Test experiment platform for linear series elastic driver

Abstract

The invention discloses a test experiment platform for a linear series elastic driver. The test experiment platform comprises a bottom fixing platform, a pull pressure sensor assembly module, a stepping motor sliding table device module and a sliding table device module with a clamping mechanism. The sliding table device module with the clamping mechanism comprises a sliding table base, a guide mechanism, a first clamping assembly and a second clamping assembly, the guide mechanism arranged in the first direction is fixed to the bottom fixing platform, and the sliding table base is provided with a cavity penetrating in the first direction; the tension and pressure sensor assembly module is fixedly connected with different positions of one end, far away from the stepping motor sliding table device module, of the guide mechanism; the sliding table seat is in sliding fit with one end, close to the stepping motor sliding table device module, of the guide mechanism; the series elastic driver penetrates through the cavity, one end of the series elastic driver is connected with the stepping motor sliding table device module, and the other end of the series elastic driver is connected with the pull pressure sensor assembly module. The first clamping assembly and the second clamping assembly are used for clamping / loosening the series elastic driver in the cavity. According to the invention, a modular design concept is adopted, and rapid installation and testing of SEA of different specifications are supported.

Description

Technical Field

[0001] The invention relates to a test experimental platform for a linear series elastic driver, belonging to the technical field of robot driving. Background Art

[0002] In recent years, emerging fields such as service robots, rehabilitation robots, and collaborative robots have rapidly emerged, placing triple performance requirements on actuators: safety, compliance, and efficiency. With the rapid development of robotics, performance requirements for robotic actuators continue to increase. Traditional rigid actuators, due to their inherent high impedance, have numerous limitations in applications such as human-robot interaction and compliant control. Research has shown that in human-robot collaborative scenarios, there is a significant correlation between actuator rigidity and the incidence of safety incidents, and that actuator compliance has a significant impact on the success rate of task completion.

[0003] Currently, the driving methods of robotic actuators can be broadly categorized into traditional rigid drives and compliant drives. Traditional rigid drives are primarily used in industrial robots requiring high-precision positioning, but their inherent high impedance poses significant safety risks in human-robot interaction scenarios. Furthermore, rigid drives are complex control strategies, requiring sophisticated force feedback control algorithms to achieve compliance, which significantly increases the difficulty and cost of system development. To overcome the limitations of rigid drives, compliant drive technology has gradually become a research hotspot. Series elastic actuators (SEAs) have become the mainstream of compliant drives due to their simple structure and hardware-level implementation of force-position decoupling and energy storage and recovery. Linear series elastic actuators, by integrating elastic elements in series within the transmission chain, can fundamentally improve the impedance characteristics of the actuator. However, the lack of an authoritative and unified performance testing platform has led to significant differences in evaluation methods, test conditions, and data caliber among different research institutions, making cross-comparison and standardized replication of experimental results difficult. The internal dynamic parameters of series elastic actuators are also difficult to measure, and there is a lack of standardized experimental platforms and algorithms for rapid identification of these dynamic parameters. Summary of the Invention

[0004] In response to the many defects of existing series elastic actuator testing platforms, the present invention provides a testing experimental platform for linear series elastic actuators. The platform adopts a modular design concept and supports the rapid installation and testing of SEAs of different specifications. Furthermore, it can drive a stepper motor slide according to a preset trajectory to apply a repeatable external load to the series elastic actuator, synchronously record sensor information, and evaluate the performance of the series elastic actuator controller.

[0005] The technical solution of the present invention is:

[0006] A test platform for a linear series elastic actuator, used for a series elastic actuator 4, comprising a bottom fixed platform 1, a tension and pressure sensor assembly module 2, a stepper motor slide module 3, and a slide module 5 with a clamping mechanism;

[0007] A stepper motor slide device module 3 is installed on one side of the bottom fixed platform 1, and a tension and pressure sensor assembly module 2 and a slide device module 5 with a clamping mechanism are installed on the other side of the bottom fixed platform 1;

[0008] The slide device module 5 with a clamping mechanism includes a slide seat, a guide mechanism, a first clamping assembly, and a second clamping assembly. The guide mechanism arranged along the first direction is fixed to the bottom fixed platform 1, and the slide seat is provided with a cavity passing through along the first direction; the tension and pressure sensor assembly module 2 is connected and fixed to different positions of the guide mechanism away from the stepper motor slide device module 3, so as to achieve the fixation of the tension and pressure sensor assembly module 2 and the guide mechanism away from the stepper motor slide device module 3 at different positions in the first direction; the slide seat and the guide mechanism are slidably matched at the end close to the stepper motor slide device module 3; the serial elastic driver 4 passes through the cavity, and one end of the serial elastic driver 4 is connected to the stepper motor slide device module 3, and the other end of the serial elastic driver 4 is connected to the tension and pressure sensor assembly module 2; the first clamping assembly is used to move along the second direction to clamp / relax the serial elastic driver 4 in the cavity, and the second clamping assembly is used to move along the third direction to clamp / relax the serial elastic driver 4 in the cavity; wherein the first direction, the second direction, and the third direction are perpendicular to each other.

[0009] Furthermore, the tension and pressure sensor assembly module 2 includes a tension and pressure sensor connecting seat 20, a planar tension and pressure sensor 21, and a serial elastic driver connecting seat 22; wherein the planar tension and pressure sensor 21 is fixed to the side of the tension and pressure sensor connecting seat 20 close to the serial elastic driver 4, and the serial elastic driver connecting seat 22 is connected to the side of the planar tension and pressure sensor 21 close to the serial elastic driver 4, and the serial elastic driver connecting seat 22 is provided with a first mounting hole that passes through along the third direction, and the first mounting hole is used to connect to the serial elastic driver 4.

[0010] Furthermore, the stepper motor slide device module 3 is used to generate a driving force to compress the spring in the series elastic driver 4 .

[0011] Furthermore, the stepper motor slide device module 3 includes a sealed dustproof ball screw slide 30, a serial elastic driver connecting plate 31, an electric slide connecting plate 34, a stepper motor 36, an electric slide connecting base 37, and a slider 39; wherein, the sealed dustproof ball screw slide 30 is fixed on the electric slide connecting base 37, a slider 39 is provided on the sealed dustproof ball screw slide 30, the electric slide connecting plate 34 is fixed on the slider 39, a stepper motor 36 for driving is installed at the end of the sealed dustproof ball screw slide 30, and the serial elastic driver connecting plate 31 is installed with the electric slide connecting plate 34 on the side of the slide device module 5 with the clamping mechanism; a second mounting hole is provided on the electric slide connecting plate 34 that passes through along the third direction, and the second mounting hole is used to connect with the serial elastic driver 4.

[0012] Furthermore, the slide seat is a hexahedral structure, including two first surfaces arranged opposite to each other, two second surfaces arranged opposite to each other and two third surfaces arranged opposite to each other, the first surfaces, the second surfaces and the third surfaces are perpendicular to each other, the cavity passes through the two first surfaces, the second surface is perpendicular to the second direction, and the third surface is perpendicular to the third direction.

[0013] Furthermore, the first clamping assembly includes a first clamping plate 52, a first boss, an anti-loosening spring II 60, and a clamping screw II 61. The first boss is provided on one side of the first clamping plate 52, and the protruding direction of the first boss is toward the second surface of the slide seat away from the stepper motor slide device module 3; the second surface of the slide seat away from the stepper motor slide device module 3 is provided with a first slotted hole that cooperates with the first boss to guide the movement of the first clamping plate 52 along the second direction; the clamping screw II 61 is passed through the anti-loosening spring II 60 and the screw holes on the second surface of the slide seat away from the stepper motor slide device module 3 in sequence, and the end portion cooperates with the first clamping plate 52 to clamp / relax the series elastic driver 4 in the cavity along the second direction through the first clamping plate 52;

[0014] The second clamping assembly includes a second clamping plate 54, a second boss, a clamping screw I56, and an anti-loosening spring I57. The second boss is arranged on one side of the second clamping plate 54 and the protruding direction of the second boss is toward the third surface of the top end of the slide seat; the third surface of the top end of the slide seat is provided with a second slot hole that cooperates with the second boss to guide the movement of the second clamping plate 54 along the third direction; the clamping screw I56 is passed through the anti-loosening spring I57 and the screw hole on the third surface of the top end of the slide seat in sequence and the end portion cooperates with the second clamping plate 54 to clamp / relax the series elastic driver 4 in the cavity along the third direction through the second clamping plate 54.

[0015] Furthermore, the present invention is used to perform parameter estimation on the series elastic driver 4 .

[0016] Furthermore, the parameter estimation includes:

[0017] The dynamic equation of the series elastic actuator 4 is rewritten into the linear regression form used for parameter estimation:

[0018]

[0019] Where x1(t) is the spring displacement; is the spring deformation speed; represents the second-order derivative of x1(t), i.e., the spring acceleration; F m (t) is the driving force generated by the electric push rod 44; M m is the equivalent mass, B m is the viscous damping on the driving side, B s is the internal damping of the spring, K s is the spring stiffness;

[0020] Will x1(t),F m (t) are input into the filter at the same time, and the following are obtained:

[0021]

[0022] Among them, z(t), Respectively x1(t),F m (t) filtering form;

[0023] Establish the regression equation after synchronous filtering:

[0024]

[0025] Among them, the dynamic parameters to be estimated θ=[θ1,θ2,θ3] T ; T represents transpose;

[0026] Establish a finite-time adaptive law to update the parameter estimates The finite-time adaptive law:

[0027]

[0028] in: express The first derivative of is the regression vector after synchronous filtering; is the current estimation error; Γ is the diagonal gain matrix; γ is the nonlinear order index;

[0029] Based on parameter estimation Get the spring stiffness K s , total damping of series elastic actuator B m +B s , equivalent mass M of the series elastic actuator m .

[0030] The beneficial effects of the present invention are:

[0031] The platform of the present invention achieves high-precision adjustment of spring compression and external force application by accurately controlling the displacement of the stepper motor slide device module and the electric push rod, ensuring the accuracy of the test and calibration results. The modular design allows each module to be flexibly fixed through multiple rows of threaded holes, which facilitates the rapid installation and replacement of series elastic drivers of different specifications, and adapts to diverse testing and calibration needs. The platform can perform output force closed-loop control tests, push rod position closed-loop control tests, dynamic response tests, and calibration of the elastic force measured by the series elastic driver itself, as well as estimation of unknown parameters, on the series elastic driver, thereby improving the systematization of testing and calibration and the comparability of data. By accurately calibrating the elastic force measured by the series elastic driver itself, the performance and reliability of the series elastic driver in practical applications are further improved, ensuring that each assembled series elastic driver can maintain a consistent force output during constant force output, significantly reducing the constant force output error. By using the data from the platform pull-up pressure sensor and thin film displacement sensor and applying an online parameter identification algorithm, key unknown dynamic parameters such as spring stiffness, total damping and equivalent mass can be estimated and updated in real time. This can automatically compensate for model deviations caused by manufacturing tolerances, lubrication wear and temperature drift in a short period of time, significantly improving the performance of the series elastic drive controller.

[0032] In summary, the test platform of the present invention is not only suitable for robot development and performance evaluation, but can also be expanded to other fields that require precise mechanical property testing and calibration, and has broad market application prospects. The platform's high-precision control, modular design, high cost-effectiveness, and standardized testing process have enabled it to play an important role in promoting the standardization and industrialization of robot drive technology. The multifunctional serial elastic actuator test experimental platform of the present invention has significant advantages in both design and function, can effectively solve many deficiencies in the existing technology, and provides reliable technical support for the research and application of serial elastic actuators. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an axonometric drawing of the present invention;

[0034] Figure 2 It is a top view of the present invention;

[0035] Figure 3 is an exploded view of the tension and pressure sensor assembly module of the present invention;

[0036] Figure 4 This is an exploded view of the stepper motor slide device module of the present invention;

[0037] Figure 5 It is an assembly diagram of the stepper motor slide device module of the present invention;

[0038] Figure 6 is a top view of the series elastic actuator of the present invention;

[0039] Figure 7 This is an exploded view of the slide device module with a clamping mechanism in the present invention;

[0040] Figure 8 This is a schematic diagram of the cooperation between the slide device module with the clamping mechanism and the series elastic drive in the present invention. Figure 1 ;

[0041] Figure 9 This is a schematic diagram of the cooperation between the slide device module with the clamping mechanism and the series elastic drive in the present invention. Figure 2 ;

[0042] The numbers in the figure are: 1-bottom fixed platform, 2-tension and pressure sensor assembly module, 3-stepping motor slide device module, 4-series elastic driver, 5-slide device module with clamping mechanism, 11-main control box, 12-stepping motor driver, 13-connecting screw I, 14-connecting screw II, 15-connecting screw III, 16-connecting screw IV, 17-pin shaft I, 18-pin shaft II, 19-connecting screw V, 20-tension and pressure sensor connecting seat, 21-planar tension and pressure sensor, 22-series elastic driver connecting seat, 23-connecting screw VI, 24-connecting screw VII, 30-sealed dustproof ball screw slide, 31-series elastic driver connecting plate, 32-connecting screw VIII, 33-connecting Screw IX, 34-electric slide connecting plate, 35-connecting screw X, 36-stepping motor, 37-electric slide connecting base, 38-connecting screw XⅠ, 39-slider, 40-serial elastic driver body, 41-spring compression rod, 42-ball head connecting rod I, 43-ball head connecting rod II, 44-electric push rod, 50-linear guide rail, 51-guide rail slider connecting plate, 52-first clamping plate, 53-clamping mechanism support plate I, 54-second clamping plate, 55-clamping mechanism upper plate, 56-clamping screw I, 57-anti-loosening spring I, 58-connecting screw XⅡ, 59-clamping mechanism support plate II, 60-anti-loosening spring II, 61-clamping screw II, 62-connecting screw XⅢ, 63-connecting screw XⅣ. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other in any way.

[0044] Example 1: Figures 1-9 As shown, a test experimental platform for a linear series elastic actuator, used for a series elastic actuator 4, the test experimental platform includes a bottom fixed platform 1, a tension and pressure sensor assembly module 2, a stepper motor slide device module 3, and a slide device module 5 with a clamping mechanism;

[0045] Furthermore, if Figure 1 、 Figure 2 As shown, there are multiple rows of threaded holes on the upper surface of the bottom fixed platform 1 for fixing various modules, including a main control box 11, a stepper motor driver 12, connecting screws I13, connecting screws II14, connecting screws III15, connecting screws IV16, and connecting screws V19; wherein the main control box 11 is fixed to the bottom fixed platform 1 by connecting screws I13, the stepper motor driver 12 is fixed to the bottom fixed platform 1 by connecting screws II14, the stepper motor slide device module 3 is connected to the bottom fixed platform 1 by connecting screws III15, the connecting screws IV16 are used to fix the right end of the slide device module 5 with a clamping mechanism to the bottom fixed platform 1, and the connecting screws V19 pass through the tension and pressure sensor assembly module 2 and the left end of the slide device module 5 with a clamping mechanism to connect to the bottom fixed platform 1, fixing the tension and pressure sensor assembly module 2 and the slide device module 5 with the clamping mechanism to the bottom fixed platform 1.

[0046] Furthermore, if Figure 3 As shown, the tension and pressure sensor assembly module 2 is used to collect the output force generated by the serial elastic driver, including a tension and pressure sensor connecting seat 20, a planar tension and pressure sensor 21, a serial elastic driver connecting seat 22, a connecting screw VI23, and a connecting screw VII24; wherein the planar tension and pressure sensor 21 is fixed to the side of the tension and pressure sensor connecting seat 20 close to the serial elastic driver 4 by the fixing screw VII24, and the serial elastic driver connecting seat 22 and the planar tension and pressure sensor 21 are fixedly connected by the fixing screw VI23.

[0047] Furthermore, if Figure 4 、 Figure 5As shown, the stepper motor slide device module 3 is used to generate a driving force for compressing the spring on the series elastic driver 4 to simulate the load force in actual application, including a sealed dustproof ball screw slide 30, a series elastic driver connecting plate 31, connecting screws VIII 32, connecting screws IX 33, an electric slide connecting plate 34, connecting screws X35, a stepper motor 36, an electric slide connecting base 37, connecting screws XⅠ 38, and a slider 39; wherein the sealed dustproof ball screw slide 30 is fixed to the electric slide connecting base 37 by connecting screws XⅠ 38, and the electric slide connecting plate 34 is fixed to the electric slide connecting base 37 by connecting screws IX 3 3 is fixed to the slider 39. The sealed and dustproof ball screw slide 30 is fixedly connected to the stepper motor 36 by connecting screws X35. The connecting screws VIII32 are used to fix the series elastic driver connecting plate 31 to the electric slide connecting plate 34. The rotation of the stepper motor 36 drives the ball screw in the sealed and dustproof ball screw slide 30 to rotate. The rotation of the ball screw drives the series elastic driver connecting plate 31 to move linearly following the slider 39. The movement of the series elastic driver connecting plate 31 drives the series elastic driver 4 connected to the series elastic driver connecting plate 31 to generate the driving force of the compression spring.

[0048] Furthermore, if Figure 6 As shown, the serial elastic driver 4 is the test object of the experimental platform, which is clamped on the slide device module 5 with a clamping mechanism, including a serial elastic driver body 40, a spring compression rod 41, a ball head connecting rod I 42, a ball head connecting rod II 43, and an electric push rod 44; wherein the spring compression rod 41 is supported by the spring in the serial elastic driver body 40 and will be compressed after being subjected to force, and the end of the spring compression rod 41 is fixedly connected to the ball head connecting rod I 42 by a thread, and the ball head connecting rod I 42 is connected to the serial elastic driver connecting plate 31 in the stepping motor slide device module 3 by a pin shaft I 17, and the electric push rod 44 is driven by the motor in the serial elastic driver body 40, can move back and forth and generate push and pull forces, and the end of the electric push rod 44 is fixedly connected to the ball head connecting rod II 43 by a thread, and the ball head connecting rod II 43 is connected to the serial elastic driver connecting seat 22 in the tension and pressure sensor assembly module 2 by a pin shaft II 18. For example, the series elastic driver 4 may be the series elastic driver disclosed in CN119257820A (with the thin film pressure sensor replaced by a thin film displacement sensor).

[0049] Furthermore, if Figure 7-Figure 9As shown, the slide device module 5 with a clamping mechanism is used to clamp the serial elastic driver 4. After clamping, the serial elastic driver 4 can slide on the guide mechanism, including a slide seat, a guide mechanism, a first clamping assembly, and a second clamping assembly. The guide mechanism arranged along the first direction is fixed to the bottom fixed platform 1, and the slide seat is provided with a cavity running through the first direction; the tension and pressure sensor assembly module 2 is connected and fixed to different positions of the guide mechanism away from the stepper motor slide device module 3, so as to realize that the tension and pressure sensor assembly module 2 and the guide mechanism are at different positions in the first direction away from the stepper motor slide device module 3. The slide seat and the guide mechanism are slidably matched near one end of the stepping motor slide device module 3; the serial elastic driver 4 passes through the cavity, and one end of the serial elastic driver 4 is connected to the stepping motor slide device module 3, and the other end of the serial elastic driver 4 is connected to the tension and pressure sensor component module 2; the first clamping component is used to move along the second direction to clamp / relax the serial elastic driver 4 in the cavity, and the second clamping component is used to move along the third direction to clamp / relax the serial elastic driver 4 in the cavity; wherein the first direction, the second direction, and the third direction are perpendicular to each other.

[0050] Specifically: the guiding mechanism includes a linear guide rail 50; the slide seat is a hexahedral structure, including two first surfaces arranged opposite to each other, two second surfaces arranged opposite to each other and two third surfaces arranged opposite to each other, the first surfaces, the second surfaces and the third surfaces are perpendicular to each other, the cavity passes through the two first surfaces, the second surface is perpendicular to the second direction, and the third surface is perpendicular to the third direction. The second side is two clamping mechanism support plates I53, and the third side is the guide rail slider connecting plate 51 and the clamping mechanism upper plate 55; the first clamping assembly includes a first clamping plate 52, a first boss, an anti-loosening spring II60, and a clamping screw II61, and the second clamping assembly includes a second clamping plate 54, a second boss, a clamping screw I56, and an anti-loosening spring I57; wherein the guide rail slider connecting plate 51 is fixed to the slider of the linear guide 50 by a connecting screw XIII62, and the connecting screw XIV63 is used to fix one end of the clamping mechanism support plate I53 and the clamping mechanism support plate II59 to the guide rail slider connecting plate 51, and the connecting screw XII58 is used to fix the other end of the clamping mechanism support plate I53 and the clamping mechanism support plate II59 to the clamping mechanism Under the upper plate 55 of the clamping mechanism, the second boss on the second clamping plate 54 passes through the slot hole on the upper plate 55 of the clamping mechanism, so that the second clamping plate 54 can only move in the vertical direction relative to the upper plate 55 of the clamping mechanism, and the clamping screw I56 passes through the anti-loosening spring I57 and is screwed into the threaded hole of the upper plate 55 of the clamping mechanism, pushing the second clamping plate 54 to apply a clamping force in the vertical direction to the series elastic driver 4, and the first boss on the first clamping plate 52 passes through the slot hole on the clamping mechanism support plate II59, so that the first clamping plate 52 can only move in the horizontal direction relative to the clamping mechanism support plate II59, and the clamping screw II61 passes through the anti-loosening spring II60 and is screwed into the threaded hole of the clamping mechanism support plate II59, pushing the second clamping plate 54 to apply a clamping force in the horizontal direction to the series elastic driver 4. Before inserting the serial elastic driver 4, the first clamping plate 52 and the second clamping plate 54 are manually adjusted to provide space for inserting the serial elastic driver 4, and then the clamping screws are used to achieve clamping. Before removing the serial elastic driver 4, the second clamping plate 54 is relaxed by loosening the clamping screws, so as to facilitate the removal of the serial elastic driver 4.

[0051] like Figures 1 to 9 As shown, this embodiment relates to an experimental platform for testing the force output stability of a linear series elastic actuator 4. The specific installation process can be as follows:

[0052] The main control box 11 is secured to the multiple rows of threaded holes on the upper surface of the bottom fixed platform 1 using connecting screws I 13. The stepper motor driver 12 is mounted on the same platform using connecting screws II 14. The stepper motor slide assembly module 3 is secured to the bottom fixed platform 1 using connecting screws III 15, while the right end of the slide assembly module 5 with a clamping mechanism is secured to the bottom fixed platform 1 using connecting screws IV 16. Subsequently, the tension and pressure sensor assembly module 2 and the slide assembly module 5 with a clamping mechanism are secured to the bottom fixed platform 1 using connecting screws V 19 to ensure stability.

[0053] The planar tension and pressure sensor 21 is fixed to the tension and pressure sensor connection base 20 via fixing screws VII 24, and the serial elastic driver connection base 22 is fixedly connected to the planar tension and pressure sensor 21 via connecting screws VI 23. Installation of the stepper motor slide assembly module 3 involves securing the stepper motor 36 to the electric slide connection base 37, securing the sealed and dustproof ball screw slide 30 to the electric slide connection base 37 via connecting screws XI 38, and then securing the electric slide connection plate 34 to the sealed and dustproof ball screw slide 30 via connecting screws X35. The serial elastic driver connection plate 31 is fixedly connected to the electric slide connection plate 34 via connecting screws VIII 32. Finally, the stepper motor slide assembly module 3 is secured to the bottom fixed platform 1 via connecting screws X35.

[0054] The installation process for the slide assembly module 5 with a clamping mechanism includes securing the guide rail and slider connecting plate 51 to the linear guide rail 50 using connecting screws XIII 62, and securing the clamping mechanism support plate I 53 and the clamping mechanism support plate II 59 to the guide rail and slider connecting plate 51 using connecting screws XIV 63. The first clamping plate 52 and the second clamping plate 54 are respectively mounted on the clamping mechanism support plate II 59 and the clamping mechanism support plate I 53. Clamping screws I 56 and II 61, combined with anti-loosening springs I 57 and II 60, provide a stable clamping force. Finally, the slide assembly module 5 with a clamping mechanism is secured to the bottom fixed platform 1 via connecting screws V19 through the tension and pressure sensor assembly module 2.

[0055] Installation of the series elastic actuator 4 involves securing the series elastic actuator body 40 to the slide assembly module 5 with a clamping mechanism. A spring compression rod 41 is connected to the stepper motor slide assembly module 3 via a ball joint 1 42. The electric push rod 44 is connected to the tension and pressure sensor assembly module 2 via a ball joint 2 43, ensuring efficient transmission of the driving force.

[0056] The tested series elastic actuator 4 typically contains two thin film displacement sensors for detecting position. One is used to detect the position of the electric push rod 44, which can be used for closed-loop control of the electric push rod position, and the other is used to detect the spring compression, so that the magnitude of the external force applied to the series elastic actuator can be calculated, which can be used for constant force output control of the series elastic actuator. When the series elastic actuator performs constant force output control, the internal controller of the series elastic actuator will perform closed-loop control of the spring compression. The controller will calculate the target value of the spring compression based on the spring pressure coefficient according to the magnitude of the target force set by the user. The controller will control the spring compression at the target value. In actual applications, the external force applied to the series elastic actuator is constantly changing. The test experimental platform of the present invention can use the stepper motor slide device module 3 to simulate the application of external force according to actual applications, use the tension and pressure sensor assembly module 2 to measure the actual output force of the series elastic actuator, and draw a comparison curve between the target force and the actual force of the series elastic actuator to evaluate the controller performance.

[0057] In actual operation, first open the main control box 11 and connect it to the stepper motor driver 12, thereby ensuring that the stepper motor 36 in the stepper motor slide device module 3 can normally receive control signals. At the same time, check that the electric push rod 44 in the series elastic driver 4 can move normally and that the internal thin film displacement sensor can provide real-time feedback of the displacement signal. The series elastic driver 4 to be tested is clamped on the slide device module 5 with a clamping mechanism to ensure that it can slide freely on the linear guide 50 and the force transmission path remains linear and stable. The main control box 11 will send a signal to the stepper motor driver 12 at a frequency of 100Hz per second to control the rotation of the stepper motor. The signal is a time position curve of a cycle pre-written into the main control box 11. It is usually set to a periodic displacement fluctuation signal with different frequencies and amplitudes, such as a sine wave, square wave, or triangle wave, and can also be set to other irregular curves. The points on the curve are extracted through an array and stored in the main control box. The main control box 11 controls the stepper motor driver 12 to apply driving force according to the preset trajectory, pushing the spring compression rod 41 to compress, realizing the simulation of the applied external force. The thin film displacement sensor within the series elastic actuator 4 collects information about spring compression and the position of the electric push rod in real time. The controller within the series elastic actuator 4 adjusts the position of the electric push rod 44 based on changes in external force, controlling the actual value of the spring compression to approach the target value, thereby achieving constant force output. The planar tension and pressure sensor 21 within the tension and pressure sensor assembly module 2 is a high-precision S-shaped tension and pressure sensor with a maximum range of 100N and a maximum measurement error of 0.02N. This sensor can record the actual output force of the series elastic actuator 4 in real time with high precision, plotting a curve of the actual output force and the target output force (the target output force is the target force of the motor driving the electric push rod 44 in the controller's closed-loop control). This curve can be used to analyze controller performance indicators such as steady-state error, overshoot, and rise time, and evaluate the controller's dynamic response performance.

[0058] Through the test process described above, the present invention elaborates in detail how a test experimental platform for linear series elastic actuators can achieve a comprehensive evaluation of the performance of series elastic actuators through the collaborative work of modular components. The platform uses the stepper motor slide device module 3 to accurately simulate external dynamic loads and uses the tension and pressure sensor assembly module 2 to measure the actual output force of the series elastic actuator 4 with high precision. Combined with the spring compression and push rod position information collected by the thin film displacement sensor inside the series elastic actuator, the platform can monitor the constant force output control performance of the series elastic actuator under variable loads in real time. By comparing the target output force of the series elastic actuator with the measured output force curve, key performance indicators such as the steady-state error, overshoot, and rise time of the controller can be intuitively analyzed, thereby effectively evaluating and optimizing the control strategy and overall performance of the series elastic actuator.

[0059] Due to spring manufacturing errors, the elastic force generated by the springs in the series elastic driver 4 at the same length may have errors. Due to the friction between the internal components of the series elastic driver 4, the actual force measured by the spring may also be inaccurate, thereby affecting the accuracy of the output force and failing to meet the use requirements of precise force output in actual applications. Therefore, the newly assembled series elastic driver requires equipment to calibrate the elastic force to improve the accuracy of the force output. The following describes how to use a test experimental platform for a linear series elastic driver of the present invention to calibrate the force measurement of the series elastic driver 4. The elastic force in the above-mentioned method is calculated by collecting the spring compression amount through a thin film displacement sensor.

[0060] First, the series elastic driver 4 to be calibrated is installed on the slide device module 5 with a clamping mechanism to ensure that it can slide freely on the linear guide rail 50 and the force transmission path remains linear and stable. When the system is initialized, the main control box 11 is opened and connected to the stepper motor driver 12 to ensure that the stepper motor slide device module 3 can normally receive the control signal. At the same time, the reading of the film displacement signal inside the series elastic driver 4 is checked to ensure that it can feedback the displacement signal in real time and check that the electric push rod 44 of the series elastic driver 4 can output force normally. When calibrating the elastic force, the main control box 11 will send a signal to the stepper motor driver 12 to control the stepper motor displacement at a frequency of 100Hz per second. According to the method in the previous example, the stepper motor slide device module 3 is moved along the preset trajectory, pushing the spring compression rod 41 to compress, and the electric push rod 44 of the series elastic driver 4 remains stationary. In this way, the spring can be compressed and moved by the stepper motor slide device module 3 according to the preset trajectory. The film displacement sensor in the series elastic driver 4 collects the spring compression data. The elastic force information measured by the series elastic driver 4 can be calculated through the spring pressure coefficient. The tension and pressure sensor group The planar tension and pressure sensor 21 in the component module 2 collects information on the accurate value of the actual output force. Through the values ​​of these two pieces of information, a curve of the elastic force measurement value of the series elastic driver 4 and the accurate value of the actual output force can be drawn. The elastic force measurement value can be fitted to the accurate value as much as possible through the algorithm. In view of the linear relationship between the force applied to the spring and its compression displacement, the accurate value of the force measured by the pressure sensor component module 2 can be used to accurately calibrate the spring pressure coefficient. In this way, the constant force output through the series elastic driver 4 controller will be more accurate, achieving the calibration effect of the spring force measured by the series elastic driver itself.

[0061] The calibration process described above demonstrates how the linear serial elastic actuator test platform of the present invention can effectively calibrate the force measurement of the serial elastic actuator 4 to overcome the effects of spring manufacturing errors and internal friction on the output force accuracy. The platform mounts and fixes the serial elastic actuator 4 to be calibrated and uses the stepper motor slide device module 3 to accurately control the compression displacement of the spring while keeping the electric push rod 44 inside the serial elastic actuator stationary. During this process, the thin film displacement sensor inside the serial elastic actuator records the spring compression and converts it into elastic force, while the tension and pressure sensor assembly module 2 provides a high-precision true value of the actual output force. By comparing the elastic force of the serial elastic actuator with the actual force measured by the platform and fitting it with an algorithm, the error in the internal force measurement of the serial elastic actuator can be corrected, significantly improving the accuracy of the serial elastic actuator when performing constant force output control, and meeting the demand for precise force output in practical applications.

[0062] Example 2:

[0063] This embodiment describes how to estimate the dynamic parameters of a series elastic actuator (4) using a test platform for linear series elastic actuators (of the present invention). Most advanced control algorithms rely on high-precision mathematical modeling of the actuator. Without this precise model, the controller cannot accurately estimate the actuator's dynamic behavior, leading to amplified tracking errors, reduced system phase and gain margins, decreased energy recovery efficiency, and even oscillation and instability under high-speed or strongly coupled conditions, compromising performance and safety. When modeling the series elastic actuator (4), certain core parameters, such as the combined moment of inertia of the ball screw and screw nut, spring equivalent damping, and gear transmission efficiency, lack economically installable sensors and are difficult to isolate through offline testing. Inertia is inherent in multiple rotating and sliding components and cannot be directly read using encoders or current loops like displacement or current. Damping is determined by material internal friction, lubrication conditions, and microscopic contact variations. Even after laboratory calibration, it can still drift rapidly with temperature and wear. Mechanical efficiency is a distributed quantity that can only be "reverse-calculated" from the overall power loss and cannot be measured in situ. Therefore, online parameter estimation becomes the only feasible means: by collecting measurable signals (motor current, screw displacement, spring compression) in real time and writing the dynamic equations in the form of "observable regression matrix × unknown constant vector", the control system can recursively update these parameters that cannot be directly measured in closed-loop operation, thereby maintaining force control accuracy and system stability.

[0064] When estimating the internal parameters of the series elastic actuator 4, the stepper motor slide assembly module 3 is used to effectively secure the load end of the series elastic actuator 4. Specifically, the spring compression rod 41 of the series elastic actuator 4 is securely connected to the series elastic actuator connection plate 31 of the stepper motor slide assembly module 3 of the experimental platform via a ball joint Ⅰ 42, ensuring that the stepper motor slide assembly module 3 maintains its displacement. The output end of the electric push rod 44 of the series elastic actuator 4 is connected to the series elastic actuator connection socket 22 of the tension and pressure sensor assembly module 2 of the experimental platform via a ball joint Ⅱ 43. The tension and pressure sensor assembly module 2 incorporates a planar tension and pressure sensor 21, which accurately measures the actual output force of the series elastic actuator 4.

[0065] The dynamic behavior of the series elastic drive 4 is mainly dominated by the characteristics of its drive-side electric push rod 44, which allows a more simplified dynamic model to be established.

[0066] Let x1(t) = l1(t) - l0 be the deformation of the spring relative to its free length l0, i.e., the spring displacement; l1(t) is directly measured by the thin film displacement sensor integrated in the series elastic actuator 4. is the spring deformation speed, and the driving force generated by the electric push rod 44 is defined as F m(t), which is the actual output force measured by the planar tension and pressure sensor 21. At this time, the dynamic equation of the series elastic actuator 4 can be simplified to:

[0067]

[0068] Among them, M m is the equivalent mass, B m is the viscous damping on the driving side, B s is the internal damping of the spring, K s is the spring stiffness.

[0069] This equation can be further rewritten in linear regression form for parameter estimation:

[0070]

[0071] θ=[θ1,θ2,θ3]T

[0072]

[0073] In order to reduce the second-order differential noise and ensure the linear regression of the parameters, the acceleration signal is converted into And the regression vector column signal θ1x2(t)+θ2x1(t)+θ3F m (t) Synchronous input to the same second-order Butterworth linear filter:

[0074]

[0075] Among them, the cutoff frequency ω c =2π×30Hz, damping coefficient s represents the input signal.

[0076] Will x1(t),F m Input the filters at the same time and obtain:

[0077]

[0078] Among them, z(t), Respectively x1(t),F m filtering form.

[0079] Establish the regression equation after synchronous filtering:

[0080]

[0081] Since the filter is exactly the same on both sides of the equation, the phase shift and amplitude attenuation cancel each other out, thus maintaining the linear observability of the unknown parameters.

[0082] By injecting a sinusoidal excitation with an amplitude of 25% of the rated current into the internal motor of the series elastic actuator 4, the frequency is swept from 0.1Hz to 10Hz in a logarithmic step manner and lasts for 10-15 cycles at each frequency point, and the spring displacement x1 and the driving force F directly measured by the external tension and pressure sensor are collected in real time. m , calculated by sliding mode differential [x1,x2,F m ] is synchronously constructed into a regression vector through the same second-order Butterworth low-pass filter, and input into the online finite-time adaptive law to update the parameter estimation Finite-time adaptive law:

[0083]

[0084] in:

[0085] express The first derivative of

[0086] is the regression vector after synchronous filtering, represents transpose;

[0087] is the current estimation error;

[0088] Γ=diag{Γ1,Γ2,Γ3}>0 is a diagonal gain matrix, where Γ1, Γ2, and Γ3 represent the learning gains in the direction of the damping parameter, the stiffness parameter, and the mass parameter, respectively.

[0089] When 0<γ<1, the parameters can be guaranteed to converge in a finite time; when γ=1, it is a conventional gradient algorithm;

[0090] The finite-time adaptive law can be updated in real time by using a simple Euler integral within a 1kHz sampling period. satisfy And after 0.5s, it is considered to be converged. At this time, the spring stiffness K can be obtained by algebraic inverse calculation using the following formula s , total damping of the series elastic actuator B m +B s , equivalent mass M of the series elastic actuator m .

[0091]

[0092] Through the above-mentioned online identification process, the linear series elastic actuator test platform of the present invention can be used to determine the key dynamic parameters of the series elastic actuator 4, the spring stiffness K, without disassembling the actuator. s, total damping B m +B s and equivalent mass M m The platform first uses a sinusoidal excitation of 25% of the rated current to sweep the frequency logarithmically from 0.1Hz to 10Hz, and maintains 10-15 cycles at each frequency point; the spring displacement measured by the thin film displacement sensor and the output force measured by the tension and pressure sensor assembly module 2 are simultaneously recorded, and the spring deformation velocity is calculated in real time using a sliding mode differentiator. Subsequently, the displacement, velocity, and force signals are all passed through the same second-order Butterworth low-pass filter to form a regression vector, and the parameter estimation is performed through online iteration of the finite time adaptive law. Convergence occurs within minutes. The newly calculated parameters can instantly correct model deviations caused by spring manufacturing errors, lubrication wear, or temperature changes, significantly improving the accuracy and stability of the series elastic actuator in real-time, meeting the practical needs of high-precision force control in complex scenarios.

[0093] After adopting the finite-time online parameter estimation of the present invention, the force control accuracy and dynamic performance of the series elastic driver are significantly improved: the same controller is used on the same series elastic driver 4 to perform a constant force output test, and the controller uses "nominal parameters" and compares the parameters obtained by online parameter estimation. The experimental data shows that the steady-state error of the output force of the series elastic driver 4 is reduced from the original ±10% (full scale) to ±2% (full scale); in the commonly used power assist frequency band of 0 to 5HZ, the output force tracking phase lag of the series elastic driver 4 is shortened by more than 40%, and the equivalent closed-loop bandwidth is increased from 3Hz to 8Hz. The updated equivalent mass compensation reduces the 5mm step overshoot amplitude by about 35% and shortens the system setting time by about 30%. Due to the precise identification of damping, the peak value of the drive current drops by about 12%, and the thermal load of the whole machine is reduced synchronously.

[0094] The specific embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A test platform for linear series elastic actuators, characterized in that: For connecting a series elastic actuator (4), the test experimental platform comprises a bottom fixed platform (1), a tension and pressure sensor assembly module (2), a stepping motor slide device module (3), and a slide device module with a clamping mechanism (5); A stepper motor slide device module (3) is installed on one side of the bottom fixed platform (1), and a tension and pressure sensor assembly module (2) and a slide device module (5) with a clamping mechanism are installed on the other side of the bottom fixed platform (1); The slide device module (5) with a clamping mechanism includes a slide seat, a guide mechanism, a first clamping assembly, and a second clamping assembly. The guide mechanism arranged along the first direction is fixed to the bottom fixed platform (1), and the slide seat is provided with a cavity penetrating along the first direction; the tension and pressure sensor assembly module (2) is connected and fixed to different positions of the guide mechanism away from the end of the stepper motor slide device module (3), so as to achieve the fixation of the tension and pressure sensor assembly module (2) and the guide mechanism away from the end of the stepper motor slide device module (3) at different positions in the first direction; the slide seat and the guide mechanism are close to the stepper motor. One end of the motor slide device module (3) is slidably engaged; the serial elastic driver (4) passes through the cavity, and one end of the serial elastic driver (4) is connected to the stepping motor slide device module (3), and the other end of the serial elastic driver (4) is connected to the tension and pressure sensor component module (2); the first clamping component is used to move along the second direction to clamp / relax the serial elastic driver (4) in the cavity, and the second clamping component is used to move along the third direction to clamp / relax the serial elastic driver (4) in the cavity; wherein the first direction, the second direction, and the third direction are perpendicular to each other.

2. The test experimental platform for linear series elastic actuators according to claim 1, characterized in that: The tension and pressure sensor assembly module (2) comprises a tension and pressure sensor connection seat (20), a planar tension and pressure sensor (21), and a serial elastic driver connection seat (22); wherein the planar tension and pressure sensor (21) is fixed to a side of the tension and pressure sensor connection seat (20) close to the serial elastic driver (4); the serial elastic driver connection seat (22) is connected to a side of the planar tension and pressure sensor (21) close to the serial elastic driver (4); and a first mounting hole is provided on the serial elastic driver connection seat (22) that is through-hole along a third direction, and the first mounting hole is used for connecting to the serial elastic driver (4).

3. The test experimental platform for linear series elastic actuators according to claim 1, characterized in that: The stepper motor slide device module (3) is used to generate a driving force to compress the spring in the series elastic driver (4).

4. The test experimental platform for linear series elastic actuators according to claim 1, characterized in that: The stepper motor slide device module (3) comprises a sealed dustproof ball screw slide (30), a serial elastic driver connecting plate (31), an electric slide connecting plate (34), a stepper motor (36), an electric slide connecting base (37), and a slider (39); wherein the sealed dustproof ball screw slide (30) is fixed on the electric slide connecting base (37), a slider (39) is provided on the sealed dustproof ball screw slide (30), the electric slide connecting plate (34) is fixed on the slider (39), a stepper motor (36) for driving is installed at the end of the sealed dustproof ball screw slide (30), and the serial elastic driver connecting plate (31) is installed on the side of the slide device module (5) with a clamping mechanism; a second mounting hole is provided on the electric slide connecting plate (34) that passes through along a third direction, and the second mounting hole is used to connect with the serial elastic driver (4).

5. The test experimental platform for linear series elastic actuators according to claim 1, characterized in that: The slide seat is a hexahedral structure, including two first surfaces arranged opposite to each other, two second surfaces arranged opposite to each other, and two third surfaces arranged opposite to each other. The first surfaces, the second surfaces, and the third surfaces are perpendicular to each other. The cavity runs through the two first surfaces, the second surface is perpendicular to the second direction, and the third surface is perpendicular to the third direction.

6. The test platform for linear series elastic actuators according to claim 5, characterized in that: The first clamping assembly includes a first clamping plate (52), a first boss, an anti-loosening spring II (60), and a clamping screw II (61), wherein the first boss is provided on one side of the first clamping plate (52) and the protruding direction of the first boss is toward the second surface of the slide seat away from the stepper motor slide device module (3); the second surface of the slide seat away from the stepper motor slide device module (3) is provided with a first slot hole that cooperates with the first boss to guide the movement of the first clamping plate (52) along the second direction; the clamping screw II (61) is passed through the screw holes on the anti-loosening spring II (60) and the second surface of the slide seat away from the stepper motor slide device module (3) in sequence, and the end portion cooperates with the first clamping plate (52) to clamp / relax the series elastic driver (4) in the cavity along the second direction through the first clamping plate (52); The second clamping assembly includes a second clamping plate (54), a second boss, a clamping screw I (56), and an anti-loosening spring I (57). The second boss is provided on one side of the second clamping plate (54) and the protruding direction of the second boss is toward the third surface of the top of the slide seat; the third surface of the top of the slide seat is provided with a second slot hole that cooperates with the second boss to guide the movement of the second clamping plate (54) along the third direction; the clamping screw I (56) is passed through the anti-loosening spring I (57) and the screw hole on the third surface of the top of the slide seat in sequence and the end portion cooperates with the second clamping plate (54) to clamp / relax the series elastic driver (4) in the cavity along the third direction through the second clamping plate (54).

7. The test experimental platform for linear series elastic actuators according to claim 1, characterized in that: Used for parameter estimation of series elastic actuators (4).

8. The test experimental platform for linear series elastic actuators according to claim 7, characterized in that: The parameter estimation includes: The dynamic equation of the series elastic actuator (4) is rewritten as a linear regression form for parameter estimation: Where x1(t) is the spring displacement; is the spring deformation speed; represents the second-order derivative of x1(t), i.e., the spring acceleration; F m (t) is the driving force generated by the electric push rod (44); M m is the equivalent mass, B m is the viscous damping on the driving side, B s is the internal damping of the spring, K s is the spring stiffness; Will Input the filter at the same time and get: in, Respectively The filtering form; Establish the regression equation after synchronous filtering: Among them, the parameters to be estimated θ=[θ1,θ2,θ3] T ; T represents transpose; Establish a finite-time adaptive law to update the parameter estimates The finite-time adaptive law: in: express The first derivative of is the regression vector after synchronous filtering; is the current estimation error; Γ is the diagonal gain matrix; γ is the nonlinear order index; Based on parameter estimation Get the spring stiffness K s , total damping of series elastic actuator B m +B s , equivalent mass M of the series elastic actuator m .

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