Gear chain based microwave driven large-curvature bending robotic arm

Abstract

The application discloses a microwave-driven large-curvature bending mechanical arm based on a gear chain and relates to the technical field of micro-mechanics.The mechanical arm comprises a rack, the rack is rotationally connected with a gear chain executing mechanism, the two sides of the gear chain executing mechanism are respectively connected with one end of a shape memory alloy spring, and the other end of the shape memory alloy spring is connected with a steel wire.When linearly polarized microwaves with the same polarization direction as the steel wire direction are irradiated on the steel wire and the microwave frequency is equal to the resonance frequency, the steel wire can generate an induced current, the shape memory alloy spring is transformed from martensite into austenite, and the gear chain executing mechanism is driven to move by contraction.The application can be used as a micro-mechanical arm to realize hooking of articles in a narrow space and provide a solution for precise operations in the fields of medical treatment, industry and spaceflight.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of microwave drive large curvature bending mechanical arm based on gear chain, belong to micro mechanical technical field. BACKGROUND

[0002] With the rapid development of minimally invasive surgery, precision manufacturing and micro robot technology, the demand for millimeter level or even smaller size mechanical arm is increasing. Traditional mechanical arm is limited by driving mode and transmission structure, and it is difficult to work stably in narrow space or electromagnetic sensitive environment. The development of micro mechanical arm is significant in breaking through the size and energy supply limit of existing technology.

[0003] In the prior art, traditional mechanical arm is mostly driven by motor or transmitted by hydraulic pressure / pneumatic pressure, which has the following limitations: in terms of volume and weight, motor and reduction mechanism make the system bulky, which is difficult to apply in minimally invasive surgery or micro robot; in terms of electromagnetic interference, motor drive may interfere with precision electronic equipment; in terms of energy supply, wired power supply or battery limits the flexibility and long-term operation ability of mechanical arm. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a large curvature bending mechanical arm driven by microwave based on gear chain, which can be used as a micro mechanical arm to realize the picking of objects in narrow space and provide a solution for precision operation in medical, industrial and aerospace fields.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] The present application provides a large curvature bending mechanical arm driven by microwave based on gear chain, which comprises a rack, the rack is rotationally connected with a gear chain execution mechanism, and the two sides of the gear chain execution mechanism are respectively connected with one end of a shape memory alloy spring, and the other end of the shape memory alloy spring is connected with a steel wire.

[0007] When linearly polarized microwave with the same polarization direction as the steel wire direction is irradiated on the steel wire, and the microwave frequency is equal to the resonance frequency, the steel wire generates induced current, so that the shape memory alloy spring changes from martensite to austenite, and shrinks to drive the gear chain execution mechanism to move.

[0008] Further, a rack shaft is arranged in the middle of the rack, and a slot hole is arranged on both sides of the rack shaft, a connecting seat is connected with the slot hole in interference, a through hole is arranged in the connecting seat, and the end of the shape memory alloy spring is bonded with the connecting seat in the through hole through metal adhesive.

[0009] Further, the gear chain execution mechanism comprises a first rod, a second rod, a third rod and a fourth rod which are sequentially connected in transmission.

[0010] Further, two ends of the first rod are respectively provided with a first incomplete gear and a first through hole, protrusions are connected to the two sides of the first rod through connecting rods, an O-shaped seat is sleeved on the protrusions, the O-shaped seat is connected with a shape memory alloy spring, two transmission shafts are vertically arranged on the rod body of the first rod, and the transmission shafts are respectively sleeved with a first idler gear and a second idler gear.

[0011] The first through hole is sleeved on a rack shaft, and a sector gear is arranged above the first through hole.

[0012] Further, two ends of the second rod are respectively provided with a second incomplete gear and a third incomplete gear, the second incomplete gear and the first incomplete gear are sleeved on a first connecting shaft, and the second incomplete gear is engaged with the second idler gear; two transmission shafts are vertically arranged on the rod body of the second rod, and the transmission shafts are respectively sleeved with a third idler gear and a fourth idler gear.

[0013] Further, one end of the third rod is provided with a fourth incomplete gear, and three transmission shafts are vertically arranged on the rod body of the third rod, wherein the fifth idler gear and the sixth idler gear are sequentially sleeved on the two transmission shafts close to the fourth incomplete gear on the third rod, the third incomplete gear and the fourth incomplete gear are sleeved on a second connecting shaft, and the third incomplete gear is engaged with the fifth idler gear.

[0014] Further, one end of the fourth rod is provided with a fifth incomplete gear, and the fifth incomplete gear is engaged with the sixth idler gear.

[0015] Further, the end portions of the first connecting shaft and the second connecting shaft are respectively provided with a stop ring for limiting.

[0016] Further, the shape memory alloy spring is connected with a steel wire through a copper pipe.

[0017] Further, the length of the steel wire is 15mm and 25mm, respectively, which corresponds to the resonance length of the microwave frequency of 5.9GHz and 4GHz, respectively.

[0018] Compared with the prior art, the beneficial effects achieved by the present application are:

[0019] The mechanical arm of the present application is driven by microwaves, and the driving direction and amplitude are controlled by microwave frequency, and the shape memory alloy spring pulls the gear chain actuator, so that the end of the gear chain actuator can realize 4 times the angle of the input end.

[0020] The mechanical arm has wide application, can be used as a micro mechanical arm, realizes hooking of articles in a narrow space, and can be widely applied to precise operations in medical, industrial and aerospace fields. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A front structure schematic view of a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0022] Figure 2 A back structure schematic view of a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0023] Figure 3 A structure schematic view of a connecting seat in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0024] Figure 4 A structure schematic view of a rack in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0025] Figure 5 A structure schematic view of a first rod in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0026] Figure 6 A structure schematic view of a second rod in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0027] Figure 7 A structure schematic view of a third rod in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0028] Figure 8 A structure schematic view of a fourth rod in a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application;

[0029] Figure 9 A structure schematic view of a microwave-driven large-curvature bending mechanical arm based on a gear chain in an embodiment of the present application in a driving state;

[0030] Figure 10 A simulation result schematic view of a microwave-driven large-curvature bending mechanical arm based on a gear chain in Embodiment 2 of the present application;

[0031] In the diagram: 1-Frame, 101-Frame shaft, 102-Slot, 2-Connecting seat, 3-Copper tube, 4-Shape memory alloy spring, 5-Steel wire, 6-Sector gear, 7-First rod, 701-First incomplete gear, 702-First through hole, 703-First idler wheel, 704-Second idler wheel, 705-Protrusion, 8-Second rod, 801-Second incomplete gear, 802-Third incomplete gear, 803-Third idler wheel, 804-Fourth idler wheel, 9-Third rod, 901-Fourth incomplete gear, 902-Fifth idler wheel, 903-Sixth idler wheel, 10-Fourth rod, 1001-Fifth incomplete gear, 11-Mounting shaft, 12-O-type seat, 13-First connecting shaft, 14-Second connecting shaft. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0033] Example 1:

[0034] like Figure 1 As shown, this embodiment of the invention provides a microwave-driven large-curvature bending robotic arm based on a gear chain, including a frame 1, a steel wire 5, a shape memory alloy spring 4, and a gear chain actuator.

[0035] The structure of rack 1 is as follows Figure 4 As shown, the frame 1 has an irregular shape and is made of 3D-printed photocurable resin, giving it a certain degree of flexibility. A frame shaft 101 is located in the middle of the frame 1, enabling rotational connection between the frame 1 and the gear chain actuator. Slots 102 are provided on both sides of the frame shaft 101, with connecting seats 2 embedded in the slots 102. The shape of the slots 102 must match the bottom of the connecting seats 2; in this embodiment, the slots 102 are square, and the connecting seats 2 and slots 102 are interference-fitted.

[0036] The structure of connector 2 is as follows Figure 3 As shown, in this embodiment, the connecting base 2 is made of stainless steel and has a through hole. One end of the shape memory alloy spring 4 is bonded to the through hole with metal adhesive. A copper tube 3 is installed at the inner diameter of the shape memory alloy spring 4, and the copper tube 3 is fixedly connected to one end of the steel wire 5 by cold pressing. The other end of the shape memory alloy spring 4 is connected to an O-ring 12, which connects the shape memory alloy spring 4 to the gear chain actuator. In this embodiment, the inner diameter of the shape memory alloy spring 4 is 1mm, the wire diameter is 0.2mm, and the phase transition temperature is 40~50℃. The steel wire 5 is stainless steel wire, with two wires 5, each with a diameter of 0.1mm and lengths of 15mm and 25mm, corresponding to the resonant lengths at microwave frequencies of 5.9GHz and 4GHz, respectively.

[0037] Wire polarized microwave irradiation on the steel wire 5, when the polarization direction and the direction of the steel wire 5 is the same, and the microwave frequency is equal to the resonant frequency, the steel wire 5 produces an induced current sufficient to make the shape memory alloy spring 4 phase transition, at this time, the shape memory alloy spring 4 is changed from martensite to austenite, and shrinks, through the O-shaped seat 12 pull gear chain actuator movement. By changing the frequency of the microwave can selectively control the gear chain actuator movement offset direction, that is, the movement offset direction is the microwave frequency corresponding to the side of the steel wire 5.

[0038] Example 2:

[0039] On the basis of example 1, the structure of the gear chain actuator of the embodiment specifically includes first rod 7, second rod 8, third rod 9 and fourth rod 10 are connected in turn.

[0040] The structure of the first rod 7 is shown in Figure 5 The first rod 7 includes a rod body, a first incomplete gear 701 and a first through hole 702, the first incomplete gear 701 and the first through hole 702 are located at both ends of the first rod 7 respectively. The first rod 7 is also provided with a protrusion 705 through the connecting rod on both sides, the protrusion 705 is cylindrical, and the O-shaped seat 12 is sleeved on the protrusion 705. The rod body of the first rod 7 is vertically provided with two mounting shafts 11, the mounting shafts 11 are respectively sleeved with a first idler 703 and a second idler 704. The first through hole 702 is sleeved on the rack shaft 101, so that the first rod 7 can rotate around the rack shaft 101. The rack shaft 101 above the first through hole 702 is sleeved with a sector gear 6, the sector gear 6 is fixed with the rack shaft 101 by glue, so that the sector gear 6 has no relative motion with the rack 1. The sector gear 6 is engaged with the first idler 703.

[0041] The second rod 8 includes a rod body, a second incomplete gear 801 and a third incomplete gear 802, the second incomplete gear 801 and the third incomplete gear 802 are respectively arranged at both ends of the second rod 8, and the rod body of the second rod 8 is vertically provided with two mounting shafts 11, the mounting shafts 11 are respectively sleeved with a third idler 803 and a fourth idler 804. The second incomplete gear 801 and the first incomplete gear 701 are sleeved on the first connecting shaft 13, and the second incomplete gear 801 is engaged with the second idler 704.

[0042] The third rod 9 comprises a rod body and a fourth incomplete gear 901 arranged at the end of the third rod 9, and three mounting shafts 11 are vertically arranged on the rod body, wherein the fifth idler gear 902 and the sixth idler gear 903 are sequentially sleeved on the two mounting shafts 11 close to the fourth incomplete gear 901, and the fourth incomplete gear 901 and the third incomplete gear 802 are sleeved on the second connecting shaft 14. The third incomplete gear 802 is engaged with the fifth idler gear 902.

[0043] In some embodiments, the end of the first connecting shaft 13 and the end of the second connecting shaft 14 are both provided with a check ring, the axial displacement of the first connecting shaft 13 and the second connecting shaft 14 is limited through the check ring, and the stability of the overall transmission is improved.

[0044] The fourth rod 10 comprises a rod body and a fifth incomplete gear 1001, and the fifth incomplete gear 1001 is sleeved on the transmission shaft of the third rod 9 away from the fourth incomplete gear 901 and is engaged with the sixth idler gear 903.

[0045] In the embodiment, the first idler gear 703 and the second idler gear 704 are both 16-tooth cylindrical gears, and the third idler gear 803, the fourth idler gear 804, the fifth idler gear 902 and the sixth idler gear 903 are all 12-tooth cylindrical gears.

[0046] The transmission principle of the embodiment is that when linearly polarized microwaves with a microwave frequency of 5.9 GHz or 4 GHz irradiate on the steel wire 5, the steel wire 5 generates an induced current, the shape memory alloy spring 4 on the side corresponding to the steel wire 5 with the resonant length of the microwave frequency of 5.9 GHz or 4 GHz changes from martensite to austenite and shrinks, and the O-shaped seat 12 pulls the first rod 7 to offset to the side corresponding to the steel wire 5 with the resonant length of the microwave frequency of 5.9 GHz or 4 GHz.

[0047] Taking the side of the steel wire 5 with the resonant length (15 mm) of the microwave frequency of 5.9 GHz as the left side and the linearly polarized microwaves with the microwave frequency of 5.9 GHz as an example, at this time, the first rod 7 offsets to the left side, the transmission state is as shown in Figure 9 The first idler gear 703 and the second idler gear 704 rotate relative to each other, the second incomplete gear 801 rotates relative to the second idler gear 704, the third idler gear 803 rotates relative to the fourth idler gear 804, the fifth idler gear 902 rotates relative to the sixth idler gear 903, and the adjacent rods rotate relative to each other.

[0048] The execution structure of the embodiment initially adopts a sector gear drive, and the incomplete gears are coupled to the end of the connecting rod through idler gears. Double idler gears are arranged between the incomplete gears of each rod to extend the length of the connecting rod, avoid the reversal of the movement direction, and maintain a constant transmission ratio. The idler gears are selected to have the same specifications as the incomplete gears (16 teeth and 12 teeth), and the key gear parameters are shown in Table 1.

[0049] Table 1: Gear Parameters

[0050]

[0051] Note that the number of teeth in Table 1 refers to the total number of teeth in the corresponding gear completion state. The module of the gears is uniformly 0.2, and the center distance between the two incomplete gears on lever 2 is... Calculated using Equation 1, the following is obtained:

[0052] (Equation 1)

[0053] in, Indicates the center distance between the two incomplete gears on the rod. , Indicates the diameter of the incomplete gears at both ends of the rod. Indicates the diameter of the idler wheel on the rod.

[0054] Using the above formula, the center distance of gear 1, i.e., the distance between the centers of the sector gear and the second incomplete gear, = d sector gear / 2+2 d Second idler wheel + d The second incomplete gear / 2, i.e., 5.6 / 2 + 2*3.2 + 4 / 2 = 11.2mm;

[0055] Similarly, the center distance between gears 2, that is, the center distance between the second incomplete gear and the third incomplete gear, is 8.4mm;

[0056] The center distance between gears 3, that is, the center distance between the third incomplete gear and the fourth incomplete gear, is 7.6mm.

[0057] To analyze the kinematic properties of the mechanism, a multibody dynamics framework was constructed based on the Denavit-Hartenberg (DH) model. k The first member is relative to the first k -1 rotation angle of the rod Due to gear ratio i The result is determined recursively, as shown in Equation 2:

[0058] (Equation 2)

[0059] in, Indicates the first k The first member is relative to the first k -1 rotation angle of the rod, Indicates joint angle, This represents the gear ratio of the m-th link.

[0060] The DH model parameters of each member can be derived from Equation 2, as shown in Table 2.

[0061] Table 2: D-H model parameters of each link

[0062]

[0063] Definition of each joint transformation matrix A k As shown in equation 3, where the joint refers to the interface between the first link and each link.

[0064] (Equation 3)

[0065] Wherein, represents the first k joint transformation matrix, represents the rotation angle of the first k link relative to the first k -1 link, represents the length of the first k link, represents the joint rotation angle.

[0066] The compact expression of the multiplication expansion of each joint coordinate is shown in equation 4:

[0067] (Equation 4)

[0068] Wherein, x n , y n represents the two-dimensional coordinates of the end of the first n link, represents the length of the first p link, represents the rotation angle of the first q link relative to the first q -1 link, n , p , q all represent variables with a unit of 1.

[0069] Simulation verification is carried out through the above calculation results, as shown in Figure 10 , when the input angle is 8°, 14°, 20°, 28°, the end trajectory is highly consistent with the three-dimensional modeling result, which shows that the derivation is correct, and the coordinates of each joint are successfully calculated.

[0070] Example 3:

[0071] The embodiment also provides a mounting method of the microwave-driven large-curvature bending mechanical arm based on the gear chain of example 2, comprising the following steps:

[0072] S1, the first through hole 702 of the first rod 7 and the sector gear 6 are coaxially installed on the rack shaft 101 in turn, the first through hole 702 is gap fit with the rack shaft 101, realizing the rotary connection, the sector gear 6 is fixed with the rack shaft 101 through glue, so that it cannot rotate relative to the rack shaft 101. Then install the first idler 703 and the second idler 704 on the mounting shaft 11 of the first rod 7, so that the first idler 703 is engaged with the sector gear 6.

[0073] S2, the second incomplete gear 801 of the second rod 8 is coaxially installed with the first incomplete gear 701 of the first rod 7 through the first connecting shaft 13, and the baffle ring is welded at both ends of the first connecting shaft 13, so that the second incomplete gear 801 of the second rod 8 is engaged with the first incomplete gear 701 of the first rod 7. The third idler 803 and the fourth idler 804 are installed on the transmission shaft of the second rod 8, so that the third idler 803 is engaged with the first incomplete gear 701 of the first rod 7.

[0074] S3, the fourth incomplete gear 901 of the third rod 9 is coaxially installed with the third incomplete gear 802 of the second rod 8 through the second connecting shaft 14, and the baffle ring is welded at both ends of the second connecting shaft 14, so that the fourth incomplete gear 901 of the third rod 9 is engaged with the third incomplete gear 802 of the second rod 8.

[0075] The fifth idler 902 and the sixth idler 903 are installed on the mounting shaft 11 of the third rod 9, the fifth incomplete gear 1001 of the fourth rod 10 is sleeved on the corresponding mounting shaft 11 of the third rod 9 away from the second rod 8, so that the fifth incomplete gear 1001 of the fourth rod 10 is engaged with the sixth idler 903.

[0076] The above only is the preferred embodiment of the present application, it should be pointed out, for ordinary skilled in the art, without departing from the technical principles of the present application, can make several improvements and deformation, these improvements and deformation also should be considered as the protection scope of the present application.

Claims

1. A gear train based, microwave driven, large-curvature bending robotic arm, characterized by, It includes frame (1), frame (1) is rotatably connected with gear chain actuator, and both sides of gear chain actuator are connected with one end of shape memory alloy spring (4) respectively, and the other end of shape memory alloy spring (4) is connected with steel wire (5); When linear polarized microwave with the same direction as steel wire direction is irradiated on steel wire (5), and microwave frequency is equal to resonance frequency, induced current is generated in steel wire (5), shape memory alloy spring (4) is transformed from martensite to austenite, and gear chain actuator is driven to move by contraction; Middle part of frame (1) is provided with frame shaft (101), and both sides of frame shaft (101) are provided with slot hole (102), and connecting seat (2) is connected with slot hole (102) in interference, and connecting seat (2) is provided with through hole, and one end of shape memory alloy spring (4) is bonded in through hole by metal adhesive; Gear chain actuator includes first lever (7), second lever (8), third lever (9) and fourth lever (10) which are connected in sequence; Both ends of first lever (7) are provided with first incomplete gear (701) and first through hole (702) respectively, and protrusion (705) is connected on both sides of first lever (7) through connecting rod, O-shaped seat (12) is sleeved on protrusion (705), O-shaped seat (12) is connected with shape memory alloy spring (4), and two mounting shafts (11) are vertically arranged on the rod body of first lever (7), and first idler (703) and second idler (704) are sleeved on mounting shaft (11) respectively; First through hole (702) is sleeved on frame shaft (101), and sector gear (6) is arranged above first through hole (702) of frame shaft (101), and sector gear (6), first idler (703) and second idler (704) are engaged in sequence; Both ends of second lever (8) are provided with second incomplete gear (801) and third incomplete gear (802) respectively, second incomplete gear (801) and first incomplete gear (701) are sleeved on first connecting shaft (13), and second incomplete gear (801) is engaged with second idler (704); two mounting shafts (11) are vertically arranged on the rod body of second lever (8), and third idler (803) and fourth idler (804) are sleeved on mounting shaft (11) respectively; One end of third lever (9) is provided with fourth incomplete gear (901), three mounting shafts (11) are vertically arranged on the rod body of third lever (9), among them, fifth idler (902) and sixth idler (903) are sleeved on two mounting shafts (11) of third lever (9) near fourth incomplete gear (901) in sequence, third incomplete gear (802) and fourth incomplete gear (901) are sleeved on second connecting shaft (14), and third incomplete gear (802) is engaged with fifth idler (902). One end of the fourth bar (10) is provided with a fifth incomplete gear (1001), which is engaged with a sixth idler gear (903).

2. The gear train based, microwave driven, large-curvature bending robotic arm of claim 1, wherein, Ends of the first connecting shaft (13) and the second connecting shaft (14) are provided with limit stopper rings.

3. The gear train based, microwave driven, large-curvature bending robotic arm of claim 1, wherein, The shape memory alloy spring (4) is connected with the steel wire (5) through a copper pipe (3).

4. The gear train based, microwave driven, large-curvature bending robotic arm of claim 1, wherein, The length of the steel wire (5) is 15mm and 25mm respectively, which corresponds to the resonant length of microwave frequency of 5.9GHz and 4GHz respectively.

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