10mm to the curved surface cylinder 03 with the radius of 55 mm. And meanwhile, acquiring output data of the flexible force sensor as curvature data. The difference between each curvature data and the no-curvature data was calculated, and the result is shown in fig. 3.
The result shows that the small curve radius can obviously influence the accuracy of the data output data of the flexible force sensor, and the offset of the data output by the flexible force sensor is increased along with the reduction of the radius. When the radius of the curved surface is smaller than 20mm, the influence of the radius of the curved surface on the output data of the flexible force sensor is greatly increased, and when the radius of the curved surface is larger than 40mm, the influence of the radius of the curved surface on the output data of the flexible force sensor is not obvious, and the sensitivity of the output data of the flexible force sensor on the radius of the curved surface is greatly reduced. It follows that flexible force sensors are suitable for measurements on flat surfaces, as well as on curved surfaces with a radius greater than about 40 mm.
2. Fixed external radial load 13 and fixed influence of circumferential shear load variation at radius of curved cylinder 03
With a 20mm radius curved cylinder 03, the external radial load 13 is 3Kg and the circumferential shear load is increased from 0.01Kg, each time by 0.01Kg, to 0.08 Kg. And meanwhile, acquiring output data of the flexible force sensor. The results are shown in FIG. 4. The results show that the influence on the output data of the flexible force sensor is more and more obvious as the circumferential shear load is increased. In combination with previous experiments, it can be known that the circumferential shear force of the surface of the flexible force sensor can significantly affect the accuracy of output data under the condition of small curved surface radius.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (9)
1. A curvature influence testing device of a flexible force sensor comprises a support and the flexible force sensor to be tested, and is characterized in that the support supports a horizontal shaft, a curved surface cylinder and a circumferential loading arm are circumferentially sleeved on the horizontal shaft, and the circumferential loading arm is fixedly connected with one end of the curved surface cylinder; the curved cylinder is provided with a cylindrical curved cylinder main body, and the circumferential loading arm extends along the radial direction of the curved cylinder main body; the central axis of the curved surface cylinder main body is superposed with the central axis of the horizontal shaft, and the circumferential loading arms are symmetrically distributed on two sides of the central axis of the horizontal shaft; the support is also provided with a longitudinal through hole positioned right above the curved surface cylinder, a radial loading rod is arranged in the longitudinal through hole, the central axis of the radial loading rod is vertically intersected with the central axis of the curved surface cylinder main body, the upper end of the radial loading rod is a load bearing end for bearing external radial load, the lower end of the radial loading rod is provided with a cambered surface, the cambered surface is a part of a cylinder, the central axis of the cylinder is superposed with the central axis of the curved surface cylinder main body, and the radius difference between the cylinder and the curved surface cylinder main body is the thickness of the flexible force sensor; the flexible force sensor is positioned between the lower end of the radial loading rod and the curved surface cylinder main body, and the center of the flexible force sensor is superposed with the central axis of the radial loading rod; the device also comprises at least one weight with a hook, and the tail end of the circumferential loading arm is provided with a protrusion or a hanging hole for hooking the weight; the signal output end of the flexible force sensor is connected with external data acquisition equipment;
the circumferential loading arm is flaky and integrally formed, the circumferential loading arm is formed by symmetrically and fixedly connecting two trapezoidal flaky pieces, the long bottom edges of the two trapezoidal flaky pieces are connected with each other, the connection part is in arc line transition, and the short bottom edges of the two trapezoidal flaky pieces are arc-line-shaped and respectively form the tail ends of the circumferential loading arm; the plane on which the circumferential loading arm is positioned is vertical to the horizontal axis.
2. The device for testing influence of curvature of the flexible force sensor according to claim 1, wherein the curved cylinder and the circumferential loading arm respectively form a rotating pair with axial constraint with a horizontal shaft; the radial loading rod and the longitudinal through hole form a longitudinal moving pair with horizontal constraint; the support and the horizontal shaft form a rotating pair with axial restraint.
3. A flexible force sensor curvature influence testing device according to claim 1, wherein the device has: adjusting the extension direction of the circumferential loading arm to be the horizontal direction, loading external radial load on a load bearing end of the radial loading rod, and under the action of the lower end of the radial loading rod, fitting the flexible force sensor with the surface of the curved cylinder main body in a first test state; and on the basis of the first test state, hanging a preset weight in a second test state of the tail end of the circumferential loading arm; when the device is in a first test state or a second test state, output data of the flexible force sensor are collected through external data collection equipment.
4. The device for testing influence of curvature of the flexible force sensor according to any one of claims 1 to 3, wherein the curved cylinder further comprises a connecting platform, the connecting platform is cylindrical and coaxial with the curved cylinder main body, the radius of the connecting platform is smaller than that of the curved cylinder main body, one end of the connecting platform is fixedly connected with the circumferential loading arm through a bolt, and the other end of the connecting platform is integrally formed with the curved cylinder main body.
5. A flexible force transducer curvature influence testing device according to any one of claims 1 to 3, wherein the curved cylinders are in a group, and the curved cylinder main bodies of the curved cylinders have different radii; the radial loading rods are in one group and correspond to the curved surface cylinders one to one.
6. A flexible force sensor curvature influence testing device according to any one of claims 1 to 3, wherein the bracket is formed of a top member, a bottom member, a first side member and a second side member, each in the shape of a block, the first side member being parallel to the second side member; the bottom ends of the first side edge piece and the second side edge piece are fixedly connected with the bottom piece respectively, and the top ends of the first side edge piece and the second side edge piece are fixedly connected with the top piece respectively; the first side piece and the second side piece are respectively provided with a through hole, and bearings for supporting the horizontal shaft are respectively arranged in the through holes.
7. A flexible force sensor curvature influence testing device according to any of claims 1 to 3, wherein the source of external radial loads carried by the load carrying end of the radial loading bar is an external weight or an external pressure device.
8. A method of testing a flexible force sensor curvature influence testing device according to any one of claims 1 to 7, comprising the steps of:
firstly, fixedly connecting a curved surface cylinder and a circumferential loading arm, sleeving the curved surface cylinder and the circumferential loading arm on a horizontal shaft, and supporting the horizontal shaft on a support; adjusting the extension direction of the circumferential loading arm to be a horizontal direction; arranging a flexible force sensor to be tested on the surface of the curved-surface cylinder main body, penetrating a radial loading rod through a longitudinal through hole of a support and pressing the radial loading rod on the flexible force sensor, so that the flexible force sensor is attached to the surface of the curved-surface cylinder main body, and the center of the flexible force sensor is overlapped with the central axis of the radial loading rod;
secondly, continuously increasing the radius of the curved cylinder to a preset maximum radius by a fixed increment under the condition of fixed external radial load, or continuously increasing the circumferential shear load to a preset maximum circumferential shear load by a fixed increment under the condition of fixed external radial load and fixed curved cylinder radius, or continuously increasing the external radial load of the load bearing end of the radial loading rod to a preset maximum external radial load by a fixed increment under the condition of fixed curved cylinder radius by a preset method; meanwhile, acquiring output data of the flexible force sensor;
thirdly, judging the influence degree of curvature change on the flexible force sensor according to the radius of the curved surface cylinder and the output data of the corresponding flexible force sensor; or judging the influence degree of the circumferential shearing load on the flexible force sensor under the fixed curvature according to the circumferential load and the output data of the corresponding flexible force sensor; and (5) finishing the test.
9. The test method according to claim 8, wherein in the second step, the predetermined method is: the radius of the curved surface cylinder is increased continuously by fixed increment by replacing the curved surface cylinders with different radii; the method comprises the following steps that weights with different weights are loaded at the tail end of a circumferential loading arm, so that the circumferential shearing load is increased continuously in a fixed increment; the external radial load is increased continuously in fixed increments by loading different weights of external radial loads at the load bearing ends of the radial load levers.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101281073A (en) * | 2008-05-21 | 2008-10-08 | 中国科学院合肥物质科学研究院 | Mechanics sensor array calibrating apparatus and working method thereof |
| CN102175388A (en) * | 2011-01-21 | 2011-09-07 | 中国科学院合肥物质科学研究院 | Three-dimensional calibration device for curve flexible touch sensor array |
| CN103344383A (en) * | 2013-07-22 | 2013-10-09 | 中国人民解放军陆军军官学院 | Calibration device of three-dimensional flexible array touch sensor |
| CN106153248A (en) * | 2016-08-09 | 2016-11-23 | 浙江大学 | A kind of high accuracy static three-dimensional force sensor caliberating device |
-
2017
- 2017-09-18 CN CN201710841370.1A patent/CN107843390B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101281073A (en) * | 2008-05-21 | 2008-10-08 | 中国科学院合肥物质科学研究院 | Mechanics sensor array calibrating apparatus and working method thereof |
| CN102175388A (en) * | 2011-01-21 | 2011-09-07 | 中国科学院合肥物质科学研究院 | Three-dimensional calibration device for curve flexible touch sensor array |
| CN103344383A (en) * | 2013-07-22 | 2013-10-09 | 中国人民解放军陆军军官学院 | Calibration device of three-dimensional flexible array touch sensor |
| CN106153248A (en) * | 2016-08-09 | 2016-11-23 | 浙江大学 | A kind of high accuracy static three-dimensional force sensor caliberating device |
Non-Patent Citations (1)
| Title |
|---|
| 加载面曲率对柔性压磁材料薄片力学性能的影响;尹益辉等;《机械强度》;20161231;第38卷(第5期);第1016-1020页 * |
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