CN117067199A - Mechanical arm electronic skin, mechanical arm and collision detection system thereof - Google Patents
Mechanical arm electronic skin, mechanical arm and collision detection system thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1674—Programme controls characterised by safety, monitoring, diagnostic
- B25J9/1676—Avoiding collision or forbidden zones
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J18/00—Arms
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Abstract
The invention discloses a mechanical arm electronic skin, a mechanical arm and a collision detection system thereof, wherein the mechanical arm electronic skin comprises: a plurality of collision detection units and shock absorbing layers; the plurality of collision detection units are arranged on the outer surface of the mechanical arm in a scattered manner, and the damping layer wraps the mechanical arm and the plurality of collision detection units; when the mechanical arm collides with the obstacle to be in direct contact, the collision detection unit generates a collision detection signal corresponding to a collision pressure value of the mechanical arm colliding with the obstacle. Through a plurality of collision sensors that dispersedly set up on the arm, the dynamics of arm and people or object collision in the surrounding environment is calculated through sensor detection signal when the collision takes place to further confirm the follow-up control measure of arm according to the dynamics of collision, have that collision detection precision is high, the security of arm adjustment after the collision advantage such as high.
Description
Technical Field
The invention relates to the technical field of mechanical arm safety control, in particular to an electronic skin of a mechanical arm, the mechanical arm and a collision detection system of the mechanical arm.
Background
In recent years, mechanical arms are increasingly used in the fields of aerospace, industry, service industry and the like. In these complex application environments, some robotic arms may allow a worker to stand in close proximity, together with performing the task of operation. Among them, physical interactions (pHRI) between a person and a robot arm, including collisions between robot arms and humans, are unavoidable. In this case, the robot arm may cause great damage to surrounding objects, human beings, and even the robot arm body. Therefore, it is important to detect the position and size of the collision accurately in time.
The current methods for realizing collision detection are mainly divided into three categories, including pre-collision pre-warning, safety design of a mechanical mechanism and post-collision sensing.
The pre-collision contact early warning refers to avoiding collision contact of a human machine in a non-structural environment. In the traditional obstacle avoidance method, the track is optimized by methods such as C space, artificial potential field and the like, and collision is avoided in the kinematic level. The method is mainly aimed at static environment, namely, the position and distance information of the obstacle are known and path planning is made. Aiming at collision detection in an unstructured (dynamic) environment, more and more visual or image information acquired by multiple sensors is adopted to estimate the distance and the moving speed between the mechanical arm and the obstacle in real time, the motion track is adjusted so as to avoid collision between the mechanical arm and the obstacle, and the requirements on algorithm and hardware processing capacity are very high based on multi-sensor information fusion and real-time operation of a large amount of data, and a large number of sensor devices are required, so that the collision detection method has no universality and economy.
The safety design of the mechanical mechanism refers to the flexible design of the mechanical structure of the system, so as to limit the occurrence of collision or reduce the contact force caused by collision, such as the increase of the flexibility of the joint mechanism, the light weight, the joint self-locking design and the like, so as to reduce the collision injury caused by the mechanical arm and the external environment. However, increasing the flexibility of the system affects the control performance and load capacity of the joint and its implementation is less safe.
The sensing after collision contact has important practical value in the specific operation process of the mechanical arm, and the sensing after collision contact means that collision signals can be sharply detected when collision occurs, so that corresponding safety measures are adopted. The key point of the method is how to quickly and accurately detect the occurrence of collision, so as to avoid further collision injury caused by accidental contact between the mechanical arm and an operator. The current collision detection comprises the following detection modes: firstly, judging whether collision with an external object/person occurs through a current loop arranged at a joint of the mechanical arm and a current detection value change; the motor at the joint outputs force to drive the mechanical arm to move, otherwise, if the mechanical arm encounters an obstacle, the mechanical arm is impacted, the joint correspondingly reacts, the current correspondingly changes, whether the mechanical arm collides is judged according to the instantaneous current value, and the mechanical arm is controlled to perform deceleration or stop operation; however, the accuracy of the current loop detection method is poor, and the accuracy requirement of detection cannot be met. Secondly, by means of a 6-degree-of-freedom moment sensor (located at the wrist joint of the robot), the robot can detect collision and measure the magnitude of collision force, but the moment sensor detection mode can greatly increase the manufacturing cost of the robot (high-precision moment sensor is expensive). Thirdly, based on collision detection of electronic skin, the bionic sensing skin integrated with a large number of micro sensors is attached to the surface of the mechanical arm, when the approach of an obstacle is sensed, the capacitance, inductance and the like of the sensors are changed, and then the mechanical arm is controlled to make corresponding reactions; however, the collision detection mode based on the electronic skin has the defects of poor anti-interference capability and complex wiring. In addition, the collision detection of the current ring, the collision detection of the moment sensor and the collision detection based on the electronic skin can only ensure the collision detection of the tail end of the robot and the object, the safe contact between the whole arm and an operator can not be realized, and the safety of people and equipment can not be ensured.
Disclosure of Invention
The invention aims to provide an electronic skin of a mechanical arm, the mechanical arm and a collision detection system thereof, wherein the mechanical arm is provided with a plurality of collision sensors which are arranged on the mechanical arm in a scattered way, the force of collision between the mechanical arm and people or objects in the surrounding environment is calculated through detection signals of the sensors when collision occurs, and subsequent control measures of the mechanical arm are further determined according to the force of collision.
To solve the above technical problem, a first aspect of an embodiment of the present invention provides an electronic skin of a mechanical arm, including: a plurality of collision detection units and shock absorbing layers;
the plurality of collision detection units are arranged on the outer surface of the mechanical arm in a dispersing way, and the damping layer wraps the mechanical arm and the plurality of collision detection units;
when the mechanical arm is in collision direct contact with an obstacle, the collision detection unit generates a collision detection signal corresponding to a collision pressure value of the mechanical arm colliding with the obstacle.
Further, the plurality of collision detection units are uniformly distributed along the axial direction and the circumferential direction of the outer surface of the mechanical arm.
Further, the collision detection unit includes: strain gages or printed circuit boards;
when the mechanical arm collides with the obstacle, the resistance change value of the strain gauge or the printed circuit board is in direct proportion to the collision pressure value received by the mechanical arm during collision.
Further, when the collision detection unit encounters a collision, the change value of the resistance value of the collision detection unit is in direct proportion to the pressure received by the mechanical arm during the collision, and the change value deltaR of the resistance value is:
ΔR＝R×K×ε；
wherein R is the normal resistance value of the strain gauge, K is the proportionality constant of the strain gauge, and epsilon is the deformation amount of the strain gauge during collision.
Further, the plurality of collision detecting units includes: a first strain gage, a second strain gage, and a third strain gage;
the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the axial direction of the mechanical arm;
the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the circumferential direction of the mechanical arm.
Further, the printed circuit board includes: a plurality of printed circuit board units covering the whole outer surface of the mechanical arm, wherein two adjacent printed circuit board units are abutted; or alternatively, the first and second heat exchangers may be,
the printed circuit boards are a plurality of printed circuit board units uniformly distributed on the surface of the mechanical arm, wherein two adjacent printed circuit board units are spaced by a first preset distance.
Accordingly, a second aspect of the embodiments of the present invention provides a mechanical arm, including the mechanical arm electronic skin described above.
Accordingly, a third aspect of the embodiments of the present invention provides a robot collision detection system, including: above-mentioned arm electronics skin still includes: the system comprises a signal transmission module, a signal processing module and a mechanical arm control module;
the mechanical arm electronic skin is arranged on the surface of the mechanical arm, generates a collision detection signal when the mechanical arm is in collision direct contact with an obstacle, and sends the collision detection signal to the signal processing module through the signal transmission module;
the signal processing module is used for preprocessing the collision detection signal, acquiring the collision position of the mechanical arm, calculating a collision pressure value and sending the collision position and the collision pressure value to the mechanical arm control module;
and the mechanical arm control module controls the mechanical arm to stop moving or retract for a second preset distance according to a preset moving route according to the collision position and the collision pressure value.
Further, the signal processing module calculates the collision pressure value according to the resistance change value of the collision detection unit, and the collision pressure value F is:
wherein R is a standard resistance value of the collision detection unit, deltaR is a resistance change value when the collision detection unit collides, K is an elastic modulus of the collision detection unit, S is an area value of a cross section of the collision detection unit, and E is a sensitivity value of the collision detection unit.
Further, the signal processing module calculates an actual collision pressure value according to the position and the acceleration of the strain gauge, wherein the actual collision pressure value F actual The method comprises the following steps:
F actual ＝F-F 0 -MA；
wherein M is the mass of the shock absorbing layer applied to each strain gauge, A is the acceleration of the position of the strain gauge, F 0 The pressure value of the strain gauge is the pressure value of the mechanical arm under the condition of no external force;
further, the method comprises the steps of,
wherein the numerical range of i is 1-n, n is the number of strain gauges, F i The impact pressure value measured for the ith strain gauge, F oi For the pressure value of the ith strain gauge under the condition of no external force, m i For the mass of the damping layer applied to the ith strain gauge, A i The acceleration at the position of the ith strain gauge,for the ith distanceThe angular velocity of the joint nearest to the strain gauge and driving the strain gauge to rotate, r i The distance from the position of the ith strain gauge of the mechanical arm to the axis of the joint is shown.
The technical scheme provided by the embodiment of the invention has the following beneficial technical effects:
the collision force of the mechanical arm and people or objects in the surrounding environment is calculated through the detection signals of the sensors when collision occurs and the subsequent control measures of the mechanical arm are further determined according to the collision force.
Drawings
FIG. 1 is a schematic illustration of a robotic arm provided with a plurality of collision detecting units according to an embodiment of the present invention;
FIG. 2a is a schematic view of an embodiment of the present invention in which a collision detecting unit is disposed along an axial direction of a mechanical arm;
fig. 2b is a schematic view of a collision detecting unit according to an embodiment of the present invention disposed along a circumferential direction of a mechanical arm.
Detailed Description
The objects, technical solutions and advantages of the present invention will become more apparent by the following detailed description of the present invention with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
In the prior art, some technical solutions detect the collision just before the collision between the mechanical arm and surrounding people or objects through the electronic skin arranged on the mechanical arm, but the collision detection mode is usually non-contact measurement, that is, the mechanical arm and the people or objects do not collide, so that the strength of the actual collision cannot be perceived, and therefore, the optimal mechanical arm control strategy cannot be adopted in a targeted manner.
Referring to fig. 1, a first aspect of an embodiment of the present invention provides an electronic skin of a mechanical arm, including: a plurality of collision detection units and shock absorbing layers; the plurality of collision detection units are arranged on the outer surface of the mechanical arm in a scattered manner, and the damping layer wraps the mechanical arm and the plurality of collision detection units; when the mechanical arm collides with the obstacle to be in direct contact, the collision detection unit generates a collision detection signal corresponding to a collision pressure value of the mechanical arm colliding with the obstacle.
Compared with the existing mechanical arm collision detection mode, the mechanical arm collision detection method has the advantages that the mechanical arm collision detection accuracy is high, the safety of mechanical arm adjustment after collision is high, and the use safety of the mechanical arm and the safety of people or other equipment in the surrounding environment are greatly improved.
Specifically, referring to fig. 2a and 2b, a plurality of collision detecting units are uniformly distributed along the axial direction and the circumferential direction of the outer surface of the mechanical arm.
Further, the collision detection unit includes: strain gages or printed circuit boards; when the mechanical arm collides with an obstacle, the resistance change value of the strain gauge or the printed circuit board is in direct proportion to the collision pressure value received by the mechanical arm during collision.
Optionally, in a specific implementation manner of the embodiment of the present invention, the collision detecting unit is a strain gauge; the plurality of strain gauges are respectively and electrically connected with a signal transmission module of the mechanical arm collision detection system; the signal detection module sends the resistance change value of at least one strain gauge on the mechanical arm when collision occurs to the signal processing module through the signal transmission module.
The strain gauge has the characteristics that the resistance value can be correspondingly changed along with stretching or compressing, and the resistance value can be increased or decreased. A single strain gage can only sense the change of the force, and cannot accurately sense the direction and position of the force. It is necessary to combine the directions and positions of the perceived forces.
Specifically, the number of strain gauges on the mechanical arm can be controlled according to the use environment and the cost.
For example, when only one collision person or object may occur on the moving route of the robot arm, only one strain gauge may be provided at a position corresponding to the side of the robot arm toward which the obstacle may occur. The mechanical arm only depends on the collision detection signal of the single strain gauge to judge whether collision occurs in the moving process.
For example, when the use environment of the mechanical arm is complex, two to three persons or objects possibly collided exist on the moving route, in order to improve the accuracy of collision detection, a plurality of strain gauges should be arranged on the mechanical arm. The strain gauges can be uniformly arranged in the axial direction and the circumferential direction of the mechanical arm, and all moving directions of the mechanical arm are covered as much as possible on the premise of limited number of the strain gauges, so that the performance of collision detection of the mechanical arm is improved under the condition of limited cost.
For example, when the use environment of the mechanical arm is extremely complicated, the use quantity of the strain gauges can be increased, a plurality of strain gauges are arranged along the axial direction of the mechanical arm, and meanwhile, a plurality of strain gauges are arranged along the circumferential direction of the mechanical arm, so that the full coverage of the axial direction and the circumferential direction of the mechanical arm is realized. The strain gauges distributed in a grid shape are arranged on the surface of the mechanical arm, so that the collision detection precision of the mechanical arm in the moving process can be greatly improved, the equipment safety of the mechanical arm and the safety of people or other equipment in the surrounding use environment are protected to the greatest extent, and the mechanical arm is suitable for the space with complex surrounding environment and high mechanical arm control precision.
Preferably, the plurality of collision detecting units includes: a first strain gage, a second strain gage, and a third strain gage; the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the axial direction of the mechanical arm; the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the circumferential direction of the mechanical arm.
The preferable setting mode of the strain gauge is higher in cost performance of the mechanical arm collision detection system, so that the multidirectional collision detection on the mechanical arm moving route can be realized, the collision detection precision is ensured, and the actual requirement of a customer on the control cost can be met.
Further, taking a strain gauge as an example, when the mechanical arm collides, the change value of the resistance value of the strain gauge is in direct proportion to the pressure received when the mechanical arm collides, and the change value deltaR of the resistance value is:
ΔR＝R×K×ε；
wherein R is the normal resistance value of the strain gauge, K is the proportionality constant of the strain gauge, and epsilon is the deformation amount of the strain gauge during collision.
Specifically, the strain gauge transmits strain information by means of the change of resistance value, and the resistance of the metal conductor with uniform section is
Wherein R is the resistance value (in omega) of the metal conductor, ρ is the resistivity (in cm) of the metal conductor, L is the length (in mm) of the metal conductor, and A is the cross-sectional area (in mm) of the metal conductor 2 )。
In addition, when the temperature changes, ρ, L, A and its change values are not only functions of the strain amount, but also functions of the temperature, i.e
R＝R(T，ε)，
Wherein R is the resistance of the strain gauge, T is the temperature of the strain gauge, and epsilon is the strain of the strain gauge.
After the strain gauge sensor is adopted (such as a strain grid), when the temperature and the strain are slightly changed at the same time, the following steps are:
wherein alpha is R Temperature coefficient of resistance, K, of strained gate 0 A is the sensitivity coefficient of the strain gate m Is the linear expansion coefficient of the test piece material, a g The linear expansion coefficient of the strained gate is Δt, which is the amount of temperature change.
When no external load or thermal stress acts, i.e., Δε=0, there are:
the conversion is carried out to obtain:
ε T ＝[α R /K 0 +(a m -a g )]ΔT；
where εT is the temperature induced spurious strain, i.e., heat output, of the strain gauge. As can be seen from the above, the thermal output characteristics of the strain gauge are the resistance temperature coefficient α of the strain resistor R Linear expansion coefficient and linear expansion coefficient a of test piece material m Sensitivity coefficient K of strain gauge 0 And the like have a direct relationship.
In another embodiment of the present invention, the collision detecting unit is a printed circuit board; the printed circuit board is electrically connected with the signal transmission module, and the signal detection module sends xx change values generated when the printed circuit board assembly collides to the signal processing module through the signal transmission module.
Further, the printed circuit board includes: a plurality of printed circuit board units which cover the whole surface of the mechanical arm and are not spaced every two or uniformly distributed on the surface of the mechanical arm; the plurality of printed circuit board units are respectively and electrically connected with the signal transmission module.
After a plurality of printed circuit boards are arranged on the surface of the mechanical arm, a layer of soft rubber is wrapped outside the printed circuit boards, signal wires are led out, and the control is performed after the ADC is used for collecting the driving board. Specifically, a plurality of printed circuit boards are distributed in subunits (blocks) in different areas of the mechanical arm, specific collision positions can be determined through the independent subunits, and pressure value changes are detected after collision.
The printed circuit boards can be distributed at preset distances, can be arranged at smaller intervals, and can be arranged in a tightly adjacent mode. And each printed circuit board is led out of a signal wire and is electrically connected with the signal processing module. Therefore, the smaller the area of the printed circuit board, the larger the number, and the smaller the interval between every two, the higher the accuracy of the robot collision detection. That is, the specific arrangement mode of the printed circuit board in the distributed structure may be the same as the arrangement direction of the strain gauge.
In addition, when the printed circuit board is small enough in area, large enough in number and small enough in gap, and the distribution mode is adopted, the detection accuracy of the collision force is ensured, and meanwhile, the detection accuracy of the collision position of the mechanical arm can be improved to the greatest extent. The detection precision of the collision position of the mechanical arm is improved, so that the precision of the mechanical arm for adjusting the moving route after collision can be improved, obstacles are avoided or bypassed, or an alarm signal of collision detection information is sent to a mechanical arm control center to prompt manual cleaning of the obstacles, so that the safety of the mechanical arm, surrounding people and objects is ensured as much as possible. The collision detection method of the printed circuit board is similar to that of the strain gauge, and will not be described herein.
In addition, in order to protect a plurality of sensors which are arranged on the mechanical arm in a dispersing way, the problem that the accuracy is reduced or the sensor is out of order due to the fact that the sensors directly collide in the moving process of the mechanical arm is prevented, and the electronic skin further comprises a damping layer which is arranged on one side of the sensor away from the mechanical arm. The material of the optional damping layer can be selected from soft rubber, TPU flexible material or other soft damping materials, and the material of the damping layer only needs to be light, thin, soft and long in service life.
Correspondingly, a second aspect of the embodiment of the invention provides a mechanical arm, which comprises the mechanical arm electronic skin, wherein the mechanical arm is provided with a plurality of detection units
Accordingly, a third aspect of the embodiments of the present invention provides a robot collision detection system, including: above-mentioned arm electronics skin still includes: the system comprises a signal transmission module, a signal processing module and a mechanical arm control module; the mechanical arm electronic skin is arranged on the surface of the mechanical arm, generates a collision detection signal when the mechanical arm collides with an obstacle to be in direct contact, and sends the collision detection signal to the signal processing module through the signal transmission module; the signal processing module is used for preprocessing the collision detection signal, acquiring the collision position of the mechanical arm, calculating a collision pressure value and sending the collision position and the collision pressure value to the mechanical arm control module; and the mechanical arm control module controls the mechanical arm to stop moving or retract for a second preset distance according to a preset moving route according to the collision position and the collision pressure value.
According to the mechanical arm collision detection system, the plurality of collision detection units are arranged on the mechanical arm in a scattered manner, the force of collision between the mechanical arm and people or objects in the surrounding environment is calculated through the detection signals of the collision detection units when collision occurs, the moving track of the mechanical arm and the feedback control force of the motor at the joint are further adjusted according to the specific collision position and the collision force, and the mechanical arm collision detection system has the advantages of being high in collision detection precision, high in safety of mechanical arm adjustment after collision and the like, and the use safety of the mechanical arm and the safety of people or other equipment in the surrounding environment are greatly improved.
Specifically, the signal processing module calculates a collision pressure value according to the resistance change value of the collision detection unit, where the collision pressure value F is:
wherein R is the standard resistance value of the collision detection unit, deltaR is the resistance change value when the collision detection unit collides, K is the elastic modulus of the collision detection unit, S is the area value of the cross section of the collision detection unit, and E is the sensitivity value of the collision detection unit.
Further, in the moving process of the mechanical arm, the magnitude of the acceleration of the mechanical arm has a certain influence on the deformation of the collision detection unit. If the acceleration of the mechanical arm is large, the influence of the corresponding generated deformation amount is relatively large; if the acceleration of the mechanical arm is small, the corresponding generated deformation amount is correspondingly small.
Through calculation and test, the actual displayed pressure value F of the mechanical arm at the specific position of each detection unit and the pressure value F under the condition of no external force can be used 0 The position acceleration value V and finally determines the actual pressure value F of the strain gauge actual 。
F actual ＝F-F 0 -MA；
Wherein M is the mass of the shock absorbing layer applied to each strain gage, including but not limited to soft rubber, TPU flexible material or other soft shock absorbing material; a is acceleration of the position of the strain gauge, F 0 The pressure value of the strain gauge is obtained under the condition that the mechanical arm is not subjected to external force.
Still further, the method further comprises the steps of,
wherein the numerical range of i is 1-n, n is the number of strain gauges, F i The impact pressure value measured for the ith strain gauge, F oi For the pressure value of the ith strain gauge under the condition of no external force, m i For the mass of the damping layer applied to the i-th strain gauge, A i The acceleration at the position of the ith strain gauge,the angular velocity of the joint nearest to the ith strain gauge and driving the strain gauge to rotate, r i The distance from the position of the ith strain gauge of the mechanical arm to the axis of the joint is shown.
Optionally, the mechanical arm control module compares the collision pressure value with a pre-stored collision pressure threshold, controls the mechanical arm to suddenly stop when the collision pressure value is smaller than the collision pressure threshold, and controls the mechanical arm to retract by a second preset distance when the collision pressure value is greater than or equal to the collision pressure threshold.
The embodiment of the invention aims to protect an electronic skin of a mechanical arm, the mechanical arm and a collision detection system thereof, wherein the electronic skin of the mechanical arm comprises: a plurality of collision detection units and shock absorbing layers; the plurality of collision detection units are arranged on the outer surface of the mechanical arm in a dispersing way, and the damping layer wraps the mechanical arm and the plurality of collision detection units; when the mechanical arm collides with the obstacle to be in direct contact, the collision detection unit generates a collision detection signal corresponding to a collision pressure value of the mechanical arm colliding with the obstacle. The technical scheme has the following effects:
the collision force of the mechanical arm and people or objects in the surrounding environment is calculated through the detection signals of the sensors when collision occurs and the subsequent control measures of the mechanical arm are further determined according to the collision force.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and are in no way limiting of the invention. Accordingly, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. Furthermore, the appended claims are intended to cover all such changes and modifications that fall within the scope and boundary of the appended claims, or equivalents of such scope and boundary.
Claims (10)
1. A robotic arm electronic skin comprising: a plurality of collision detection units and shock absorbing layers;
the plurality of collision detection units are arranged on the outer surface of the mechanical arm in a dispersing way, and the damping layer wraps the mechanical arm and the plurality of collision detection units;
when the mechanical arm is in collision direct contact with an obstacle, the collision detection unit generates a collision detection signal corresponding to a collision pressure value of the mechanical arm colliding with the obstacle.
2. The robotic arm electronic skin according to claim 1, wherein the plurality of collision detecting units are evenly distributed along an axial direction and a circumferential direction of the robotic arm outer surface.
3. The robotic arm electronic skin according to claim 1 or 2, wherein the collision detection unit comprises: strain gages or printed circuit boards;
when the mechanical arm collides with the obstacle, the resistance change value of the strain gauge or the printed circuit board is in direct proportion to the collision pressure value received by the mechanical arm during collision.
4. A robotic arm electronic skin according to claim 3, wherein the collision detecting unit has a resistance value that varies in proportion to the pressure received by the robotic arm when it encounters a collision, and the resistance value Δr varies in proportion to the pressure received by the robotic arm when it encounters a collision:
ΔR＝R×K×ε；
wherein R is the normal resistance value of the strain gauge, K is the proportionality constant of the strain gauge, and epsilon is the deformation amount of the strain gauge during collision.
5. A robotic arm electronic skin as claimed in claim 3, wherein the number of collision detecting units comprises: a first strain gage, a second strain gage, and a third strain gage;
the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the axial direction of the mechanical arm;
the first strain gauge, the second strain gauge and the third strain gauge are uniformly distributed along the circumferential direction of the mechanical arm.
6. The mechanical arm electronic skin of claim 3, wherein,
the printed circuit board includes: a plurality of printed circuit board units covering the whole outer surface of the mechanical arm, wherein two adjacent printed circuit board units are abutted; or alternatively, the first and second heat exchangers may be,
the printed circuit boards are a plurality of printed circuit board units uniformly distributed on the surface of the mechanical arm, wherein two adjacent printed circuit board units are spaced by a first preset distance.
7. A robotic arm comprising the robotic arm electronic skin of any one of claims 1-6.
8. A robot collision detection system, comprising: the robotic arm electronic skin of any one of claims 1-6, further comprising: the system comprises a signal transmission module, a signal processing module and a mechanical arm control module;
the mechanical arm electronic skin is arranged on the surface of the mechanical arm, generates a collision detection signal when the mechanical arm is in collision direct contact with an obstacle, and sends the collision detection signal to the signal processing module through the signal transmission module;
the signal processing module is used for preprocessing the collision detection signal, acquiring the collision position of the mechanical arm, calculating a collision pressure value and sending the collision position and the collision pressure value to the mechanical arm control module;
and the mechanical arm control module controls the mechanical arm to stop moving or retract for a second preset distance according to a preset moving route according to the collision position and the collision pressure value.
9. The robot arm collision detection system of claim 8, wherein,
the signal processing module calculates the collision pressure value according to the resistance change value of the collision detection unit, and the collision pressure value F is:
wherein R is a standard resistance value of the collision detection unit, deltaR is a resistance change value when the collision detection unit collides, K is an elastic modulus of the collision detection unit, S is an area value of a cross section of the collision detection unit, and E is a sensitivity value of the collision detection unit.
10. The robot arm collision detection system of claim 9, wherein,
the signal processing module calculates an actual collision pressure value according to the position and the acceleration of the strain gauge, and the actual collision pressure value F actual The method comprises the following steps:
F actual ＝F-F 0 -MA；
wherein M is the mass of the shock absorbing layer applied to each strain gauge, A is the acceleration of the position of the strain gauge, F 0 The pressure value of the strain gauge is the pressure value of the mechanical arm under the condition of no external force;
further, the method comprises the steps of,
wherein the numerical range of i is 1-n, n is the number of strain gauges, F i The impact pressure value measured for the ith strain gauge, F oi For the pressure value of the ith strain gauge under the condition of no external force, m i For the mass of the damping layer applied to the ith strain gauge, A i The acceleration at the position of the ith strain gauge,the angular velocity of the joint nearest to the ith strain gauge and driving the strain gauge to rotate, r i The distance from the position of the ith strain gauge of the mechanical arm to the axis of the joint is shown.
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