Manipulator control system based on flexible sensor and wireless technology

Abstract

The invention relates to the technical field of flexible electronics and man-machine interaction, in particular to a manipulator control system based on a flexible sensor and a wireless technology. The invention discloses a manipulator control system based on a flexible sensor and a wireless technology. The manipulator wireless control system is mainly composed of a flexible sensing unit, a main control unit, a wireless communication unit and an execution unit. Human body action signals are captured in real time through the flexible sensor unit, and intelligent interaction of the manipulator is achieved in combination with Bluetooth low-delay transmission and high-precision steering engine control. The functional application scene of the flexible sensor is expanded, and the flexible sensor has a wide application prospect in dangerous tasks such as hazardous chemical substance disposal and fire rescue.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics and human-computer interaction technology, specifically to a robotic arm control system based on flexible sensors and wireless technology, which is particularly suitable for high-precision motion capture, low-latency transmission, and multi-scenario collaborative control. Background Technology

[0002] With advancements in flexible electronics and human-computer interaction technologies, robotic arms are increasingly being used in industrial collaboration, medical assistance, and consumer services. Existing robotic arm control systems largely rely on rigid structures and wired transmission. These systems, dependent on physical cables for signal transmission, have limited operational freedom and are ill-suited for complex or remote scenarios. In dynamic interaction scenarios, rigid transmission structures are prone to mechanical damage from accidental collisions (such as gear jamming or link deformation), and can even cause destructive impacts on objects they contact (especially fragile items or human tissue). Furthermore, the low strain detection range (typically <5%) and hysteresis of traditional sensors limit the precise feedback of robotic arms to subtle movements, making it difficult to achieve compliant touch responses similar to those found in biological tissues.

[0003] While existing flexible sensors have partially solved the compliance problem of robotic arms, bottlenecks such as material fatigue (e.g., conductive layer peeling), signal hysteresis (response time > 500 ms), and poor environmental adaptability still exist. Therefore, there is an urgent need for a robotic arm system with high sensitivity, high stability, and support for wireless intelligent control.

[0004] Therefore, developing novel robotic arm systems with flexible transmission mechanisms and high environmental adaptability has become a key breakthrough in improving the safety and operational accuracy of human-machine collaboration. This invention proposes a robotic arm control system based on flexible sensors and wireless communication. Compared to traditional wired robotic arms, wireless robotic arms are highly flexible, free from the constraints of cables, and can capture real-time changes in the operator's hand posture, allowing for more flexible movement to various corners and the completion of more complex tasks. It achieves high-precision reproduction of human movements and is characterized by stability and durability. This invention improves the efficiency and naturalness of human-machine interaction and has broad application potential in fields such as medical rehabilitation, industrial automation, and virtual reality. Summary of the Invention

[0005] To overcome the shortcomings of existing technical solutions, this invention proposes a robotic arm control system based on flexible sensors and wireless communication, aiming to achieve high-precision motion capture, low-latency transmission, and multi-scenario collaborative control through modular design.

[0006] The system disclosed in this invention adopts a four-layer architecture, including a flexible sensing unit, a main control unit, a wireless communication unit, and an execution unit. Each unit has independent functions and works collaboratively through a standardized interface.

[0007] The flexible sensing unit is responsible for real-time detection of human body movement deformation and outputting electrical signals.

[0008] The main control unit is used to filter, calibrate, and encapsulate sensor signals to generate standardized control commands.

[0009] The wireless communication unit is used to establish a two-way communication link between the main control unit and the execution unit to ensure efficient instruction transmission.

[0010] The execution unit is used to parse instructions and generate pulse width modulation (PWM) signals to achieve multi-channel servo motor coordinated control and drive the robot arm to reproduce actions.

[0011] Flexible sensing unit:

[0012] The conductive fiber strain sensor adopts a multi-layer composite design, including: an elastic fiber skeleton; a conductive layer covering the surface of the elastic fiber skeleton to form a strain-sensitive structure; and an encapsulation layer encapsulating the conductive layer to form a multi-layer structure sensor.

[0013] Conductive fiber strain sensors have the ability to identify the amplitude of motion and the location of movement. Human movement causes deformation of the sensor, and the change in resistance of the conductive layer is linearly related to the strain, thus enabling accurate detection of the amplitude and location of the movement.

[0014] Main control unit:

[0015] The system employs an STM32F103C8T6 microcontroller based on the ARM Cortex-M3 core, with a main frequency of 72 MHz, integrating a 12-bit ADC (sampling rate 1kHz) and a direct memory access module. It is configured with a 16 MHz crystal oscillator, a serial line debugging interface, and an ASEMI linear regulator chip (AMS11173.3) as an automatic regulator.

[0016] By combining moving average filtering and Kalman filtering algorithms, environmental noise can be suppressed.

[0017] Based on a preset calibration curve (such as the ΔV / V0-bending angle mapping table), the original signal is converted into an action angle value, and then the angle value is further bound to the action position encoding to generate a fixed format instruction frame.

[0018] Wireless communication unit:

[0019] This master-slave integrated Bluetooth serial port module, based on the Bluetooth 4.0 protocol standard, has a transmission distance of up to 10 meters. The master and slave Bluetooth modules complete Bluetooth pairing and establish a stable serial port pass-through link at a baud rate of 9600 bps. It supports redundant link design; in the event of single-channel interference, it automatically switches to a backup link with a switching time of <50 ms.

[0020] Based on data compression and priority scheduling, data transmission is optimized by packaging multi-sensor signals into a single instruction frame to reduce the number of transmissions; critical instructions (such as emergency stop) are transmitted first to ensure system security.

[0021] Execution unit:

[0022] The PCA9685 multi-channel PWM controller is selected and connected to the slave HC05 Bluetooth module through a universal asynchronous transceiver. It supports 16 independent PWM signal outputs, each with a resolution of 12 bits (0.5° accuracy).

[0023] Motion control logic: Parse command frames and match preset motion libraries (such as "grasp" and "extend"); generate corresponding PWM signals through internal timers and dynamically adjust the duty cycle to control the servo angle; multi-servo coordination, using phase offset technology to avoid current surges caused by simultaneous switching of multiple PWM channels.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) The sensor adopts a multi-layer composite design with a thickness of only 1 mm and a weight of <5 g. It can be attached to the back of the finger without any binding sensation, making it suitable for long-term rehabilitation training or industrial operation. Its three-dimensional conductive network linear response (R²=0.996) significantly suppresses signal hysteresis (response time <20 ms), solving the problem of accuracy loss in fine motion capture of traditional sensors.

[0026] (2) The direct memory access module of STM32F103C8T6 directly processes the original voltage signal, eliminating the need for external ADC conversion; combined with the moving average and Kalman filtering algorithms, it suppresses signal fluctuations in industrial noise environments and maps angle values ​​in real time through a preset calibration curve, laying the core foundation for low-latency control.

[0027] (3) Construct a dual-channel redundant link and use Bluetooth 4.0 transparent transmission technology to achieve wireless operation with a radius of 10 m (effective distance through walls is 8 m), thus getting rid of the physical cable limitation; master-slave pre-pairing and automatic switching mechanism, communication is restored within 42 ms under 2.4 GHz band interference (interruption rate <1%), and the robot arm moves stably and synchronously, overcoming the reliability problem of wireless control in dynamic scenarios. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the robotic arm control system provided in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the physical connection structure of the robotic arm control system provided in an embodiment of the present invention.

[0030] Figure 3This is a schematic diagram of the finger sensing signal provided in an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of multi-gesture signal monitoring provided in an embodiment of the present invention.

[0032] Figure 5 This is one of the schematic diagrams of robotic arm control provided in an embodiment of the present invention.

[0033] Figure 6 This is a second schematic diagram of the robotic arm control provided in an embodiment of the present invention. Detailed Implementation

[0034] To better illustrate the content of this invention, the following description is provided in conjunction with the accompanying drawings and embodiments. It should be noted that the descriptions in the embodiments are only for explaining the solutions of this invention and are not intended to limit this invention.

[0035] Example: Flexible sensor signal detection and low-latency collaborative control of robotic arm

[0036] A robotic arm control system based on flexible sensors and wireless communication aims to achieve high-precision motion capture, low-latency transmission, and multi-scenario collaborative control through modular design. Figure 1 As shown, the system adopts a four-layer architecture, including a flexible sensing unit, a main control unit, a wireless communication unit, and an execution unit. Each unit has independent functions and works together through standardized interfaces.

[0037] The flexible sensing unit uses a MWCNTs / SPF@Ecoflex sensor, and the composite structure includes: an elastic fiber skeleton, a multi-walled carbon nanotube (MWCNTs) conductive layer, and an Ecoflex flexible material-encapsulated conductive layer.

[0038] The physical connection structure of the wireless robotic arm control system consists of MWCNTs / SPF@Ecoflex sensors fixed to the back of the human finger, along with a main control chip, Bluetooth transmission module, voltage regulator, driver chip, and robotic arm, forming a wirelessly controlled robotic arm. Figure 2 (As shown).

[0039] Resistance measurements were performed using a KEYSIGHT 34465A digital multimeter (sampling rate 1000 Hz). The measurement of resistance changes was achieved by measuring the stretching strain in the flexible sensor caused by finger movement, which in turn caused a change in the sensor's electrical signal. Figure 3 As shown, the ΔR / R0 corresponding to finger joint bending at 20°, 30°, 60° and 90° is monitored (e.g. 20° corresponds to ΔR / R0=0.8, 90° corresponds to ΔR / R0=3.5).

[0040] The system detects and recognizes multiple hand gestures, starting from the extended five-finger state and sequentially performing hand gestures representing numbers such as "three", "two", "six", "four" and "zero". Before each next action, the hand gesture is restored to the extended five-finger state. Figure 4 As can be seen, the MWCNTs / SPF@Ecoflex flexible strain sensor exhibits excellent repeatability and stability during multiple gesture transitions. When the sensor switches from a stretched state to a relaxed state, the servo voltage signal shows a steep falling edge and a short signal response time; conversely, the signal response remains rapid even when the sensor switches from a stretched state to a relaxed state.

[0041] Based on data compression and priority scheduling, data transmission is optimized by packaging multi-sensor signals into a single instruction frame to reduce the number of transmissions; critical instructions (such as emergency stop) are transmitted first to ensure system security.

[0042] The robotic arm's motion control works as follows: when a finger bending angle is detected, the host machine encapsulates the finger motion data collected and processed by the sensor into a fixed-format command frame and transmits it wirelessly to the slave machine via Bluetooth. Upon receiving the command, the slave control chip generates a corresponding (PWM) signal based on the parsed command through its internal timer module. The PWM signal is amplified by the PCA9685 servo driver chip to provide sufficient current to drive multiple servos in coordinated motion.

[0043] Synchronized motion and gripping control: Wearable flexible sensors capture changes in the operator's hand posture, driving the robotic arm to accurately reproduce movements, completing gestures symbolizing numbers such as "two," "three," "six," and "four," as well as gripping gestures. Figure 5 and 6 (As shown). The small synchronization error between the robot's motion trajectory and the operator's hand posture proves the accuracy of dynamic signal capture and the stability of the hardware and software coordination of the robot control system.

[0044] Delay and synchronization tests showed an end-to-end latency of ≤300 ms, with a 150 ms latency from sensor data acquisition to data processing. This latency was accelerated using the STM32's direct memory access functionality. The execution response latency was 300 ms (servo motor speed 60° / 0.1 s), and the synchronization error between the robot arm angle and the operator's hand posture was <2°.

Claims

1. A flexible sensor and wireless technology mechanical hand control system, characterized by, The application relates to a flexible sensor system for human motion replication. The system comprises a flexible sensor unit, a main control unit, a wireless communication unit and an execution unit. The flexible sensor unit is selected from conductive fiber strain sensors for detecting human motion deformation and outputting electric signals. The main control unit comprises a voltage stabilizer and a main control chip for filtering and data processing of the electric signals. The wireless communication unit realizes bidirectional data transmission between the main control unit and the execution unit based on a low-delay protocol. The execution unit comprises a slave and a mechanical hand for converting the processed signals into mechanical hand motion instructions to realize motion replication.

2. A robot control method based on a flexible strain signal and low latency wireless communication, characterized by, The application comprises the following steps: (1) The resistance of the flexible sensor changes due to human motion deformation, and the voltage signal is sent to the driving chip after voltage division; (2) The signal is filtered and data-encapsulated in real time to form control instructions; (3) The instructions are transmitted to the execution end through a wireless communication protocol; and (4) The instructions are parsed and pulse width modulation signals are generated to drive the mechanical hand to replicate the motion. In step (1), the flexible sensor is attached to the back of a human finger, covering the area from the proximal phalanx to the distal phalanx, and the joint motion amplitude is distinguished by detecting the deformation of different parts. In step (2), the data encapsulation comprises binding the sensor signal and the motion position code to form a fixed-format instruction frame. In step (3), the wireless communication protocol supports master-slave redundant link design, and the encapsulated data is sent from the main control chip to the slave, and the single channel is automatically switched to the standby link when disturbed. In step (4), the generation of the pulse width modulation signal comprises matching a preset motion library through an internal timer module and dynamically adjusting the pulse width to realize accurate angle control.

3. The flexible sensing unit of claim 1, wherein, The flexible sensor has a multilayer composite structure. The conductive fiber strain sensor structure comprises an elastic fiber framework, a conductive layer covering the surface of the elastic fiber framework to form a strain-sensitive structure and an encapsulation layer wrapping the conductive layer to form a multilayer structure sensor. The resistance of the flexible sensor changes, and the voltage signal is sent to the main control chip after voltage division.

4. The master unit of claim 1, wherein, The main control unit integrates a signal filtering algorithm, directly processes the original sensor data, converts the voltage from an analog signal to a digital signal, reduces the time consumption of intermediate links and makes the overall system delay less than 300 ms. The voltage stabilizer is used for inhibiting high-frequency noise and outputting stable voltage to ensure communication reliability. Further, the main control chip is preferably a microcontroller based on the ARM Cortex-M series kernel.

5. The wireless communication unit of claim 1, wherein, The wireless communication protocol comprises but is not limited to Bluetooth, WIFI and Zigbee, the communication baud rate is not less than 9600 bps and the transmission distance is greater than or equal to 10 m. Further, a master-slave integrated serial port module supporting the Bluetooth 4.0 standard is preferably used. Further, the Bluetooth module is connected with the main control chip and the slave through a universal asynchronous receiver-transmitter. Further, the encapsulated instructions are transmitted to the slave through Bluetooth.

6. The execution unit of claim 1, wherein, The slave selects a multi-channel pulse width modulation signal output chip and supports simultaneous driving of multiple servo motors for cooperative action. The slave reads target angle and motion speed information in real time through a serial port, parses the sending instructions and sends the instructions to the mechanical hand. The mechanical hand rapidly responds to the issued instructions under the cooperative working mechanism of software and hardware.

7. A flexible sensor and wireless technology based robot control system having the control system of any one of claims 1-6.

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