A driving control system of a robot dexterous hand based on Mecanum wheels

Abstract

The application discloses a driving control system of a robot dexterous hand based on Mecanum wheels, which communicates with an upper computer through a data line, the dexterous hand is provided with a rudder that controls the movement and rotation of the finger joints, and a DC motor that controls the rotation of the Mecanum wheels in the finger joints, and the system comprises a single-chip microcomputer, a voltage drop module, a motor driving board and a DC stabilized power supply; one end of the DC stabilized power supply is connected with the voltage drop module in series to supply power to the rudder after voltage reduction, and the other end is connected with the motor driving board to supply power to the DC motor; the single-chip microcomputer and the upper computer use serial communication, the control signals sent by the upper computer are processed and sent to the rudder and the motor driving board, and the motor driving board drives the DC motor according to the signals. The system of the application reduces the complexity and manufacturing cost of the system while maintaining the flexibility of the dexterous hand operation, realizes multi-degree-of-freedom operation on objects, and has potential application fields and expansion prospects.

Description

Technical Field

[0001] This invention belongs to the field of intelligent robot technology and relates to a drive control system for a robot dexterous hand based on Mecanum wheels. Background Technology

[0002] Since the beginning of the 21st century, industrial robots have played an increasingly important role in military, aerospace, healthcare, and industrial production. As the final link in the interaction between the robot and its environment, the design of the end effector has a significant impact on the robot's compliance and maneuverability; its performance directly affects the robot's work performance. However, traditional industrial robot end effectors suffer from drawbacks such as fixed application scenarios, limited grasping targets, and insufficient dexterity, requiring a wide range of movements of the robotic arm to complete the pose adjustment operations on objects such as express delivery boxes and logistics packages. To address the issue of large workspace requirements for robots performing complex operations, designing a dexterous robotic hand capable of in-hand manipulation is a relatively effective solution.

[0003] Intrahand manipulation capability of a dexterous hand refers to its ability to shift from an initial grasping configuration to other grasping configurations and reposition an object. For example, it may have the ability to contact surfaces of objects not touched in the initial grasping position, or the ability to change the pose of the grasped object in its current position to establish a more stable grip. Based on the existing dexterous hands described above, their methods of achieving intrahand manipulation can be broadly categorized into the following two types:

[0004] I. Finger Coordination Movements: Using the coordinated movements of the fingers in a dexterous hand to manipulate objects is a common method. Dexterous hand fingers typically consist of joints and knuckles, which can simulate the movements of the human hand and possess good flexibility. By controlling the joints and knuckles of the dexterous hand to achieve coordinated movements between the fingers, hand manipulation of objects can be realized. Table 1 shows the parameters of some existing dexterous hands that perform hand manipulations of objects through finger coordination movements.

[0005] Table 1. Dexterous hands that perform intramanual operations through coordinated finger movements.

[0006]

[0007]

[0008] As shown in the table, although dexterous hands that rely on this method to manipulate objects have strong in-hand manipulation capabilities, they generally have a relatively complex drive control system, a relatively large number of finger joints, and a relatively complex structural design. Therefore, they have high manufacturing costs, are difficult to maintain, and have low equipment robustness. As a result, they have not been widely used in other scenarios outside of laboratory research.

[0009] II. Fingers with Movable Surfaces: In recent years, an increasing number of dexterous hand devices have focused on structural simplification. These dexterous hands add extra degrees of freedom to the fingers, using the movement of movable surfaces (such as drive belts) within the fingers after grasping to perform complex intramanual operations that would otherwise require multi-finger coordination or wrist rotation. This is equivalent to enabling a directional intramanual transfer of the manipulated object, thus allowing manipulation of objects without significantly altering the dexterous hand's grasping posture. Movable surfaces have the ability to form new contact points without completely detaching from the object, especially for objects whose geometry remains stable during intramanual manipulation, minimizing pose changes of the dexterous hand and its attached robotic arm during testing. Furthermore, actively driven movable surfaces can be designed modularly, expanding existing dexterous hand design concepts. Table 2 shows the parameters of some existing dexterous hands that perform intramanual manipulation by adding movable surfaces to the fingers.

[0010] Table 2. Dexterous hands that perform intra-hand operations using fingers with movable surfaces.

[0011]

[0012]

[0013] The above research demonstrates that utilizing one or more drivable moving surfaces can enhance the in-hand manipulation capabilities of dexterous hands. However, while these simplified dexterous hands reduce design complexity and manufacturing costs, the movement direction of the moving surface is often limited, resulting in a very limited range of in-hand manipulations and sacrificing the dexterous hand's flexibility. Therefore, these dexterous hands are often designed for specific applications such as pulling a bucket axially inward or rotating a hand drill along its handle.

[0014] From the two methods of achieving in-hand manipulation described above, it can be seen that the in-hand manipulation capability of a dexterous hand is mainly related to its structural design, and each design method has its own characteristics. By controlling the angle and position of each finger joint, multi-finger coordinated movement can be achieved. This method gives the dexterous hand strong in-hand manipulation flexibility, enabling in-hand manipulation of the grasped object in all degrees of freedom. Arranging movable surfaces on the fingers that can be actively driven or passively adapted results in a relatively simplified mechanical structure. The current challenge in dexterous hand development is how to combine the advantages of both methods, ensuring excellent object manipulation capability while maintaining sufficient simplicity in the mechanism, all while ensuring grasping ability. Summary of the Invention

[0015] To address the aforementioned technical problems in the existing technology, this invention proposes a drive control system for a robot dexterous hand based on Mecanum wheels, the specific technical solution of which is as follows:

[0016] A drive control system for a robot dexterous hand based on Mecanum wheels communicates with a host computer via a data cable. The dexterous hand is equipped with servo motors that control the movement and rotation of its finger joints, and DC motors located in the finger joints that control the rotation of the Mecanum wheels. The system includes a microcontroller, a voltage drop module, a motor driver board, and a DC regulated power supply. One end of the DC regulated power supply is connected in series with the voltage drop module to provide step-down power to the servo motors, and the other end output powers the DC motors via the motor driver board. The microcontroller communicates with the host computer via a serial port, processing the control signals sent by the host computer and sending them to the servo motors and the motor driver board. The motor driver board drives the DC motors according to the signals.

[0017] Furthermore, the servo motor has a built-in position feedback device, and the microcontroller returns the angular position information of the servo motor output shaft to the host computer via a serial port.

[0018] Furthermore, the DC motor is controlled by a microcontroller signal control motor drive board, and the direction of the motor is controlled by outputting control level through the I / O port. The rotation angle of the output shaft of the DC motor is controlled by controlling its power-on time, thereby controlling the rotation of the Mecanum wheel connected to it. The DC motor, as the drive motor of the Mecanum wheel, is equipped with a reduction mechanism to transmit and amplify torque.

[0019] Furthermore, the microcontroller uses an Arduino Mega 2560 development board, which has 5 internal timers, 54 digital inputs and outputs, 16 analog inputs and 4 UART interfaces. The signal lines of each servo are connected to the digital signal pins corresponding to different timers.

[0020] Furthermore, the servo motor is selected by comprehensively considering five performance and physical parameters: output torque, working angle, control accuracy, appearance size and mass. The controllable working angle of the servo motor rotation is 0 to 360°, the control accuracy is ±1°, and the output torque is 10 kgf·cm.

[0021] Furthermore, the motor drive board adopts the L298n motor drive board, which has 4 logic drive circuits. When the TTL logic level signal from the outside is received by the full-bridge driver of the two H-bridges inside, the single motor drive board can simultaneously drive and control two DC motors.

[0022] Furthermore, a switch is connected in series on the live wire of the DC regulated power supply, which is connected to the voltage drop module and the motor drive board respectively. When the switch is turned on, the output voltage of one end of the DC regulated power supply is converted into the rated voltage of the servo motor through the voltage drop module. At the same time, it can control the rotation of the servo motor output shaft according to the servo motor command signal issued by the host computer. The output voltage of the other end of the DC regulated power supply powers the DC motor through the motor drive board, and controls the movement of the Mecanum wheel on the finger joint according to the DC motor signal command issued by the host computer.

[0023] Furthermore, the format of the servo command signal is "lowercase letter + number". The lowercase letter represents the servo code being controlled, and the number represents the angle code of the corresponding servo. This angle code does not directly represent the angle of the controlled servo, but is an optimized value for simplifying control. This value needs to be calculated and restored before being returned to the servo. At this point, the value is the integer of the servo duty cycle. After the microcontroller reads the control command each time, the microcontroller's internal timer will update the servo input angle. At this time, the servo control function receives the angle and rotation direction signal command corresponding to the duty cycle sent by the host computer. After the algorithm in the function calculates the PWM pulse width modulation signal corresponding to the duty cycle, the frequency of the PWM pulse width modulation signal is 50Hz, the period is 20ms, the pulse width is from 0.5ms to 2.5ms, and the corresponding servo position is 0 to 360°, which changes linearly. When the servo rotates to the angle required by the control command, the next control command is read through the serial port to complete the sequential execution of the commands.

[0024] Furthermore, the format of the DC motor signal is "uppercase letter / command value", where the uppercase letter "Q" represents the Mecanum wheel assembly rotating forward, the uppercase letter "H" represents the Mecanum wheel assembly rotating backward, the uppercase letter "Z" represents the Mecanum wheel assembly rotating left, the uppercase letter "Y" represents the Mecanum wheel assembly rotating right, and the uppercase letters "S" and "N" represent clockwise and counterclockwise rotation of the Mecanum wheels, respectively. The command values ​​"1", "2", "3", and "4" respectively represent... The Mecanum wheel assembly rotates diagonally to the upper left, lower right, upper right, and lower left. The DC motor is controlled by the high and low level signals on its red and black pins. The DC regulated power supply is connected to the two pins of the DC motor through the motor driver board, providing power to the DC motor. There are four forms of high and low level signals: "00", "01", "10", and "11", where "0" represents a low level voltage and "1" represents a high level voltage. The signals control the DC motor to perform standby, forward, reverse, and braking movements in sequence through the motor driver board.

[0025] Furthermore, the configuration recognition has 6 capture modes, including:

[0026] The patterns are distinguished based on the position of the Mecanum wheel assembly's rotation axis, specifically: when the rotation axis axes of the Mecanum wheel assembly are coplanar and when the rotation axis axes of the Mecanum wheel assembly are non-coplanar.

[0027] The finger configuration is differentiated based on the shape of the object being grasped, specifically: the mode when the object being grasped is a cylindrical shape and the mode when the object being grasped is not a cylindrical shape.

[0028] The pattern is distinguished based on the position of the Mecanum wheel assembly in contact with the object. Specifically, it is the pattern when the Mecanum wheel assembly contacts the outer surface of the object being grasped and when it contacts the inner surface of the object being grasped.

[0029] Beneficial effects:

[0030] This invention utilizes the omnidirectional mobility of the Mecanum wheel to simplify the drive control system of the dexterous hand, reduce complexity and manufacturing costs, while maintaining the dexterous hand's operational flexibility, and achieves multi-degree-of-freedom manipulation of objects.

[0031] This invention has potential application areas and expansion prospects:

[0032] (1) Warehousing and Logistics: This technology can be applied to warehouse automation and logistics operations, such as the sorting, loading, and rearranging of express parcels. The multi-degree-of-freedom maneuverability of the dexterous hand can improve logistics efficiency and reduce labor costs.

[0033] (2) Manufacturing: This technology can be used in the processes of assembling, fitting, and adjusting products. The multi-degree-of-freedom maneuverability of this dexterous hand can help achieve precise component installation and positioning, improving production efficiency and product quality.

[0034] In conclusion, this invention has broad application prospects. The multi-degree-of-freedom manipulation capabilities of this dexterous hand can improve the robot's work efficiency and operational accuracy, thereby enhancing its operational flexibility and providing innovative solutions for various tasks and scenarios. Furthermore, the continuous development and improvement of this technology will open up even broader possibilities for future automation and robotics applications. Attached Figure Description

[0035] Figure 1 This is a three-dimensional structural schematic diagram of a robot dexterous hand based on a Mecanum wheel according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the working process of a drive control system for a robot dexterous hand based on a Mecanum wheel according to an embodiment of the present invention.

[0037] Figure 3This is a flowchart of the control program for a drive control system of a robot dexterous hand based on a Mecanum wheel, according to an embodiment of the present invention.

[0038] Figure 4 This is a circuit diagram of a drive control system for a robot dexterous hand based on a Mecanum wheel, according to an embodiment of the present invention.

[0039] Figures 5(a) to 5(f) This is a schematic diagram of six different finger grasping modes configured for different grasping objects in a drive control system for a robot dexterous hand based on a Mecanum wheel according to an embodiment of the present invention.

[0040] In the figure, 1 is the base, 2 is the Mecanum wheel moving finger mechanism, 3 is the underactuated fixed finger mechanism, 4 is the reconfigurable opening and closing mechanism, and 5 is the finger centering mechanism. Detailed Implementation

[0041] To make the objectives, technical solutions, and technical effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0042] like Figure 1 As shown, a robotic dexterous hand based on Mecanum wheels includes: a base 1, a Mecanum wheel moving finger mechanism 2, an underactuated fixed finger mechanism 3, a reconfigurable opening and closing mechanism 4, and a finger centering mechanism 5. The base 1 comprises detachable upper and lower parts. Two mirror-image reconfigurable opening and closing mechanisms 4 are symmetrically mounted on the lower half of the base 1, allowing horizontal rotation. Two mirror-image finger centering mechanisms 5 are symmetrically mounted on the upper half of the base 1 and the reconfigurable opening and closing mechanisms 4. Two mirror-image Mecanum wheel moving finger mechanisms 2 are respectively mounted on the end rotating structures of the finger centering mechanisms 5, allowing rotation around an axis and joint bending. The underactuated fixed finger mechanism 3 is mounted in the rear bearing groove of the base 1 via a bearing and a connecting rod telescopic component. The underactuated fixed finger mechanism 3 and the two Mecanum wheel moving finger mechanisms 2 form a triangular configuration. The connecting rod telescopic component allows the underactuated fixed finger mechanism 3 to elastically compress and reset when grasping and releasing objects.

[0043] Each Mecanum wheel movement mechanism 2 includes a left-handed Mecanum wheel and a right-handed Mecanum wheel, as well as a corresponding DC motor for drive connection. The left-handed and right-handed Mecanum wheels constitute the Mecanum wheel set of the mechanism.

[0044] The reconfigurable opening and closing mechanism 4 and the finger centering mechanism 5 are each equipped with two servo motors, and the two servo motors are connected to the finger joints through gear meshing to control the horizontal movement and angular rotation of the finger joints.

[0045] During operation, because the first joint of the Mecanum wheel moving finger mechanism 2 has a certain tilt angle in the vertical direction compared to the second joint, the left-hand Mecanum wheel of the first joint will contact the object first. After the Mecanum wheel moving finger mechanism 2 receives an external force, it will trigger the underactuated structure at the finger joint, and the tilt angle of the first joint relative to the second joint will decrease until the right-hand Mecanum wheel of the second joint also contacts the object. After ensuring that each Mecanum wheel is in effective contact with the object, the rotation direction and speed of the four DC motors are controlled to change the rotation direction and speed of the left-hand and right-hand Mecanum wheels. This changes the relative position of the grasped object with respect to the robot hand through effective contact, thus realizing the in-hand operation of the grasped object.

[0046] In practical applications, for the reconfigurable opening and closing mechanism 4, when its two servo motors are powered on and receive signals, the output shaft of the servo motors rotates and resets to the initial position. The servo disk, which is fastened to the output shaft of the servo motor, drives the gear to rotate, causing the meshing gear to rotate, which in turn drives the swing arm, which is fastened to it, to rotate, so that the finger joints move horizontally. The movement directions of the left and right servo motors are always opposite, so that the left and right swing arms can perform symmetrical opening and closing movements.

[0047] For the finger centering mechanism 5, when its two servo motors are powered on and receive a signal, the servo motor output shaft rotates and resets to the initial position. The servo disk, which is fastened to the servo motor output shaft, drives the gear to rotate, which in turn drives the gear meshing with it to rotate, causing the Mecanum wheel moving finger mechanism 2, which is fixed to it, to rotate. The movement directions of the left and right servo motors are always opposite, so that the Mecanum wheel moving finger mechanism 2 can rotate and center symmetrically with the object being grasped, ensuring effective contact with the object being grasped.

[0048] This invention addresses the aforementioned Mecanum wheel-based robot dexterity hand by designing a drive control system. It also selects components for each part of the system and designs a control command format based on the control principles of each motor and the structure and operation of the Mecanum wheel-based robot dexterity hand, thereby constructing the drive control system required for this dexterity hand.

[0049] The drive control system connects to a host PC via a USB 2.0 cable. The host PC sends control commands to the drive control system via a serial port, and the system returns the angular position information of each servo motor's output shaft to the host PC via the serial port. This serial communication enables real-time control and parameter return of the Mecanum wheel's finger opening and closing angles and fingertip orientation. Furthermore, the system can power all eight motors and related drivers of the dexterous hand, using a single DC regulated power supply with a voltage drop module to power all internal components, reducing the hand's weight and system complexity. The motors controlled by the drive control system are installed inside the dexterous hand, and all components of the drive control system are integrated within a 3D-printed frame.

[0050] To meet the design goals of the dexterous hand, the control and drive system has the following functions: 1) The drive control system can communicate with the host computer in real time via a serial port, receiving control commands from the host computer while returning its own angle parameter information to the host computer; 2) The drive control system can control the opening and closing angle of the opening and closing fingers within the palm of the dexterous hand; 3) The drive control system can control the orientation of the fingertips of the Mecanum wheels in the dexterous hand; 4) The drive control system can achieve precise and effective coordinated motion control of a set of Mecanum wheels mounted on the Mecanum wheel moving fingers; 5) The drive control system can provide stable power to all internal components of the device through an external regulated power supply.

[0051] Based on the aforementioned functional requirements, this drive control system is identified as the control object required to perform this function. One of the control objects of this drive control system is the position and fingertip orientation angle of the Mecanum wheel fingers on the dexterous hand. The two control parameters are the angle of the opening and closing of the finger joint at the base of the finger and the angle of the third pair of gears on which the finger is mounted. The other control object is the Mecanum wheel assembly mounted on the Mecanum wheel moving finger, which can perform coordinated rotational motion. Its control parameters are the rotational direction and rotational speed of each wheel. Therefore, this drive control system selects the angle, speed, and direction of rotation of each motor output shaft as control parameters to control the two Mecanum wheel fingers of the dexterous hand and the individual Mecanum wheels on the fingers.

[0052] Regarding the control of the motor output shaft, there are some differences in the internal hardware working principles and control methods for servo motors and DC motors. Firstly, a servo motor is a motor with controllable rotation angle and position. It uses a built-in position feedback device, such as a rotary encoder, to determine the angular position of the output shaft and precisely rotates the output shaft to a specific angular position based on the input pulse width modulation signal. Therefore, it can easily control the rotation angle, direction, and speed. However, DC motors typically do not have an internal angular position feedback device. Therefore, to control the angular position of the output shaft, it is usually necessary to use an external encoder or sensor to provide feedback and use a closed-loop control algorithm to adjust the motor's rotation to achieve the target angular position. Considering the limited finger space and simplicity of this dexterous hand, after referring to relevant research on multi-motor rotation control and determining the motor and drive board models, a precise relationship between the rotational speed and the voltage difference between the two motor pins was derived through parameter calculation and experimental verification. Subsequently, the rotation angle of the DC motor's output shaft was indirectly controlled by controlling the energizing time.

[0053] To characterize the design goals of this drive system, after determining the angle, speed, and direction of rotation of each motor output shaft as control parameters, and the servo motor pulse width modulation signal, pin voltage drop, and DC motor energization time as control methods, the following functional requirements and their performance indicators are listed in detail:

[0054] Functional requirements:

[0055] a) It has the function of changing the position of the Mecanum wheel fingers: This dexterous hand mainly relies on the position change of the Mecanum wheel moving fingers to achieve effective grasping of objects. Therefore, the movement space of the Mecanum wheel moving fingers should be as large as possible.

[0056] b) It has the function of changing the fingertip orientation of the Mecanum wheel: ensuring that each Mecanum wheel on the finger is in perpendicular contact with the surface of the object being touched;

[0057] c) It has the function of returning the angle between the open and closed knuckles and the direction of the fingertips in real time: real-time monitoring of the position and angle of the controlled object, which facilitates parameter adjustment and test data analysis;

[0058] d) It has the function of coordinated motion of Mecanum wheel set: the relative motion between the finger and the contact object is realized by the omnidirectional movement of Mecanum wheel set;

[0059] e) Small size and low weight: Convenient for mounting on dexterous hands, reducing the hardware requirements of the mounted robotic arm and increasing load capacity.

[0060] Performance metrics:

[0061] a) The microcontroller can independently control 8 motors and return the real-time angle of the servo motors via serial port;

[0062] b) The servo motor has an operating angle greater than 300 degrees, an output shaft torque less than 0.54 N·m, and a control accuracy of less than 2%.

[0063] c) The DC motor has high synchronization, a response time of less than 5μsec, and an output shaft torque of greater than 10kgf·cm;

[0064] d) The DC motor has a volume of less than 80.0×25.0×20.0mm and a mass of less than 50g;

[0065] e) The motor drive board can drive multiple motors simultaneously with good stability;

[0066] f) The power supply unit can provide a regulated DC voltage greater than 8V and can output a current greater than 1.5A.

[0067] Based on the functional requirements and performance indicators derived from the above analysis of the design objectives of the drive control system, the key components of this system are identified as follows: microcontroller, servo motor, DC motor, motor driver board, voltage drop module, and power supply. Specifically, the Arduino Mega 2560 development board is selected as the microcontroller, four Dsservo DS3210s are selected as the servo motors, four Sunkee SK51S motors are selected as the DC motors, two dual-channel H-bridge drivers (L298n) are selected as the motor driver boards, a Dsservo LM-2596S is selected as the voltage drop module, and a Mashehong MS-152D is selected as the power supply.

[0068] During the selection process, it was discovered that the Arduino IDE comes pre-installed with a series of standard library files. When calling the internal Servo library, a small number of servos can be directly controlled using the IDE. However, when using the Servo library and device serial communication simultaneously, the Servo library's underlying code uses timer interrupts, and the serial communication also requires a timer. Therefore, they share the same timer: T / C1, meaning T / C1 simultaneously handles multiple functions, leading to internal timer conflicts. To address this, and to achieve independent control of eight motors, this invention resolves the conflict by modifying the code. Specifically, it avoids calling the built-in Servo library and directly uses PWM signals and a delay function loop to control the servos. In this case, the Arduino's delay() function calls timer T / C0, not the T / C1 used for serial communication, thus avoiding the shared use of the same timer. Furthermore, since this drive control system uses a large number of servos, in order to avoid multiple servo control signals corresponding to the same timer, which could lead to mutual interference and drift / jitter between servo signals, the Arduino Mega 2560 development board was chosen as the microcontroller for this drive control system. This development board has 5 internal timers, 54 digital inputs / outputs, 16 analog inputs, and 4 UART interfaces, making it suitable for hardware designs that require a large number of I / O interfaces. The signal lines of each servo are designed to be connected to the digital signal pins corresponding to different timers, thus avoiding such phenomena from a hardware perspective.

[0069] To achieve wide-range, high-precision motion control of the Mecanum wheel's moving finger, a servo motor needs to be selected. Eight servo motors were compared in terms of performance parameters, dimensions, and weight, as shown in Table 1. Considering five performance and physical parameters—output torque, operating angle, control accuracy, dimensions, and weight—this invention ultimately selected the DS3210 servo motor from Dsservo. This servo motor has a controllable operating angle of 0 to 360°, a control accuracy of ±1°, an output torque of 10 kgf·cm, a physical shape of a cuboid with a length of 40 mm, a width of 40 mm, a thickness of 20 mm, a weight of 60 g, and an operating voltage of 6 V.

[0070] Table 1. Parameters of Selected Servo Units

[0071]

[0072] The primary goal was to fit the four DC motors controlling the Mecanum wheel assembly into the space of a finger, and the size of the DC motors was the primary parameter for selection. After considering the size parameters of various DC motors, the SUNKEE SK51S DC motor, with the simplest structure and smallest size, was selected as the drive motor for the Mecanum wheel assembly. Combined with a reduction gear mechanism, and through torque transmission and amplification, it is sufficient to achieve effective movement of the Mecanum wheel under various functions.

[0073] One of the more mature solutions for driving and controlling DC motors is the L298n board. This driver board has four logic drive circuits. When an external TTL logic level signal is received by the two internal H-bridge full-bridge drivers, it can simultaneously drive and control two DC motors with one module. Furthermore, this driver board also features feedback detection and overheat self-shutdown functions to ensure system safety. When driving a motor using the L298n board, the main control chip only needs to output control levels through the I / O ports to control the motor's direction, making programming simple and offering good stability. When current flows through the L298n motor driver board, the voltage drop of the internal switching transistors when forward biased is approximately 1V, and since the H-bridge requires current to pass through two transistors, a total voltage drop of 2V is generated. However, the power supply for both the servo motor and the DC motor during normal operation is 6V, and the DC motor is connected in series with the L298n motor driver board. Therefore, an 8V voltage needs to be supplied to this circuit to ensure the motor's normal operation. To keep the power supply as simple as possible, a MASHEHNG MS-152D single DC regulated power supply is used to provide 8V. This DC regulated power supply can provide a stable supply of any voltage within 15V, with a rated current of 2A. A Dsservo LM-2596SDC-DC voltage drop module is connected in series with each servo circuit to step down the 2V voltage of the servo circuit, thus providing normal power to all relevant motors in this system. Furthermore, since a single L298n motor driver board can only control two DC motors, two L298n motor driver boards are required to control the DC motors corresponding to the four Mecanum wheels.

[0074] This completes the selection of all major components within the drive control system.

[0075] The prerequisite for the normal operation of the drive control system of this invention is ensuring the stable operation of both the power supply system and the control system. The control system and power supply system designed in this invention share a common ground but are independent of each other and do not interfere with each other, thus maximizing the stability of system operation. The system's workflow is as follows: Figure 2 As shown, the working process of this drive control system will be explained below through the power supply system circuit and the control system circuit respectively.

[0076] refer to Figure 2 The solid line with arrows represents the power supply system circuit, which is powered by an 8V DC regulated power supply. A switch is connected in series on the live wire of the power supply, which controls whether the entire system is powered. Three branch power supply circuits extend from the switch, namely:

[0077] (1) Starting from the switch, it reaches the voltage drop module, which converts the 8V power supply voltage into the 6V rated voltage of the servo motor to ensure the normal operation of the servo motor. Then it is connected to the servo motor group in the system to supply power to it, and controls the position of the servo motor output shaft servo disk according to the servo motor command signal issued by the host computer.

[0078] (2) Starting from the switch, through the DC motor drive board 1, power is supplied to the two DC motors that control the Mecanum wheel in the left finger, and the movement of the Mecanum wheel on the left hand finger is controlled according to the DC motor signal command issued by the host computer.

[0079] (3) Starting from the switch, the power supply is provided to the two DC motors controlling the Mecanum wheel on the right finger through the DC motor drive board 2, and the movement of the Mecanum wheel on the right finger is controlled according to the DC motor signal command issued by the host computer.

[0080] The dashed lines with arrows in the diagram represent the control system circuit. This invention has developed a lower-level machine instruction format. The upper-level PC sends instructions to the lower-level machine via serial port according to this format. The instruction format and meaning are shown in Table 2.

[0081] Table 2 Control Command Format and Meaning

[0082]

[0083]

[0084] First, the host PC sends control signal commands to the microcontroller via serial port. Since serial communication consumes significant resources and time, these commands are presented as strings consisting of individual numbers, letters, or a combination of both to improve system efficiency. There are two types of commands: servo control commands starting with lowercase "k" or "d" followed by a number, and DC motor control commands consisting of individual uppercase letters "Q", "H", "Z", "Y", "S", "N" or the numbers "1", "2", "3", "4". The control program flowchart is shown below. Figure 3 As shown.

[0085] Servo control signal: The format of this signal command is "letter + value". The initial letter in the command represents the servo code being controlled. The lowercase letter "k" represents an opening / closing servo, and the lowercase letter "d" represents a centering servo. The value following the letter represents the angle code of the corresponding servo. This angle code does not directly represent the angle of the controlled servo; it is an optimized value for simplified control, allowing for more intuitive control of the servo angle. It needs to be calculated and restored before being returned to the servo. This value is the integer of the servo duty cycle. All paired servos in the hand are symmetrically placed left and right along the central axis of the hand base. Taking the opening / closing servo as an example, if two Mecanum wheel fingers are to open and close symmetrically, the rotation directions of their respective opening / closing knuckles must be exactly opposite. Therefore, one opening / closing servo control signal actually achieves the movement of two servos in opposite directions with identical absolute values ​​of rotational speed and angle change. After the microcontroller reads each control command, its internal timer updates the servo input angle. At this time, the servo control function receives the angle and rotation direction signals corresponding to the duty cycle from the host computer. The function's algorithm calculates the PWM wave corresponding to the duty cycle. The PWM signal has a frequency of 50Hz, a period of 20ms, and a pulse width ranging from 0.5ms to 2.5ms, corresponding to a servo head position of 0-360°, exhibiting a linear variation. Once the servo rotates to the required control angle, the next control command is read via the serial port, completing the sequential execution of commands.

[0086] DC motor control signals: The format of this signal command is "uppercase letter / command value". Uppercase letter "Q" represents forward rotation of the Mecanum wheel assembly, uppercase letter "H" represents backward rotation, uppercase letter "Z" represents left rotation, uppercase letter "Y" represents right rotation, and uppercase letters "S" and "N" represent clockwise and counterclockwise rotation of the Mecanum wheels, respectively. Commands "1", "2", "3", and "4" indicate... These represent the coordinated rotation of the Mecanum wheel assembly diagonally to the upper left, lower right, upper right, and lower left, respectively. The DC motor is controlled by the high and low level signals on its red and black pins. The power supply is connected to the two pins of the DC motor through the motor driver board, simultaneously supplying power to the motor. This signal has four forms: "00", "01", "10", and "11", where "0" represents a voltage of 0V and "1" represents a voltage of 6V. The signal, through the motor driver board, controls the DC motor to sequentially achieve standby, forward rotation, reverse rotation, and braking movements.

[0087] Table 3 shows the high and low levels of each pin of the DC motor corresponding to the movement of the manipulated object in each direction.

[0088]

[0089]

[0090] With the direction away from the dexterous hand as the upward direction, the normal plane from the Mecanum wheel moving finger to the omnidirectional wheel fixed finger direction is taken as the operation motion plane. The high and low level of each DC motor pin corresponding to the direction of movement within the object's hand is shown in Table 3. In the table, motor 1 controls the top Mecanum wheel of the left Mecanum wheel moving finger, motor 2 controls the middle Mecanum wheel of the left Mecanum wheel moving finger, motor 3 controls the top Mecanum wheel of the right Mecanum wheel moving finger, and motor 4 controls the middle Mecanum wheel of the right Mecanum wheel moving finger.

[0091] The circuit principle of this drive control system is as follows: Figure 4 As shown in the diagram. This drive control system connects the Arduino Mega 2560 microcontroller to the host PC via a single USB 2.0 data cable. Serial communication is used to receive control signals from the microcontroller and simultaneously return the angle parameters of each servo motor to the host PC. The microcontroller then processes the control signals and sends them to the respective servos and motor driver boards via their pins. Finally, the motor driver boards drive the DC motors according to the signals. Except for the Arduino Mega 2560 microcontroller, all components in this system are powered by an 8V DC regulated power supply. Therefore, a regulated power supply capable of handling high current was chosen as the power supply for the entire system to avoid insufficient current causing some components to stop working or malfunction. The usage and corresponding functions of the relevant pins of the Arduino Mega 2560 microcontroller are shown in Table 4 below.

[0092] Table 4: Functions of each pin on the Arduino Mega 2560

[0093]

[0094]

[0095]

[0096] Thanks to its reconfigurable hand design, this dexterous hand possesses the ability to grasp and manipulate various objects. Different finger configurations can be selected based on the object's shape and size to accomplish the grasping and manipulation tasks. (Reference) Figure 1 This dexterous hand can achieve real-time control of four servo motors inside the hand through a drive control system, thereby completing six different finger grasping configurations.

[0097] The six finger grasping configurations of the dexterous hand are now distinguished.

[0098] First, distinguish the positions of the rotation axes of the Mecanum wheel assembly. When the rotation axes of the Mecanum wheel assembly are coplanar, such as... Figure 5(a) , 5(c) As shown, this finger configuration is abbreviated as C; conversely, when the rotation axes of the Mecanum wheel assembly are not in the same plane, as... Figure 5(b) , 5(d) As shown in 5(e) and 5(f), this finger grasping configuration is abbreviated as N.

[0099] Secondly, the finger configuration is differentiated based on the shape of the object being grasped. When the object being grasped is a cylindrical shape, the finger grasping configuration is abbreviated as A, such as... Figure 5(c) , 5(d) As shown; conversely, when the object being grabbed is not a cylinder-like shape, such as Figure 5(a) , 5(b) As shown in the cuboids drawn in 5(e) and 5(f), this finger configuration is abbreviated as P.

[0100] Finally, the distinction is made based on the position of the wheel assembly in contact with the object. When the contact is with the outer surface of the object being grasped, as shown in Figures 5(a), 5(b), and 5(c), the finger configuration is abbreviated as O; conversely, when the contact is with the inner surface of the object being grasped, as shown in Figures 5(d), 5(e), and 5(f), the finger grasping configuration is abbreviated as I.

[0101] Based on the three distinction rules mentioned above, each grasping configuration can be reasonably divided, and the resulting combination of three uppercase letters is the finger grasping configuration for this experiment.

[0102] Of the six combinations mentioned above, five are frequently used due to their versatility and ease of use: CPO, NPO, NAO, NAI, and NPI. Therefore, all grasping operations of this robot's dexterous hand are also implemented based on these five finger grasping configurations.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the implementation process of the present invention has been described in detail above, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A driving control system of a robot dexterous hand based on Mecanum wheels, which communicates with the host computer through a data line, the dexterous hand is provided with a steering wheel to control the movement and rotation of the finger joints, and a DC motor located in the finger joint to control the rotation of the Mecanum wheel, characterized in that, The system comprises a single-chip microcomputer, a voltage drop module, a motor driving board and a direct current stabilized power supply; one end of the direct current stabilized power supply is connected in series with the voltage drop module to supply power to the servo motor after voltage drop, and the other end of the direct current stabilized power supply is connected to the motor driving board to supply power to the direct current motor; the single-chip microcomputer communicates with the upper computer through a serial port, processes the control signals sent by the upper computer and sends the processed signals to the servo motor and the motor driving board, and the motor driving board drives the direct current motor according to the signals; The system is configured to identify six kinds of grabbing modes, including: A mode for distinguishing according to the positions of the rotating shafts of the Mecanum wheel sets, specifically, a mode for when the rotating shaft axes of the Mecanum wheel sets are coplanar and a mode for when the rotating shaft axes of the Mecanum wheel sets are non-coplanar; A mode for distinguishing according to the shapes of the objects to be grabbed, specifically, a mode for when the grabbed object is a cylinder-like object and a mode for when the grabbed object is not a cylinder-like object; A mode for distinguishing according to the positions of the contact surfaces of the Mecanum wheel sets and the objects, specifically, a mode for when the Mecanum wheel sets contact the outer surface of the grabbed object and a mode for when the Mecanum wheel sets contact the inner surface of the grabbed object.

2. The drive control system of a Mecanum wheel-based robotic hand according to claim 1, wherein, The servo motor is provided with a position feedback device, and the single-chip microcomputer returns the angle position information of the output shaft of the servo motor to the upper computer through a serial port.

3. The drive control system of a Mecanum wheel-based robotic hand according to claim 1, wherein, The direct current motor is controlled in rotation by the single-chip microcomputer through the I / O port of the motor driving board, and the rotation angle of the output shaft of the direct current motor is controlled by controlling the power-on time, so as to control the rotation of the Mecanum wheel connected thereto, and the direct current motor serves as the driving motor of the Mecanum wheel and is provided with a speed reduction mechanism to transmit and amplify the torque.

4. The drive control system of a Mecanum wheel-based robotic hand of claim 1, wherein, The single-chip microcomputer adopts an Arduino Mega 2560 development board, which has five internal timers, 54 digital input and output channels, 16 analog input channels and four UART interfaces, and the signal lines of each servo motor are connected to the digital signal pins corresponding to different timers.

5. The drive control system of a Mecanum wheel-based robotic hand according to claim 1, wherein, The servo motor is selected based on the output torque, working angle, control accuracy, appearance size, mass and physical parameters, wherein the controllable working angle of the servo motor is 0-360°, the control accuracy is ±1°, and the output torque is 10 kgf·cm.

6. The drive control system of a Mecanum wheel-based robotic hand according to claim 1, wherein, The motor driving board adopts an L298n motor driving board, which has four logic driving circuits, and when the TTL logic level signals from the outside are received by the full-bridge drivers of the two H-bridges in the motor driving board, the single motor driving board can simultaneously drive and control two direct current motors.

7. The drive control system of a Mecanum wheel-based robotic hand according to claim 1, wherein, A switch is connected in series with the live wire of the direct current stabilized power supply, and the switch is connected to the voltage drop module and the motor driving board, respectively; the output voltage of one end of the direct current stabilized power supply is converted into the rated voltage of the servo motor through the voltage drop module, and the servo motor output shaft can be rotated according to the servo motor instruction signals sent by the upper computer, and the output voltage of the other end of the direct current stabilized power supply is used to supply power to the direct current motor through the motor driving board, and the movement of the Mecanum wheel on the finger joint is controlled according to the direct current motor signal instruction sent by the upper computer.

8. The drive control system of a Mecanum wheel-based robotic hand according to claim 7, wherein, The rudder instruction signal is in the format of "lowercase letter + numerical value", the lowercase letter represents the controlled rudder code, and the numerical value represents the angle code of the corresponding rudder. The angle code is not directly represented by the controlled rudder angle, but is an optimized value for simplifying control. The value needs to be restored by numerical calculation and returned to the rudder. At this time, the value is the rudder duty cycle integer. After the single-chip microcomputer reads the control instruction each time, the internal timer of the single-chip microcomputer updates the rudder input angle. At this time, the rudder control function receives the angle and rotation direction signal instruction corresponding to the duty cycle sent by the upper computer. After the algorithm calculation in the function, the corresponding PWM pulse width modulation signal is obtained. The PWM pulse width modulation signal frequency is 50Hz, the period is 20ms, the pulse width is from 0.5ms to 2.5ms, and the corresponding steering wheel position is 0-360°, which changes linearly. When the rudder rotates to the required angle of the control instruction, the next control instruction is read through the serial port to complete the sequential execution of the instruction.

9. The drive control system of a Mecanum wheel-based robotic hand according to claim 7, wherein, The format of the DC motor signal is "capital letter / instruction numerical value". The capital letter "Q" represents the forward rotation of the Mecanum wheel group, the capital letter "H" represents the rear rotation of the Mecanum wheel group, the capital letter "Z" represents the left rotation of the Mecanum wheel group, the capital letter "Y" represents the right rotation of the Mecanum wheel group, the capital letters "S" and "N" represent the clockwise rotation and counterclockwise rotation of the Mecanum wheel group, respectively. The instruction numerical values "1", "2", "3", "4" represent the oblique rotation of the Mecanum wheel group to the upper left, lower right, upper right and lower left, respectively. The control of the DC motor is controlled by the high and low level signals of the motor red and black two pins. The DC stabilized power supply is connected with the two pins of the motor driving board and the DC motor, and at the same time, it supplies power for the DC motor. There are four forms of high and low level signals: "00", "01", "10", "11". Among them, "0" represents the corresponding low level voltage, and "1" represents the corresponding high level voltage. The signal can control the DC motor to perform standby, forward rotation, reverse rotation and braking motion in sequence through the motor driving board.

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