A non-hollow joint four-layer stacked driver with a very small diameter and high integration

Abstract

The application discloses a non-hollow joint four-layer stack driver with a small diameter and high integration, which comprises an interface plate, a signal plate, a core plate and a power plate, the interface plate, the signal plate, the core plate and the power plate are sequentially stacked along an axial direction and locked by studs, and the interface plate and the signal plate, the signal plate and the core plate and the core plate and the power plate are electrically connected by connectors. The application reduces the crosstalk of PWM switch noise on sensitive signals by deploying strong and weak electrical plates and independent horizontal planes, solves the joint jitter problem, locks the power heat source on the bottom layer and blocks heat conduction by using air gap, avoids the temperature drift and reset of the master control chip, realizes the effective thermal isolation of the power heat source and the precision control circuit, and completes the four-layer plate stacking and accommodates high-performance devices in a limited height by using low-height male and female connectors and stud locking, thus breaking the bottleneck of insufficient space integration.

Description

Technical Field

[0001] This application relates to the field of humanoid robot joint drive technology, specifically to a highly integrated non-hollow joint four-layer stacked driver with an extremely small diameter. Background Technology

[0002] As humanoid robots develop towards higher dynamic response, higher precision control, and higher integration, their joint drive systems, as the core execution units of the robots, directly determine the overall motion performance and energy efficiency. In recent years, the industry has conducted extensive research on the miniaturization, lightweighting, and high power density design of joint drives, but various technical approaches still exist in terms of drive circuit topology, power device layout, and electromagnetic compatibility.

[0003] Currently, the joint actuators of commonly used humanoid robots on the market typically employ one of the following two schemes in their internal circuit structure:

[0004] Option A, Single-board integration: The control circuit, drive circuit, and signal sampling circuit are all integrated onto a single circular or square circuit board, which is placed inside the rear end cover of the articulated motor. Some options use flexible printed circuit boards (FPCs) that are bent to fit the cylindrical inner cavity.

[0005] Option B, Hollow Wiring Solution: For high-torque joints, a hollow motor structure is adopted, with a large-diameter through hole in the center of the circuit board. The three-phase power lines of the power supply and the encoder harness pass through the center hole, and long pin headers or long-distance flying wires are used for inter-board connections.

[0006] However, both of these approaches currently have the following drawbacks:

[0007] 1. For single-board integration solutions

[0008] Within a tiny space of only 29mm in diameter, single-board integration prevents the high-voltage areas (power MOSFETs) from effectively separating the low-voltage areas (MCU controller, encoder interface). The high temperatures generated by the power devices are conducted through the copper foil, causing the entire board to heat up, leading to temperature drift in the main control chip, and even resetting it. At the same time, high-current PWM switching noise is directly coupled to sensitive signal lines through the ground plane, causing a decrease in position sampling accuracy and joint jitter.

[0009] 2. Regarding the hollow cable routing solution

[0010] A diameter of 29mm already falls into the category of micro joints. If a hollow structure is adopted, after deducting the space for the motor rotor, bearings, and wiring, the effective net width of the circuit board is often less than 5mm, which is simply insufficient to accommodate high-performance drive MOSFET arrays and electrolytic capacitors. This results in limited joint torque density, and the hollow structure will significantly increase the processing cost of micro motors.

[0011] In addition, within a cavity with a diameter of 29mm and a limited height, conventional pin header and female header connections would occupy too much axial height (approximately 4-6mm for a connector socket plus pins), making it impossible to complete the encapsulation of the four-layer board within the limited height. Summary of the Invention

[0012] To address these issues, this application provides a highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter, which solves the problems of crosstalk between strong and weak electrical signals, ineffective thermal isolation between power heat sources and precision control circuits, and insufficient spatial integration to accommodate high-performance devices and multi-layer stacking under the constraint of extremely small diameter non-hollow technology.

[0013] To achieve the above objectives, this application provides the following technical solution:

[0014] A highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter includes an interface board, a signal board, a core board, and a power board. The interface board, signal board, core board, and power board are stacked sequentially along the axial direction and locked together by studs. The interface board and the signal board, the signal board and the core board, and the core board and the power board are all electrically connected by connectors.

[0015] The power board integrates a buck circuit, a driver chip, a three-phase inverter full bridge, sampling resistors, and a differential sampling amplifier. The buck circuit converts the input DC power into a drive power supply and a low-voltage total input power supply. The drive power supply powers the driver chip, and the low-voltage total input power supply is transmitted to the core board through a connector between the power board and the core board. The three-phase inverter full bridge converts the input DC power into a three-phase AC voltage and outputs it. The sampling resistor collects the current flowing through the lower arm of the three-phase inverter full bridge and converts it into a sampling voltage. The sampling voltage is amplified by the differential sampling amplifier and transmitted to the core board through the connector between the power board and the core board.

[0016] The core board integrates a microcontroller, a first DC-DC converter network, a second DC-DC converter network, a detection circuit, and a reset circuit. The first DC-DC converter network converts the total low-voltage input power into two paths: one path powers the detection circuit and the reset circuit separately, and the other path is converted into two sensitive power rails through the second DC-DC converter network. The microcontroller receives the sampled voltage amplified by the differential sampling amplifier, generates a PWM drive signal, and transmits it to the driver chip through the connector between the power board and the core board.

[0017] The signal board integrates an industrial real-time communication controller chip and its matching network isolation transformer and RS485 transceiver.

[0018] The interface board integrates a physical interface that directly contacts the external wiring harness.

[0019] Preferably, the interface board, signal board, core board, and power board are stacked sequentially from top to bottom along the axial direction.

[0020] Preferably, all connectors are male-female connectors, and the signal board and the core board are electrically connected through two male-female connectors.

[0021] Preferably, the three-phase inverter full bridge is composed of MOSFETs.

[0022] Preferably, the step-down circuit is a BUCK step-down circuit, which is used to convert the input 48V DC power into a 12V drive power supply and a low-voltage total input power supply.

[0023] Preferably, the first DC-DC converter network is used to convert the 12V low-voltage total input power supply into two 5V DC voltages; the two sensitive power rails are 3.3V and 1.2V DC voltages.

[0024] Preferably, the PWM drive signal is a six-channel PWM drive signal.

[0025] Preferably, the side of the interface board closest to the signal board is fully covered with a copper grounding layer.

[0026] Preferably, the physical interfaces integrated on the interface board include: an Ethernet interface, a motor temperature sensor interface, an analog input interface, an encoder input interface, and a system debugging interface.

[0027] Preferably, the interface board, signal board, core board, and power board are all circular circuit boards with a diameter not exceeding 29mm; the studs are metal studs that penetrate the four circuit boards and are used to lock the four circuit boards into a cylindrical electrical module.

[0028] Compared with the prior art, this application has at least the following beneficial effects:

[0029] 1. This application provides a highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter, comprising: an interface board, a signal board, a core board, and a power board. The interface board, signal board, core board, and power board are stacked sequentially along the axial direction and locked together by studs. The interface board and signal board, the signal board and core board, and the core board and power board are electrically connected by connectors. The power board integrates a step-down circuit, a driver chip, a three-phase inverter full bridge, a sampling resistor, and a differential sampling amplifier. The core board integrates a microcontroller, a first DC-DC converter network, a second DC-DC converter network, a detection circuit, and a reset circuit. The signal board integrates an industrial real-time communication controller chip and its matching network isolation transformer and RS485 transceiver. The interface board integrates a physical interface that directly contacts an external wiring harness. This application reduces the crosstalk of PWM switching noise to sensitive signals by deploying strong and weak current circuits separately and on an independent ground plane, thus solving the problem of joint jitter. By locking the power heat source at the bottom layer and using air gaps to block heat conduction, it avoids temperature drift and reset of the main control chip, achieving effective thermal isolation between the power heat source and the precision control circuit. By using low-height male and female connectors and studs for locking, it completes the stacking of four-layer boards within a limited height and accommodates high-performance devices, breaking through the bottleneck of insufficient space integration.

[0030] 2. The side of the interface board closest to the signal board is fully covered with a copper grounding layer to form an electromagnetic shield, suppressing the impact of external static electricity and electromagnetic interference on the high-frequency communication circuit of the signal board. Attached Figure Description

[0031] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0032] Figure 1 A schematic diagram of a highly integrated, non-hollow joint four-layer stacked actuator with an extremely small diameter provided in this application;

[0033] Figure 2 The circuit block diagram of a highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter is provided in this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Interface board; 2. Signal board; 3. Core board; 4. Power board. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] In the description of this application: unless otherwise stated, "a plurality of" means two or more. The terms "first," "second," "third," etc., in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "including," "comprising," and "having" also mean "not limited to" (certain units, components, materials, steps, etc.).

[0038] The terms used in this application, such as "upper," "lower," "left," "right," and "middle," are generally used to indicate the general relative positional relationship for the purpose of intuitive understanding by referring to the accompanying drawings, and are not absolute limitations on the positional relationship in the actual product.

[0039] This application provides a highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter, aiming to solve three deep-seated hardware contradictions in micro-drive systems under a 29mm non-hollow constraint:

[0040] 1. Power distribution conflict: How to build a "noise reduction" vertical power supply link on a four-layer physically separated circuit board to ensure that the high-voltage BUCK does not interfere with the low-voltage BUCK and achieve a system-level power supply with a high power rejection ratio.

[0041] 2. Signal isolation contradiction: How to use vertical space to replace horizontal space and physically isolate the three functional domains of EtherCAT high-frequency communication, MCU logic operation and power inverter in three dimensions to block crosstalk paths from a structural perspective.

[0042] 3. Thermal-electric coupling contradiction: How to lock the power heat source at the bottom layer through forced partitioning of hardware layout, block the conduction of heat to MCU and precision operational amplifier, and achieve constant temperature precision control.

[0043] Based on the above objectives, this application provides a highly integrated non-hollow joint four-layer stacked driver with an extremely small diameter (hereinafter referred to as: four-layer stacked driver). The four-layer stacked driver is a 29mm micro joint driving system based on a four-layer physical stack and signal isolation architecture. It solves the conflict between electromagnetic compatibility and thermal management under extremely small size by decoupling the strong and weak current, communication and control, and power conversion in a vertical three-dimensional hardware manner.

[0044] Please see Figure 1This application provides a highly integrated, non-hollow joint four-layer stacked driver with an extremely small diameter, comprising: an interface board 1, a signal board 2, a core board 3, and a power board. The interface board 1, signal board 2, core board 3, and power board are stacked sequentially from top to bottom along the axial direction and locked together by studs. The interface board 1 and signal board 2, the signal board 2 and core board 3, and the core board 3 and power board 4 are electrically connected by connectors. The connectors are convex and concave connectors (hereinafter referred to as convex and concave connectors).

[0045] Please see Figure 2 The power board 4 integrates a buck circuit, a driver chip, a three-phase inverter bridge, sampling resistors, and a differential sampling amplifier. The buck circuit uses a BUCK buck circuit, and the three-phase inverter bridge is composed of MOSFETs. The buck circuit converts the input 48V DC power into a 12V drive power supply and a low-voltage total input power supply. The drive power supply powers the driver chip, and the low-voltage total input power supply is transmitted to the core board 3 through the connector between the power board and the core board 3. The three-phase inverter bridge converts the input DC power into a three-phase AC voltage for output. The sampling resistor collects the current flowing through the lower arm of the three-phase inverter bridge and converts it into a sampling voltage. The sampling voltage is amplified by the differential sampling amplifier and transmitted to the core board 3 through the connector between the power board 4 and the core board 3.

[0046] The core board 3 integrates a microcontroller (MCU), a first DC-DC converter network, a second DC-DC converter network, a detection circuit, and a reset circuit. The first DC-DC converter network converts the 12V low-voltage main input power into two 5V DC voltages. One 5V DC voltage is used to power the detection circuit and the reset circuit separately, and the other is converted into two sensitive power rails of 3.3V and 1.2V respectively through the second DC-DC converter network. The microcontroller receives the sampled voltage after it is amplified by the differential sampling amplifier, generates six PWM drive signals, and transmits them to the driver chip through the connector between the power board 4 and the core board 3.

[0047] In this application, power board 4 and core board 3 implement a power tree architecture and a hierarchical power supply network, wherein the power supply network adopts a layout of graded step-down and physical isolation:

[0048] Power stage power supply (power board 4): The power board 4 is equipped with a 48V to 12V BUCK step-down circuit. The 12V output is divided into two paths: the first path directly supplies the MOSFET driver chip on the power board 4 as the driving power supply; the second path transmits upward to the core board 3 through the convex and concave connectors as the total input power supply for subsequent low-voltage circuits.

[0049] Logic-level power supply (core board 3): Core board 3 receives 12V voltage from power board 4. Core board 3 integrates a two-stage DC-DC conversion network (i.e., the first DC-DC conversion network and the second DC-DC conversion network). Specifically, it includes: one 12V to 5V DC-DC circuit, used to supply the detection chip and reset chip on core board 3; and another 5V to 3.3V or 1.2V DC-DC circuit, which supplies the MCU core and I / O ports, encoder chip and communication PHY chip on core board 3 respectively.

[0050] Beneficial effects: This vertical power tree structure, which places the high-voltage, high-current BUCK at the bottom layer and the low-voltage precision power supply in the middle layer, utilizes the axial distance to naturally attenuate the conducted interference of high-voltage BUCK switching noise on the 3.3V or 1.2V sensitive power rails.

[0051] In this application, power board 4 and core board 3 also implement a cross-board signal interaction architecture for power circuits and low-voltage control, wherein the electrical isolation interface between the high-voltage power circuit and the low-voltage control circuit is located at the connector between power board 4 and core board 3:

[0052] Power circuit physical layout (power board 4): Power board 4 is equipped with a three-phase inverter full bridge composed of MOSFETs and a sampling resistor connected in series between the source of the lower bridge arm MOSFET and ground. Power board 4 also integrates a differential sampling amplifier, which is used to amplify the weak voltage drop across the sampling resistor and convert it into a single-ended voltage signal with reference to ground.

[0053] Sampling and vertical transmission of the PWM signal, including:

[0054] Current sampling signal uplink: The current feedback analog signal output by the differential amplifier is transmitted to the MCU analog-to-digital conversion pin on the core board 3 through the convex and concave connectors between the power board 4 and the core board 3.

[0055] Downward PWM control signal: The 6-channel PWM drive signal generated by the MCU on the core board 3 based on the current feedback is also sent vertically downward to the input terminal of the MOSFET driver chip on the power board 4 via this connector.

[0056] Beneficial effects: This architecture achieves hardware isolation where "power board 4 only carries large currents and does not process small signals; core board 3 only performs calculations and is not subject to thermal stress." The heat generated by the copper foil on power board 4 will not affect the drift of the sampling reference voltage of the core board MCU through heat conduction.

[0057] Signal board 2 integrates an industrial real-time communication controller chip and its matching network isolation transformer and RS485 transceiver; the industrial real-time communication controller chip adopts an EtherCAT slave controller. In this application, signal board 2 receives EtherCAT data frames from the network port of interface board 1, parses them, and transmits the target position or torque command to core board 3 through the inter-board connector; at the same time, the actual position, current, and temperature status calculated by core board 3 are transmitted back to signal board 2 through the connector for packaging and uploading.

[0058] This application centrally deploys the susceptible high-frequency communication signals and sensitive analog signals on the signal board 2, and uses the core board 3 and interface board 1 above and below it for physical shielding, thereby realizing the convergence of the intermediate layer of real-time industrial communication and sensor interface.

[0059] Interface board 1 integrates physical interfaces that directly contact external wiring harnesses, including: an Ethernet interface, a motor temperature sensor interface, an analog input interface, an encoder input interface, and a system debugging interface. This application integrates all physical interfaces that directly contact external wiring harnesses onto interface board 1, achieving fault tolerance and protection for the external interfaces.

[0060] In this application, the interface board 1 is fully covered with a copper grounding layer on the side closest to the signal board 2. When the four boards are locked together by studs, the interface board 1 not only undertakes the electrical connection function, but also serves as the top cover electromagnetic shield of the entire drive module to suppress the impact of external electrostatic discharge on the internal signal board.

[0061] In the ultra-small diameter, highly integrated, non-hollow joint four-layer stacked driver provided in this application, the interface board 1, signal board 2, core board 3, and power board 4 are all circular circuit boards with a diameter not exceeding 29 mm; the studs are metal studs that penetrate the four circuit boards and are used to lock the four circuit boards into a cylindrical electrical module. That is to say, in this application, the above four circuit boards are stacked axially through board-to-board male-female connectors and physically locked into a cylindrical electrical module with a diameter not exceeding 29 mm by two through studs. This module can be directly inserted into the rear end of the joint motor and connected to the external power supply and the three-phase windings of the motor through edge wiring notches.

[0062] The extremely small diameter, highly integrated, non-hollow joint four-layer stacked driver provided in this application has the following advantages:

[0063] 1. High power integrity: Through a three-dimensional power tree architecture, the high-voltage BUCK and low-voltage BUCK are separated in the Z-axis direction and the parasitic inductance of the inter-board connector is used for filtering. When the system is running at full load, the 1.2V core ripple of the MCU is reduced compared with the single-board solution, and the program lock-up caused by power noise is suppressed.

[0064] 2. High signal fidelity: By confining the current sampling analog link and the EtherCAT high-speed digital link to two independent physical entities, power board 4 and signal board 2, respectively, the common-mode noise coupling path is reduced. The signal-to-noise ratio of current sampling is consistently improved, enabling smooth torque control rather than coarse position control even for 29mm micro-joints.

[0065] 3. Thermal Stability: The power heat source is forcibly locked to the power board 4 through hardware layout, and the conduction path of heat to the core board 3 is blocked by air gaps and connector thermal resistance. The MCU operating temperature remains relatively constant, avoiding the decrease in torque control accuracy caused by temperature drift.

[0066] 4. System-level modularity: The four circuit boards correspond to the interface domain, protocol domain, computing power domain, and power domain, respectively. During R&D, debugging, or after-sales maintenance, if an EtherCAT communication anomaly is found, only signal board 2 needs to be replaced; if low efficiency is found, only power board 4 needs to be optimized. This strict correspondence between functionality and physical entities lowers the maintenance threshold of micro-precision systems.

[0067] In summary, this application reduces the crosstalk of PWM switching noise to sensitive signals and solves the joint jitter problem by deploying strong and weak current circuits separately and on an independent ground plane; by locking the power heat source at the bottom layer and using air gaps to block heat conduction, it avoids temperature drift and reset of the main control chip and achieves effective thermal isolation between the power heat source and the precision control circuit; by using low-height male and female connectors and studs for locking, it completes the stacking of four-layer boards within a limited height and accommodates high-performance devices, breaking through the bottleneck of insufficient space integration.

[0068] The technical features of the above embodiments can be combined in any way (as long as there is no contradiction in the combination of these technical features). For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A highly integrated, non-hollow joint four-layer stacked actuator with an extremely small diameter, characterized in that, include: The interface board, signal board, core board, and power board are stacked sequentially along the axial direction and locked together by studs. The interface board and the signal board, the signal board and the core board, and the core board and the power board are all electrically connected by connectors. The power board integrates a buck circuit, a driver chip, a three-phase inverter full bridge, sampling resistors, and a differential sampling amplifier. The buck circuit converts the input DC power into a drive power supply and a low-voltage total input power supply. The drive power supply powers the driver chip, and the low-voltage total input power supply is transmitted to the core board through a connector between the power board and the core board. The three-phase inverter full bridge converts the input DC power into a three-phase AC voltage and outputs it. The sampling resistor collects the current flowing through the lower arm of the three-phase inverter full bridge and converts it into a sampling voltage. The sampling voltage is amplified by the differential sampling amplifier and transmitted to the core board through the connector between the power board and the core board. The core board integrates a microcontroller, a first DC-DC converter network, a second DC-DC converter network, a detection circuit, and a reset circuit. The first DC-DC converter network converts the total low-voltage input power into two paths: one path powers the detection circuit and the reset circuit separately, and the other path is converted into two sensitive power rails through the second DC-DC converter network. The microcontroller receives the sampled voltage amplified by the differential sampling amplifier, generates a PWM drive signal, and transmits it to the driver chip through the connector between the power board and the core board. The signal board integrates an industrial real-time communication controller chip and its matching network isolation transformer and RS485 transceiver. The interface board integrates a physical interface that directly contacts the external wiring harness.

2. The ultra-small diameter, highly integrated, non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The interface board, signal board, core board, and power board are stacked sequentially from top to bottom along the axial direction.

3. The ultra-small diameter, highly integrated, non-hollow joint four-layer stacked driver according to claim 1, characterized in that, All connectors are male-female connectors, and the signal board and the core board are electrically connected through two male-female connectors.

4. The ultra-small diameter, highly integrated non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The three-phase inverter full bridge is composed of MOSFETs.

5. The ultra-small diameter, highly integrated, non-hollow joint four-layer stacked actuator according to claim 1, characterized in that, The step-down circuit is a BUCK step-down circuit, which is used to convert the input 48V DC power into a 12V drive power supply and a low-voltage main input power supply.

6. The ultra-small diameter, highly integrated non-hollow joint four-layer stacked driver according to claim 5, characterized in that, The first DC-DC converter network is used to convert the 12V low-voltage total input power supply into two 5V DC voltages; the two sensitive power rails are 3.3V and 1.2V DC voltages.

7. The ultra-small diameter, highly integrated non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The PWM drive signal is a six-channel PWM drive signal.

8. The ultra-small diameter, highly integrated, non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The interface board is fully covered with a copper grounding layer on the side closest to the signal board.

9. The ultra-small diameter, highly integrated non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The physical interfaces integrated on the interface board include: an Ethernet interface, a motor temperature sensor interface, an analog input interface, an encoder input interface, and a system debugging interface.

10. The ultra-small diameter, highly integrated, non-hollow joint four-layer stacked driver according to claim 1, characterized in that, The interface board, signal board, core board, and power board are all circular circuit boards with a diameter not exceeding 29mm; the studs are metal studs that penetrate the four circuit boards and are used to lock the four circuit boards into a cylindrical electrical module.

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