Power-down braking system, control method and robot for a robotic arm

Abstract

The application discloses a power-off braking system of a mechanical arm, a control method and a robot. The power-off braking system of the mechanical arm comprises a power supply detection circuit connected to a power supply of the mechanical arm, which is used for detecting a power supply voltage of the mechanical arm and outputting a detection signal; a motor driving circuit connected to the power supply and connected to the motor and the power supply detection circuit; the motor driving circuit is used for judging the power supply state of the power supply according to the detection signal, entering a PWM short-circuit braking mode when the power supply is in a power-off state, outputting a PWM driving signal, and controlling the motor to short-circuit brake at a preset duty cycle; the motor driving circuit is also used for receiving the electric energy fed back by the motor in the off interval of the PWM driving signal and storing the electric energy, and maintaining the motor driving circuit to continuously output the PWM driving signal in the power-off state by using the stored electric energy until the mechanical arm stops moving. The technical scheme provided by the embodiment of the application improves the motor control effect when the mechanical arm is powered off.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a power-off braking system, control method, and robot for a robotic arm. Background Technology

[0002] With the rapid popularization of industrial automation, collaborative robots and desktop robotic arms, the safe control of multi-joint robotic arms under power failure or system power loss conditions has become a key technical issue affecting equipment reliability, personnel safety and equipment lifespan.

[0003] When a robotic arm is working normally, its joints are maintained by torque provided by motors. In the event of a sudden power outage, power failure, or driver malfunction, the motors instantly lose power and torque output. Under the influence of gravity and load torque, the joints will continue to rotate, potentially leading to free fall, rapid slippage, or uncontrolled swinging. This can easily cause collisions with the robotic arm itself, damage to the end effector, damage to surrounding equipment, and even personal injury. Therefore, it is necessary to maintain control of the motors when the robotic arm loses power, achieving controlled descent within a limited space without adding hardware or relying on an external power source. However, current technologies offer poor motor control for robotic arms during power outages. Summary of the Invention

[0004] This invention provides a power-off braking system, control method, and robot for a robotic arm to solve the problem of poor motor control when the robotic arm loses power.

[0005] According to one aspect of the present invention, a power-off braking system for a robotic arm is provided, comprising: A power detection circuit, connected to the power supply of the robotic arm, is used to detect the power supply voltage of the robotic arm and output a detection signal. The motor drive circuit is connected to a power supply and is also connected to the motor and the power supply detection circuit. The motor drive circuit is used to determine the power supply status of the power supply according to the detection signal, and when the power supply is in a power-off state, it enters the PWM short-circuit braking mode, outputs the PWM drive signal, and controls the motor to perform short-circuit braking with a preset duty cycle. The motor drive circuit is also used to receive and store the electrical energy fed back by the motor during the off-range of the PWM drive signal, and to use the stored electrical energy to maintain the motor drive circuit continuously outputting the PWM drive signal in the power-off state until the robotic arm stops moving.

[0006] Optionally, the motor drive circuit includes: A microcontroller, connected to the power detection circuit, is used to determine the power supply status of the power supply based on the detection signal, and output an active short-circuit signal when the power supply is in a power-off state. The drive module is connected to the three-phase windings of the motor and also to the microcontroller. The drive module is used to perform pulse width modulation according to the active short-circuit signal and the preset duty cycle, so that the three-phase windings of the motor form a short-circuit closed loop and generate braking torque. The motor decelerates at a deceleration corresponding to the preset duty cycle.

[0007] Optionally, the driving module includes; A driving circuit, connected to the microcontroller, is used to generate the PWM driving signal based on the active short-circuit signal; The three-phase inverter circuit is connected to the drive circuit and also to the three-phase windings of the motor. The three-phase inverter circuit has multiple built-in switching devices. The drive circuit is used to drive the switching devices in the three-phase inverter circuit to conduct periodically according to the preset duty cycle through the PWM drive signal, so that the three-phase windings of the motor are short-circuited with the preset duty cycle.

[0008] Optionally, the three-phase inverter circuit includes: The first bridge arm, the second bridge arm, and the third bridge arm are connected in parallel, and the output terminals of the first bridge arm, the second bridge arm, and the third bridge arm are respectively connected to the three-phase windings of the motor; each of the first bridge arm, the second bridge arm, and the third bridge arm includes an upper bridge arm and a lower bridge arm. The three-phase inverter circuit is used to drive the switching devices in each upper bridge arm to turn off according to the PWM drive signal, and the switching devices in each lower bridge arm alternately turn on and off with the preset duty cycle; or, according to the PWM drive signal, drive the switching devices in each lower bridge arm to turn off, and the switching devices in each upper bridge arm alternately turn on and off with the preset duty cycle.

[0009] Optionally, the three-phase inverter circuit further includes: The bus capacitor is connected in parallel with the first bridge arm and also connected to the microcontroller. The bus capacitor is used to receive and store the electrical energy fed back by the motor during the off-range of the PWM drive signal, and to continuously supply power to the microcontroller with the stored electrical energy. The microcontroller operates in a minimum system mode.

[0010] Optionally, the power detection circuit includes: a first resistor and a second resistor; The first end of the first resistor is connected to the power supply of the robotic arm, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is grounded; the second end of the first resistor is also connected to the microcontroller; the detection signal is the voltage of the second resistor; The microcontroller is used to calculate the power supply voltage based on the detection signal and to determine the power supply status of the power supply based on a set voltage threshold.

[0011] According to another aspect of the present invention, a power-off braking control method for a robotic arm is provided, applied to the power-off braking system of the robotic arm described in any embodiment of the present invention, the power-off braking control method for the robotic arm comprising: Detect the power supply status; When the power supply is in a power-off state, it enters the PWM short-circuit braking mode, controls the motor of the robotic arm to perform short-circuit braking with a preset duty cycle, and stores the electrical energy fed back by the motor. The motor of the robotic arm slows down by the deceleration corresponding to the preset duty cycle.

[0012] Optionally, when the power supply is in a power-off state, the system enters a PWM short-circuit braking mode, controlling the robotic arm's motor to perform short-circuit braking with a preset duty cycle, while simultaneously storing the electrical energy fed back by the motor, including: Pulse width modulation is performed according to the preset duty cycle, so that the three-phase windings of the motor form a short-circuit closed loop and generate braking torque.

[0013] Optionally, the power supply status of the detection power supply includes: Connect the power detection circuit to the power supply terminal and acquire the detection signal of the power detection circuit. The power supply voltage is calculated based on the detection signal. When the power supply voltage is less than a set voltage threshold, the power supply is in a power-off state.

[0014] Optionally, after detecting the power supply status, the method further includes: When the power supply is in a power-off state, different motors in the control robot arm are actively short-circuited with different preset duty cycles. The different motors of the robotic arm reduce speed by using different deceleration rates corresponding to the preset duty cycles.

[0015] According to another aspect of the present invention, a robot is provided, comprising: a power-off braking system for a robotic arm as described in any embodiment of the present invention.

[0016] The technical solution provided by this invention addresses the unique safety issue of a robotic arm falling due to gravity after a power outage. By detecting the power supply status, the microcontroller can maintain control of the robotic arm even when the power supply is off and the robotic arm loses external power. Throughout the control process, no new backup batteries or supercapacitors are required, and the braking function can be achieved without altering the original circuit structure. This is particularly suitable for collaborative robots and humanoid robots with limited joint space. Furthermore, precise control of deceleration is achieved through a preset duty cycle, reducing the impact and vibration on the motor during deceleration, avoiding structural impact and load slippage caused by sudden stops, and eliminating the need for additional joint space and hardware costs. This invention employs an open-loop control strategy throughout, utilizing the continued descent of the robotic arm joints under gravity to force the motor to rotate, converting mechanical energy into electrical energy to maintain its braking control. This completely eliminates dependence on external power, resulting in lower energy consumption and improved microcontroller control over the robotic arm's descent speed when power is lost.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a power-off braking system for a robotic arm according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of another power-off braking system for a robotic arm according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of another power-off braking system for a robotic arm according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a three-phase inverter circuit according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a power detection circuit according to an embodiment of the present invention; Figure 6 This is a flowchart of a power-off braking control method for a robotic arm according to an embodiment of the present invention; Figure 7This is a flowchart of another power-off braking control method for a robotic arm provided according to an embodiment of the present invention; Figure 8 This is a flowchart of another power-off braking control method for a robotic arm provided according to an embodiment of the present invention; Figure 9 This is a flowchart of another power-off braking control method for a robotic arm provided according to an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] This invention provides a power-off braking system for a robotic arm. Figure 1 This is a schematic diagram of a power-off braking system for a robotic arm, provided as an embodiment of the present invention. (Reference) Figure 1 The power-off braking system of the robotic arm includes: a power detection circuit 1, a motor drive circuit 10, and a motor 5. The power detection circuit 1 is connected to the power supply 6 of the robotic arm and is used to detect the supply voltage of the power supply 6 and output a detection signal. The motor drive circuit 10 is connected to the power supply 6, and also to the motor 5 and the power detection circuit 1. The motor drive circuit 10 is used to determine the power supply status of the power supply 6 based on the detection signal, and when the power supply 6 is in a power-off state, it enters a PWM short-circuit braking mode, outputs a PWM drive signal, and controls the motor 5 to perform short-circuit braking with a preset duty cycle. The motor drive circuit 10 is also used to receive and store the electrical energy fed back from the motor 5 during the off-range of the PWM drive signal, and uses the stored electrical energy to maintain the continuous output of the PWM drive signal in the power-off state until the robotic arm stops moving.

[0023] When power supply 6 is off, the robotic arm completely loses power and stops operating. At this time, motor 5 will lose control; however, even without control, motor 5 will continue to drive the robotic arm due to inertia. Therefore, even when power supply 6 is off, it is still necessary to maintain speed control of motor 5 to control the robotic arm.

[0024] The motor drive circuit 10 can determine the power supply status of the power supply 6 by detecting the signal. When the power supply 6 is in a power-off state, the motor drive circuit 10 controls the motor 5 of the robotic arm and performs active short circuit according to the preset duty cycle corresponding to the PWM drive signal.

[0025] For example, the motor 5 of the robotic arm has a three-phase winding, which is connected to a three-phase inverter circuit in the motor drive circuit 10. The motor drive circuit 10 is used to adjust the voltage of the input three-phase winding, thereby adjusting the speed of the motor 5.

[0026] When power supply 6 is de-energized, motor 5 will continue to rotate due to inertia. In this state, motor 5 acts as a generator, and the back electromotive force (induced voltage) it generates will be fed back to motor drive circuit 10 and stored therein, thus providing continuous energy to motor drive circuit 10. Therefore, motor drive circuit 10 can maintain a long-term PWM short-circuit braking mode and continuously output PWM drive signals after power failure, causing motor 5 to brake continuously until it stops rotating.

[0027] When the motor drive circuit 10 detects that the power supply 6 is in a power-off state, the motor drive circuit 10 enters the PWM short-circuit braking mode and controls the motor 5 to actively short-circuit with a preset duty cycle. The three-phase windings of the motor 5 generate induced current, which in turn forms a reverse magnetic field, hindering the rotor rotation, thereby achieving the deceleration braking of the motor 5.

[0028] By adopting a control method with a preset duty cycle, the impact and vibration on motor 5 during deceleration can be reduced. By adjusting the preset duty cycle, the power-off braking effect of the robotic arm can be adjusted.

[0029] Specifically, the preset duty cycle is proportional to the braking torque. The larger the preset duty cycle, the greater the braking torque of motor 5 and the greater the deceleration of motor 5.

[0030] For example, the preset duty cycle can be 90%, meaning that the active short circuit time of the three-phase windings accounts for 90% of the total time. The preset duty cycle is inversely proportional to the descent speed of the robotic arm. The larger the duty cycle, the longer the active short circuit time of the three-phase windings, the greater the braking torque of motor 5, and the faster the deceleration of motor 5. This allows for more counteracting of the rotational or falling force caused by the robotic arm's own weight. In other words, the acceleration of the robotic arm is significantly suppressed, and the robotic arm will descend at a slower speed, thus achieving power-off braking control of the robotic arm.

[0031] The technical solution provided by this invention addresses the unique safety issue of a robotic arm falling due to gravity after a power outage. By detecting the power supply status, the microcontroller can maintain control of the robotic arm even when the power supply is off and the robotic arm loses external power. Throughout the control process, no new backup batteries or supercapacitors are required, and the braking function can be achieved without altering the original circuit structure. This is particularly suitable for collaborative robots and humanoid robots with limited joint space. Furthermore, precise control of deceleration is achieved through a preset duty cycle, reducing the impact and vibration on the motor during deceleration, avoiding structural impact and load slippage caused by sudden stops, and eliminating the need for additional joint space and hardware costs. This invention employs an open-loop control strategy throughout, utilizing the continued descent of the robotic arm joints under gravity to force the motor to rotate, converting mechanical energy into electrical energy to maintain its braking control. This completely eliminates dependence on external power, resulting in lower energy consumption and improved microcontroller control over the robotic arm's descent speed when power is lost.

[0032] Figure 2 A schematic diagram of another power-off braking system for a robotic arm provided in an embodiment of the present invention. (Reference) Figure 2 Based on the above embodiments, optionally, the motor drive circuit 10 includes a microcontroller 2 and a drive module 11. The microcontroller 2 is connected to the power detection circuit 1 and is used to determine the power supply status of the power supply 6 based on the detection signal, and output an active short-circuit signal when the power supply is in a power-off state. The drive module 11 is connected to the three-phase windings of the motor 5 and also to the microcontroller 2. The drive module 11 is used to perform pulse width modulation according to a preset duty cycle based on the active short-circuit signal, so that the three-phase windings of the motor 5 form a short-circuit closed loop and generate braking torque, and the motor 5 decelerates at a deceleration corresponding to the preset duty cycle.

[0033] The active short-circuit signal includes a preset duty cycle, and different preset duty cycles correspond to different braking torques.

[0034] When the drive module 11 receives an active short-circuit signal, it first reads the preset duty cycle in the active short-circuit signal and generates a pulse width modulation drive waveform based on the preset duty cycle. The drive module 11 outputs the modulation waveform to control the internal switching devices to conduct in an orderly manner, connecting the three-phase windings of the motor 5 in pairs to form a three-phase winding short-circuit closed loop.

[0035] When the three-phase windings of motor 5 are short-circuited, the rotor cutting the magnetic field lines will generate a reverse induced electromotive force, and a braking current will be formed in the three-phase short-circuit circuit, which will hinder the rotation of the rotor of motor 5, thereby achieving braking of motor 5.

[0036] The duty cycle of pulse width modulation determines the conduction time of the short-circuit loop per unit cycle. The larger the duty cycle, the longer the short-circuit conduction time, the larger the loop braking current, and the stronger the corresponding braking torque. By matching the braking torque corresponding to the preset duty cycle, the motor can be precisely controlled to smoothly decelerate, achieving graded and controllable active short-circuit braking.

[0037] The embodiments of the present invention, by setting a microcontroller, can generate an active short-circuit signal with a preset duty cycle, which can immediately perform open-loop control of the motor through the drive module when the power supply is in a power failure state. It has a fast response time and low energy consumption, and the control method of pulse width modulation has a good control effect.

[0038] Figure 3 A schematic diagram of another power-off braking system for a robotic arm provided in an embodiment of the present invention. (Reference) Figure 3 Based on the above embodiments, optionally, the drive module 11 includes a drive circuit 3 and a three-phase inverter circuit 4. The drive circuit 3 is connected to the microcontroller 2 and is used to generate a PWM drive signal according to the active short-circuit signal. The three-phase inverter circuit 4 is connected to the drive circuit 3 and also to the three-phase windings of the motor 5. The three-phase inverter circuit 4 has multiple built-in switching devices. The drive circuit 3 is used to drive the switching devices in the three-phase inverter circuit 4 to periodically conduct according to a preset duty cycle through the PWM drive signal, so that the three-phase windings of the motor 5 are short-circuited with a preset duty cycle.

[0039] For example, the drive circuit 3 is connected to the control terminal of each switching device, and the PWM drive signal is used to control the switching devices to turn on or off.

[0040] Figure 4 This is a schematic diagram of a three-phase inverter circuit provided in an embodiment of the present invention. (Combined with...) Figure 3 and Figure 4Based on the above embodiments, optionally, the three-phase inverter circuit 4 includes: a first bridge arm 41, a second bridge arm 42, and a third bridge arm 43; the first bridge arm 41, the second bridge arm 42, and the third bridge arm 43 are connected in parallel, and the output terminals of the first bridge arm 41, the second bridge arm 42, and the third bridge arm 42 are respectively connected to the three-phase windings of the motor 5; each of the first bridge arm 41, the second bridge arm 42, and the third bridge arm 43 includes: an upper bridge arm and a lower bridge arm. The three-phase inverter circuit 4 is used to drive the switching devices in each upper bridge arm to turn off according to the PWM drive signal, and the switching devices in each lower bridge arm alternately turn on and off with a preset duty cycle; or, according to the PWM drive signal, it drives the switching devices in each lower bridge arm to turn off, and the switching devices in each upper bridge arm alternately turn on and off with a preset duty cycle.

[0041] The upper arm of the first bridge arm 41 includes a first switching device S1, the upper arm of the second bridge arm 42 includes a third switching device S3, and the upper arm of the third bridge arm 43 includes a fifth switching device S5. The lower arm of the first bridge arm 41 includes a second switching device S2, the lower arm of the second bridge arm 42 includes a fourth switching device S4, and the lower arm of the third bridge arm 43 includes a sixth switching device S6. The first bridge arm 41 is connected to the inductance L1 of the first phase winding of the motor 5, the second bridge arm 42 is connected to the inductance L2 of the second phase winding of the motor 5, and the third bridge arm 43 is connected to the inductance L3 of the third phase winding of the motor 5.

[0042] The three-phase windings of the motor have two short-circuit modes. One mode controls the upper bridge arm switching device in the three-phase inverter circuit 4 to always be in the off state, and controls the lower bridge arm to alternately turn on and off according to a preset duty cycle via a PWM drive signal. When the lower bridge arm of the three-phase inverter circuit 4 is on, the three-phase windings form a closed loop through the lower bridge arm, generating a short-circuit current to brake the motor 5.

[0043] Another method involves controlling the switching devices of the lower bridge arm in the three-phase inverter circuit 4 to always be in the off state, and controlling the upper bridge arm to alternately turn on and off according to a preset duty cycle via a PWM drive signal. When the upper bridge arm of the three-phase inverter circuit 4 is on, the three-phase windings form a closed loop through the upper bridge arm, generating a short-circuit current to brake the motor 5.

[0044] For example, when the upper bridge arm switching device in the three-phase inverter circuit 4 is always in the off state, and the lower bridge arm is controlled to alternately turn on and off according to the preset duty cycle corresponding to the PWM drive signal, the conduction time of the second switching device S2, the fourth switching device S4 and the sixth switching device S6 can be staggered. At any given time, only one or two phases are conducting, and the remaining phases are floating, so that a potential difference is formed between the three-phase windings, generating a controllable induced current, achieving smooth damping, and avoiding instantaneous large braking impact.

[0045] Continue to combine Figure 3 and Figure 4 Based on the above embodiments, optionally, the three-phase inverter circuit 4 further includes: a bus capacitor C1, which is connected in parallel with the first bridge arm 41 and also connected to the microcontroller 2. The bus capacitor C1 is used to receive and store the electrical energy fed back by the motor 5 during the off-range of the PWM drive signal, and to continuously supply power to the microcontroller 2 with the stored electrical energy. The microcontroller 2 operates in minimum system mode.

[0046] Specifically, when the upper arm of the three-phase bridge is off and the lower arm is on, the inductance of the three-phase windings forms a closed loop through the lower arm, generating a short-circuit current for motor braking. When the lower arm switches to off, the current in the inductance of the three-phase windings is pumped to the bus capacitor C1 through the freewheeling diodes in the upper and lower arms for energy feedback.

[0047] When all the switching devices in the three-phase inverter circuit are turned off, the energy stored in the inductors L1 of the first phase winding, L2 of the second phase winding, and L3 of the third phase winding is fed back to the bus capacitor C1 through the freewheeling diodes in the switching devices. This serves two purposes: firstly, it clamps the turn-off overvoltage of each switching device, protecting its safe operation; secondly, by converting mechanical energy into the electric field energy of the bus capacitor C1, it increases the electrical damping coefficient of the motor, achieving flexible braking. Simultaneously, the raised voltage of the bus capacitor C1 provides a stable voltage reference point for the next pulse width modulation conduction cycle, effectively suppressing current oscillations caused by sudden changes in duty cycle.

[0048] The minimum system of microcontroller 2 is the minimum peripheral hardware circuit necessary for microcontroller 2 to maintain basic power-on operation and execute core logic, that is, the most basic working circuit of microcontroller 2.

[0049] When the power supply is off, the microcontroller 2 loses the power supply from the power source 6. By retaining the basic working circuit, it relies on the limited electrical energy provided by the inertial power generation of the motor 5. It only needs to continuously supply power to the minimum system of the microcontroller 2. The microcontroller 2 can rely on the minimum system to complete the control of the three-phase inverter circuit 4, thereby realizing the speed reduction regulation of the motor 5.

[0050] Specifically, at the moment of power failure, the charge in the bus capacitor C1 of the three-phase inverter circuit will not be immediately depleted. The charge stored in the bus capacitor C1 will maintain the voltage for a few milliseconds to tens of milliseconds. The microcontroller 2 uses this brief window to detect the power failure and control the motor 5 of the robotic arm to slow down.

[0051] When the microcontroller 2 initially controls the motor 5 of the robotic arm to decelerate, it sends a PWM drive signal with a preset duty cycle to control the switching devices in the three-phase inverter circuit 4 to turn on or off, causing a short circuit or a closed circuit in the three-phase windings. At this time, the robotic arm continues to rotate under gravity or inertia, and the motor 5 passively rotates due to its own inertia, cutting magnetic field lines to generate reverse electrical energy, thus becoming a generator. The reverse electrical energy it generates is fed back to the bus capacitor C1 through the freewheeling diode of the three-phase inverter, providing a continuous energy supply to the microcontroller.

[0052] In the subsequent control phase, the energy of the microcontroller 2 comes entirely from the electrical energy converted from the mechanical energy of the motor 5. The stronger the braking of the motor 5, the greater the energy feedback, and the acceleration of the robotic arm is significantly suppressed, thereby achieving braking of the robotic arm while also ensuring low-power operation of the microcontroller 2.

[0053] This invention reduces the power consumption of the microcontroller by maintaining the operation of the minimum system of the microcontroller when the power supply is off. This allows the microcontroller to maintain effective control of the three-phase inverter circuit even after the loss of external power, resulting in better control performance.

[0054] Figure 5 This is a schematic diagram of a power detection circuit provided in an embodiment of the present invention. (Reference) Figure 5 Based on the above embodiments, optionally, the power supply detection circuit includes: a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the power supply of the robotic arm, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded; the second end of the first resistor R1 is also connected to the microcontroller 2; the detection signal is the voltage of the second resistor R2. The microcontroller 2 is used to calculate the power supply voltage based on the detection signal and determine the power supply status of the power supply 6 according to a set voltage threshold.

[0055] Since the resistance values ​​of the first resistor R1 and the second resistor R2 are fixed, the detection signal generated by the second resistor R2 will differ depending on the power supply voltage. Therefore, the power supply voltage can be deduced from the detection signal of the second resistor R2. If the power supply voltage is lower than the set voltage threshold, the power supply is determined to be in a power-off state; if the power supply voltage is greater than or equal to the set voltage threshold, the power supply is determined to be in a normal power supply state.

[0056] This invention, through the inclusion of a power detection circuit, eliminates the need for sophisticated voltage detection hardware. Instead, the power detection circuit and the microcontroller jointly calculate the specific value of the power supply voltage. Even in a power-off state, the microcontroller can still be powered in reverse by the energy from the three-phase inverter circuit, ensuring that the microcontroller can always detect the power supply voltage through the power detection circuit and maintain optimal operating conditions.

[0057] The voltage divider-style power supply detection circuit used in the embodiments of the present invention is not intended to limit the present invention. In other embodiments, comparator-type detection circuits, isolated detection circuits, or other voltage detection methods known to those skilled in the art may also be used.

[0058] This invention also provides a power-off braking control method for a robotic arm. Figure 6 A flowchart illustrating a power-off braking control method for a robotic arm, provided as an embodiment of the present invention. (See reference) Figure 6 Methods for slow descent of robotic arms in the event of power failure include: S110, Detect the power supply status.

[0059] S120. When the power supply is off, enter the PWM short-circuit braking mode, control the motor of the robotic arm to perform short-circuit braking with a preset duty cycle, and store the electrical energy fed back by the motor.

[0060] S130, the motor of the robotic arm slows down by the deceleration corresponding to the preset duty cycle.

[0061] Figure 7 A flowchart illustrating another power-off braking control method for a robotic arm provided in an embodiment of the present invention. (See reference...) Figure 7 Based on the above embodiments, optionally, in S120, when the power supply is in a power-off state, the system enters the PWM short-circuit braking mode, controls the robotic arm's motor to perform short-circuit braking with a preset duty cycle, and stores the electrical energy fed back by the motor, including: S121. Perform pulse width modulation according to the preset duty cycle to make the three-phase windings of the motor form a short-circuit closed loop and generate braking torque.

[0062] Figure 8 A flowchart illustrating another power-off braking control method for a robotic arm provided in an embodiment of the present invention. (See reference) Figure 8 Based on the above embodiments, optionally, S110, detecting the power supply status of the power supply includes: S111. Connect the power supply detection circuit to the power supply terminal and detect the detection signal of the power supply detection circuit.

[0063] S112. Calculate the power supply voltage based on the detection signal. When the power supply voltage is less than the set voltage threshold, the power supply is in a power-off state.

[0064] In various embodiments of the power-off braking system of the robotic arm, specific descriptions of braking control methods for the power-off braking system of the robotic arm are provided. These control methods can all be considered as braking control methods for the power-off braking system of the robotic arm provided in the embodiments of the present invention, and repeated content will not be described here.

[0065] Figure 9 A flowchart illustrating another method for the slow descent of a robotic arm in the event of a power failure, provided as an embodiment of the present invention. (See reference...) Figure 9 Based on the above embodiments, optionally, after detecting the power supply status of the power supply in S110, the method further includes: S220. When the power supply is off, control the different motors in the robotic arm to actively short-circuit with different preset duty cycles.

[0066] S230: Different motors of the robotic arm reduce speed by using different preset duty cycles corresponding to different deceleration rates.

[0067] When the robotic arm is a multi-axis robotic arm, it has multiple joints, and each joint is equipped with at least one motor. Because each motor controls a different direction of movement of the robotic arm, the rotation direction of each joint will also be different when the power is off. Therefore, different preset duty cycles can be set to control different motors.

[0068] For example, when a motor controls a robotic arm to move vertically perpendicular to the ground, a power outage could cause the robotic arm to crash directly into the ground. Therefore, the motors of these joints can be set to a larger preset duty cycle. Alternatively, if a robotic arm connected to a certain joint is likely to collide with robotic arms connected to other joints during movement, the motors of those joints can also be set to a larger preset duty cycle. This configuration ensures that the robotic arm will not collide, allowing it to continue operating safely even during a power outage.

[0069] When a robotic arm connected to a certain joint does not collide with robotic arms connected to other joints during movement, the preset duty cycle of the motors controlling these joints can be adaptively reduced, thereby reducing the mechanical impact on the motors and avoiding fatigue damage to gears, bearings, and the motor body.

[0070] The technical solution provided by the embodiments of the present invention improves the targeted adjustment of each motor by setting different preset duty cycles for different motors. This ensures that the robotic arm will not collide with itself, the end load will not be damaged, and the peripheral equipment will not be damaged. It also reduces the mechanical impact on the motors and has a flexible and reliable control effect.

[0071] This invention also provides a robot. The robot includes a power-off braking system for a robotic arm provided in any embodiment of this invention, which has similar beneficial effects to the power-off braking system for a robotic arm, and will not be described in detail here.

[0072] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0073] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A power-off braking system for a robotic arm, characterized in that, include: A power detection circuit, connected to the power supply of the robotic arm, is used to detect the power supply voltage of the robotic arm and output a detection signal. The motor drive circuit is connected to a power supply and is also connected to the motor and the power supply detection circuit. The motor drive circuit is used to determine the power supply status of the power supply according to the detection signal, and when the power supply is in a power-off state, it enters the PWM short-circuit braking mode, outputs the PWM drive signal, and controls the motor to perform short-circuit braking with a preset duty cycle. The motor drive circuit is also used to receive and store the electrical energy fed back by the motor during the off-range of the PWM drive signal, and to use the stored electrical energy to maintain the motor drive circuit continuously outputting the PWM drive signal in the power-off state until the robotic arm stops moving.

2. The power-off braking system for the robotic arm according to claim 1, characterized in that, The motor drive circuit includes: A microcontroller, connected to the power detection circuit, is used to determine the power supply status of the power supply based on the detection signal, and output an active short-circuit signal when the power supply is in a power-off state. The drive module is connected to the three-phase windings of the motor and also to the microcontroller. The drive module is used to perform pulse width modulation according to the active short-circuit signal and the preset duty cycle, so that the three-phase windings of the motor form a short-circuit closed loop and generate braking torque. The motor decelerates at a deceleration corresponding to the preset duty cycle.

3. The power-off braking system for the robotic arm according to claim 2, characterized in that, The drive module includes; A driving circuit, connected to the microcontroller, is used to generate the PWM driving signal based on the active short-circuit signal; The three-phase inverter circuit is connected to the drive circuit and also to the three-phase windings of the motor. The three-phase inverter circuit has multiple built-in switching devices. The drive circuit is used to drive the switching devices in the three-phase inverter circuit to conduct periodically according to the preset duty cycle through the PWM drive signal, so that the three-phase windings of the motor are short-circuited with the preset duty cycle.

4. The power-off braking system for the robotic arm according to claim 3, characterized in that, The three-phase inverter circuit includes: The first bridge arm, the second bridge arm, and the third bridge arm are connected in parallel, and the output terminals of the first bridge arm, the second bridge arm, and the third bridge arm are respectively connected to the three-phase windings of the motor; each of the first bridge arm, the second bridge arm, and the third bridge arm includes an upper bridge arm and a lower bridge arm. The three-phase inverter circuit is used to drive the switching devices in each upper bridge arm to turn off according to the PWM drive signal, and the switching devices in each lower bridge arm alternately turn on and off with the preset duty cycle; or, according to the PWM drive signal, drive the switching devices in each lower bridge arm to turn off, and the switching devices in each upper bridge arm alternately turn on and off with the preset duty cycle.

5. The power-off braking system for the robotic arm according to claim 4, characterized in that, The three-phase inverter circuit also includes: The bus capacitor is connected in parallel with the first bridge arm and also connected to the microcontroller. The bus capacitor is used to receive and store the electrical energy fed back by the motor during the off-range of the PWM drive signal, and to continuously supply power to the microcontroller with the stored electrical energy. The microcontroller operates in a minimum system mode.

6. The power-off braking system for the robotic arm according to claim 2, characterized in that, The power detection circuit includes: a first resistor and a second resistor; The first end of the first resistor is connected to the power supply of the robotic arm, the second end of the first resistor is connected to the first end of the second resistor, and the second end of the second resistor is grounded; the second end of the first resistor is also connected to the microcontroller; the detection signal is the voltage of the second resistor; The microcontroller is used to calculate the power supply voltage based on the detection signal and to determine the power supply status of the power supply based on a set voltage threshold.

7. A power-off braking control method for a robotic arm, characterized in that, A power-off braking system applied to the robotic arm according to any one of claims 1-6, wherein the power-off braking control method of the robotic arm includes: Detect the power supply status; When the power supply is in a power-off state, it enters the PWM short-circuit braking mode, controls the motor of the robotic arm to perform short-circuit braking with a preset duty cycle, and stores the electrical energy fed back by the motor. The motor of the robotic arm slows down by the deceleration corresponding to the preset duty cycle.

8. The power-off braking control method for a robotic arm according to claim 7, characterized in that, When the power supply is in a power-off state, it enters the PWM short-circuit braking mode, controlling the robotic arm's motor to perform short-circuit braking with a preset duty cycle, and simultaneously storing the electrical energy fed back from the motor, including: Pulse width modulation is performed according to the preset duty cycle, so that the three-phase windings of the motor form a short-circuit closed loop and generate braking torque.

9. The power-off braking control method for a robotic arm according to claim 7, characterized in that, The power supply status of the detection power supply includes: Connect the power detection circuit to the power supply terminal and acquire the detection signal of the power detection circuit. The power supply voltage is calculated based on the detection signal. When the power supply voltage is less than a set voltage threshold, the power supply is in a power-off state.

10. The power-off braking control method for a robotic arm according to claim 7, characterized in that, Following the detection of the power supply status, the following is also included: When the power supply is in a power-off state, different motors in the control robot arm are actively short-circuited with different preset duty cycles. The different motors of the robotic arm reduce speed by using different deceleration rates corresponding to the preset duty cycles.

11. A robot, characterized in that, include: The power-off braking system for the robotic arm according to any one of claims 1-6.

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