High-precision space unfolding and folding telescopic arm driven by lead screw
By combining modular multi-stage sleeves with precision guide structures, and integrating trapezoidal lead screws with locking mechanisms and magnetic scale sensors, the structural complexity and weight issues of traditional telescopic booms are solved, achieving high-precision extension and retraction performance and meeting internal wiring requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional multi-stage screw-driven telescopic arms are complex in structure, heavy in weight, difficult to manufacture, and have low extension and retraction accuracy, which cannot meet the internal wiring requirements of serial robotic arms.
It adopts a modular multi-stage sleeve combined with a precision guide structure, and achieves high-precision extension and retraction control through the combination of trapezoidal lead screw and multi-stage sleeve, combined with locking mechanism and magnetic scale sensor.
It achieves lightweight design, high-precision extension and retraction performance, sub-millimeter resolution and 0.2mm repeatability, solving the structural complexity and weight problems of traditional telescopic arms and meeting the internal wiring requirements of robotic arms.
Smart Images
Figure CN121798673A_ABST
Abstract
Description
TECHNICAL FIELD
[0002] This invention relates to the field of aerospace technology and is a high-precision space extension and retraction boom driven by a lead screw. BACKGROUND
[0004] A single-degree-of-freedom telescopic boom typically consists of a drive unit, a multi-stage telescopic structure, a guiding and limiting mechanism, and a sensing and control system. Its overall design emphasizes a high degree of integration between transmission and structure to achieve large-stroke deployment and retraction within a limited cabin volume. This type of mechanism offers advantages such as compact structure, high extension ratio, and excellent transmission accuracy. It maintains high positioning stability and motion reliability in complex space environments and, to a certain extent, enhances its anti-interference capability through transmission self-locking characteristics.
[0005] Currently available traditional multi-stage screw-driven telescopic arms mostly employ a multi-stage screw connection method. This method results in a complex structure, high manufacturing difficulty, complex assembly, and a large overall weight. Furthermore, some existing single-screw telescopic arms use linear guides and electric actuators, further complicating the overall structure and increasing the weight. Moreover, these one-dimensional telescopic arms cannot meet the internal wiring requirements of serial robotic arms, and their telescopic accuracy is generally low. SUMMARY
[0007] To address the aforementioned issues, this invention proposes a high-precision spatial telescopic arm driven by a lead screw. By combining a modular multi-stage sleeve with a precision guide structure, it achieves the design requirements of lightweight construction and possesses excellent telescopic accuracy.
[0008] A high-precision spatial telescopic arm driven by a lead screw includes an outer sleeve, an intermediate sleeve, and an inner sleeve, all of which are cylindrical. The three sleeves are coaxially nested from the outside to the inside. The inner walls of the top of the outer sleeve and the intermediate sleeve are designed with annular shoulders, which are used to limit the movement of the intermediate sleeve and the inner sleeve when they are fully extended.
[0009] The outer stage sleeve is coaxially mounted with an outer stage base at its bottom end. A drive motor and a reducer are coaxially mounted on the top surface of the outer stage base. The output shaft is coaxially connected to a trapezoidal lead screw, forming a single-degree-of-freedom rotary drive unit. The bottom end of the trapezoidal lead screw is also designed with a smooth rod section. Meanwhile, the bottom ends of the intermediate stage sleeve and the inner stage sleeve are respectively fixed with intermediate stage bases and inner stage bases, and threaded holes are opened in the center of both.
[0010] The outer stage sleeve and the inner wall of the intermediate stage sleeve are designed with guide protrusions at equal angular intervals along the circumference and along the sleeve axis. Simultaneously, keyways are designed at equal angular intervals along the circumference of the intermediate stage base and the inner stage base, respectively mate with the guide protrusions on the inner walls of the outer stage base and the intermediate stage base. A pre-existing gap is reserved between the inner ring of the annular shoulder at the top of the outer stage sleeve and the outer wall of the intermediate stage sleeve; a pre-existing gap is also reserved between the inner ring of the annular shoulder at the top of the intermediate stage sleeve and the outer wall of the inner stage sleeve; bushings are installed at these gaps.
[0011] The outer sleeve has lock seats installed at equal angular intervals around its top; the middle sleeve has lock heads installed at equal angular intervals around its top; and the inner sleeve has lock slots opened at equal angular intervals on its bottom side wall.
[0012] When the three sleeves are in the retracted state, the three circumferential keyways of the intermediate base engage with the three outer stage bosses respectively; the three circumferential keyways of the inner stage base engage with the three intermediate stage bosses respectively. The intermediate base is located at the bottom of the smooth section of the trapezoidal screw and is not subject to driving force; the inner stage base engages with the threaded portion of the trapezoidal screw, is located at the bottom of the threaded portion of the trapezoidal screw, and is in contact with the intermediate base. Simultaneously, the roller of the locking head at the top of the intermediate sleeve contacts the inner wall of the inner sleeve, and the outer end of the locking head engages with the locking seat, thus locking the outer and intermediate sleeves.
[0013] When the drive motor is working, the drive screw rotates, causing the inner stage base to move axially along the trapezoidal screw, gradually extending the inner stage sleeve until it contacts the top shoulder of the intermediate stage sleeve, at which point the inner stage sleeve extends to its designed limit position and is fully unfolded. Simultaneously, the locking head at the top of the intermediate stage sleeve moves inward under the spring's restoring force, its inner end inserting into the locking slot on the side wall of the inner stage sleeve, locking the inner and intermediate stage sleeves together. At the same time, the outer end of the locking head disengages from the locking seat, unlocking the intermediate and outer stage sleeves.
[0014] As the trapezoidal screw continues to rotate, the inner sleeve moves along with the intermediate sleeve, causing the intermediate base to engage with the threaded portion of the trapezoidal screw. Simultaneously, the inner base disengages from the threaded portion of the trapezoidal screw. Then, the rotation of the trapezoidal screw causes the intermediate sleeve to extend outwards until the intermediate base contacts the top shoulder of the outer sleeve, at which point the intermediate sleeve extends to its design limit and is fully deployed.
[0015] When the sleeves at each level are being closed, the process proceeds from the outside in, which is the reverse of the aforementioned unfolding process.
[0016] The advantages of this invention are:
[0017] 1. The high-precision telescopic arm of the present invention, through the combination of a single trapezoidal screw and a multi-stage screw nut, combined with the locking mechanism, interlocking mechanism and magnetic scale sensor assembly on the multi-stage sleeve, can realize the sequential unfolding and retraction of the multi-stage sleeve within a limited axial space. Moreover, at the end of the unfolding, the trapezoidal screw self-locking and locking mechanism work together to achieve high rigidity and high precision spatial positioning.
[0018] 2. The high-precision telescopic arm of this invention achieves seamless engagement and sequential action during the multi-stage sleeve unfolding and retracting process by controlling coaxiality and fit clearance during the processing stage, and adjusting the phase angle of the two-stage nuts and lead screw and the axial installation position of the locking mechanism during the assembly stage.
[0019] 3. The high-precision telescopic arm of this invention features three internally protruding keys evenly distributed on the outer wall of each sleeve stage, and keyways that mate with the internally protruding keys are opened on the corresponding nuts. A predetermined gap is left between the keys and the keyways. At the same time, a nylon wear-resistant bushing is set between two adjacent cylindrical sleeve stages, forming a dual circumferential and radial guiding and supporting structure. This ensures that the sleeve maintains stable movement during the unfolding and retraction process, effectively reducing swaying.
[0020] 4. This invention provides a high-precision telescopic arm for deployment and retraction, which uses a magnetic scale sensor assembly to achieve precise measurement of the deployment displacement of multiple sleeves. The magnetic head is fixed to the inner nut and moves with it. Magnetic strips are respectively attached to the inner walls of the intermediate and outer sleeves. Through continuous acquisition and calculation of the magnetic scale signals, real-time monitoring and closed-loop control of the deployment position of each sleeve can be achieved, improving the deployment accuracy and repeatability of the one-dimensional telescopic arm.
[0021] 6. This invention relates to a high-precision telescopic arm that allows for easy internal wiring by utilizing the structural space of a shaped nut (sleeve base). Simultaneously, the magnetic head is fixed to the inner nut, and the magnetic strip is attached to the inner wall of the sleeve, forming a high-precision position feedback system. This design provides sub-millimeter resolution (1µm) and positioning accuracy (measured repeatability better than 0.2mm) without increasing the additional envelope volume, effectively solving the problem of large cumulative errors in multi-stage telescopic control using traditional open-loop control. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 This is a schematic diagram of the overall structure of the high-precision telescopic arm of the present invention in its deployed state.
[0024] Figure 2 This is a schematic diagram of the outer sleeve structure in the high-precision telescopic arm of the present invention.
[0025] Figure 3 This is a schematic diagram of the intermediate sleeve structure in the high-precision telescopic arm of the present invention;
[0026] Figure 4 This is a schematic diagram of the inner sleeve structure in the high-precision telescopic arm of the present invention;
[0027] Figure 5 This is a schematic diagram of the intermediate base structure in the high-precision telescopic arm of the present invention.
[0028] Figure 6 This is a schematic diagram of the inner stage base structure in the high-precision telescopic arm of the present invention.
[0029] Figure 7 This is a schematic diagram of the locking seat structure in the high-precision telescopic arm of the present invention.
[0030] Figure 8 This is a schematic diagram of the locking head structure in the high-precision telescopic arm of the present invention;
[0031] Figure 9 This is a schematic diagram of the high-precision telescopic arm of the present invention in its retracted state;
[0032] Figure 10 This is a schematic diagram of the inner sleeve in the deployed state of the high-precision telescopic arm of the present invention.
[0033] In the picture:
[0034] 1-Outer stage sleeve; 2-Intermediate stage sleeve; 3-Inner stage sleeve; 4-Trapezoidal lead screw;
[0035] 101 - Outer stage base; 201 - Intermediate stage base; 301 - Inner stage base; 501 - Drive motor; 502 - Reducer;
[0036] 601-convex key; 602-keyway; 603-bushing; 701-lock seat; 702-lock head; 703-lock hole; 701a-slot;
[0037] 701b - Inclined groove; 702a - Intermediate shaft; 702b - Locking fastener; 702c - Slider; 702d - Spring; 702e - Locking pin DETAILED DESCRIPTION
[0039] The high-precision spatial telescopic arm driven by a lead screw and its working principle of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only for illustrating the present invention and are not intended to limit the present invention.
[0040] The present invention relates to a high-precision spatial extension and retraction arm driven by a lead screw, such as... Figure 1 As shown, it includes an outer sleeve 1, an intermediate sleeve 2, an inner sleeve 3, a trapezoidal lead screw 4, a drive assembly, a guide and support assembly, a locking interlock assembly, and a magnetic scale sensor assembly.
[0041] like Figure 2 , Figure 3 As shown, the outer stage sleeve 1, intermediate stage sleeve 2, and inner stage sleeve 3 are cylindrical tubes, coaxially nested from the outside to the inside. The outer stage sleeve 1 and intermediate stage sleeve 2 have annular shoulders circumferentially designed on their top inner walls; a 1mm gap is reserved between the inner ring of the annular shoulder at the top of the outer stage sleeve 1 and the circumferential outer wall of the intermediate stage sleeve 2; similarly, a 1mm gap is reserved between the inner ring of the annular shoulder at the top of the intermediate stage sleeve 2 and the circumferential outer wall of the inner stage sleeve 1.
[0042] An outer stage base 101 is mounted on the bottom end of the outer stage sleeve 1. A cylindrical drive chamber is designed at the center of the outer stage base 101, housing the drive assembly. For example... Figure 1 As shown, the drive assembly includes a drive motor 501 and a reducer 502. The drive motor 501 and reducer 502 are connected and coaxially mounted with the outer sleeve 1, fixed to the outer base 101. The output shaft of the reducer 502 is coaxially connected to the bottom end of the trapezoidal screw 4, forming a single-degree-of-freedom rotary drive unit. The top of the trapezoidal screw 4 does not extend beyond the top surface of the outer sleeve 1, and its bottom end has a smooth section for switching the "driven / disengaged" state of the intermediate base 201 on the trapezoidal screw during different stages of the telescopic arm's extension and retraction.
[0043] like Figure 3 , Figure 4 As shown, intermediate sleeve 2 and inner sleeve 3 are respectively fixed with intermediate base 201 and inner base 301 at their bottom ends, and both have threaded holes in their centers, as shown. Figure 5 , Figure 6 As shown, the screw is threaded into the trapezoidal lead screw 4 inside the outer sleeve 1 via a threaded hole, and can be considered as the lead screw nut of the trapezoidal lead screw 4. Holes are provided on the intermediate base 201 and the inner base 301 to facilitate internal wiring of the telescopic arm.
[0044] The guiding and supporting assembly includes three guide protrusions 601 that are equidistant from each other on the inner walls of the outer sleeve 1 and the intermediate sleeve 2 and designed along the sleeve axis, and three U-shaped keyways 602 that extend beyond the outer wall of the sleeve and are equidistant from each other on the inner walls of the intermediate base 201 and the inner base 301. These keyways 602 respectively mate with the guide protrusions 601 on the inner walls of the outer base 201 and the intermediate base 201. A gap (approximately 0.5 mm) is reserved between the guide protrusions 601 and the keyways 602 to accommodate machining and assembly errors and avoid jamming caused by assembly errors and thermal expansion.
[0045] Therefore, during the extension / retraction of the telescopic boom, the cooperation between the guide key 601 and the keyway 602 provides circumferential and radial support, effectively reducing the swaying between adjacent sleeves; and the rotation of the trapezoidal screw 4 can drive the inner sleeve 3 and the intermediate sleeve 2 to move axially along the trapezoidal screw. The aforementioned guide and support assembly 6 also includes two 1mm thick nylon wear-resistant bushings 9, which are coaxially placed inside the outer sleeve 1 and the intermediate sleeve 2, respectively, with their outer walls fitted and fixed to the inner wall of the top shoulder of the sleeve; thus, the bushing 603 on the outer sleeve can contact the outer wall surface of the inner sleeve, forming a support structure similar to a sliding bearing. Through the guide and support assembly, the sleeves at each stage maintain good coaxiality and stability during axial movement throughout the entire extension and retraction process of the telescopic boom, significantly reducing swaying and vibration, and ensuring the extension and retraction accuracy and service life of the telescopic boom.
[0046] Based on the requirements of the telescopic arm's outer diameter, length, and sleeve wall thickness, the sleeves of the above structure are machined in an integrated manner using core processes such as electrical discharge machining (EDM) to ensure the machining accuracy and smooth surface of the inner guide key 601. This achieves coaxiality and roundness control of the inner and outer circles of each sleeve and ensures the installation accuracy of the magnetic strip of the magnetic scale.
[0047] In this invention, a locking interlocking assembly is also designed between the three sleeves, including a lock seat 701 installed at equal angular intervals around the top of the outer sleeve 1, a lock head 702 installed at equal angular intervals around the top of the middle sleeve 2, and lock holes 703 at equal angular intervals on the circumferential side wall at the bottom of the inner sleeve 3. Figure 7 , Figure 8 and Figure 5 As shown.
[0048] The lock head 702 includes an intermediate shaft 702a and locking blocks 702b and sliders 702c designed at both its inner and outer ends. Slider 701c is located within a groove 203 radially designed at the top of the intermediate sleeve 2, restricting its circumferential displacement. A roller is mounted on slider 702c, with its axis perpendicular to the axis of the intermediate shaft 702a. The intermediate shaft 702a is located within a through hole on the outer wall of the groove 203, and the locking blocks 702b are located on the outer side of this outer wall. A spring 702d is fitted onto the intermediate shaft 702a, with its two ends contacting the outer wall of the groove 203 and the slider 702c, respectively. Locking pins 702e are symmetrically designed on both sides of the intermediate shaft, with their axes perpendicular to the axis of the intermediate shaft 702a.
[0049] The top of the lock base 701 has a slot 701a that can accommodate the locking block 702b; at the same time, the left and right side walls of the slot 701a are provided with inclined grooves 701b that slope outwards at the bottom to accommodate the locking pins 702e on both sides of the locking block 702b; and the bottom end of the inclined groove 701b has an extension groove 701c that is designed to extend outwards horizontally.
[0050] Through the above design, when the three-stage nested sleeves are in the retracted state, as follows: Figure 9 As shown, the three keyways 602 of the intermediate base 201 are respectively engaged with the three outer bosses 102; the three keyways 602 of the inner base 301 are respectively engaged with the three guide protrusions 601. The intermediate base 201 is located at the bottom of the bare rod section of the trapezoidal screw 4 and is not driven by any force. The inner base 301 engages with the threaded part of the trapezoidal screw 4, is located at the bottom of the threaded engagement part of the trapezoidal screw 4, and is in contact with the intermediate base 201. At the same time, the roller of the locking head 702 at the top of the intermediate sleeve 2 is in contact with the inner wall of the inner sleeve 3. The locking block 702b and the two locking pins 702e are located in the slots 701a and slanted slots 701b of the lock seat 701, respectively. The inward displacement of the locking head 702 is restricted by the inner sleeve 3. The spring 702d is in a contracted state, so that the locking pin 702e reaches the extension slot 701c, thereby achieving the locking between the outer sleeve 1 and the intermediate sleeve 2 and preventing the intermediate sleeve 2 from moving prematurely due to friction or external disturbance.
[0051] like Figure 10 As shown, when the drive motor is working, the drive screw rotates. At this time, the inner stage base 301 moves along the axial direction of the trapezoidal screw 4 under the action of the screw thread lead, causing the inner stage sleeve 3, which is fixed to it, to gradually extend; while the intermediate stage base 201 is still in the bare rod section. Until the inner stage base 301 contacts and is limited by the top shoulder of the intermediate stage sleeve 2, the inner stage sleeve 3 extends to the design limit position and is fully extended. At the same time, the locking hole 703 on the side wall of the inner stage sleeve 3 reaches the position of the locking head 702, causing the spring 702d of the locking head 702 to rebound, and the locking head 702 moves inward as a whole. The slider 702c is inserted into the locking hole 703, realizing the locking between the inner stage sleeve 3 and the intermediate stage sleeve 2. At the same time, after the locking head 702 moves inward as a whole, the locking pins 702e on both sides of the locking block 702b leave the extension groove, realizing the unlocking between the intermediate stage sleeve 2 and the outer stage sleeve 1.
[0052] As the trapezoidal screw 4 continues to rotate, since the inner sleeve 3 and the intermediate sleeve 2 are relatively fixed, the inner sleeve 3 will drive the intermediate sleeve 2 to move together, causing the intermediate base 201 to change its axial position relative to the trapezoidal screw 4 and enter the threaded portion of the trapezoidal screw 4, engaging with the thread of the trapezoidal screw 4; simultaneously, the inner base 301 disengages from the threaded area. Afterwards, the rotation of the trapezoidal screw 4 only drives the axial movement of the intermediate base 201, causing the intermediate sleeve 2 to extend outward until the intermediate base 201 contacts the top shoulder of the outer sleeve 1, at which point the intermediate sleeve 2 extends to its designed limit position and is fully extended. At this point, utilizing the self-locking characteristic of the trapezoidal screw 4, a reliable lock is achieved between the intermediate sleeve 2 and the outer sleeve 1, and the telescopic arm is fully extended, as shown... Figure 1 As shown.
[0053] To ensure seamless engagement when the intermediate base 201 enters the thread engagement zone of the trapezoidal lead screw 4, this invention calculates the total number of revolutions N = (L1 + L2) / P of the trapezoidal lead screw 4 from retraction to full extension based on the multi-stage sleeve unfolding strokes L1 and L2 and the lead screw pitch P. N is then decomposed into integer revolutions Nc and fractional revolutions Nf, with the fractional revolutions corresponding to an angle Δφ = 360°·Nf. During assembly, the circumferential position of the second-stage lead screw nut 402 relative to the trapezoidal lead screw 4 is adjusted to create a theoretical phase difference Δφ between it and the first-stage lead screw nut 401.
[0054] When the sleeves at each stage are retracted, the process proceeds from the outside in, which is the reverse of the aforementioned unfolding process. Initially, the intermediate base 201 is positioned on the threaded section of the trapezoidal screw 4, and the inner sleeve 3 and the intermediate sleeve 2 are locked together. The drive motor 501 drives the trapezoidal screw 4 to rotate in the opposite direction, causing the intermediate base 201 to pull the intermediate sleeve 2 inward toward the outer sleeve 1.
[0055] When the intermediate sleeve 2 retracts until the locking block 702b reaches the slot of the locking seat 701 on the outer sleeve 1, it continues to move so that the locking block 702b enters the slot 701a. At the same time, the two locking pins 702e enter the two inclined slots 701b respectively. Then, the inclined slots 701b will drive the locking head 702 to move outward as a whole, and the spring 702d will be compressed until it reaches the bottom of the inclined slot, so that the slider 702c disengages from the locking hole 703 on the side wall of the inner sleeve 3. At this time, the inner base 101 enters the thread engagement area of the trapezoidal screw 4, and the intermediate base 201 retracts to the lead screw rod section and stops being driven, completing the retraction between the intermediate sleeve 2 and the outer sleeve 1. Then the trapezoidal screw 4 continues to rotate, driving the inner sleeve 3 to retract into the intermediate sleeve 2 until the telescopic arm returns to the fully retracted state. At the beginning of the retraction process of the inner sleeve 3, the upper edge of the locking hole on the inner sleeve 2 engages with the upper arc surface of the slider, applying an outward pushing force to the locking head 702 until the roller on the slider 702c contacts the outer wall of the inner sleeve 3. During this process, the locking block 702b further enters the extension groove 701c and is restricted in its displacement by the outer wall of the inner sleeve 3, at which point the intermediate sleeve 2 and the outer sleeve 1 are locked together. At this point, the inner sleeve 3 and the intermediate sleeve 2 are unlocked; simultaneously, the inner sleeve 2 is locked together by the outer wall of the inner sleeve 3.
[0056] The magnetic scale sensor is used to achieve high-precision detection of relative displacement between adjacent sleeves and can be installed between two adjacent sleeves according to actual needs. The magnetic scale sensor includes a magnetic head and a magnetic strip, which are respectively installed on a set of keyways 602 and guide protrusions 601 that cooperate with each other in adjacent sleeves. The magnetic strip is pasted and fixed to the guide protrusion 601 along the sleeve axial direction; the magnetic head is fixedly installed at the inner end of the keyway 602, so that the magnetic head and magnetic strip have a certain gap after the guide protrusion 601 and keyway 602 are engaged, meeting the sensor's working requirements. To avoid interference between the guide protrusion 602 and the inner outer wall of the sleeve, a groove corresponding to the guide protrusion 601 where the magnetic strip is located can be further formed on the inner outer wall of the sleeve. After installing the magnetic scale sensor, multiple extension and retraction tests of the telescopic arm can be performed by driving the motor drive assembly, collecting the magnetic scale output signal, and calibrating the positions of adjacent sleeves in the extended, locked, and retracted positions to form a one-dimensional high-precision displacement calibration curve of the telescopic arm.
[0057] Based on the above-described three-stage telescopic arm structure, multiple intermediate sleeves 2 can be designed to form a multi-stage telescopic arm, increasing the extension length of the telescopic arm. Specifically, based on the aforementioned intermediate sleeve 2 structure, locking seats 701 are installed on the top circumference of each of the multiple intermediate sleeves 2 for engaging with the top locking heads 702 of the adjacent outer intermediate sleeve 2 for locking. Additionally, except for the intermediate sleeve 2 adjacent to the outer sleeve 1, the bottom circumference of the remaining intermediate sleeves 2 is also designed with locking holes 703 for engaging with the top locking heads 702 of the adjacent outer intermediate sleeve 2 for locking when fully extended. Furthermore, since the telescopic arm unfolds sequentially from the inside out, when the telescopic arm is in the retracted state, the intermediate bases 201 of the multiple intermediate sleeves 2 should all be located at the smooth section of the trapezoidal screw 4. Considering that the stroke of each intermediate sleeve 2 gradually increases, the length of the trapezoidal screw 4 can be increased or the thickness of each base can be reduced so that after each level of sleeve is fully unfolded, it can continue to move a certain distance on the trapezoidal screw 4 and then disengage, ensuring that the base of the adjacent outer sleeve can move to the thread engagement area of the trapezoidal screw 4 and engage with the trapezoidal screw 4.
Claims
1. A high-precision spatial telescopic arm driven by a lead screw, comprising an outer sleeve, an intermediate sleeve, and an inner sleeve, all three being cylindrical tubes, coaxially nested from the outside in; the outer and intermediate sleeves have circumferentially designed annular shoulders on their top inner walls, used to limit the movement of the intermediate and inner sleeves when fully extended; characterized in that: The outer stage base is coaxially mounted at the bottom of the outer stage sleeve. The drive motor and reducer are coaxially mounted on the top surface of the outer stage base. The output shaft is coaxially connected to the trapezoidal lead screw, forming a single-degree-of-freedom rotary drive unit. The bottom of the trapezoidal lead screw is also designed with a smooth rod section. Meanwhile, the bottom of the intermediate stage sleeve and the inner stage sleeve are respectively fixed with the intermediate stage base and the inner stage base, and threaded holes are opened in the center of both. The outer stage sleeve and the inner wall of the intermediate stage sleeve are designed with guide protrusions at equal angular intervals in the circumferential direction and along the sleeve axis. At the same time, keyways are designed with equal angular intervals in the circumferential direction on the intermediate stage base and the inner stage base, respectively, to mate with the guide protrusions on the inner walls of the outer stage base and the intermediate stage base. A gap is reserved between the inner ring of the annular shoulder at the top of the outer stage sleeve and the circumferential direction of the outer wall of the intermediate stage sleeve. A gap is also reserved between the inner ring of the annular shoulder at the top of the intermediate stage sleeve and the circumferential direction of the outer wall of the inner stage sleeve. A bushing is installed at the gap. The outer sleeve is equipped with lock seats at equal angular intervals around its top; the middle sleeve is equipped with lock heads at equal angular intervals around its top; and the inner sleeve has lock slots at equal angular intervals on its bottom side wall. When the three sleeves are in the retracted state, the three circumferential keyways of the intermediate base engage with the three outer bosses respectively; the three circumferential keyways of the inner base engage with the three intermediate bosses respectively; the intermediate base is located at the bottom of the smooth section of the trapezoidal screw and is not subject to driving force; the inner base engages with the threaded part of the trapezoidal screw, is located at the bottom of the threaded part of the trapezoidal screw, and is in contact with the intermediate base; at the same time, the roller of the locking head at the top of the intermediate sleeve contacts the inner wall of the inner sleeve, and the outer end of the locking head cooperates with the locking seat to lock the outer sleeve and the intermediate sleeve. When the drive motor is working, the drive screw rotates. At this time, the inner stage base moves along the axial direction of the trapezoidal screw, causing the inner stage sleeve to gradually extend. Until the inner stage base contacts the top shoulder of the intermediate stage sleeve and is limited, the inner stage sleeve extends to its designed limit position and is fully extended. At the same time, the top locking head of the intermediate stage sleeve moves inward under the action of the spring return force, and the inner end of the locking head inserts into the locking hole opened on the side wall of the inner stage sleeve, locking the inner stage sleeve and the intermediate stage sleeve. At the same time, the outer end of the locking head disengages from the locking seat, unlocking the intermediate stage sleeve and the outer stage sleeve. As the trapezoidal screw continues to rotate, the inner sleeve moves along with the intermediate sleeve, causing the intermediate base to enter the threaded portion of the trapezoidal screw and engage with the threaded portion. Simultaneously, the inner base disengages from the threaded portion of the trapezoidal screw. Then, the rotation of the trapezoidal screw causes the intermediate sleeve to extend outward until the intermediate base contacts the top shoulder of the outer sleeve, at which point the intermediate sleeve extends to its design limit and is fully deployed. When the sleeves at each level are being closed, the process proceeds from the outside in, which is the reverse of the aforementioned unfolding process.
2. The high-precision spatial telescopic arm driven by a lead screw as described in claim 1, characterized in that: A high-precision telescopic arm for extending and retracting as described in claim 1, characterized in that: there are more than n intermediate sleeves, n>1, forming an n-stage telescopic arm. Specifically, based on the intermediate sleeve structure, locking seats are installed on the top circumference of each of the n intermediate sleeves for locking with the top locking head of the adjacent outer intermediate sleeve; at the same time, except for the intermediate sleeves adjacent to the outer sleeves, the bottom circumference of the remaining intermediate sleeves is also designed with locking ports for locking with the top locking head of the adjacent outer intermediate sleeve when fully extended; when the telescopic arm is in the retracted state, the intermediate bases of the n intermediate sleeves are all located at the smooth section of the trapezoidal screw, and by increasing the length of the trapezoidal screw or decreasing the thickness of each base, after each stage of the sleeve is fully extended, it continues to move a certain distance on the trapezoidal screw before disengaging from the threaded part, thereby ensuring that the base of the adjacent outer sleeve can move to the thread engagement area of the trapezoidal screw and engage with the trapezoidal screw.
3. A high-precision spatial telescopic arm driven by a lead screw as described in claim 1 or 2, characterized in that: Based on the unfolding strokes L1 and L2 of the inner and intermediate sleeves in the adjacent three-stage sleeves and the screw pitch P, the total number of revolutions N = (L1 + L2) / P of the trapezoidal screw from retraction to full unfolding is calculated. N is decomposed into integer revolutions Nc and decimal revolutions Nf, with the decimal revolutions corresponding to an angle Δφ = 360°·Nf. During assembly, the circumferential position of the second-stage screw nut relative to the trapezoidal screw is adjusted to create a theoretical phase difference Δφ between it and the first-stage screw nut.
4. A high-precision telescopic arm for extending and retracting as described in claim 1 or 2, characterized in that: Based on the outer diameter and length of the telescopic arm and the wall thickness requirements of each sleeve, each level of sleeve is machined using electrical discharge machining (EDM) to ensure the machining accuracy and smooth surface of the inner guide key.
5. A high-precision spatial telescopic arm driven by a lead screw as described in claim 1 or 2, characterized in that: It also includes a magnetic scale sensor for high-precision detection of relative displacement between adjacent sleeves, which is specifically installed between two adjacent sleeves according to actual needs; the magnetic scale sensor includes a magnetic head and a magnetic strip, which are respectively installed on a set of keyways and guide convex keys that cooperate with each other in adjacent sleeves.
6. The high-precision spatial telescopic arm driven by a lead screw as described in claim 5, characterized in that: A groove corresponding to the guide key where the magnetic strip is located is further opened on the inner outer wall of the sleeve to avoid interference between the magnetic strip and the outer wall of the sleeve.
7. The high-precision spatial telescopic boom driven by a lead screw as described in claim 5, characterized in that: After installing the magnetic scale sensor, the telescopic arm is driven by the motor drive assembly to conduct multiple extension and retraction tests. The output signal of the magnetic scale is collected to calibrate the positions of adjacent sleeves when they are fully extended, locked, and retracted, forming a one-dimensional high-precision displacement calibration curve of the telescopic arm.
8. The high-precision spatial telescopic arm driven by a lead screw as described in claims 1 and 2, characterized in that: A gap is reserved between the guide key and the keyway.
9. A high-precision spatial telescopic arm driven by a lead screw as described in claims 1 and 2, characterized in that: The lock head has a central shaft and locking blocks and sliders designed at both the inner and outer ends of the central shaft. The slider is located in a groove designed radially along the top of the intermediate sleeve, which restricts the circumferential displacement of the slider. A roller is installed on the slider, and the roller axis is perpendicular to the axis of the central shaft. The central shaft is located in a through hole opened on the outer wall of the groove, and the locking block is located on the outer side of the outer wall. At the same time, a spring is sleeved on the central shaft, and the two ends of the spring contact the outer wall of the groove and the slider, respectively. Locking pins are symmetrically designed on both sides of the central shaft, and the axis of the locking pins is perpendicular to the axis of the central shaft. The top of the lock seat has a slot for accommodating the locking block. At the same time, inclined grooves with an outward lower part are opened on the left and right side walls of the slot to accommodate the locking pins on both sides of the locking block. And there is an extension groove designed horizontally outward at the bottom of the inclined groove.
10. The high-precision spatial telescopic arm driven by a lead screw as described in claim 9, characterized in that: When the intermediate sleeve retracts until the locking block reaches the slot on the outer sleeve's locking seat, it continues to move so that the locking block enters the slot. At the same time, the two locking pins enter the two inclined slots respectively. The inclined slots then drive the entire locking head to move outward, compressing the spring until it reaches the bottom of the inclined slot, causing the slider to disengage from the locking hole on the inner sleeve's side wall; thus unlocking the intermediate sleeve from the inner sleeve. Simultaneously, the outer sleeve further compresses the spring, ultimately causing the locking pins to reach the extension slot, thus locking the outer and intermediate sleeves.