A three-degree-of-freedom spherical joint device based on spherical gears and a control method thereof

Abstract

The application relates to the technical field of robot joint design, and particularly discloses a three-degree-of-freedom spherical joint device based on a spherical gear and a control method thereof. The three-degree-of-freedom spherical joint device based on the spherical gear comprises a supporting base, a spherical gear, a supporting mechanism, a controller and three groups of driving mechanisms. The three-degree-of-freedom spherical joint device based on the spherical gear takes the spherical gear driving an output rod as a to-be-adjusted attitude component, three single-pole gears respectively form conjugate meshing transmission pairs with the spherical gear from different spatial directions to respectively drive the spherical gear to rotate around a ball center and drive the output rod to synchronously rotate, and three-degree-of-freedom attitude output is realized. The output rotation center of the application is concentrated on the same ball center, and the joint axial size increase and multi-stage transmission error accumulation can be effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of robot joint design technology, and particularly to: 1. a three-degree-of-freedom spherical joint device based on spherical gears; 2. a control method for the three-degree-of-freedom spherical joint device based on spherical gears. Background Technology

[0002] The wrist of a robotic arm is usually located between the robotic arm body and the end effector. It is used to adjust the spatial posture of the end effector so that the end effector can perform tasks such as gripping, assembling, and handling according to the position and orientation of the target workpiece.

[0003] Existing robotic arms are typically designed with six degrees of freedom in space, and their wrists often employ a three-axis serial structure. Pitch, yaw, and rotation are achieved through three sequentially arranged rotary drive devices. For example, Chinese invention patent application "A Robotic Arm Wrist Layout Structure" (application number: 201811602232.9, application date: 2018.12.26, publication number: CN109397330A) discloses a robotic arm wrist layout structure, which includes wrist drive device I, wrist drive device II, and wrist drive device III. These three wrist drive devices are connected in series, and their rotation axes intersect at a single point. This design places wrist drive device III within the space between wrist drive devices I and II, bringing the end effector mounting flange closer to the three-axis intersection center, thereby improving the wrist structure layout. Although the wrist of this robotic arm has adjusted the position of the three wrist drive devices, its three degrees of freedom of posture are still realized by the three wrist drive devices respectively, and the three wrist drive devices are still connected in series. This design requires multiple drive components, connectors and support components to be arranged along the wrist direction. The transmission chain is long and the axial dimension is large. The end inertia, assembly error and transmission clearance are easy to accumulate with the series structure, which affects the compactness of the wrist structure and the accuracy of posture adjustment. Summary of the Invention

[0004] To address the problems of excessively large axial dimensions of the wrist in existing robotic arms, and the accumulation of end-effector inertia, assembly errors, and transmission backlash due to serial structures, this invention provides a three-degree-of-freedom spherical joint device based on spherical gears and its control method.

[0005] This invention is achieved using the following technical solution: In a first aspect, the present invention discloses a three-degree-of-freedom spherical joint device based on a spherical gear, comprising: a support base, a spherical gear, a support mechanism, a controller, and three sets of drive mechanisms.

[0006] The support base is used to support the support mechanism and the three sets of drive mechanisms; The support mechanism is used to connect with the spherical gear in a ball-and-socket manner to support the spherical gear; the part of the support mechanism that covers the spherical gear has three through slots evenly arranged circumferentially to expose the spherical gear; Three sets of drive mechanisms are evenly arranged around the periphery of the support mechanism. Each of them uses a drive motor as a power source and acts on the spherical gear through three through slots to drive the spherical gear to rotate from different spatial directions. The output main shaft direction of the three sets of drive mechanisms forms the same acute angle with the central axis direction of the support mechanism. The side of the spherical gear away from the support mechanism is connected to an output rod that rotates synchronously with the spherical gear; The controller is used to control the operation of three drive motors to drive the spherical gear to rotate and make the output rod reach the target position.

[0007] The implementation of this three-degree-of-freedom spherical joint device based on spherical gears is based on the method or process of an embodiment of this disclosure.

[0008] Secondly, the present invention discloses a control method for a three-degree-of-freedom spherical joint device based on spherical gears, comprising the following steps: Step 1: Compare the current pose and target pose of the output rod to determine the pose adjustment process required for the spherical gear. Step 2: Determine whether the output rod interferes with the support mechanism when adjusting according to the required pose adjustment process of the spherical gear; If it is determined that the output rod and the support mechanism do not interfere with each other, proceed directly to step three; otherwise, first use the robotic arm to perform coarse pose adjustment on the three-degree-of-freedom spherical joint device based on spherical gears, and then return to step one. Step 3: Divide the required pose adjustment process of the spherical gear into intermediate postures arranged according to the control time, and perform inverse kinematics solution for each intermediate posture to obtain the target drive angle of the three drive motors at each control time; Step four: Based on the target drive angle changes of the three drive motors at adjacent control moments, construct the corresponding drive trajectory, and control the three drive motors to perform corresponding actions to achieve coordinated rotation until the spherical gear drives the output rod to adjust to the target posture.

[0009] The control method for this three-degree-of-freedom spherical joint device based on spherical gears is implemented according to the method or process of the embodiments of this disclosure.

[0010] The present invention has the following beneficial effects: 1. This invention designs a three-degree-of-freedom spherical joint device based on spherical gears. The spherical gears drive an output rod as the controlled attitude component. Three single-pole gears, each from a different spatial direction, form conjugate meshing transmission pairs with the spherical gears to drive the spherical gears to rotate around the center of the sphere, and simultaneously drive the output rod to rotate synchronously, thus achieving three-degree-of-freedom attitude output. Compared to a serial wrist device with multiple rotating joints connected in sequence, the output rotation center of this invention is concentrated at the same sphere center, effectively reducing the increase in joint axial dimensions and the accumulation of multi-stage transmission errors.

[0011] 2. The three drive mechanisms of the present invention are evenly distributed around the spherical gear support mechanism, and their output main shaft direction is at the same acute angle as the central axis direction of the support mechanism. This makes the output directions of the three single-pole transmission mechanisms orthogonal to each other in space, thereby enabling the three single-pole gears to mesh with the spherical gear from three orthogonal directions and jointly drive the spherical gear to rotate around the center of the sphere, thus improving the force concentration caused by unilateral drive.

[0012] 3. The present invention incorporates a differential mechanism and a bidirectional anti-reverse mechanism in the drive mechanism. During active output, the bidirectional anti-reverse mechanism restricts the differential housing from moving, allowing the power output from the drive motor to be transmitted to the single-pole gear. During passive rotation, the bidirectional anti-reverse mechanism supports the transmission of the rotation of the housing bevel gear driven by the single-pole housing into the rotation of the differential housing, thus avoiding affecting the passive rotation of the drive motor output.

[0013] 4. This invention provides a control method for a three-degree-of-freedom spherical joint device. It determines the required pose adjustment process of the spherical gear based on the difference between the current pose of the output rod and the target pose. When it is determined that the output rod and the support mechanism will interfere during the adjustment process, the pose is coarsely adjusted by a robotic arm to ensure that the three-degree-of-freedom spherical joint device is within a reasonable range of movement, which effectively improves the safety of the adjustment.

[0014] 5. The present invention provides a control method for a three-degree-of-freedom spherical joint device. It divides the required pose adjustment process of the spherical gear into intermediate postures arranged according to the control time, and converts each intermediate posture into the target drive angle of the three drive motors at each control time. Then, it constructs the drive trajectory of the corresponding drive motors by the change of the target drive angle over time to facilitate execution, thereby ensuring that the spherical gear drives the output rod to reach the target posture. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural diagram of a three-degree-of-freedom spherical joint device based on spherical gears provided in Embodiment 1 of the present invention; Figure 2 for Figure 1 Connection structure diagram of the middle support mechanism, spherical gear, and output rod; Figure 3 for Figure 1 Connection structure diagram of the three drive mechanisms and the support base; Figure 4 for Figure 3 Structural diagram of the single-unit drive mechanism; Figure 5 for Figure 3 A schematic diagram of the meshing of three single-pole gears with a spherical gear; Figure 6 A flowchart of the control method for a three-degree-of-freedom spherical joint device based on spherical gears provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram showing the coincidence of the fixed base coordinate system {O} and the spherical gear follower coordinate system {S} provided in Embodiment 2 of the present invention. Figure 8 This is a schematic diagram of the fixed base coordinate system {O} and the spherical gear follower coordinate system {S} being misaligned according to Embodiment 2 of the present invention.

[0017] The symbols in the attached diagram have the following meanings: 1. Support base; 101. Upper mounting platform; 102. Lower mounting platform; 103. Supporting components; 104. Support cover; 105. Mounting plate; 2. Drive mechanism, 211. Drive motor, 212. Coupling, 213. Motor drive shaft, 214. Motor shaft bevel gear, 221. Differential housing, 222. Housing bearing, 223. Differential bevel gear, 224. Differential shaft, 225. Differential bearing, 226. Differential timing pulley, 227. Reversing bevel gear, 228. Reversing shaft, 229. Reversing bearing, 230. Drive shaft, 231. Reversing bevel gear, 232. Drive bevel gear, 233. Drive bearing, 240. Housing bevel gear, 241. Single 242. Pole housing, 243. Drive bevel gear, 244. Driven bevel gear, 245. Input synchronous shaft, 246. Input synchronous belt pulley, 247. Single-pole synchronous belt pulley, 248. Single-pole drive gear, 249. Single-pole gear, 251. Shift fork bevel gear, 252. Shift fork shaft, 253. Bidirectional backstop, 261. Inner disc synchronous belt pulley, 262. Brake synchronous belt, 263. Brake, 264. Locking shaft; 3. Support mechanism, 301. Spherical gear support seat, 302. Fixed connecting rod, 303. Anti-detachment limiting component; 401. Spherical gear; 402. Output rod. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Example 1

[0021] This embodiment 1 provides a three-degree-of-freedom spherical joint device based on spherical gears, which serves as the wrist of a robotic arm and drives the spherical gears 401 through three sets of circumferentially arranged drive mechanisms 2, thereby improving the transmission and support reliability of the joint device under different motion states and different installation postures.

[0022] like Figure 1 As shown, this three-degree-of-freedom spherical joint device based on spherical gears mainly includes: a support base 1, three sets of drive mechanisms 2, spherical gears 401, and support mechanism 3. It may also include: a controller (not shown).

[0023] In summary, the support base 1 is used to support the support mechanism 3 and the three sets of drive mechanisms 2; the support mechanism 3 is used to connect with the spherical gear 401 via a ball-and-socket connection to support the spherical gear 401; the part of the support mechanism 3 that encloses the spherical gear 401 has three through slots evenly arranged circumferentially to expose the spherical gear 401; the three sets of drive mechanisms 2 are evenly arranged around the support mechanism 3, each using a drive motor 211 as a power source, and acting on the spherical gear 401 through the three through slots to drive the spherical gear 401 to rotate from different spatial directions; the output spindle direction of the three sets of drive mechanisms 2 forms the same acute angle with the central axis direction of the support mechanism 3; the side of the spherical gear 401 away from the support mechanism 3 is connected to an output rod 402 that rotates synchronously with the spherical gear 401; the controller is used to control the three drive motors 211 to drive the spherical gear 401 to rotate and make the output rod 402 reach the target position.

[0024] In other words, the center of the spherical gear 401 is the rotation center of the three-degree-of-freedom spherical joint device based on the spherical gear, and the output rod 402 serves as the adjusted attitude component of the three-degree-of-freedom spherical joint device based on the spherical gear. This achieves the concentration of the output rotation center at the same spherical center, effectively reducing the increase in the axial dimension of the joint and the accumulation of errors in multi-stage transmission.

[0025] The following is a detailed explanation with reference to the attached diagram: The support base 1 is designed to include: an upper mounting platform 101, a lower mounting platform 102, and a support member 103. The upper mounting platform 101 and the lower mounting platform 102 are arranged vertically at intervals (i.e., longitudinally at intervals); the support member 103 is connected between the upper mounting platform 101 and the lower mounting platform 102.

[0026] The support mechanism 3 is located on the side of the upper mounting platform 101 away from the lower mounting platform 102. For example... Figure 1 It is recommended that the support mechanism 3 be located in the central area of ​​the support base frame to facilitate component layout and subsequent control.

[0027] The support mechanism 3 includes a spherical gear support seat 301 and a fixed connecting rod 302. The fixed connecting rod 302 serves as the central shaft of the support mechanism, with its bottom end vertically connected to the upper mounting platform 101 and its top end connected to the outer bottom surface of the spherical gear support seat 301. A spherical support groove is formed within the spherical gear support seat 301 to accommodate, but not completely enclose, the spherical gear 401, and a circular opening is formed on the top surface of the spherical gear support seat 301. The spherical gear 401 is connected to the spherical support groove via a ball-and-socket connection and can move around its center within the spherical support groove. Three through slots are evenly distributed around the bottom circumference of the spherical gear support seat 301, exposing the spherical gear 401. The output rod 402 extends from the circular opening on the top surface of the spherical gear support seat 301. In addition, to prevent the spherical gear 401 from falling off, an annular anti-disengagement limiting member 303 can be provided in the circular opening on the top surface of the spherical gear support 301 to limit the spherical gear 401 from falling off from the spherical support groove. When the three-degree-of-freedom spherical joint device based on the spherical gear is in different installation postures, the anti-disengagement limiting member 303 can limit the spherical gear 401.

[0028] The top surface of the upper mounting platform 101 is provided with three mounting plates 105 evenly arranged along the circumference of the support mechanism (i.e., the included angle between two adjacent mounting plates 105 in the downward viewing direction is 120°); in addition, it is recommended to set the mounting plates 105 at an angle relative to the top surface of the upper mounting platform 101 - the angle of inclination is set at 50°~60°, for example 54.74°.

[0029] The second and third sets of drive mechanisms 2 have the same structure and are installed in the support base 1, and are respectively connected to the three mounting plates 105 for transmission; the output end of each of the three sets of drive mechanisms 2 is provided with a single-pole gear 249; the three single-pole gears 249 respectively mesh with the spherical gear 401 from different spatial directions through three through slots on the bottom surface of the spherical gear support 301.

[0030] Each set of drive mechanisms 2 drives the single-pole gear 249 at its output end to rotate, which in turn drives the spherical gear 401 to rotate around the center of the sphere, thereby further driving the output rod 402 to rotate synchronously. Thus, the three-degree-of-freedom attitude motion of the output rod 402 is achieved through the three sets of drive mechanisms 2.

[0031] Of course, a support cover 104 can also be provided on the top surface of the upper mounting platform 101 to cover the three sets of drive mechanisms 2, and a mounting hole can be provided on the top of the support cover 104 to install the spherical gear support seat 301.

[0032] Taking one of the drive mechanisms 2 as an example, it mainly includes: drive components, differential mechanism, bidirectional anti-reverse mechanism, reversing transmission mechanism, and single-stage transmission mechanism; it may also include: braking mechanism.

[0033] The drive assembly serves as the power input; the differential mechanism is located between the drive assembly and the reversing transmission mechanism to transmit the power from the drive motor 211 when it actively outputs power to the reversing transmission mechanism; the reversing transmission mechanism is located between the differential mechanism and the single-pole transmission mechanism to change the direction of power transmission to act on the single-pole transmission mechanism; the single-pole transmission mechanism serves as the output end of the drive assembly to drive the spherical gear 401 to rotate around its center; the bidirectional anti-reverse mechanism cooperates with the differential mechanism and the reversing transmission mechanism to limit or release the relevant rotating parts in the differential mechanism; the braking mechanism cooperates with the differential mechanism to brake after the output rod 402 reaches the target position.

[0034] The following is for reference. Figures 2-4 The various mechanisms within drive mechanism 2 will be described below: ① The drive assembly includes: drive motor 211, motor transmission shaft 213, coupling 212, and motor shaft bevel gear 214.

[0035] The drive motor 211 is fixed on the lower mounting platform 102, and its output end extends upward and is connected to the motor drive shaft 213 through the coupling 212. The motor shaft bevel gear 214 is fixed to the top of the motor drive shaft 213 and rotates synchronously with the motor drive shaft 213.

[0036] Among them, the drive motor 211 is recommended to be a servo motor, stepper motor or other functional motor that can achieve position locking, which is directly controlled by the controller.

[0037] ② The differential mechanism includes: differential housing 221, housing bearing 222, differential bevel gear 223, differential shaft 224, differential bearing 225, and differential timing pulley 226.

[0038] The differential housing 221 is a cylindrical cavity. Its top end is rotatably connected to the upper mounting platform 101 via housing bearing 222, and its bottom end is fixedly connected to the differential synchronous pulley 226 on the same axis. The differential synchronous pulley 226 has a through hole in its center. The differential shaft 224 is rotatably mounted in the differential housing 221 via differential bearing 225 in a direction perpendicular to the axial direction (i.e., transverse) of the differential housing 221. The differential bevel gear 223 is fixed on the differential shaft 224. The top end of the motor drive shaft 213 extends into the differential housing 221 through the through hole in the center of the differential synchronous pulley 226 and has a gap with the differential synchronous pulley 226. The motor shaft bevel gear 214 is located in the differential housing 221 and meshes perpendicularly with the differential bevel gear 223.

[0039] In other words, the motor drive shaft 213 can only drive the motor shaft bevel gear 214, and cannot drive the differential synchronous pulley 226.

[0040] ③ The reversing transmission mechanism includes: reversing bevel gear 227, reversing shaft 228, reversing bearing 229, output main shaft 230, transmission bearing 233, reversing bevel gear 231, and transmission bevel gear 232.

[0041] The reversing shaft 228 is rotatably connected to the top of the differential housing 221 via the reversing bearing 229; the bottom end of the reversing shaft 228 extends into the differential housing 221 and is fixedly connected to the reversing bevel gear 227; the reversing bevel gear 227 meshes perpendicularly with the differential bevel gear 223; the top end of the reversing shaft 228 extends out of the differential housing 221 and is fixedly connected to the reversing bevel gear 231; the output spindle 230 is perpendicular to the mounting plate 105 and is rotatably connected to the mounting plate 105 via the transmission bearing 233; the bottom end of the output spindle 230 is fixedly connected to the transmission bevel gear 232, which meshes with the reversing bevel gear 231.

[0042] ④ The single-pole transmission mechanism includes: a single-pole housing 241, a transmission bevel gear 242, a driven bevel gear 243, an input synchronous shaft 244, an input synchronous belt pulley 245, a single-pole synchronous belt, a single-pole synchronous belt pulley 246, a single-pole synchronous shaft 247, a single-pole drive gear 248, a single-pole gear 249, and a housing bevel gear 240.

[0043] A single-pole housing 241 is fixedly connected to a housing bevel gear 240 at its bottom end, perpendicular to the mounting plate 105. A through hole is provided in the center of the housing bevel gear 240, through which the top end of the output spindle 230 extends into the single-pole housing 241 and is fixedly connected to a transmission bevel gear 242. An input synchronous shaft 244 is rotatably mounted inside the single-pole housing 241 in an axial direction perpendicular to the transmission shaft 230. A driven bevel gear 243 is fixedly connected to the input synchronous shaft 244 and meshes perpendicularly with the transmission bevel gear 242. An input synchronous pulley 245 is fixedly connected to... The input synchronous shaft 244 is mounted on the input synchronous shaft 244; the single-pole synchronous shaft 247 is also rotatably mounted in the single-pole housing 241 in a direction perpendicular to the output main shaft 230; the single-pole synchronous pulley 246 is fixedly connected to the single-pole synchronous shaft 247; the input synchronous pulley 245 and the single-pole synchronous pulley 246 are connected by a single-pole synchronous belt drive; the single-pole drive gear 248 is fixedly connected to the single-pole synchronous shaft 247; the single-pole gear 249 is rotatably mounted on the top of the single-pole housing 241, with one side meshing with the single-pole drive gear 248 and the other side forming a conjugate meshing transmission pair with the spherical gear 401.

[0044] Because the output shaft direction of the three sets of drive mechanisms forms an acute angle with the central shaft direction of the support mechanism, the single-pole gear will mesh with the spherical gear 401 at an inclined angle, such as... Figure 5 As shown.

[0045] In fact, the output directions of the three single-pole transmission mechanisms are orthogonal in space, so that the three single-pole gears mesh with the spherical gear from three orthogonal directions respectively, which can effectively improve the force concentration caused by unilateral drive.

[0046] ⑤ The bidirectional anti-reverse mechanism includes: shift fork bevel gear 251, shift fork shaft 252, bidirectional anti-reverse device 253, and locking shaft 264.

[0047] The shift fork shaft 252, the bidirectional backstop 253, and the locking shaft 264 are arranged sequentially from top to bottom, and are coaxially aligned. The shift fork shaft 252 passes through the upper mounting platform 101 and is rotatably connected to the upper mounting platform 101 via a shift fork bearing; the top of the shift fork shaft 252 is fixedly connected to the shift fork bevel gear 251; the shift fork bevel gear 251 meshes with the housing bevel gear 240; the top of the outer plate of the bidirectional backstop 253 is fixedly connected to the upper mounting platform 101, the top of the inner plate is fixedly connected to the bottom of the shift fork shaft 252, and the bottom of the inner plate is fixedly connected to the top of the locking shaft 264; the locking shaft 264 is rotatably positioned between the upper mounting platform 101 and the lower mounting platform 102. When the shift fork shaft 252 acts as the driving element, the bidirectional backstop 253 supports power transmission and causes the locking shaft 264 to rotate synchronously; when the locking shaft 264 acts as the driving element, the bidirectional backstop 253 prevents power transmission and causes the shift fork shaft 252 to be undriven.

[0048] The bidirectional backstop 253 mainly utilizes the roller interlocking action between its inner and outer discs: when the shift fork shaft 252 acts as the driving element, it will move the rollers in the bidirectional backstop 253 out of the wedge-tight position or keep them in the non-wedge-tight position, thereby preventing the wedge-tightening effect and allowing the inner disc to rotate relative to the outer disc to achieve power transmission; when the locking shaft 264 acts as the driving element, it will move the rollers in the bidirectional backstop 253 into the wedge-tight position, thereby generating the wedge-tightening effect and locking the inner disc relative to the outer disc to prevent power transmission.

[0049] ⑥ The braking mechanism includes: inner disc synchronous pulley 261, braking synchronous belt 262, and brake 263.

[0050] The brake 263 is located at the bottom of the locking shaft 264; the inner disc synchronous pulley 261 is fixedly connected to the locking shaft 264 and is connected to the differential synchronous pulley 226 through the brake synchronous belt 262.

[0051] The brake 263 can be directly controlled by the controller: when the locking shaft 264 is not braked, the locking shaft 264 can rotate freely; when the locking shaft 264 is braked, the locking shaft 264 cannot rotate.

[0052] It should be noted that, based on the above-designed three-degree-of-freedom spherical joint device using spherical gears, the spherical gear 401 can simultaneously receive active drives from up to three sets of drive mechanisms 2. It is particularly important to note that if not all three sets of drive mechanisms 2 are operational, the non-operating drive mechanism 2 will be subjected to the reverse action of the spherical gear 401; if more than one set of drive mechanisms 2 is operational, then any operational drive mechanism 2 will also be subjected to the reverse action of the other operational drive mechanisms 2 via the spherical gear 401.

[0053] Therefore, for any one of the drive mechanisms 2, there are three working states: (a) Only actively outputting the state: Drive motor 211 outputs power, which drives motor shaft bevel gear 214 to rotate via coupling 212 and motor drive shaft 213. Differential bevel gear 223 is driven by motor shaft bevel gear 214 to rotate, which in turn drives reversing bevel gear 227, reversing shaft 228, and reversing bevel gear 231 to rotate synchronously. Reversing bevel gear 231 then drives transmission bevel gear 232 to rotate output main shaft 230. Output main shaft 230 drives transmission bevel gear 242 to rotate driven bevel gear 243 and input synchronous shaft 244. Input synchronous shaft 244 drives single-pole synchronous shaft 247 to rotate via synchronous belt transmission. The moving gear 248 drives the single-pole gear 249 to rotate and acts on the spherical gear 401 from one side to make the spherical gear 401 rotate around its center. At the same time, the single-pole transmission mechanism is not subjected to the reverse action of the spherical gear 401. The single-pole housing and the housing bevel gear 240 do not rotate, so the shift fork bevel gear 251 has no power input. The outer disk of the bidirectional backstop does not rotate, and the inner disk does not rotate either. The motor drive shaft 213 cannot drive the differential synchronous pulley 226 to rotate, so the inner disk synchronous pulley 261 has no power input. At this time, the brake 263 has no effect on whether the locking shaft 264 is braked or not (generally, the brake 263 is set not to brake).

[0054] (ii) Passive rotation only: Spherical gears produce a reverse effect on a single-stage transmission mechanism—there are two possibilities: 1. If the single-pole gear 249 is passively rotated (relative to the single-pole housing 241), then according to the reverse power transmission in (I), the output end of the drive motor will be passively rotated. This requires the drive motor to have a certain tolerance to external torque in order to avoid problems in the operation of the drive motor.

[0055] 2. The single-pole housing 241 drives the housing bevel gear 240 to rotate (the single-pole housing and its internal components can be considered as a single unit at this time); the housing bevel gear 240 drives the shift fork bevel gear 251 to rotate, thereby making the shift fork shaft 252 the driving component; the brake 263 is set to not brake, allowing the locking shaft 264 to rotate freely, then the shift fork shaft drives the locking shaft 264 to rotate synchronously via the bidirectional backstop 253, and then drives the differential synchronous pulley 226 to rotate the differential housing 221 via the synchronous belt drive; and there is a gap between the differential housing 221 and the motor drive shaft 213, which prevents the output end of the drive motor 211 from being passively rotated.

[0056] (III) A combined working state in which active output and passive rotation coexist: Referring to the descriptions in (I) and (II), the spherical gear is driven by the drive mechanism 2 from one side and rotates around its center. At the same time, the spherical gear is also driven by other working drive mechanisms 2, which in turn act on the drive mechanism 2. If the single-pole gear 249 is rotated, it is equivalent to enhancing or weakening the active output of the drive motor 211. If the single-pole housing 241 drives the housing bevel gear 240 to rotate, it has no effect on the active output of the drive motor 211.

[0057] Based on the above working state, the controller can control the drive motors 211 in the three sets of drive mechanisms 2 to move the spherical gear 401 with the output rod 402 to the target position. The specific control logic is described in the following embodiment 2, and will not be elaborated here.

[0058] Of course, the controller can also be used to keep the output rod 402 in the target pose: after the output rod 402 reaches the target pose, the controller controls the drive motors in the three sets of drive mechanisms to lock the position of their motor output shafts (to ensure that the three single-pole gears no longer rotate) and controls the three brakes 263 to brake the three locking shafts 264 (to keep the three single-pole housings no longer rotate), thereby enabling the output rod 402 to keep the target pose.

[0059] Example 2

[0060] This embodiment 2 provides a control method (i.e., the control logic of the controller) for a three-degree-of-freedom spherical joint device based on spherical gears, which is used to adjust the pose of the three-degree-of-freedom spherical joint device based on spherical gears disclosed in embodiment 1, with the aim of adjusting the output rod 402 to the target pose.

[0061] See Figure 6 The control method for a three-degree-of-freedom spherical joint device based on spherical gears includes: Step 1: Compare the current pose and target pose of the output rod 402 to determine the pose adjustment process required for the spherical gear 401.

[0062] Since the pose includes position and attitude information, by comparing the current pose of the output rod 402 (which can be obtained through external monitoring equipment) and the target pose (which can be considered a known quantity), the deflection direction and deflection amplitude required for the output rod 402 to adjust from the current pose to the target pose can be determined. The output rod 402 and the spherical gear 401 can be considered as a single unit; therefore, the pose adjustment process required for the spherical gear 401 is the same as that for the output rod 402. For example, if the current pose of the output rod 402 is to the left of the target pose, the spherical gear 401 needs to be rotated to the right by a certain amount to deflect the output rod 402 by the same amount; if the current position of the output rod 402 is to the right of the target pose, the spherical gear 401 needs to be rotated to the left by a certain amount to deflect the output rod 402 by the same amount; other cases are similar and will not be elaborated further.

[0063] Step 2: Determine whether the output rod 402 interferes with (i.e. collides with) the support mechanism 3 when adjusting according to the required pose adjustment process of the spherical gear 401.

[0064] As described above, the rotation of the spherical gear 401 will move the output rod 402 together. The reasonable range of movement of the output rod 402 is determined by the support mechanism 3: if the anti-disengagement limiter 303 is not provided, it is only necessary to check whether the output rod 402 and the spherical gear support 301 will interfere; if the anti-disengagement limiter 303 is provided, it is only necessary to check whether the output rod 402 and the anti-disengagement limiter 303 will interfere.

[0065] In other words, see Figure 2 If we take the coaxial position of the output rod 402 and the center line of the support mechanism 3 as the reference position, then the output rod 402 has the same maximum deflection amplitude in all directions: as long as the rotation amplitude of the output rod 402 is less than the maximum deflection amplitude, it means that it is within the reasonable range of movement.

[0066] If it is determined that the output rod 402 does not interfere with the support mechanism 3, it means that it is within the reasonable range of movement and can be realized, so proceed directly to step three; if it is determined that the output rod 402 interferes with the support mechanism 3, it means that it exceeds the reasonable range of movement and will cause operational problems. It is necessary to first use the robotic arm to perform coarse adjustment of the pose of the three-degree-of-freedom spherical joint device based on spherical gears, and then return to step one.

[0067] Step 3: Divide the required pose adjustment process of the spherical gear 401 into M intermediate poses arranged according to the control time, and perform inverse kinematics solution for each intermediate pose to obtain the target drive angle of the three drive motors 211 at each control time.

[0068] Step 3 aims to determine the target drive angle of the three drive motors 211 at each control moment, so as to assist the three drive motors in achieving coordinated rotation.

[0069] The specific process of step three is as follows: S301, the m-th intermediate attitude is represented as the target attitude matrix R d,m ; m∈[1,M].

[0070] Among them, R d,m Constructed based on a fixed base coordinate system {O} and a spherical gear follower coordinate system {S}: Establish a fixed base coordinate system {O} (with its three coordinate axes being the x-axis, y-axis, and z-axis) and a spherical gear follower coordinate system {S} (with its three coordinate axes being the x-axis, y-axis, and z-axis) with the center of the spherical gear 401 as the origin. s axis, y saxis, z s (Shaft). {S} will rotate with the spherical gear 401, while {O} will remain in the same position. See also Figure 7 It shows the situation where {S} and {O} coincide when the spherical gear 401 is in the positive position; see [link / reference] Figure 8 It shows the situation where {S} and {O} are misaligned after the spherical gear 401 rotates.

[0071] So, R d,m The mathematical expression is: ; In the formula, R d,m It is a 3×3 three-dimensional rotation matrix, which contains the projection of the spherical gear 401 in {S} onto {O} at the m-th control time; The x represents the m-th intermediate posture of the spherical gear 401. s The projection of the x-axis coordinates onto the x-axis direction; The x represents the m-th intermediate posture of the spherical gear 401. s The projection of the y-axis coordinate onto the y-axis direction; The x represents the m-th intermediate posture of the spherical gear 401. s The projection of the x-axis coordinate onto the z-axis direction; The y-value of the spherical gear 401 in the m-th intermediate posture is represented by... s The projection of the x-axis coordinates onto the x-axis direction; The y-value of the spherical gear 401 in the m-th intermediate posture is represented by... s The projection of the y-axis coordinate onto the y-axis direction; The y-value of the spherical gear 401 in the m-th intermediate posture is represented by... s The projection of the x-axis coordinate onto the z-axis direction; This represents the z-axis of the spherical gear 401 in the m-th intermediate posture. s The projection of the x-axis coordinates onto the x-axis direction; This represents the z-axis of the spherical gear 401 in the m-th intermediate posture. s The projection of the y-axis coordinate onto the y-axis direction; This represents the z-axis of the spherical gear 401 in the m-th intermediate posture. s The projection of the x-axis coordinate onto the z-axis direction.

[0072] S302, according to the kinematic relationship between the spherical gear 401 and the three single-pole gears 249, based on R d,m The target active angle θ of the three single-pole gears 249 at the m-th control moment was calculated. 1,m ~θ 3,m .

[0073] In constructing R d Then, by performing inverse kinematics based on the meshing design of the spherical gear 401 and the three single-pole gears 249, we can obtain: θ 1,m ~θ 3,m The mathematical expression is: ; Where, θ i,m Let be the angle through which the i-th single-pole gear 249 rotates around its own drive shaft at the m-th control moment, representing the rotation angle of the i-th single-pole gear 249 at the m-th control moment; i=1,2,3.

[0074] It is important to note that θ i,m This characterizes the actual rotation angle of the i-th single-pole gear 249 relative to the i-th single-pole housing 241 around the driving axis (i.e., the central axis around which the i-th single-pole gear 249 rotates relative to the i-th single-pole housing 241). Therefore, even if the i-th single-pole gear 249 is subjected to passive rotation, it is already included in θ. i,m In the actual value, there is no need to calculate it separately as an additional rotation angle.

[0075] In addition, the meshing azimuth angle of the three single-pole gears 249 at the m-th control moment can be solved simultaneously. Its mathematical expression is: ; in, It represents the meshing orientation angle of the i-th single-pole gear 249 relative to the spherical gear 401 at the m-th control moment, and it characterizes the rotation angle of the single-pole housing 241 to which the i-th single-pole gear 249 belongs at the m-th control moment.

[0076] It should be noted that, as illustrated in Example 1, θ 1,m ~θ 3,m The driving of the three drive motors 211 is directly related to the driving of the three drive motors 211, and is subsequently used to deduce the target drive angle α of the three drive motors 211 at the m-th control time. 1,m ~α 3,m ;and This will not affect the driving of the three drive motors 211 and can be used as an indicator of reverse action.

[0077] S303, according to the kinematic relationship between the drive motor 211 and the single-pole gear 249, based on θ 1,m ~θ 3,m Calculate the target drive angle α of the three drive motors 211 at the m-th control moment. 1,m ~α 3,m .

[0078] For the i-th drive mechanism, if the transmission design from the drive motor 211 to the single-pole gear 249 is fixed, then θ i,m With α i,m There exists a fixed correspondence, namely: ; In the formula, F i Represents θ i,m With α i,m The correspondence between them.

[0079] Step four: Based on the target drive angle changes of the three drive motors 211 at adjacent control moments, construct the corresponding drive trajectory, and control the three drive motors 211 to perform corresponding actions to achieve coordinated rotation until the spherical gear 401 drives the output rod 402 to adjust to the target posture.

[0080] Specifically, step four employs a piecewise S-shaped velocity planning algorithm—based on α 1,m ~α 3,m α 1,m+1 ~α 3,m+1 The changes in angular velocity, angular acceleration, and angular jerk are considered, and the corresponding motion constraints (including the acceptable range of angular velocity, angular acceleration, and angular jerk) are taken into account. The drive trajectories of the three drive motors 211 from the m-th control time to the (m+1)-th control time are generated, so that the three drive motors 211 can rotate in coordination when they execute the corresponding drive trajectories, and finally the output rod 402 reaches the target posture at the M-th control time.

[0081] Of course, if it is necessary to maintain the output lever 402 in the target posture, the control method may also include: Step 5: Control the three drive motors 211 to lock the position of the motor output shaft, and control the three brakes 263 to brake the three locking shafts 264.

[0082] Example 3

[0083] This embodiment 3 discloses a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the control method for the three-degree-of-freedom spherical joint device based on spherical gears disclosed in embodiment 2.

[0084] The computer equipment can be either a mobile terminal or a fixed terminal. Examples of the former include mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (such as in-vehicle navigation terminals); examples of the latter include digital TVs and desktop computers.

[0085] This embodiment 3 also discloses a readable storage medium storing computer program instructions. When the computer program instructions are read and executed by a processor, the steps of the control method for the three-degree-of-freedom spherical joint device based on spherical gears disclosed in embodiment 1 are performed.

[0086] The readable storage medium may include, but is not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above.

[0087] This embodiment 3 also discloses a computer program product, including a computer program. When executed by a processor, the computer program implements the steps of the control method for the three-degree-of-freedom spherical joint device based on spherical gears disclosed in embodiment 1.

[0088] It should be noted that the computer program used to execute the above can be written in one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages—such as Java, Smalltalk, and C++—as well as conventional procedural programming languages—such as C or similar languages. The computer program can be executed entirely on the user's computer, partially on the user's computer, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer through any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN).

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A three-degree-of-freedom spherical joint device based on spherical gears, characterized in that: It includes: Support base, spherical gear, support mechanism, controller, and three sets of drive mechanisms; The support base is used to support the support mechanism and the three sets of drive mechanisms; The support mechanism is used to connect with the spherical gear in a ball-and-socket manner to support the spherical gear; the part of the support mechanism that covers the spherical gear has three through slots evenly arranged circumferentially to expose the spherical gear; Three sets of drive mechanisms are evenly arranged around the periphery of the support mechanism. Each of them uses a drive motor as a power source and acts on the spherical gear through three through slots to drive the spherical gear to rotate from different spatial directions. The output main shaft direction of the three sets of drive mechanisms forms the same acute angle with the central axis direction of the support mechanism. The side of the spherical gear away from the support mechanism is connected to an output rod that rotates synchronously with the spherical gear; The controller is used to control the operation of three drive motors to drive the spherical gear to rotate and make the output rod reach the target position.

2. The three-degree-of-freedom spherical joint device based on spherical gears according to claim 1, characterized in that, The support base includes: an upper mounting platform, a lower mounting platform, and a support component; the upper mounting platform and the lower mounting platform are spaced apart; the support component connects the upper mounting platform and the lower mounting platform; The support mechanism is located on the side of the upper mounting platform away from the lower mounting platform; the top surface of the upper mounting platform is provided with three mounting plates evenly arranged around the circumference of the support mechanism; the mounting plates are inclined relative to the top surface of the upper mounting platform, and the inclination angle is 50°~60°. The support mechanism includes: a spherical gear support seat and a fixed connecting rod; the fixed connecting rod serves as the central axis of the support mechanism, with its bottom end vertically connected to the upper mounting platform and its top end connected to the outer bottom surface of the spherical gear support seat; the spherical gear support seat has a spherical support groove formed inside to accommodate but not completely enclose the spherical gear, and a circular opening is formed on the top surface of the spherical gear support seat; the spherical gear is connected to the spherical support groove via a ball-and-socket connection and can move around its center within the spherical support groove; three through slots are evenly arranged circumferentially at the bottom of the spherical gear support seat to expose the spherical gear; the output rod extends from the circular opening on the top surface of the spherical gear support seat; The three sets of drive mechanisms have the same structure, are installed in the support base, and are respectively connected to the three mounting plates for transmission; the output end of each of the three sets of drive mechanisms is equipped with a single-pole gear; the three single-pole gears respectively mesh with the spherical gear from different spatial directions through three through slots on the bottom surface of the spherical gear support.

3. The three-degree-of-freedom spherical joint device based on spherical gears according to claim 2, characterized in that, The drive mechanism includes: drive components, differential mechanism, two-way anti-reverse mechanism, reversing transmission mechanism, and single-stage transmission mechanism; The drive assembly serves as the power input; the differential mechanism is located between the drive assembly and the reversing transmission mechanism to transmit the power from the drive motor when it is actively outputting to the reversing transmission mechanism; the reversing transmission mechanism is located between the differential mechanism and the single-pole transmission mechanism to change the direction of power transmission to act on the single-pole transmission mechanism; the single-pole transmission mechanism serves as the output end of the drive assembly to drive the spherical gear to rotate around its center; the bidirectional anti-reverse mechanism works in conjunction with the differential mechanism and the reversing transmission mechanism to limit or release the relevant rotating parts in the differential mechanism.

4. The three-degree-of-freedom spherical joint device based on spherical gears according to claim 3, characterized in that, The drive assembly includes: a drive motor, a motor drive shaft, a coupling, and a motor shaft bevel gear; the drive motor is fixed on the lower mounting platform, its output end extends upward and is connected to the motor drive shaft through the coupling; the motor shaft bevel gear is fixed to the top of the motor drive shaft and rotates synchronously with the motor drive shaft; The differential mechanism includes: a differential housing, a housing bearing, a differential bevel gear, a differential shaft, a differential bearing, and a differential timing pulley. The differential housing is a cylindrical cavity, with its top end rotatably connected to an upper mounting platform via the housing bearing, and its bottom end fixedly connected coaxially to the differential timing pulley. A through hole is provided in the center of the differential timing pulley. The differential shaft is rotatably mounted inside the differential housing via the differential bearing in a direction perpendicular to the differential housing axis. The differential bevel gear is fixed on the differential shaft. The top end of the motor drive shaft extends into the differential housing through the through hole in the center of the differential timing pulley and has a gap with the differential timing pulley. The motor shaft bevel gear is located inside the differential housing and meshes perpendicularly with the differential bevel gear. The reversing transmission mechanism includes: a reversing bevel gear, a reversing shaft, a reversing bearing, an output main shaft, a transmission bearing, a reversing bevel gear, and a transmission bevel gear; the reversing shaft is rotatably connected to the top of the differential housing via the reversing bearing; the bottom end of the reversing shaft extends into the differential housing and is fixedly connected to the reversing bevel gear; the reversing bevel gear meshes perpendicularly with the differential bevel gear; the top end of the reversing shaft extends out of the differential housing and is fixedly connected to the reversing bevel gear; the output main shaft is perpendicular to the mounting plate and is rotatably connected to the mounting plate via the transmission bearing; the bottom end of the output main shaft is fixedly connected to the transmission bevel gear, which meshes with the reversing bevel gear; The single-pole transmission mechanism includes: a single-pole housing, a transmission bevel gear, a driven bevel gear, an input synchronous shaft, an input synchronous pulley, a single-pole synchronous belt, a single-pole synchronous pulley, a single-pole synchronous shaft, a single-pole drive gear, a single-pole gear, and a housing bevel gear. The single-pole housing is perpendicular to the mounting plate, and the housing bevel gear is fixedly connected to its bottom end. A through hole is provided in the center of the housing bevel gear, and the top end of the output main shaft passes through this through hole, extends into the single-pole housing, and is fixedly connected to the transmission bevel gear. The input synchronous shaft is rotatably mounted inside the single-pole housing in a direction perpendicular to the transmission shaft axially. The driven bevel gear... The input synchronous belt pulley is fixedly connected to the input synchronous shaft and meshes perpendicularly with the transmission bevel gear; the input synchronous belt pulley is fixedly connected to the input synchronous shaft; the single-pole synchronous shaft is also rotatably mounted in the single-pole housing in a direction perpendicular to the output main shaft axis; the single-pole synchronous belt pulley is fixedly connected to the single-pole synchronous shaft; the input synchronous belt pulley and the single-pole synchronous belt pulley are connected by a single-pole synchronous belt drive; the single-pole drive gear is fixedly connected to the single-pole synchronous shaft; the single-pole gear is rotatably mounted on the top of the single-pole housing, with one side meshing with the single-pole drive gear and the other side forming a conjugate meshing transmission pair with a spherical gear; The bidirectional anti-reverse mechanism includes: a shift fork bevel gear, a shift fork shaft, a bidirectional anti-reverse device, and a locking shaft; the shift fork shaft, bidirectional anti-reverse device, and locking shaft are arranged sequentially from top to bottom, and are coaxial; the shift fork shaft passes through the upper mounting platform and is rotatably connected to the upper mounting platform through a shift fork bearing; the shift fork bevel gear is fixedly connected to the top of the shift fork shaft; the shift fork bevel gear meshes with the housing bevel gear; the top of the outer plate of the bidirectional anti-reverse device is fixedly connected to the upper mounting platform, the top of the inner plate is fixedly connected to the bottom of the shift fork shaft, and the bottom of the inner plate is fixedly connected to the top of the locking shaft; the locking shaft is rotatably positioned between the upper and lower mounting platforms; when the shift fork shaft is the driving component, the bidirectional anti-reverse device supports power transmission and makes the locking shaft rotate synchronously; when the locking shaft is the driving component, the bidirectional anti-reverse device prevents power transmission and prevents the shift fork shaft from being driven.

5. The three-degree-of-freedom spherical joint device based on spherical gears according to claim 4, characterized in that, The circular opening on the top surface of the spherical gear support is equipped with an annular anti-disengagement limiting element to prevent the spherical gear from disengaging from the spherical support groove. Or / and, the top surface of the mounting platform is provided with a support cover to enclose the three sets of drive mechanisms; the top of the support cover is provided with mounting holes to install spherical gear support seats.

6. The three-degree-of-freedom spherical joint device based on spherical gears according to claim 4, characterized in that, The drive mechanism also includes a braking mechanism, which works in conjunction with the differential mechanism to brake after the output rod reaches the target position. The braking mechanism includes an inner disc synchronous pulley, a brake synchronous belt, and a brake. The brake is located at the bottom of the locking shaft. The inner disc synchronous pulley is fixedly connected to the locking shaft and is connected to the differential synchronous pulley via the brake synchronous belt. The controller is also used to control the drive motors in the three drive mechanisms to lock their motor output shaft positions and control the three brakes to brake the three locking shafts after the output rod reaches the target pose, so as to keep the output rod in the target pose.

7. A control method for a three-degree-of-freedom spherical joint device based on spherical gears, characterized in that, It is used for pose adjustment of the three-degree-of-freedom spherical joint device based on spherical gears as described in any one of claims 1-6; The control method for the three-degree-of-freedom spherical joint device based on spherical gears includes: Step 1: Compare the current pose and target pose of the output rod to determine the pose adjustment process required for the spherical gear. Step 2: Determine whether the output rod interferes with the support mechanism when adjusting according to the required pose adjustment process of the spherical gear; If it is determined that the output rod and the support mechanism do not interfere with each other, proceed directly to step three; otherwise, first use the robotic arm to perform coarse pose adjustment on the three-degree-of-freedom spherical joint device based on spherical gears, and then return to step one. Step 3: Divide the required pose adjustment process of the spherical gear into intermediate postures arranged according to the control time, and perform inverse kinematics solution for each intermediate posture to obtain the target drive angle of the three drive motors at each control time; Step four: Based on the target drive angle changes of the three drive motors at adjacent control moments, construct the corresponding drive trajectory, and control the three drive motors to perform corresponding actions to achieve coordinated rotation until the spherical gear drives the output rod to adjust to the target posture.

8. The control method for a three-degree-of-freedom spherical joint device based on spherical gears according to claim 7, characterized in that, Step three includes: S301, the m-th intermediate attitude is represented as the target attitude matrix R d,m m∈[1,M]; Among them, R d,m Constructed based on a fixed base coordinate system {O} and a spherical gear follower coordinate system {S}; ; The x represents the spherical gear in the m-th intermediate posture. s The projection of the x-axis coordinates onto the x-axis direction; The x represents the spherical gear in the m-th intermediate posture. s The projection of the y-axis coordinate onto the y-axis direction; The x represents the spherical gear in the m-th intermediate posture. s The projection of the x-axis coordinate onto the z-axis direction; The y-value of the spherical gear in the m-th intermediate posture represents... s The projection of the x-axis coordinates onto the x-axis direction; The y-value of the spherical gear in the m-th intermediate posture represents... s The projection of the y-axis coordinate onto the y-axis direction; The y-value of the spherical gear in the m-th intermediate posture represents... s The projection of the x-axis coordinate onto the z-axis direction; The z-axis represents the z-axis of the spherical gear in the m-th intermediate posture. s The projection of the x-axis coordinates onto the x-axis direction; The z-axis represents the z-axis of the spherical gear in the m-th intermediate posture. s The projection of the y-axis coordinate onto the y-axis direction; The z-axis represents the z-axis of the spherical gear in the m-th intermediate posture. s The projection of the x-axis coordinate onto the z-axis direction; S302, according to the kinematic relationship between the spherical gear and the three single-pole gears, based on R d,m Calculate the target active angle θ of the three single-pole gears at the m-th control moment. 1,m ~θ 3,m ; ;θ i,m Let be the angle through which the i-th single-pole gear rotates around its own drive shaft at the m-th control moment; i=1,2,3; S303, according to the kinematic relationship between the drive motor and the single-pole gear, based on θ 1,m ~θ 3,m Calculate the target drive angle α of the three drive motors at the m-th control moment. 1,m ~α 3,m ; ;F i Represents θ i,m With α i,m The correspondence between them.

9. The control method for a three-degree-of-freedom spherical joint device based on spherical gears according to claim 8, characterized in that, S302 also includes: solving for the meshing azimuth angle of the three single-pole gears at the m-th control moment. ; ; This represents the meshing azimuth angle of the i-th single-pole gear relative to the spherical gear at the m-th control moment.

10. The control method for a three-degree-of-freedom spherical joint device based on spherical gears according to claim 8 or 9, characterized in that, In step four: a piecewise S-shaped velocity planning algorithm is adopted, based on α. 1,m ~α 3,m α 1,m+1 ~α 3,m+1 The changes in angular velocity, angular acceleration, and angular jerk are considered, and the acceptable ranges of these parameters are taken into account to generate the drive trajectories of the three drive motors from the m-th control time to the (m+1)-th control time.

Images