A mechanical arm wire harness fatigue detection system

Abstract

The utility model discloses a kind of mechanical arm wire harness fatigue degree detection systems, belong to mechanical detection technical field, including custom wire harness and detection circuit, and electrically connected between the custom wire harness and detection circuit;The custom wire harness includes insulating protective layer, wire portion and the detected wire;The insulating protective layer is wrapped in wire portion and the detected wire outside, for insulation protection;The wire portion at least contains 1 pair of power line and 1 pair of signal line, for the power supply and signal transmission of mechanical arm;The detected wire is made of multiple alloy metal wires with preset impedance, and one end is short-circuited by PCB jumper, and the other end leads out two terminals, as the input / output terminal of detection signal.The system has short-circuit protection, chip replaceability is strong, health quantization and other advantages, can improve robot reliability and safety, reduce maintenance cost.

Description

Technical Field

[0001] This utility model relates to the field of mechanical testing technology, specifically a fatigue testing system for robotic arm wiring harnesses. Background Technology

[0002] During the operation of robots (especially industrial robots and service robots), the robotic arms, robotic legs, joints and other parts need to move frequently, which causes the wiring harness (including power lines, signal lines and communication lines) in this area to be repeatedly bent, and the bending radius is usually small (≤5mm in some scenarios).

[0003] In existing technologies, most robots do not have fatigue detection mechanisms for the wiring harnesses in the aforementioned critical parts: after long-term bending, the wiring harnesses are prone to fatigue damage such as wire breakage and insulation layer damage. Initially, the damage may not show obvious changes in appearance, but it can lead to unstable power supply and signal transmission interruption. In severe cases, it can cause the robot to stop, malfunction, or even cause equipment damage or safety accidents.

[0004] In addition, the existing few wire harness detection solutions have the following defects: 1) They rely on imported dedicated chips, which are costly and easily subject to "bottleneck" restrictions; 2) They can only detect the continuity of the wire harness, but cannot quantify the degree of fatigue, making it difficult to provide early warning; 3) The circuit has no protection design, and components are easily burned out due to short circuits, resulting in low reliability.

[0005] Therefore, there is an urgent need for a low-cost, highly reliable, and quantifiable fatigue detection system for robotic arm harnesses to address the aforementioned technical challenges. Utility Model Content

[0006] The purpose of this invention is to provide a fatigue detection system for robotic arm wiring harnesses to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution: A fatigue detection system for a robotic arm wiring harness includes a custom wiring harness and a detection circuit, wherein the custom wiring harness and the detection circuit are electrically connected. The customized wiring harness includes an insulating protective layer, a conductor portion, and a conductor to be tested. The insulating protective layer wraps around the conductor portion and the conductor to be tested for insulation protection. The conductor portion includes at least one pair of power lines and one pair of signal lines for power supply and signal transmission to the robotic arm. The conductor to be tested is made of multiple alloy metal wires with preset impedance twisted together. One end of the conductor is shorted by a PCB jumper, and the other end leads out to two terminals as input / output terminals for the detection signal. The detection circuit includes an output circuit and an input circuit. The two terminals of the wire being tested are electrically connected to the wire harness fatigue detection output terminal of the output circuit and the wire harness fatigue detection input terminal of the input circuit, respectively, forming a closed detection loop. The output circuit includes a high-side output chip U2, a current-limiting resistor R12, and voltage-dividing resistors R18 and R19. The IN pin of the high-side output chip U2 is connected to the enable signal output terminal of the MCU through R12, the VS pin of the high-side output chip U2 is connected to a 5V power supply, and the OUT pin of the high-side output chip U2 is the output terminal for wire harness fatigue detection. One end of the resistor R18 is connected to the OUT pin of the high-side output chip U2, and the other end of the resistor R18 is connected to one end of the resistor R19 and the wire harness fatigue detection output feedback terminal of the MCU. The other end of the resistor R19 is grounded. The high-side output chip U2 has a short-circuit protection function, and automatically cuts off the output when the output current of the OUT pin is too large. The input circuit includes a differential operational amplifier U1, an N-type MOSFET M1, a comparator U3, a transistor Q3, and resistors R8, R10, R13, R14, R15, R16, R17, and a capacitor C1. The IN+ pin of the differential operational amplifier U1 is connected to resistor R8 and capacitor C1. The other end of resistor R8 is connected to resistor R9 and the wire harness fatigue detection input terminal. The IN- pin of the differential operational amplifier U1 is connected to the other end of capacitor C1 and resistor R10. The other end of resistor R10 is connected to the other end of resistor R9 and the drain of the N-type MOSFET M1. The GS1 pin of the differential operational amplifier U1 is connected to resistor R11, and the other end of resistor R11 is connected to… The differential operational amplifier U1 has its GS0 pin connected to ground. The differential operational amplifier U1 outputs a differential amplified output voltage via its OUT pin. The source of the N-type MOSFET M1 is connected to resistor R17 and the inverting input V- of comparator U3, with the other end of resistor R17 grounded. The gate of the N-type MOSFET M1 is connected to the OUT pin of U3 via resistor R14 and simultaneously connected to a 5V power supply via pull-up resistor R13. The non-inverting input V+ of comparator U3 obtains a 0.5V reference voltage through a voltage divider between resistors R15 and R16. The base of transistor Q3 is connected to the gate of the N-type MOSFET M1, the emitter of transistor Q3 is grounded, and the collector of transistor Q3 is connected to the gate of the N-type MOSFET M1.

[0008] As a further technical solution of this utility model: the high-side output chip U2 is model BTT6200-1ENA. When the MCU enable signal output is high, the OUT pin of the high-side output chip U2 outputs 5V voltage; when the MCU enable signal output is low, the OUT pin of the high-side output chip U2 outputs 0V.

[0009] As a further technical solution of this utility model: the differential operational amplifier U1 is model AD8221, the resistance values ​​of R8 and R10 are both 100Ω, and the capacitance value of C1 is 0.1μF, so as to filter out high-frequency noise in the input signal.

[0010] As a further technical solution of this utility model: the differential operational amplifier U1 is model AD8221, the resistance values ​​of R8 and R10 are both 100Ω, and the capacitance value of C1 is 0.1μF, so as to filter out high-frequency noise in the input signal.

[0011] As a further technical solution of this utility model: the comparator U3 is model LM339, and the resistance of R17 is 10Ω; when the voltage across R17 is >0.5V, U3 outputs a low level and M1 is disconnected; when the voltage across R17 is <0.5V, U3 outputs a high level and M1 is turned on, so that the current of the detection circuit is dynamically stabilized at 50mA.

[0012] As a further technical solution of this utility model: the protection transistor Q3 is of model S9013; when U3 fails and the voltage at point G is ≥0.7V, Q3 turns on and pulls down the voltage at point J, forcing M1 to turn off; when the voltage at point G is <0.7V, Q3 turns off, M1 turns on again, so that the current of R17 is stabilized at 70mA to achieve overload protection.

[0013] Compared with the prior art, the beneficial effects of this utility model are: 1. Real-time and early warning: Fatigue can be monitored in real time by measuring the impedance change of the tested wire, and an early warning can be given before the wire breaks completely (health level 4%-100%), thus avoiding sudden robot failure; 2. High reliability: The detection circuit is designed with short-circuit protection (U2), overload protection (Q3) and interference filtering (C1), and the circuit failure rate is ≤0.1% / thousand cycles; 3. Material universality: The core chips (U2=BTT6200-1ENA, U1=AD8221, U3=LM339) are all domestically produced alternatives, which reduces reliance on imported chips and lowers supply chain risks; 4. Measurable Health: The abstract "fatigue level" is transformed into a specific value of 4%-100%, which makes it easier for users to set thresholds according to the scenario (such as setting higher thresholds for joints with high-frequency movement), thus improving maintenance convenience. 5. Low cost and easy implementation: The additional cost of customized wiring harnesses only increases by 15%-20% compared to conventional wiring harnesses. The detection circuit components are all universal models, and the overall solution can be directly integrated into the existing robotic arm control system without major modifications. Attached Figure Description

[0014] Figure 1 A structural diagram of a custom wire harness; Figure 2 This is the circuit diagram for the output circuit; Figure 3 This is the circuit diagram for the input circuit. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are merely one circuit embodiment of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0016] Please see Figures 1-3 A robotic arm wiring harness fatigue detection system is disclosed. This invention achieves real-time, quantitative detection of wiring harness fatigue through a collaborative design of "customized wiring harness + dedicated detection circuit + diagnostic calculation". The specific technical solution is as follows: 1. Customized wire harness design (corresponding to) Figure 1 ) Customized wire harnesses are the core carrier for testing, and their structure must meet the dual requirements of "transmission function" and "detection function": Insulation protection layer: Made of silicone rubber (0.8mm thick), it is wrapped around the conductor and the outside of the conductor being tested. It has the characteristics of high frequency bending resistance (insulation resistance ≥100MΩ after 100,000 bends) and temperature resistance (-40℃-85℃), which is suitable for the motion scenarios of robotic arm joints. The wiring harness includes two power cables (AWG22 specification, copper core, 1.5A current carrying capacity) and three signal cables (AWG24 specification, tinned copper core, 2Mbps transmission rate), which are used for power supply and signal interaction of the robotic arm, respectively, and have the same function as conventional wiring harnesses. The conductor under test: the core component of the detection function, consisting of 7 nickel-chromium alloy wires (0.1mm in diameter, resistivity 1.08×10⁻⁻). 6 The wire is twisted together (Ω・m), with an initial impedance of 88Ω (at 25℃). One end is shorted by a 0Ω jumper on the PCB (to ensure the current loop is open), and the other end has two silver-plated terminals (2.54mm apart) as the signal input / output terminals of the detection circuit. When the wire harness is repeatedly bent, causing the alloy metal wire to break or suffer fatigue damage, the impedance of the wire being tested will increase with the degree of damage, providing a physical basis for fatigue detection.

[0017] 2. Detection circuit design (corresponding) Figure 2 , Figure 3 ) The detection circuit is the core of the "impedance change → electrical signal conversion" process. It is divided into an output circuit (signal transmitting end) and an input circuit (signal acquisition end). The two circuits form a closed loop through the wires being detected in a custom-designed wiring harness. The specific structure and function are as follows: 2.1 Output Circuit ( Figure 2 ) The output circuit functions to provide a stable 5V detection voltage and to achieve real-time sampling of the output current. Its structural details are as follows: The high-side output chip U2, model BTT6200-1ENA (an integrated chip with short-circuit protection), has its IN pin connected to the MCU's "MCU-Enable Signal Output" terminal via a current-limiting resistor R12 (1KΩ), its VS pin connected to a 5V DC power supply, and its OUT pin defined as the "Wire Harness Fatigue Detection Output" terminal (connected to one of the terminals of the wire being tested). When the MCU outputs a high-level enable signal, U2's OUT pin outputs a 5V voltage; when the OUT pin output current > 9A (short circuit or overload), U2 automatically cuts off the output to prevent circuit burnout. Voltage divider feedback unit: It consists of resistors R18 (10KΩ) and R19 (2KΩ). One end of R18 is connected to the OUT pin of U2, and the other end is connected to R19 and the "wire harness fatigue detection output feedback" terminal of the MCU. The other end of R19 is grounded. This unit reduces the 5V voltage of the OUT pin to (5V×2KΩ / (10KΩ+2KΩ))≈0.83V by voltage divider, so that the MCU can sample back to confirm whether the output circuit is normal (if the sampling voltage is 0V, it is determined that U2 is not enabled or is faulty).

[0018] 2.2 Input Circuit ( Figure 3 ) The function of the input circuit is to convert the impedance change of the conductor being detected into an acquireable voltage signal, and to ensure detection accuracy through constant current control and protection design. The structural details are as follows: Differential Amplification Unit: The core is the differential operational amplifier U1 (model AD8221). Its IN+ pin is defined as the "wire harness fatigue detection input" terminal (connected to another terminal of the wire being tested), and the IN- pin is grounded; C1 (0.1μF ceramic capacitor) is connected in parallel between IN+ and IN- to filter out high-frequency interference in the environment (such as electromagnetic noise from the robotic arm motor); R8 and R10 (both 100Ω) are connected in series between the OUT pin of U1 and the AD sampling port of the MCU to limit the current input to the MCU (to prevent the AD port from burning out); the GS1 and GS0 pins of U1 are both connected to GND (low level), at which time the amplification gain is fixed at 25 times, ensuring that weak impedance changes can be amplified into a recognizable voltage signal; The constant current control unit consists of an N-type MOSFET M1 (model IRF540), a comparator U3 (model LM339), and resistors R13 (1KΩ), R14 (1KΩ), R15 (9KΩ), R16 (1KΩ), and R17 (10Ω). The drain (D) of M1 is connected to the IN+ pin of U1 (i.e., the "wire harness fatigue detection input"), and the source (S) is connected to one end of R17, with the other end of R17 grounded. The gate (G) of M1 is connected to the OUT pin of U3 through R14, and simultaneously pulled up to 5V through R13 (in the default state, the gate of M1 is high, and the drain and source (DS) are conducting). The V+ pin of U3 obtains a base voltage of 0.5V through a voltage divider between R15 and R16. The reference voltage is 5V × 1KΩ / (9KΩ + 1KΩ) = 0.5V. The V- pin is connected to the voltage acquisition point across R17. When the current in the detection loop increases, the voltage across R17 (V = IR) increases. If V > 0.5V, U3 outputs a low level, the gate voltage of M1 decreases, the conduction degree of DS weakens, and the loop current decreases. If V < 0.5V, U3 outputs a high level, the gate voltage of M1 increases, the conduction degree of DS strengthens, and the loop current increases. Through this negative feedback mechanism, the current in the detection loop is stabilized at 50mA (because R17 = 10Ω, I = 0.5V / 10Ω = 50mA), ensuring the accuracy of impedance calculation. Overload protection unit: The core is an NPN transistor Q3 (model S9013), whose base is connected to the gate (G) of M1 (defined as point G), its emitter is grounded, and its collector is connected to the junction of the source (S) of M1 and R17 (defined as point J). When U3 fails (e.g., the chip burns out) and the voltage at point G continues to rise to ≥0.7V, the emitter junction of Q3 conducts forward, the voltage at point J is pulled low, and the drain-switcher of M1 is forced to disconnect. When the voltage at point G is <0.7V, Q3 is cut off, and M1 resumes conduction. This design can limit the maximum current of R17 to 70mA (I=0.7V / 10Ω=70mA), preventing excessive loop current from burning out the detected wire or U1.

[0019] This design uses an MCU (such as an STM32F103 microcontroller) to convert the voltage signal of the input circuit into the "real-time resistance value" and "health status" of the wire harness. The specific process is as follows: Signal acquisition: The MCU acquires the differential amplified output voltage V_OUT of U1 through the AD sampling port (sampling accuracy 12-bit, range 0-3.3V). Parameter calculation: Key parameters are calculated based on preset formulas. Loop current I = V_OUT / (amplification gain × R9) = V_OUT / (25 × 2Ω) (R9 is a fixed resistor in the output circuit with a resistance of 2Ω); The total resistance of the circuit, R_total, is 5V / I (according to Ohm's law, the total voltage of the circuit is 5V). The impedance of the wire being tested, R_wire = R_total - R9 - R17 = R_total - 2Ω - 10Ω = R_total - 12Ω (after deducting the effect of the fixed resistance in the circuit); Health quantification: Conductor health = (initial impedance 88Ω / R_wire) × 100%. The correspondence between health and V_OUT and R_wire is shown in Table 1 (for example: when V_OUT = 2.4V, I = 2.4 / (25×2) = 0.048A = 48mA, R_total = 5 / 0.048 ≈ 104.17Ω, R_wire = 104.17 - 12 = 92.17Ω, health = (88 / 92.17) × 100 ≈ 96%). Early warning control: Users can set a health threshold according to the usage scenario of the robotic arm (e.g., 80% for industrial robots and 60% for service robots). When the diagnostic calculation module detects that the health level is lower than the threshold, the MCU outputs an early warning signal to the robot's main control system via the serial port, or directly drives the audible and visual alarm to prompt maintenance personnel to replace the wiring harness.

[0020] To enable those skilled in the art to fully reproduce this utility model, the implementation process is described in detail below with reference to Table 1 and specific parameters: Table 1: Resistance and Health Status of the Tested Wires

[0021] System setup steps: Custom wire harness fabrication: Insulation protection layer: Made of silicone rubber extrusion molding, with an inner diameter adapted to the total outer diameter of the conductor and the conductor being tested (approximately 5mm). The conductor section consists of two AWG22 power wires twisted together with three AWG24 signal wires, with an outer diameter of approximately 3mm. The conductor under test: Twist seven 0.1mm nickel-chromium alloy wires together, measure the initial impedance (ensure it is 88±2Ω), short one end through a PCB jumper, and crimp the other end to two silver-plated terminals; Final assembly: Place the wire section parallel to the wire being tested, wrap it with an insulating protective layer, and strip the wires at both ends to expose the terminals (5mm in length).

[0022] Testing circuit soldering: PCB board fabrication: according to Figure 2 , Figure 3 The circuit schematic design PCB should include reserved terminal interfaces for "wire harness fatigue detection output" and "wire harness fatigue detection input"; Component soldering: Solder U2, U1, U3, M1, Q3 and all resistors and capacitors in sequence. After soldering, use a multimeter to check the continuity of each pin (to avoid cold solder joints). MCU Connection: Connect the IN pin of U2 to the PA0 pin of the MCU (MCU - enable signal output) through R12, connect the sampling terminal of U2 to the PA1 pin of the MCU (wire harness fatigue detection output sampling), connect the OUT pin of U1 to the PA2 pin of the MCU (AD sampling), and connect the VCC of the MCU to the 5V power supply and the GND to ground.

[0023] Diagnostic calculation module programming: Initialization configuration: Configure AD sampling (PA2 pin, 12-bit precision, 10Hz sampling rate) and GPIO (PA0 is a push-pull output, controlling U2 enable) in the MCU. Formula implementation: Formulas 1, 2, and 3 are written as software functions. Inputting V_OUT will output R_wire and health status. Threshold setting: The health warning threshold (default 80%) can be set via serial port command. When the health level is less than the threshold, the MCU's PB0 pin outputs a high level, driving the LED alarm light.

[0024] System debugging and verification: No-load debugging: Disconnect the custom wiring harness and check the voltage at the "wiring harness fatigue detection output" terminal of the output circuit (should be 5V), and the constant current of the input circuit (should be 0, because the circuit is open). Load testing: Connect the custom wiring harness, the MCU outputs a high level to enable U2, and collect V_OUT (should be 2.5V, corresponding to a health level of 100%). Fatigue simulation: The customized wire harness was fixed on the bending test machine (bending radius 5mm, frequency 1 time / second). V_OUT and health status were collected every 10,000 bends. After 50,000 bends, V_OUT dropped to 2.0V, the health status was 80%, and the LED alarm light lit up, which met the design expectations.

[0025] 4.3 Application Scenario Examples: Taking the joint harness of a robotic arm of an industrial robot as an example, the effect of applying this system is as follows: Original solution: The wiring harness was not inspected, and the robot would stop once every 6 months on average due to fatigue breakage, with maintenance costs (including downtime losses) of about 5,000 yuan. This solution sets a health threshold of 80% (corresponding to 50,000 bends). When the health level is detected to be below the threshold, an early warning is issued. Maintenance personnel can replace the wiring harness when the robot is idle (replacement time is 30 minutes). The annual maintenance cost is reduced to 1,000 yuan, and the number of downtimes is reduced to 0.

[0026] It will be apparent to those skilled in the art that this invention is not limited to the details of the foregoing exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A fatigue detection system for robotic arm wiring harnesses, characterized in that, Includes a custom wiring harness and a detection circuit, which are electrically connected; The customized wiring harness includes an insulating protective layer, a conductor portion, and a conductor to be tested. The insulating protective layer wraps around the conductor portion and the conductor to be tested for insulation protection. The conductor portion includes at least one pair of power lines and one pair of signal lines for power supply and signal transmission to the robotic arm. The conductor to be tested is made of multiple alloy metal wires with preset impedance twisted together. One end of the conductor is shorted by a PCB jumper, and the other end leads out to two terminals as input / output terminals for the detection signal. The detection circuit includes an output circuit and an input circuit. The two terminals of the wire being tested are electrically connected to the wire harness fatigue detection output terminal of the output circuit and the wire harness fatigue detection input terminal of the input circuit, respectively, forming a closed detection loop. The output circuit includes a high-side output chip U2, a current-limiting resistor R12, and voltage-dividing resistors R18 and R19. The IN pin of the high-side output chip U2 is connected to the enable signal output terminal of the MCU through R12, the VS pin of the high-side output chip U2 is connected to a 5V power supply, and the OUT pin of the high-side output chip U2 is the output terminal for wire harness fatigue detection. One end of the resistor R18 is connected to the OUT pin of the high-side output chip U2, and the other end of the resistor R18 is connected to one end of the resistor R19 and the wire harness fatigue detection output feedback terminal of the MCU. The other end of the resistor R19 is grounded. The high-side output chip U2 has a short-circuit protection function, and automatically cuts off the output when the output current of the OUT pin is too large.

2. The robotic arm wiring harness fatigue detection system according to claim 1, characterized in that, The input circuit includes a differential operational amplifier U1, an N-type MOSFET M1, a comparator U3, a transistor Q3, and resistors R8, R10, R13, R14, R15, R16, R17, and a capacitor C1. The IN+ pin of the differential operational amplifier U1 is connected to resistor R8 and capacitor C1. The other end of resistor R8 is connected to resistor R9 and the wire harness fatigue detection input terminal. The IN- pin of the differential operational amplifier U1 is connected to the other end of capacitor C1 and resistor R10. The other end of resistor R10 is connected to the other end of resistor R9 and the drain of the N-type MOSFET M1. The GS1 pin of the differential operational amplifier U1 is connected to resistor R11, and the other end of resistor R11 is connected to… The differential operational amplifier U1 has its GS0 pin connected to ground. The differential operational amplifier U1 outputs a differential amplified output voltage via its OUT pin. The source of the N-type MOSFET M1 is connected to resistor R17 and the inverting input V- of comparator U3, with the other end of resistor R17 grounded. The gate of the N-type MOSFET M1 is connected to the OUT pin of U3 via resistor R14 and simultaneously connected to a 5V power supply via pull-up resistor R13. The non-inverting input V+ of comparator U3 obtains a 0.5V reference voltage through a voltage divider between resistors R15 and R16. The base of transistor Q3 is connected to the gate of the N-type MOSFET M1, the emitter of transistor Q3 is grounded, and the collector of transistor Q3 is connected to the gate of the N-type MOSFET M1.

3. The robotic arm wiring harness fatigue detection system according to claim 1, characterized in that, The high-side output chip U2 is model BTT6200-1ENA. When the MCU enable signal output is high, the OUT pin of the high-side output chip U2 outputs 5V voltage; when the MCU enable signal output is low, the OUT pin of the high-side output chip U2 outputs 0V.

4. The robotic arm wiring harness fatigue detection system according to claim 2, characterized in that, The differential operational amplifier U1 is model AD8221, with R8 and R10 both having a resistance of 100Ω and C1 having a capacitance of 0.1μF.

5. The robotic arm wiring harness fatigue detection system according to claim 2, characterized in that, The comparator U3 is an LM339, and the resistance of R17 is 10Ω.

6. The robotic arm wiring harness fatigue detection system according to claim 2, characterized in that, The transistor Q3 is model S9013.

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