Strength training apparatus and method of controlling the same

Abstract

The strength training device and its control method of the present invention can smoothly perform strength training in various modes such as isokinetic motion. The strength training device includes: a permanent magnet motor; a strength output input structure; a current sensor for measuring the current of the permanent magnet motor; an inverter for driving the permanent magnet motor; a current controller for generating a drive control signal based on a position detection signal, a sampled current, and a given current value; a speed controller for generating a given current value based on the current speed and a target speed; and a motion and display controller that generates a target speed and outputs force curve information based on at least one of a training stroke setpoint, a training speed or a training tension setpoint, and the current position / speed of the strength output input structure. The strength output input structure is connected to the rotor of the permanent magnet motor through a transmission mechanism with low transmission resistance. The current speed and current position are obtained based on the position detection signal, and the current tension value is obtained from the sampled current through calculation.

Description

Technical Field

[0001] This invention relates to the field of fitness equipment technology, and in particular to an electronic weighted strength training device capable of providing strength training functions and its control method. Background Technology

[0002] In recent years, home fitness equipment has seen significant development, with a variety of intelligent home fitness equipment with comprehensive functions hitting the market. These include fitness equipment that uses a smart home bicycle for aerobic exercise, fitness equipment that uses a smart home fitness mirror for aerobic exercise, and new types of intelligent home strength training equipment that use motor-driven resistance (i.e., electronic weights) instead of the traditional weight blocks found in strength training equipment.

[0003] Electronic weight training equipment uses electronic weights instead of physical weights, and provides resistance by controlling a motor to generate magnetic force. The user resists the resistance generated by the motor, pulling outwards through a cable connected to the motor, simulating the fitness method of traditional resistance bands that use physical weights.

[0004] On the other hand, isokinetic exercise training, a type of strength training, also known as isokinetic muscle strength training, adjustable resistance training, or constant angular velocity training, usually uses specialized equipment to adjust the external resistance according to the changes in muscle strength during the exercise process, so that the entire joint moves at a preset speed. During the exercise, the muscles exert force only to increase muscle tension and increase torque output.

[0005] Isokinetic exercise techniques have excellent accuracy, reliability, and repeatability in muscle function testing, and excellent safety, efficiency, and rationality in muscle strength training. Therefore, they have broad application prospects in clinical practice and scientific research in sports training and rehabilitation medicine. Summary of the Invention

[0006] With the development of multifunctional smart home fitness equipment, people are exploring technologies that utilize this equipment to provide isokinetic exercise. In electronic weight-based strength training equipment, the output of the device (rope handles or linkage grips, etc.) can be made to move at a constant speed. This is typically achieved using a small motor driving a transmission structure with a large reduction ratio.

[0007] However, multifunctional strength training equipment needs to achieve multiple training modes such as isotonic training and isokinetic training on the same device. If a large reduction ratio transmission structure with high resistance is used, the resistance of isotonic training will be relatively large, and the smoothness will also be affected.

[0008] In addition, existing isokinetic strength training devices all require torque sensors to detect the output torque in order to adjust the motor output. This requires strength training equipment to be equipped with torque sensors at the output end, which greatly limits the structural design space of strength training equipment and increases the size and system complexity of strength training equipment.

[0009] Therefore, the present invention provides a strength training device that can reduce the resistance of the strength training device and realize multiple training modes, including isokinetic training.

[0010] Furthermore, this invention provides a strength training device and its control method, which can accurately acquire external force to control the speed of the motor without the need for an external force sensor, and realize multiple training modes including constant speed training.

[0011] Technical means to solve the problem

[0012] To address the aforementioned problems, this invention provides a strength training device, including a permanent magnet motor providing electronic counterweights for strength training, and a force output / input structure coupled to the rotor of the permanent magnet motor. The strength training device includes: a rotary encoder for measuring the rotation angle of the permanent magnet motor; a current sensor for measuring the current of the permanent magnet motor; an inverter for driving the permanent magnet motor; a current controller that generates a drive control signal output to the inverter based on a position detection signal from the rotary encoder, a sampled current from the current sensor, and a given current value from an external source; and a speed controller that generates the given current value based on the current speed of the permanent magnet motor and a given target speed, and sets the given current value... The output is sent to the current controller; and the motion and display controller, which generates the target speed based on at least one of the training stroke setting value, training speed or training tension setting value from the user or host computer, and the current position / speed of the force output input structure, and outputs the target speed to the speed controller, and outputs the current tension value and current position of the force output input structure as force curve information, wherein the force output input structure is connected to the rotor of the permanent magnet motor through a transmission mechanism with low transmission resistance, wherein the current speed and current position are obtained based on the position detection signal of the rotary encoder, and the current tension value is obtained from the sampled current of the current sensor through a prescribed calculation.

[0013] Preferably, the training stroke includes a centripetal motion stroke and an centrifugal motion stroke in the opposite direction to the centripetal motion. The motion and display controller controls the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches the proximal limit position during the centripetal motion stroke, and switches the direction of the target rotation speed to the direction of the centripetal motion when the current position of the force output input structure reaches the distal limit position during the centrifugal motion stroke. In at least either the centripetal motion stroke or the centrifugal motion stroke, the force output input structure is made to move at a constant speed or the permanent magnet motor is made to rotate at a constant speed.

[0014] Preferably, the current tension value is obtained by taking the current rotation speed constant for a specified first time period and performing the specified calculations from the sampled current of the current sensor during that specified first time period.

[0015] Preferably, the permanent magnet motor is a three-phase permanent magnet synchronous motor. The current sensor measures at least two phase current signals of the three-phase permanent magnet synchronous motor. The inverter is a three-phase inverter circuit. The given current value is a given Q-axis current value. The drive control signal is an SVPWM signal. The system also includes a current converter, which converts the at least two phase current signals into D-axis current values ​​and Q-axis current values ​​based on the at least two phase current signals and the position detection signal from the rotary encoder. The current tension value is obtained based on the Q-axis current value.

[0016] Preferably, the current tension value is obtained by keeping the current rotational speed constant within the specified first time period, acquiring the Q-axis current value Iq multiple times, and then filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value. 平均 Based on Iq 平均 What I'm asking for.

[0017] Preferably, the motion and display controller also controls based on the current tension value of the force output input structure, and sets the target rotation speed to 0 when the current tension value is less than the specified minimum tension setting value.

[0018] Furthermore, this invention provides a control method for a strength training device, wherein the strength training device is as described above. The control method controls the rotation of the permanent magnet motor to enable the user to perform isokinetic strength training including centripetal and centrifugal motion strokes. The control method includes: isokinetic motion control steps (S1A, S2A), in which, based on the target rotational speed output by the motion and display controller, the position detection signal of the rotary encoder, and the sampling current of the current sensor, the permanent magnet motor is controlled to rotate at a preset training speed via the speed controller, the current controller, and the inverter. Specifically, in at least one of the centripetal and centrifugal motion strokes, the force output / input structure is made to perform isokinetic motion or the permanent magnet motor is made to rotate at a isokinetic speed. The force curve information acquisition and output steps (S1B, S2B) involve obtaining the current position of the force output input structure based on the position detection signal of the rotary encoder during the centripetal motion stroke and the centrifugal motion stroke, obtaining the current tension value of the force output input structure from the sampling current of the current sensor through a prescribed calculation, and outputting the current tension value and the current position as force curve information; and the motion direction switching step (S3) involves the motion and display controller controlling the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches a preset near-end limit position during the centripetal motion stroke, and switching the direction of the target rotation speed to the direction of the centripetal motion when the current position of the force output input structure reaches a preset far-end limit position during the centrifugal motion stroke.

[0019] Preferably, the current rotational speed is kept constant for a specified first time period, and the current tension value is obtained from the sampled current of the current sensor through the specified calculation within the specified first time period.

[0020] Preferably, the permanent magnet motor is a three-phase permanent magnet synchronous motor. The current sensor measures at least two phase current signals of the three-phase permanent magnet synchronous motor. The inverter is a three-phase inverter circuit. The given current value is a given Q-axis current value. The drive control signal is an SVPWM signal. The system also includes a current conversion step, which converts the at least two phase current signals into D-axis current values ​​and Q-axis current values ​​based on the at least two phase current signals and the position detection signal from the rotary encoder. The current tension value is obtained based on the Q-axis current value.

[0021] Preferably, the current tension value is obtained by keeping the current rotational speed constant within the specified first time period, acquiring the Q-axis current value Iq multiple times, and then filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value.平均 Based on Iq 平均 What I'm asking for.

[0022] Preferably, during the centripetal motion stroke and the centrifugal motion stroke, the motion and display controller also controls based on the current tension value of the force output input structure, and sets the target rotational speed to 0 when the current tension value is less than the specified minimum tension setting value.

[0023] Beneficial effects

[0024] The strength training device of the present invention, since the strength output input structure is connected to the rotor of the motor through a transmission mechanism with low transmission resistance, and the motor operation is controlled by generating a target speed based on at least one of the training stroke setting value, training speed or training tension setting value from the user or host computer, and the current position / speed of the strength output input structure, can significantly reduce the resistance of the strength training device, thereby enabling smooth strength training in various modes, including constant speed exercise.

[0025] The strength training device and control method of this invention can obtain the current speed of the motor based on the position detection signal of the rotary encoder, and obtain the current tension value based on the current current value of the motor. Furthermore, a target speed of the motor is generated based on a user-defined mass tension model, and the motor is controlled by a speed controller, a current controller, and an inverter to achieve this target speed. In this way, external force can be accurately acquired to control the motor speed without the need for an external force sensor, enabling various training modes, including constant speed training. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating an example of the basic structure of an electronic weighted strength training device that provides strength training functions in one embodiment.

[0027] Figure 2 This is a block diagram illustrating the structure of the control device for the strength training apparatus of the present invention.

[0028] Figure 3 This is a circuit diagram illustrating the circuit structure of a motor driver according to one embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram representing two mechanical models of strength training.

[0030] Figure 5 This is a flowchart illustrating the control method of the strength training device of the present invention.

[0031] Figure 6 It is a graph showing the change of positional tension over time during isokinetic exercise training.

[0032] Figure 7 This is a schematic curve representing the change in motor speed in the control method of the present invention.

[0033] Figure 8 This is a flowchart showing how to calculate the tension value by repeatedly obtaining the Q-axis current value. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0035] (Basic structure of electronic weight-based strength training equipment)

[0036] Electronic weight training equipment uses electronic weights instead of physical weights, and provides resistance by controlling a motor to generate magnetic force. The user resists the resistance generated by the motor, pulling outwards through a cable connected to the motor, simulating the fitness method of traditional resistance bands that use physical weights.

[0037] In one embodiment of the present invention, the basic structure of the electronic weight-type strength training device that provides strength training function can be: Figure 1 The structure shown.

[0038] Specifically, Figure 1 This is a diagram illustrating an example of the basic structure providing strength training functions in an electronic weight-based strength training device according to one embodiment. (See diagram for example.) Figure 1 As shown, the strength training equipment includes two motors 20 serving as resistance sources or electronic counterweights, two winches 21 fixed to the rotors of each motor for winding ropes, two ropes 22 each with one end fixed to the respective winch, two pulley systems including a first fixed pulley 23, a second fixed pulley 24, a third pulley 25, and a fourth pulley 26, two swing arms 30 respectively located on the left and right sides, and two training handles 31 respectively connected to the other ends of the two ropes. The rope 22 passes through the first fixed pulley 23, its direction changes to upward along the side of the machine, then passes through the second fixed pulley 24 at the top, adjusting its direction downward along the guide rail, and then passes through the third pulley 25 and the fourth pulley 26 into the swing arm 30. The rope 22 passes through the wrist joint pulley (not shown) of the swing arm 30 and exits, fixed to the training handle 31.

[0039] When the motor driver drives the motor 20, causing the winch 21 to rotate in the opposite direction to the pull rope 22, a force opposing the motor resistance is generated. When the pulling force is greater than the motor resistance, it's like pulling up a physical weight. Figure 1The training handle 31 is pulled outward by a pulling force counteracting the force of equal weight generated by the motor 20 connected via the rope 21. When the pulling force is less than the motor resistance, the motor 20 rotates, causing the winch 21 to wind and retract the rope 22, equivalent to the weight falling back, and the training handle 31 is pulled inward. It should be noted that the motor resistance has a different nature from traditional resistance, such as friction. The direction of traditional resistance is opposite to the direction of motion, while the direction of motor resistance is a definite direction, which can be the same as the direction of motion, such as when the winch 21 winds and retracts the rope 22. The nature of the motor resistance is more similar to the counterweight in traditional strength training equipment. Here, the winch 21, the rope 22, and the pulley group including the first fixed pulley 23, the second fixed pulley 24, the third pulley 25, and the fourth pulley 26 constitute the transmission mechanism, and the rope 22 and the training handle 31 constitute the force input and output structure.

[0040] Here, two winches 21 for winding the rope are fixed to the rotors of each motor 20. The rope 22 is connected to the training handle 31 via a pulley system including a first fixed pulley 23, a second fixed pulley 24, a third pulley 25, and a fourth pulley 26. Instead of using a high-reduction-ratio transmission structure such as a gear set, the resistance when pulling the rope is significantly reduced, achieving high overall transmission efficiency. This allows for smooth strength training in various modes, including isokinetic and constant-speed movements. Furthermore, the use of two independently controllable motors 20 and two sets of rope pulley mechanisms connected to the rotors of each motor allows for independent generation of motor resistance on the two training handles 31 extending from the two swing arms 30 on the left and right sides, greatly increasing the freedom of strength training.

[0041] However, the basic structure providing strength training functionality is not limited to the structure described above. Any electronic weight-type strength training device with a transmission structure possessing low transmission resistance can be used to implement this invention. Specifically, as long as it has a motor capable of generating resistance and a force output / input structure coupled to the motor's rotor via a transmission structure with a total transmission efficiency greater than or equal to 85%, allowing the user to apply force or perform work on the motor through this force output / input structure, and to receive force or work from the motor on the user through this force output / input structure, other structures can be used. For example, a mechanism with a winch, ropes, and pulleys can be used, but the number and configuration of the ropes and pulleys are not limited. Figure 1 The method shown, and it is also possible to not have. Figure 1 The swing arm 30 in the original design can be replaced with other structures, such as a slider. Alternatively, a linkage structure can be used instead of a winch rope structure. As for the transmission structure, a gear transmission mechanism can also be used, provided that the overall transmission efficiency is high.

[0042] As the motor generating resistance or electronic weight, a flat motor, as described in Chinese invention patent application number 202210461292.3, can be used. This flat motor has a multi-pole structure, enabling it to rotate at a lower speed and output a larger torque. Therefore, the low speed and high torque required by strength training equipment can be met without using a large reduction ratio transmission structure such as a gear set. Of course, the motor generating motor resistance or electronic weight is not limited to the aforementioned flat motor; motors with other structures and shapes can also be used.

[0043] (Control device for strength training equipment)

[0044] The strength training device of the present invention also includes the control device described below.

[0045] Figure 2 This is a block diagram illustrating the structure of the control device for the strength training apparatus of the present invention.

[0046] like Figure 2 As shown, the control device of the strength training equipment of the present invention includes: a rotary encoder 11 for measuring the rotation angle of a permanent magnet motor 10; a current sensor 12 for measuring the current of the motor 10; an inverter 13 for driving the permanent magnet motor 10; a current controller (also called a current control loop) 14, which generates a drive control signal output to the inverter 13 based on the position detection signal from the rotary encoder 11, the sampled current from the current sensor 12, and a given current value from an external source; a speed controller (also called a speed control loop) 15, which generates the given current value based on the current speed of the permanent magnet motor and the given target speed, and outputs the given current value to the current controller 14; and a motion and display controller 16, which generates the target speed based on at least one of the training stroke setting value, the training speed or the training tension setting value from the user or the host computer, and the current position / speed of the force output input structure, and outputs the target speed to the speed controller 15, and outputs the current tension value and the current position of the force output input structure as force curve information. As will be explained in detail below, the current rotational speed is obtained based on the position detection signal of the rotary encoder 11, and the current tension value is obtained from the sampled current of the current sensor 12 through a prescribed calculation.

[0047] The motion and display controller 16 can generate a target speed to control the motor's operation based on at least one of the training stroke setting value, training speed or training tension setting value, and the current position / speed of the force output input structure, provided by the user or host computer. Specifically, during a constant-speed motion stroke, the target speed can be generated based on the training speed setting value provided by the user or host computer to control the motor's operation, thereby achieving constant-speed motion within a stroke. During a non-constant-speed motion stroke, the target speed can be generated based on the training tension setting value provided by the user or host computer and the current speed of the force output input structure to control the motor's operation, thereby achieving non-constant-speed motion within a stroke. Furthermore, the motion and display controller 16 can generate a target speed based on the training stroke setting value and the current position of the force output input structure to control the motor's operation, thereby enabling switching of the motion direction between motion strokes.

[0048] Figure 2 The control device for the strength training equipment shown is particularly suitable for controlling the equipment to achieve isokinetic motion because it has a motion and display controller. Specifically, it employs... Figure 2 The control device of the strength training equipment shown can generate a target rotational speed to control the motor's operation based on training stroke settings, training speed settings, and the current position of the force output input structure from the user or host computer. This enables training functions including constant-speed motion, including switching of motion direction between strokes. Furthermore, it can acquire the motor's current rotational speed based on the position detection signal from the rotary encoder and obtain the current tension value based on the motor's current current value. In this way, it can accurately acquire external force to control the motor speed without the need for an external force sensor. While achieving constant-speed training, it can also output the current tension value and current position of the force output input structure as force curve information.

[0049] Preferably, the training stroke includes a centripetal motion stroke and an centrifugal motion stroke in the opposite direction to the centripetal motion. The motion and display controller controls the direction of the target rotational speed to the direction of the centrifugal motion when the current position of the force output input structure reaches the proximal limit position during the centripetal motion stroke, and switches the direction of the target rotational speed to the direction of the centripetal motion when the current position of the force output input structure reaches the distal limit position during the centrifugal motion stroke. In at least either the centripetal motion stroke or the centrifugal motion stroke, the force output input structure is made to move at a constant speed or the permanent magnet motor is made to rotate at a constant speed.

[0050] As a training mode, isokinetic exercise can be considered isokinetic training as long as it involves isokinetic control of a certain time or distance within a reciprocating motion that includes a concentric movement and an eccentric movement. For example, isokinetic training can be performed during the concentric movement and the eccentric movement can be isotonic or unresisted; or the eccentric movement can be isokinetic training and the concentric movement can be isotonic or unresisted; or both the concentric and eccentric movements can be performed as isokinetic training.

[0051] As will be explained later, preferably, the current tension value is obtained by performing the specified calculation on the sampled current of the current sensor within a specified first time period while keeping the current rotational speed constant.

[0052] Preferably, the permanent magnet motor is a three-phase permanent magnet synchronous motor, the current sensor measures the three-phase current signal of the three-phase permanent magnet synchronous motor, the inverter is a three-phase inverter, the target current value is the target Q-axis current value, and the drive control signal is an SVPWM signal. The control device also includes a current converter, which converts the three-phase current signal into D-axis current value and Q-axis current value based on the three-phase current signal and the position detection signal from the rotary encoder, and the current tension value is obtained based on the Q-axis current value.

[0053] As will be explained later, preferably, the current tension value is obtained by keeping the current rotational speed constant within the specified first time period, acquiring the Q-axis current value Iq multiple times, and filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value. 平均 Based on Iq 平均 What I'm asking for.

[0054] Preferably, the motion and display controller also controls based on the current tension value of the force output input structure, and sets the target rotation speed to 0 when the current tension value is less than the specified minimum tension setting value.

[0055] The control device of the strength training equipment in this embodiment will be described in more detail below, taking the use of a three-phase AC permanent magnet synchronous motor as an example.

[0056] With the technological advancements in three-phase AC permanent magnet synchronous motors (3PH PMSMs), superior magnetic circuit simulation techniques and electromagnetic materials have emerged. Through meticulous design, the 3PH PMSM exhibits extremely low torque ripple (less than 0.4% in one embodiment). Under Id=0 control, the input Q-axis current Iq of the 3PH PMSM is precisely linearly proportional to the output torque M. If the torque ripple is large, for example, 2%, then for a constant input Iq, M will fluctuate by 2%. If the target M is 10 Nm, then the actual M will vary between 9.9 Nm and 10.1 Nm. If a winch with a radius R=4.5 cm is used, then the motor output force F will vary between 220 N and 224.4 N. This 4.4 N force variation will negatively impact the user's handling experience and will also affect the accuracy of tension measurement, as described below.

[0057] like Figure 2 As shown, in order for the driver to drive the 3PH PMSM, the control device has two control loops: a current control loop and a speed control loop.

[0058] A high-precision rotary encoder (which can be a photoelectric encoder, magnetic encoder, rotary transformer, etc.) is mounted on the motor shaft. In this embodiment, a magnetic encoder is used to reduce size and control costs. The rotary encoder can acquire the angle of the motor shaft in real time, with an accuracy that can easily reach 4000 p / r (1 / 4000th of a revolution, 0.09 degrees), and its real-time performance is very high, with an output frequency that can easily reach above 2kHz. The Park transformation and SVPWM in the current control loop both require calculating the motor electrical angle θE based on the absolute position P of the motor shaft output by the encoder and the number of motor stages.

[0059] The inputs to the current controller (current control loop) are the given D-axis power Id and the given Q-axis power Iq. Id and Iq need to be transformed into target three-phase currents IU, IV, and IW through Park and Clark transformations. The system inputs specific voltages to the three phase coils of the motor via SVPWM, and, acting as a current sensor, samples the actual three-phase currents IU', IV', and IW' through at least one sampling resistor in a time-division manner. The actual three-phase currents IU', IV', and IW' are then transformed through Park and quadrature transformations to obtain the actual Id' and Iq', forming the sampling feedback of the current control loop. With the current control loop feedback, the voltages input to the three-phase coils by SVPWM can be adjusted using a PI (Proportional-Integral) control algorithm, thereby controlling Id' and Iq' to quickly and accurately approximate Id and Iq.

[0060] The input to the speed controller (speed control loop) is the target speed v. Since the encoder can provide real-time feedback on the absolute position P of the motor shaft, the actual speed v' = (P2 - P1) / Δt can be calculated by continuously acquiring data at small intervals Δt (e.g., 0.3 ms). v' serves as speed feedback, and the magnitude of Iq can be adjusted using a PI (proportional-integral) control algorithm to change the magnitude of the motor's output torque. Therefore, v' can be controlled to quickly and accurately approximate v.

[0061] Figure 3 This is a circuit diagram illustrating the circuit structure of a motor driver according to one embodiment of the present invention.

[0062] like Figure 3 As shown, the permanent magnet motor in this embodiment is a three-phase permanent magnet synchronous motor. The motor driver includes an MCU controller that can realize the functions of current controller and speed controller, and a three-phase inverter circuit composed of 6 switching transistors, with a diode connected in reverse parallel to each switching transistor.

[0063] The following explains in more detail how to utilize... Figure 3 The circuit structure shown is used for resistance control of the motor.

[0064] Six switching transistors 101-106 form a three-phase inverter circuit. The control logic is determined by six PWM control signals 114 output by the MCU controller 112. These six PWM control signals are amplified and isolated by the drive circuit 115 to control the IGBT switching transistors. 101 and 102 serve as inverter switches for the U-phase 107, 103 and 104 for the V-phase 108, and 105 and 106 for the W-phase 109. The control signal output for the three-phase permanent magnet synchronous motor 110 is achieved through inverter modulation algorithms such as SVPWM or SPWM.

[0065] 116, 117, and 118 are the current sampling resistors for the three-phase switching transistors. According to Ohm's law U = R * I, the current 119 flowing through the three-phase switching transistors and sampling resistors can be calculated by collecting the voltage values ​​of the current sampling resistors. 101 and 102 cannot be simultaneously in the open state, 103 and 104 cannot be simultaneously in the open state, and 105 and 106 cannot be simultaneously in the open state; otherwise, a short circuit will occur. Based on this principle, knowing the current values ​​flowing through the current sampling resistors, the output currents 107, 108, and 109 can be obtained.

[0066] The three-phase current sampling method for motors is not limited to the above-described forms. High-level sampling can also be used, where at least two resistors are connected in series with two of the motor's three-phase power lines to sample the current. Furthermore, there are various options for the sampling sensors, including but not limited to: Hall effect current sampling devices, current transformers, etc.

[0067] In addition, to reduce costs, only two phase currents can be sampled, and the third phase current can be calculated by the sum of the three phase currents being zero.

[0068] The three-phase permanent magnet synchronous motor 110 provides photoelectric encoders, magnetic rotary encoders, Hall sensors, etc. The MCU controller 112 can obtain feedback information such as the position and speed of the motor by connecting these sensors.

[0069] The MCU controller 112 collects the bus voltage 121 of the inverter circuit. When necessary, it controls the IGBT switch 111 to form a discharge circuit with the braking resistor 113 and the capacitor 122 to achieve the discharge function, thereby preventing the bus voltage from being too high and damaging the components.

[0070] The above explains how to achieve precise motor speed control of the 3PH PMSM through the current control loop and speed control loop. It also demonstrates that in the torque control loop of the 3PH PMSM, Iq and torque M are precisely linearly proportional. Based on this, we can achieve torque monitoring of the 3PH PMSM without the need for external force (torque) / weighing / spring or other external force (torque) monitoring sensors. This will be explained in detail below.

[0071] First, it will be explained how mass and tension simulation is performed in the electronic weight-type strength training device of the present invention.

[0072] Figure 4 These are schematic diagrams representing two mechanical models of strength training. The mechanical model represented by traditional weight machines is [A]. The model represented by digital strength training equipment using a motor as the resistance source is [B]. Because the moment of inertia of the motor rotor is constant and cannot change with the training force setting F, the experience will be significantly different from model [A].

[0073] The electronic weighted strength training device of the present invention can not only use model [B] to simulate the feeling of model [A], but also use model B to simulate the feeling of any m and F.

[0074] Specifically, in model [A], for a counterweight of mass m, when subjected to an upward pulling force T and a gravitational force mg, where g is the acceleration due to gravity (taking upward as the positive direction), the counterweight should move with an acceleration a = (T - mg) / m. Therefore, within a very small time slice Δt (e.g., ranging from 1 to 10 ms), the change in velocity of the counterweight is Δv = a * Δt. After time slice Δt, the new velocity v' is v' = v + Δv. If we know T, we can use the known conditions m, Δt, and the velocity v from the previous time slice to obtain the velocity v' after time slice Δt. After the next Δt, the new v' can be calculated using the same method.

[0075] Similarly, in model [B], it is possible to use the formula v'=(TF)*Δt / m 虚拟配重 +v, calculate the velocity v' after Δt, where T represents the current tension value, m 虚拟配重 This represents the virtual mass setting value, and F represents the training pull setting value.

[0076] If there is an object at this moment, regardless of its mass and the friction it is subjected to, as long as it can move according to the above algorithm when subjected to an external force T, a person will feel that the object has a mass of m.

[0077] Below is a brief explanation of an example of the motion patterns that can be achieved using model [B].

[0078] (1) Isotonic motion

[0079] Isotonic motion refers to a state in which the force input and output mechanisms maintain a relatively constant tension value throughout strength training. This is described by the formula v'=(T–F)*Δt / m. 虚拟配重 In +v, T and F are approximately equal, while m 虚拟配重 This refers to cases where m is taken as a very small value. In practical control, m can be... 虚拟配重 Set it to a very small non-zero value. According to the formula above, as long as TF≠0, it is subject to the denominator m. 虚拟配重 A very small influence can cause a very drastic change in v2. This is the feeling of low inertia, which can be compared to stretching a rubber band.

[0080] (2) Constant velocity motion

[0081] Isokinetic motion refers to the process where the force input and output mechanisms maintain approximately a constant speed throughout strength training. This is defined in the formula v'=(T–F)*Δt / m. 虚拟配重 In +v, m 虚拟配重 The case where m takes a very large value. 虚拟配重 When it is infinite, (T–F)*Δt / m 虚拟配重 As it approaches zero, v' = v.

[0082] The following explains how to monitor tension without setting up an external force measuring mechanism.

[0083] The strength training device of this invention has a high-precision encoder to monitor the position P of the motor rotor. It can calculate the rotor speed v = (P2 - P1) / Δt by monitoring P1 and P2 twice at intervals of Δt. Alternatively, it can calculate the rotor speed a = ((P3 - P2) / Δt - (P2 - P1) / Δt) / Δt = (P3 + P1 - 2P2) / Δt2 by monitoring P1, P2, and P3 three times at intervals of Δt.

[0084] If, within a time period Δt1 (e.g., more than 1 ms), the acceleration a of the rotor structure is 0 and v is constant, then the sum of the radial external forces acting on the rotor structure at this time can be considered to be 0. The external forces acting on the rotor structure are mainly the electromagnetic force F (the force between the motor stator and rotor), the user's tension T (transmitted to the winch through rope tension), and the frictional force f. f can be considered sufficiently small to be negligible (in one embodiment, f is less than 0.1 N). Because a = 0, F = T (if f is not negligible, it can be approximated by measurement; the formula is F = T ± f, with the plus or minus sign depending on the direction of rotor motion). Since F is proportional to Iq, and Iq is obtained from feedback from the current loop PI automatic control system, it can be expressed by the formula F = k1 * Iq, then T = F = k1 * Iq. Therefore, as long as the rotor structure is controlled to move at a constant speed within Δt1, the user's tension T can be calculated from Iq. This eliminates the need for tension monitoring using an external force / weighing / elastic force structure.

[0085] The value of k1 can be determined, for example, as follows: When the motor input Iq = 1A, measure T with a force gauge. After changing Iq and measuring multiple times, obtain a table showing the correspondence between Iq and T. If the linearity is good, a linear function can be directly used for fitting. The specific k1 can be fixed or obtained from a table.

[0086] The specific implementation method for calculating the user's pulling force T based on Iq will be explained in detail in the description of the control method.

[0087] In the above embodiments of the present invention, the motor providing the electronic counterweight is a three-phase AC permanent magnet synchronous motor. However, the present invention is not limited to the above embodiments, and other motors may be used to provide the electronic counterweight.

[0088] (Control methods for strength training equipment)

[0089] This invention provides a control method for a strength training device. As described above, the strength training device includes a permanent magnet motor that provides electronic counterweights for strength training, and a force output / input structure coupled to the rotor of the permanent magnet motor. The strength training device also includes a control unit comprising: a rotary encoder for measuring the rotation angle of the permanent magnet motor; a current sensor for measuring the motor current; an inverter for driving the permanent magnet motor; a current controller; a speed controller; and a motion and display controller. Based on a training stroke setpoint and a training speed setpoint from a user or host computer, and the current position of the force output / input structure, the controller generates a target rotational speed and outputs the target rotational speed to the speed controller. It also outputs the current tension value and current position of the force output / input structure as force curve information.

[0090] Figure 5 This is a flowchart illustrating a control method for a strength training device according to one embodiment of the present invention. This control method is used when performing isokinetic training with the strength training device of the present invention, controlling the rotation of the permanent magnet motor to enable the user to perform isokinetic strength training including concentric and eccentric strokes.

[0091] like Figure 5 As shown, the control method of the present invention includes the following steps: constant velocity motion control steps (S1a, S2a), in the centripetal motion stroke and the centrifugal motion stroke, based on the target rotation speed output by the motion and display controller, the position detection signal of the rotary encoder and the sampling current of the current sensor, the permanent magnet motor is controlled to rotate at a preset training speed by the speed controller, the current controller and the inverter, wherein, in at least either the centripetal motion stroke and the centrifugal motion stroke, the force output input structure is made to perform constant velocity motion or the permanent magnet motor is made to rotate at a constant speed;

[0092] Steps S1b and S2b for acquiring and outputting force curve information: During the centripetal and centrifugal motion strokes, the current position of the force output input structure is acquired based on the position detection signal of the rotary encoder; the current tension value of the force output input structure is obtained from the sampled current of the current sensor through a prescribed calculation; and the current tension value and the current position are output as force curve information.

[0093] The motion direction switching step (S3) involves the motion and display controller controlling the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches a preset proximal limit position during the centrifugal motion stroke, and switching the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches a preset distal limit position during the centrifugal motion stroke.

[0094] use Figure 5The control method shown can control a permanent magnet motor to rotate at a preset training speed or training mode during the centripetal and centrifugal motion strokes, based on a given target rotational speed, the position detection signal from the rotary encoder, and the sampling current from the current sensor. This is achieved through a speed controller, a current controller, and an inverter, enabling multiple training modes, including a constant-speed motion training mode. Furthermore, during the centripetal and centrifugal motion strokes, the current position of the force output input structure is obtained based on the position detection signal from the rotary encoder. The current tension value of the force output input structure is obtained through prescribed calculations from the sampling current from the current sensor. The current tension value and the current position are then output as force curve information, achieving real-time detection and output of the current tension value. Moreover, the direction of the target rotational speed can be switched based on preset proximal and distal limit positions, enabling repeated centripetal and centrifugal motions within a given stroke range.

[0095] In isokinetic motion control methods, any reciprocating motion that includes a concentric motion and an eccentric motion, as long as it involves isokinetic control for a certain time or distance, can be considered isokinetic training. For example, isokinetic training can be performed during the concentric motion, with the eccentric motion in an isotonic or unresisted state; or the eccentric motion can be performed during isokinetic training, with the concentric motion in an isotonic or unresisted state; or both the concentric and eccentric motions can be performed during isokinetic training.

[0096] Figure 6 This is a graph showing the change in position / tension over time during isokinetic exercise training. The graph illustrates the case where both concentric and eccentric movements are performed at an isokinetic rate. Figure 6 In the diagram, the left coordinate axis P represents position, and the corresponding slanted straight lines represent the change of position over time. The right coordinate axis T represents tension, and the corresponding roughly arc-shaped curves represent the change of tension over time.

[0097] like Figure 6 As shown, during isokinetic motion training, position P periodically changes between its proximal and distal extreme positions. The distance between these positions represents the distance traveled in either a centripetal or eccentric motion. A linear change in position over time indicates isokinetic motion, with the slope of the line representing the training speed. Tension changes with time in a roughly arc-shaped curve, based on real-time tension changes detected by the motor's current.

[0098] Isokinetic training has two main functions: training and measurement. Under isokinetic training, muscle recruitment is faster, making it easier to overcome the bottlenecks of isotonic exercise. Measurement is used to test the maximum force exerted by muscles at different lengths. Because muscle length and joint angles affect the magnitude of force exertion, measuring the force exerted by muscles at a single location is insufficient for a comprehensive evaluation of muscle ability. This invention can detect tension change curves in real time throughout the entire isokinetic training process. For users, especially professional athletes, this comprehensive measurement of muscle ability helps them find the most efficient force exertion range.

[0099] Preferably, during the centripetal motion stroke and the centrifugal motion stroke, the motion and display controller also controls based on the current tension value of the force output input structure, and sets the target rotational speed to 0 when the current tension value is less than the specified minimum tension setting value.

[0100] Therefore, when the system detects that the current tension value is less than a certain threshold, it determines that the user is not using the equipment or has stopped applying force. The system stops and waits for the user to apply force again before resuming speed. This function is for energy saving and safety reasons, and also to prevent users from slacking off, ensuring that the user always applies force exceeding a specific value.

[0101] The following explains how to perform pull testing and speed control during strength training. First, we will discuss movement patterns other than isokinetic exercise, that is, movement patterns that can have arbitrary speed curves.

[0102] In this invention, the current tension value is acquired and the speed is controlled within two consecutive time periods on the order of milliseconds, namely a specified first time Δt1 and a specified second time Δt2, to achieve tension detection and speed control.

[0103] Specifically, control is performed within a specified first time Δt1 to maintain the current rotational speed constant. At this time, T = F, and F is proportional to the motor current. The current tension value can be obtained by performing a specified calculation on the sampled current from the current sensor within the specified first time Δt1.

[0104] In the next specified second time interval Δt2, based on the formula v2=(T–F)*Δt2 / m 虚拟配重 +v, calculate the target rotational speed after the specified second time Δt2, where v2 represents the target rotational speed, T represents the current tension value, and m 虚拟配重 Here, F represents the virtual mass setting value, F represents the training tension setting value, and v represents the current rotational speed. Furthermore, within the specified second time interval Δt2, the motor's rotational speed is controlled to reach the target rotor speed v2.

[0105] By repeatedly performing the control process with Δt1+Δt2 as a unit using the above control method, the motion speed based on a given mass tension model can be obtained by continuously responding to the tension applied by the user.

[0106] Figure 7 This is a schematic curve representing the change in motor speed in the control method of the present invention. For example... Figure 7 As shown, during the first Δt1 time interval, the motor speed is maintained at v1. During this period, the current tension value is obtained based on the current motor current value, and the target motor speed v2 is obtained based on the current tension value. During the first Δt2 time interval, the motor speed is controlled to reach the target speed v2. Then, during the second Δt1 time interval, the motor speed is maintained at v2. During this period, the current tension value is obtained based on the current motor current value, and the target motor speed v3 is obtained based on the current tension value. During the second Δt2 time interval, the motor speed is controlled to reach the target speed v3. This same control is then performed to continuously respond to the tension applied by the user to obtain the motion speed based on a given mass tension model.

[0107] from Figure 7 As can be seen, the rotational speed of the motor rotor is not continuous; in fact, the motor rotor operates within a stepped curve. However, as long as Δt1 and Δt2 are sufficiently small, it can closely approximate a continuous curve. Of course, Δt1 and Δt2 also have lower limits, determined by the response speed of the rotary encoder, the operating frequency of the controller that controls the motor speed, etc. Preferably, the specified first time Δt1 is greater than 1 ms and less than 10 ms, and the specified second time Δt2 is greater than 0.5 ms and less than 5 ms. In this invention, since sensors such as strain gauges, rod-type pressure measuring elements, and weight sensors that cause sampling lag in the tension T are not used, and the current tension value is obtained based on the current current value of the motor, the response speed and accuracy of speed control can be greatly improved compared to existing technologies, thus enhancing the user experience for strength training.

[0108] Preferably, the permanent magnet motor is a three-phase permanent magnet synchronous motor, the current sensor measures the three-phase current signal of the three-phase permanent magnet synchronous motor, the inverter is a three-phase inverter, the target current value is the target Q-axis current value, the drive control signal is an SVPWM signal, and the control method further includes a current conversion step, which converts the three-phase current signal into D-axis current value and Q-axis current value based on the three-phase current signal and the position detection signal from the rotary encoder, and the current tension value is obtained based on the Q-axis current value.

[0109] Preferably, the current tension value is obtained by keeping the current rotational speed constant within the specified first time Δt1, acquiring the Q-axis current value Iq multiple times, and then filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value. 平均 Based on Iq 平均 What I'm asking for.

[0110] The following reference Figure 8 This document details an embodiment of determining the current tension value by repeatedly acquiring the Q-axis current value Iq within the first time interval Δt1.

[0111] Figure 8 This is a flowchart showing how to calculate the tension value by repeatedly obtaining the Q-axis current value.

[0112] like Figure 8 As shown, in step S11, timing begins for a predetermined Δt1, for example, 1 ms. In step S12, the speed of the motor rotor is controlled to remain constant at v1. In step S13, the time Δt3 is waited for, which can be 1 / 5 to 1 / 10 of Δt1. In step S14, it is determined whether the time Δt1 has been reached. If not, proceed to step S15; if so, proceed to step S16. In step S15, the current Q-axis current value Iq is obtained and recorded in an array, then the process returns to step S12. This cycle from step S12 to step S15 is repeated multiple times to obtain the Q-axis current value Iq. In step S16, the multiple Iq values ​​stored in the array are filtered and averaged to obtain the final Iq. 平均 In step S17, via Iq 平均 Calculate the current tension value.

[0113] The average Q-axis current value Iq is obtained by acquiring the Q-axis current value Iq multiple times, and then filtering and averaging these acquired values. 平均 Based on Iq 平均 Calculating the current tension value, compared to calculating the current tension value based on a single Q-axis current value Iq, can improve the accuracy of the obtained current tension value and achieve more precise control of the motor speed.

[0114] The following explains how to control speed during constant-speed motion.

[0115] During constant-speed motion, the above control method can achieve constant-speed control within a centripetal motion stroke or a centrifugal motion stroke, the duration of which is 1 second to several seconds, i.e., a relatively long time period. Maintaining constant-speed motion for such a long time period is achieved by continuously controlling the speed in units on the order of milliseconds.

[0116] Specifically, we consider a short period of time Δt1. When the external force T increases, the current speed will suddenly increase. At this time, the error value in the speed controller will increase, and thus the setpoint value of Iq will increase. The current controller generates a control signal based on the current error value, which increases the motor's Iq, thereby increasing the motor's torque to balance the increase in external force T and keep the speed constant.

[0117] More specifically, Δt3 is the current loop control cycle, with current sampling feedback and PID adjustment performed once every Δt3. Δt1 is the speed loop control cycle, with speed sampling feedback and PID adjustment performed once every Δt1. Generally, Δt1 is one or more Δt3 cycles, which can adequately meet the speed and current control requirements. If a slight deviation from the target speed is detected in Δt1, the Iq setpoint will be adjusted in the next Δt1 based on the PID calculation results, so that the speed is closer to the target speed in the next Δt1. Δt3 is typically 100-500 microseconds. Δt1 is typically 1-10 times Δt3.

Claims

1. A strength training device, comprising a permanent magnet motor providing electronic weights for strength training, and a force output / input structure coupled to the rotor of the permanent magnet motor, characterized in that it includes: A rotary encoder for measuring the rotation angle of the permanent magnet motor; A current sensor for measuring the current of the permanent magnet motor; Inverter used to drive the permanent magnet motor; A current controller generates a drive control signal output to the inverter based on the position detection signal from the rotary encoder, the sampled current from the current sensor, and a given current value from an external source. A speed controller generates the given current value based on the current speed of the permanent magnet motor and the given target speed, and outputs the given current value to the current controller; and The motion and display controller generates the target rotational speed based on at least one of the training stroke setting, training speed or training tension setting, and the current position / rotational speed of the force output input structure from the user or host computer, and outputs the target rotational speed to the speed controller. It also outputs the current tension value and current position of the force output input structure as force curve information. The force output input structure is connected to the rotor of the permanent magnet motor through a transmission mechanism with low transmission resistance. The current rotational speed and current position are obtained based on the position detection signal of the rotary encoder, and the current tension value is obtained from the sampled current of the current sensor through a prescribed calculation. The training stroke includes a centripetal motion stroke and a centrifugal motion stroke in the opposite direction to the centripetal motion. The motion and display controller controls the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches the proximal limit position during the centripetal motion stroke, and switches the direction of the target rotation speed to the direction of the centripetal motion when the current position of the force output input structure reaches the distal limit position during the centrifugal motion stroke. In at least either the centripetal motion stroke or the centrifugal motion stroke, the force output input structure is made to move at a constant speed or the permanent magnet motor is made to rotate at a constant speed.

2. The strength training device as described in claim 1, characterized in that, The current tension value is obtained by performing a predetermined calculation on the sampled current from the current sensor within a predetermined first time period while keeping the current rotation speed constant.

3. The strength training device as described in claim 1 or 2, characterized in that, The permanent magnet motor is a three-phase permanent magnet synchronous motor. The current sensor measures the current signals of at least two phases of the three-phase permanent magnet synchronous motor. The inverter is a three-phase inverter circuit. The given current value is the given Q-axis current value. The drive control signal is an SVPWM signal. It also includes a current converter that converts the at least two-phase current signals into D-axis and Q-axis current values ​​based on the at least two-phase current signals and the position detection signal from the rotary encoder. The current tension value is obtained based on the Q-axis current value.

4. The strength training device as described in claim 3, characterized in that, The current tension value is obtained by keeping the current rotational speed constant within the specified first time period, acquiring the Q-axis current value Iq multiple times, and filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value, and then calculating the average value Iq based on the average value Iq.

5. The strength training device as described in claim 1 or 2, characterized in that, The motion and display controller also controls the target rotation speed based on the current tension value of the force output input structure. When the current tension value is less than the specified minimum tension setting value, the target rotation speed is set to 0.

6. A method for controlling a strength training device, wherein, The strength training device is the strength training device of claim 1, and the control method controls the rotation of the permanent magnet motor so that the user can perform isokinetic strength training including concentric and eccentric motion strokes. The control method is characterized by comprising: The constant velocity motion control steps (S1A, S2A) involve controlling the permanent magnet motor to rotate at a preset training speed during the centripetal motion and centrifugal motion strokes, based on the target rotation speed output by the motion and display controller, the position detection signal of the rotary encoder, and the sampling current of the current sensor. This is achieved through the speed controller, the current controller, and the inverter. In at least one of the centripetal motion and centrifugal motion strokes, the force output input structure is made to perform constant velocity motion or the permanent magnet motor is made to rotate at a constant speed. The force curve information acquisition and output steps (S1B, S2B) involve obtaining the current position of the force output input structure based on the position detection signal of the rotary encoder during the centripetal and centrifugal motion strokes, obtaining the current tension value of the force output input structure from the sampled current of the current sensor through a prescribed calculation, and outputting the current tension value and the current position as the force curve information; and In the motion direction switching step (S3), the motion and display controller controls the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches a preset proximal limit position during the centrifugal motion stroke, and switches the direction of the target rotation speed to the direction of the centrifugal motion when the current position of the force output input structure reaches a preset distal limit position during the centrifugal motion stroke.

7. The control method for the strength training device as described in claim 6, characterized in that, The current rotational speed is kept constant within a specified first time period, and the current tension value is obtained from the sampled current of the current sensor through the specified calculation within the specified first time period.

8. The control method for the strength training device as described in claim 6 or 7, characterized in that, The permanent magnet motor is a three-phase permanent magnet synchronous motor. The current sensor measures the current signals of at least two phases of the three-phase permanent magnet synchronous motor. The inverter is a three-phase inverter circuit. The given current value is the given Q-axis current value. The drive control signal is an SVPWM signal. It also includes a current conversion step, which converts the at least two-phase current signals into D-axis current values ​​and Q-axis current values ​​based on the at least two-phase current signals and the position detection signal from the rotary encoder. The current tension value is obtained based on the Q-axis current value.

9. The control method for the strength training device as described in claim 8, characterized in that, The current tension value is obtained by keeping the current rotational speed constant within the specified first time period, acquiring the Q-axis current value Iq multiple times, and filtering and averaging the acquired Q-axis current values ​​Iq to obtain the average value Iq of the Q-axis current value, and then calculating the average value Iq based on the average value Iq.

10. The control method for the strength training device as described in claim 6 or 7, characterized in that, During the centripetal and centrifugal motion strokes, the motion and display controller also controls the motion based on the current tension value of the force output input structure. When the current tension value is less than the specified minimum tension setting value, the target rotational speed is set to 0.

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