CN115592672A - Muscle rope driven variable-rigidity soft manipulator and grabbing method thereof - Google Patents
Muscle rope driven variable-rigidity soft manipulator and grabbing method thereof Download PDFInfo
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- CN115592672A CN115592672A CN202211385741.7A CN202211385741A CN115592672A CN 115592672 A CN115592672 A CN 115592672A CN 202211385741 A CN202211385741 A CN 202211385741A CN 115592672 A CN115592672 A CN 115592672A
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- 230000002457 bidirectional effect Effects 0.000 claims description 18
- 230000005540 biological transmission Effects 0.000 claims description 11
- 230000001681 protective effect Effects 0.000 claims description 5
- 229910001000 nickel titanium Inorganic materials 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 2
- 239000010409 thin film Substances 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 239000000741 silica gel Substances 0.000 description 8
- 229910002027 silica gel Inorganic materials 0.000 description 8
- 238000005266 casting Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920001651 Cyanoacrylate Polymers 0.000 description 1
- MWCLLHOVUTZFKS-UHFFFAOYSA-N Methyl cyanoacrylate Chemical compound COC(=O)C(=C)C#N MWCLLHOVUTZFKS-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1694—Programme controls characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J15/00—Gripping heads and other end effectors
- B25J15/0033—Gripping heads and other end effectors with gripping surfaces having special shapes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J15/00—Gripping heads and other end effectors
- B25J15/08—Gripping heads and other end effectors having finger members
- B25J15/12—Gripping heads and other end effectors having finger members with flexible finger members
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
- B25J19/02—Sensing devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G49/00—Conveying systems characterised by their application for specified purposes not otherwise provided for
- B65G49/05—Conveying systems characterised by their application for specified purposes not otherwise provided for for fragile or damageable materials or articles
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- Engineering & Computer Science (AREA)
- Robotics (AREA)
- Mechanical Engineering (AREA)
- Manipulator (AREA)
Abstract
The invention discloses a muscle rope driven variable-rigidity soft manipulator and a grabbing method thereof; the manipulator comprises a base, a negative pressure generating device and a grabbing unit. The plurality of grasping units mounted on the base can be bent inward or outward to grasp an object. The grabbing unit comprises a bending driving mechanism and a variable-rigidity soft finger. The variable-rigidity soft finger comprises a connecting block, an elastic sheet, a soft finger base, a muscle rope, an air duct, a rigidity adjusting device and a clamping outer sleeve. The invention adopts the muscle rope driven soft robot to arrange the rigidity adjusting device formed by the laminated fiber cloth, can freely adjust the rigidity of each soft finger of the soft robot, thereby adapting to the clamping requirements of different objects; in addition, the invention can clamp the object with smaller rigidity and increase the rigidity of the soft fingers when the object is transferred, thereby not only avoiding damaging the target object in the clamping process, but also ensuring the clamping reliability in the transferring process and avoiding damaging the clamping state of each soft finger on the object by external vibration or impact.
Description
Technical Field
The invention belongs to the technical field of soft robots, and particularly relates to a muscle rope driven variable-stiffness soft manipulator and a grabbing method thereof.
Background
With the rapid development of science and technology, more and more functional robots permeate into various fields of production and life to assist people in completing various tasks. The soft mechanical arm is used as an execution component of the robot acting with the external environment, so that the robot has the capabilities of grabbing, sorting, assembling and the like. The traditional rigid gripping clamp has the advantages of high positioning precision, high response speed, high degree of freedom and the like, is often applied to repeated and dangerous industrial fields, but has limited universality, is easy to damage articles in the gripping process of fragile articles, and cannot realize flexible gripping of the fragile articles, such as spectacle lenses, glass bottles, glass sheets, ceramic bottles and the like. The invention provides a method for replacing the traditional rigid gripping and clamping, which realizes the gripping and clamping function of fragile articles by utilizing the inherent compliance of elastic materials (rubber and silica gel) used by the robot, and keeps the integrity of the fragile articles to the maximum extent.
Disclosure of Invention
The invention aims to provide a muscle rope driven variable-rigidity soft manipulator and a grabbing method thereof.
The invention relates to a muscle rope driven variable-rigidity soft manipulator which comprises a base, a negative pressure generating device and a grabbing unit. The plurality of grasping units mounted on the base can be bent inward or outward to grasp an object. The grabbing unit comprises a bending driving mechanism and a variable-rigidity soft finger. The variable-rigidity soft finger comprises a connecting block, an elastic sheet, a soft finger base, a muscle rope, an air duct, a rigidity adjusting device and a clamping outer sleeve. The soft finger base is arranged on the bending driving mechanism.
The elastic sheet and the inner ends of the two rigidity adjusting devices are fixed with the middle part of the soft finger base. The outer ends of the elastic sheet and the two rigidity adjusting devices are fixed with the middle part of the connecting block. One end of each muscle rope is fixed with the connecting block. The other ends of the two muscle ropes are connected to a bending driving mechanism; the two muscle ropes are pulled to drive the variable-rigidity soft finger to bend. The two rigidity adjusting devices are respectively arranged on the opposite sides of the elastic sheet. The two muscle ropes are respectively arranged on the opposite sides of the two rigidity adjusting devices. The clamping outer sleeve is sleeved outside the connecting block, the elastic sheet, the muscle rope and the rigidity adjusting device, and the inner end of the clamping outer sleeve is fixed with the soft finger base.
The rigidity adjusting device comprises a rigidity adjusting medium and a wrapping layer wrapping the outer side of the rigidity adjusting medium. The rigidity adjusting medium includes a plurality of fiber cloth layers that are sequentially stacked. The arrangement direction and change of each fiber cloth layer the bending directions of the soft fingers are consistent. The inner cavity of the wrapping layer is connected to the air exhaust port of the negative pressure generating device through an air duct. When the pressure in the wrapping layer is reduced, the gaps between the fiber cloth layers are reduced, and the integral rigidity of the rigidity adjusting device is increased.
Preferably, an opening degree adjusting mechanism is arranged between the grabbing unit and the base; the opening degree adjusting mechanism is arranged on the base; the opening degree adjusting mechanism comprises a range adjusting motor, a bevel gear set and a radial transmission assembly. The radial transmission assembly comprises a slideway, a radial lead screw, a radial slide block, a roller and a bevel gear set. The base is provided with n slide ways arranged along the radial direction of the base. n is the number of grabbing units. The n slide ways are sequentially arranged along the circumferential direction of the central axis of the base; the n slideways are respectively and rotatably connected with a radial lead screw and a radial slide block; and the position where the radial sliding block is connected with the base is provided with a roller. The threaded holes on the n radial sliding blocks and the n radial lead screws form screw pairs respectively. The bevel gear set includes a drive bevel gear and n driven bevel gears. The range adjusting motor is fixed at the central position of the base. And a driving bevel gear is fixed on an output shaft of the range adjusting motor. The inner ends of the n radial lead screws are all fixed with driven bevel gears. The n driven bevel gears are all meshed with the driving bevel gear. The inner ends of the n grabbing units are respectively arranged on the n radial sliding blocks.
Preferably, the bending driving mechanism comprises a bidirectional screw rod, a clamping driving motor, a bracket, a first slide block and a second slide block. The bidirectional screw rod is rotatably connected to the bracket. The bidirectional screw rod is driven to rotate by a clamping driving motor. The first sliding block and the second sliding block are both connected on the support in a sliding mode, and form a screw pair with two screw thread sections on the bidirectional screw rod in opposite rotating directions respectively. The soft finger base is fixed with the outer end of the bracket. Two muscle ropes in the same variable-stiffness soft finger are respectively fixed with the first sliding block and the second sliding block on the corresponding bending driving mechanism.
Preferably, the rigidity adjusting device is provided with protective sheets on both sides. Gaps are arranged between the rigidity adjusting device and the protection plates on the two sides.
Preferably, both sides of the connecting block are provided with V-shaped grooves. The middle position of the connecting block in the thickness direction is provided with an annular groove. The end part of the inner cavity of the clamping outer sleeve is provided with a bulge corresponding to the V-shaped groove and the annular groove of the connecting block in shape. The protrusion is embedded in the V-shaped groove and the annular groove of the connecting block.
Preferably, both the inner side surface and the outer side surface of the clamping outer sleeve are wavy.
Preferably, the tip of the variable-stiffness soft finger is of a solid structure, and the longitudinal section of the tip is in an isosceles triangle shape; resistance type force sensors are bonded on two sides of the tip of the variable-stiffness soft finger; fixed force transmission piece in film induction zone outside resistance-type force sensor
Preferably, an independent on-off valve is arranged between the rigidity adjusting device and the negative pressure generating device 5 in each variable rigidity soft finger.
Preferably, the negative pressure generating device is fixed on the base
Preferably, the number of the grabbing units is three; the three grabbing units are uniformly distributed along the circumferential direction of the central axis of the base.
Preferably, the elastic sheet is made of nickel-titanium alloy and has a thickness of 0.3mm.
The grabbing method of the muscle rope driven variable-rigidity soft manipulator comprises the following steps:
step one, according to the external dimension or the inner hole size of a grabbed object; the range adjusting motor in the opening degree adjusting mechanism rotates to adjust the inner end distance of each grabbing unit.
And step two, moving the variable-rigidity soft fingers to the periphery of the grabbed object or extending into an inner hole of the grabbed object.
And step three, if the variable-rigidity soft fingers are positioned around the grabbed object, the bending driving mechanism drives the variable-rigidity soft fingers to bend inwards to clamp the outer side surface of the grabbed object. If all the rigidity-variable soft fingers are positioned in the inner hole of the grabbed object, the bending driving mechanism drives the rigidity-variable soft fingers to bend outwards to abut against the side wall of the inner hole of the grabbed object.
Fourthly, starting the negative pressure generating device, and pumping out the gas in the rigidity adjusting device, so that the rigidity of the rigidity adjusting device is increased, and the clamping stability is improved; after the rigidity-variable soft manipulator transfers the clamped object to the target position, the negative pressure in the rigidity adjusting device is released, and each rigidity-variable soft finger resets to release the clamping of the clamped object.
The invention has the beneficial effects that:
1. the invention adopts the muscle rope driven soft robot to arrange the rigidity adjusting device formed by the laminated fiber cloth, can freely adjust the rigidity of each soft finger of the soft robot, thereby adapting to the clamping requirements of different objects; in addition, the invention can clamp the object with smaller rigidity and increase the rigidity of the soft fingers when transferring the object, thereby not only avoiding damaging the target object in the clamping process, but also ensuring the clamping reliability in the transferring process and avoiding the damage of external vibration or impact to the clamping state of each soft finger on the object.
2. The invention adopts a method of respectively controlling three soft fingers, which not only can realize the simultaneous work of the three soft fingers, but also can realize the successive work of the three soft fingers, and can grasp regular and irregular objects in the grasping range; meanwhile, the position of the soft finger can be adjusted according to the size of the grabbed object, and the grabbing range is enlarged. In addition, the soft fingers can be bent outwards, and the fragile articles such as apertures can be grabbed.
3. The invention provides a rigidity-variable soft robot gripper which is driven by a muscle rope and used for clamping fragile articles, has an active contact force feedback control function, realizes flexible gripping of the fragile articles by utilizing the inherent compliance of the gripper, and avoids the damage of the articles to a great extent.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Fig. 2 is a schematic structural view of the radial drive assembly of the present invention.
Fig. 3 is a schematic structural view of the bending driving mechanism of the present invention.
Fig. 4 is a perspective view of a variable stiffness soft finger of the present invention.
Fig. 5 is a cross-sectional view of a variable stiffness soft finger of the present invention.
Fig. 6 is an internal structural view of a variable stiffness soft finger according to the present invention.
Fig. 7 is a perspective view of the rigidity adjusting device of the present invention.
Fig. 8 is a schematic view showing inward bending of three gripper units in embodiment 1 of the present invention.
Fig. 9 is a schematic view showing outward bending of three gripper units in embodiment 2 of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Example 1
As shown in figure 1, the muscle rope driven variable-rigidity soft manipulator comprises a base 7, an opening degree adjusting mechanism, a negative pressure generating device 5 and three grabbing units. The opening degree adjusting mechanism is arranged on the base 7; three grabbing units arranged on the opening degree adjusting mechanism are uniformly distributed along the central axis of the opening degree adjusting mechanism. The opening degree adjusting mechanism is used for adjusting the distance between the three grabbing units so as to clamp objects with different sizes.
As shown in fig. 2, the opening degree adjustment mechanism includes a range adjustment motor 1, a bevel gear set 6, and a radial transmission assembly 2. The radial transmission assembly 2 comprises a slideway 21, a radial lead screw 22, a radial slide block 23, a roller 24 and a bevel gear set 6. Three slide rails 21 arranged along the radial direction of the base 7 are arranged on the base 7. The three slide ways 21 are uniformly distributed along the circumferential direction of the central axis of the base 7; the three slideways 21 are internally and rotatably connected with radial lead screws 22 and are connected with radial slide blocks 23 in a sliding manner; the radial slider 23 is provided with a roller 24 at a position connected to the base 7 to reduce sliding resistance of the radial slider 23. The axes of the three radial lead screws 22 are vertically intersected with the central axis of the base 7; the threaded holes on the three radial sliders 23 and the three radial lead screws 22 respectively form a screw pair. The bevel gear set 6 includes a drive bevel gear and three driven bevel gears. The range adjusting motor 1 is fixed at the center of the base 7. A driving bevel gear is fixed on an output shaft of the range adjusting motor 1. The inner ends of the three radial lead screws 22 are all fixed with driven bevel gears. The three driven bevel gears are all meshed with the driving bevel gear.
The inner ends of the three gripping units are respectively mounted on three radial sliders 23. The range adjusting motor 1 can drive the synchronous rotation of the three radial lead screws 22 by controlling the bevel gear set 6, and drive the three grabbing units to approach to each other or to be away from each other, so as to adjust the grabbing ranges of the three grabbing units.
As shown in fig. 1, the gripper unit comprises a bending drive mechanism 3 and a stiffening soft finger 4. The variable stiffness soft fingers 4 are arranged on the corresponding radial sliding blocks 23 through the bending driving mechanism 3; the bending driving mechanism 3 is used for driving the variable-stiffness soft fingers 4 to perform bending deformation; the negative pressure generating device 5 is used for adjusting the bending rigidity of the rigidity-variable soft fingers 4 so as to adjust the clamping force on the clamped object.
As shown in fig. 3, the bending driving mechanism 3 includes a bidirectional screw 31, a rope connecting base 32, a clamping driving motor 33, a bracket 34, a first slider 35, and a second slider 36. The inner ends of the brackets 34 are fixed to the corresponding radial slides 23. The bidirectional screw 31 is rotatably connected to the bracket 34. The clamp driving motor 33 is fixed to the bracket 34, and the output shaft is fixed to one end of the bidirectional screw 31. The first slider 35 and the second slider 36 are both slidably connected to the bracket 34, and form a screw pair with two opposite-rotation thread sections on the bidirectional screw rod 31. The inner end of the variable stiffness soft finger 4 is fixed with the outer end of the bracket 34.
As shown in fig. 4, 5 and 6, the variable stiffness soft finger 4 comprises a force transmission sheet 41, a resistance type force sensor 42, a connecting block 43, an elastic sheet 44, a soft finger base 45, a muscle rope 46, an air duct 47, a stiffness adjusting device 48 and a clamping outer sleeve 49. The elastic sheet 44 is made of nickel-titanium alloy and has a thickness of 0.3mm. The holding sleeve 49 is made of silica gel. The soft finger base 45 is fixed at the outer end of the bracket 34. The inner ends of the elastic sheet 44 and the two rigidity adjusting devices 48 are fixed with the middle part of the soft finger base 45. The outer ends of the elastic piece 44 and the two rigidity adjusting devices 48 are fixed to the middle of the connecting block 43. One end of each muscle rope 46 is fixed with the connecting block 43. The other ends of the two muscle ropes 46 are respectively fixed with the first slide block 35 and the second slide block 36 on the corresponding bending driving mechanism 3 through the rope connecting base 32. Two rigidity adjusting devices 48 are provided on opposite sides of the elastic piece 44, respectively. Two muscle cords 46 are provided on opposite sides of the two stiffness adjusting means 48, respectively. The thickness direction of the elastic piece 44 is aligned with the arrangement direction of the two muscle strings 46, and when the two muscle strings 46 are pulled by the bending drive mechanism 3, the elastic piece 44 is deformed in a corresponding bending manner. Protective sheets are provided on both sides of the rigidity adjusting device 48. The protective sheet is used to avoid damage to the stiffness adjustment device 48 from the stiffness adjustment device 48 and the muscle string 46. The clamping outer sleeve 49 is sleeved outside the connecting block 43, the elastic sheet 44, the muscle rope 46 and the rigidity adjusting device 48, and the inner end of the clamping outer sleeve is fixed with the soft finger base 45.
Both sides of the connecting block 43 are provided with V-shaped grooves. The connecting block 43 is provided with an annular groove at a middle position in the thickness direction (i.e., the length direction of the variable stiffness soft finger 4). The end of the inner cavity of the clamping sleeve 49 is provided with protrusions corresponding to the shapes of the V-shaped groove and the annular groove of the connecting block 43. The projections are fitted into the V-shaped groove and the annular groove of the joint block 43, thereby preventing slippage between the outer clamp sleeve 49 and the joint block 43, so as to improve the control accuracy. The inner side (the side where the three rigidity-variable soft fingers 4 are close to each other is the inner side) and the outer side of the clamping outer sleeve 49 are both provided with rectangular grooves which are sequentially arranged, so that the bending capacity of the clamping outer sleeve 49 is improved, and the clamping force is improved.
The tip of the variable-rigidity soft finger 4 is of a solid structure, and the longitudinal section of the variable-rigidity soft finger is in an isosceles triangle shape; two sides of the tip of the variable-stiffness soft finger 4 are both bonded with a resistance type force sensor 42 through cyanoacrylate; the force transfer plate 41 is secured to the thin film sensing area outside the resistive force sensor 42 to ensure that the force is fully transferred to the sensing area of the sensor. The elastic sheet 44 ensures the stability of the connecting block and the plastic base 7 while increasing the transversal rigidity when the muscle string 46 is stretched. A gap is left between the rigidity adjusting device 48 and the protective sheet, which is beneficial to the working deformation of the rigidity adjusting device 48.
As shown in fig. 7, the rigidity adjusting device 48 includes an outer wrap 482 and an inner rigidity adjusting medium 481. The rigidity adjusting medium includes a plurality of fiber cloth layers that are sequentially stacked. The arrangement direction of each fiber cloth layer is consistent with the bending direction of the variable stiffness soft fingers 4. The single fiber cloth layer is easy to bend; the wrapping layer 482 forms a sealed cavity; the inner end of the wrapping 482 is provided with a vent. The air vent of the wrapping layer 482 is connected with the air suction port of the negative pressure generating device 5 fixed on the base 7 through an air duct 47. The rigidity adjusting devices 48 in the three rigidity-variable soft fingers 4 are connected with the negative pressure generating device 5 through independent on-off valves. The negative pressure generating device 5 adopts a vacuum pump.
When the rigidity-variable soft finger 4 is not bent, the negative pressure generating device 5 does not pump air to the rigidity adjusting device 48, and the rigidity-variable soft finger 4 is in a softer state as a whole at the moment; when a gripper grips an object, the variable-stiffness soft finger 4 is bent, the negative pressure generating device 5 vacuumizes the stiffness adjusting device 48, the gap between each layer of fiber cloth layers of the stiffness adjusting medium 481 is compressed, the stiffness of the stiffness adjusting device 48 is increased, and the soft finger is in a hard state at the moment, so that the variable-stiffness soft finger 4 is changed in stiffness, the stiffness of the variable-stiffness soft finger 4 is increased after the object is gripped, the gripping stability can be improved, and the situation that a variable-stiffness soft manipulator driven by a muscle rope cannot effectively grip the gripped object due to impact or vibration is avoided.
The external structure of the variable-rigidity soft finger 4 is designed into a corrugated shape, so that the resistance of the soft finger in the bending process can be reduced, the self-adaptability is good, meanwhile, the friction force can be increased, and the soft finger is firm and is not easy to fall off when grabbing objects.
The clamping outer sleeve 49 is made of silica gel, the specific model of which is Dragon Skin FX-Pro, and the silica gel is made of Shore 2A hardness and is very soft; the low-viscosity casting liquid has the characteristic of low viscosity, and can reduce bubbles during casting so as to make the casting easier; meanwhile, the curing time (40 minutes) is reduced to the maximum extent, and the casting and molding time is shortened. The soft finger outer structure is formed by twice casting of silica gel materials, the soft finger silica gel sleeve is cast for the first time, the soft finger silica gel sleeve and the inner structure are assembled and then cast again around the soft finger base 45, and the soft finger outer structure is aimed at enabling no silica gel material to be arranged around the inner structure of the soft finger, facilitating the sliding of the muscle rope inside the soft finger and reducing the resistance of the soft finger in the bending process.
In the working process, when the clamping driving motor 33 rotates forwards, the bidirectional screw rod 31 rotates forwards, the first sliding block 35 moves downwards, the inner muscle rope in the variable-stiffness soft finger 4 shortens, the second sliding block 36 moves upwards, the outer muscle rope in the variable-stiffness soft finger 4 extends, and the variable-stiffness soft finger 4 bends inwards. When the clamping driving motor 33 rotates reversely, the bidirectional screw 31 rotates reversely, the first slide block 35 moves upwards, the medial muscle rope inside the variable-stiffness soft finger 4 extends, the second slide block 36 moves downwards, the lateral muscle rope inside the variable-stiffness soft finger 4 shortens, and the variable-stiffness soft finger 4 bends outwards. The bending driving mechanism 3 uses a PID controller to control the stepping speed of the clamping driving motor according to the difference between the finger contact force required by the PID controller and the force value measured by the sensor.
Example 1
As shown in fig. 8, the process of grabbing the target object from the outer sidewall by using the above-mentioned variable stiffness soft manipulator is as follows:
the method comprises the following steps: according to the size of a target object, the range adjusting motor 1 drives the bevel gear set 6 to enable the bending driving mechanism 3 and the rigidity-variable soft fingers 4 to move on the radial transmission assembly 2, and therefore the three rigidity-variable soft fingers 4 are adjusted to be at proper intervals.
Step two: the clamping driving motor 33 rotates positively, the bidirectional screw 31 rotates positively, the first slide block 35 moves downwards, the inner side muscle rope inside the variable-rigidity soft finger 4 is shortened, the second slide block 36 moves upwards, the outer side muscle rope inside the variable-rigidity soft finger 4 is extended, the variable-rigidity soft finger 4 bends inwards, and after an object is clamped, the clamping driving motor 33 stops working.
Step three: the negative pressure generating device 5 vacuumizes the rigidity adjusting device 48, the gap between the fiber cloth layers in the rigidity adjusting medium 481 is compressed, the rigidity-variable soft finger 4 is in a hard state, and the object is firmly grabbed by the rigid body 2.
Step four: when an object is released, the negative pressure generating device 5 is closed, the rigidity adjusting device 48 returns to the initial state, gaps among fiber cloth layers in the rigidity adjusting medium 481 are increased, the rigidity-variable soft fingers 4 are in a soft state, the clamping driving motor 33 rotates reversely, the bidirectional screw 31 rotates reversely, the first sliding blocks 35 move upwards, inner muscle ropes in the rigidity-variable soft fingers 4 stretch, meanwhile, the second sliding blocks 36 move downwards, outer muscle ropes in the rigidity-variable soft fingers 4 shorten, the rigidity-variable soft fingers 4 gradually restore to the initial positions, the object falls, the clamping driving motor 33 stops working, and the actions are repeated to continuously grab the next object.
Example 2
As shown in fig. 9, the process of grabbing the target object from the inner hole by using the variable-stiffness soft manipulator is as follows:
step one, according to the bore diameter of an inner hole of a target object, the range adjusting motor 1 drives the bevel gear set 6 to enable the bending driving mechanism 3 and the rigidity-variable soft fingers 4 to move on the radial transmission assembly 2, and therefore the distance between the rigidity-variable soft fingers 4 is adjusted to be a proper size. In this embodiment, the inner hole of the target object is a stepped hole with a large inside and a small outside, and the stiffness-variable soft finger 4 that is turned outwards can be limited by the position of the step hole.
Step two, the end part of each variable-rigidity soft finger 4 extends into an inner hole of a target object; the clamping driving motor 33 rotates reversely, the bidirectional screw 31 rotates reversely, the first slide block 35 moves upwards, the inner side muscle rope in the variable stiffness soft finger 4 extends, meanwhile, the second slide block 36 moves downwards, the outer side muscle rope in the variable stiffness soft finger 4 shortens, and the variable stiffness soft finger 4 bends outwards to abut against an inner hole of a target object. The grip driving motor 33 stops operating.
And step three, the negative pressure generating device 5 vacuumizes the rigidity adjusting device 48, the gaps between the fiber cloth layers in the rigidity adjusting medium 481 are compressed, and the rigidity-variable soft fingers 4 are in a hard state.
Step four, when the object is released, the negative pressure generating device 5 is closed, the rigidity adjusting device 48 returns to the initial state, the gap between the fiber cloth layers in the rigidity adjusting medium 481 is increased, the rigidity-variable soft finger 4 is in a softer state, the clamping driving motor 33 rotates forwards, the bidirectional screw 31 rotates forwards, the first sliding block 35 moves downwards, the inner side muscle rope in the rigidity-variable soft finger 4 is shortened, the second sliding block 36 moves upwards, the outer side muscle rope in the rigidity-variable soft finger 4 extends, the rigidity-variable soft finger 4 gradually restores to the initial position, the object falls, and the clamping driving motor 33 stops working.
Claims (10)
1. A muscle rope driven variable stiffness soft manipulator comprises a base (7), a negative pressure generating device (5) and a grabbing unit; the method is characterized in that: also comprises a negative pressure generating device (5); a plurality of gripping units mounted on the base (7) capable of being bent inward or outward to grip an object; the grabbing unit comprises a bending driving mechanism (3) and a variable-rigidity soft finger (4); the variable-rigidity soft finger (4) comprises a connecting block (43), an elastic sheet (44), a soft finger base (45), a muscle rope (46), an air duct (47), a rigidity adjusting device (48) and a clamping outer sleeve (49); the soft finger base (45) is arranged on the bending driving mechanism (3);
the inner ends of the elastic sheet (44) and the two rigidity adjusting devices (48) are fixed with the middle part of the soft finger base (45); the outer ends of the elastic sheet (44) and the two rigidity adjusting devices (48) are fixed with the middle part of the connecting block (43); one ends of the two muscle ropes (46) are fixed with the connecting block (43); the other ends of the two muscle ropes (46) are connected to the bending driving mechanism (3); the two muscle ropes (46) are pulled to drive the rigidity-variable soft finger (4) to bend; the two rigidity adjusting devices (48) are respectively arranged on the opposite sides of the elastic sheet (44); the two muscle ropes (46) are respectively arranged on the opposite sides of the two rigidity adjusting devices (48); the clamping outer sleeve (49) is sleeved outside the connecting block (43), the elastic sheet (44), the muscle rope (46) and the rigidity adjusting device (48), and the inner end of the clamping outer sleeve is fixed with the soft finger base (45);
the rigidity adjusting device (48) comprises a rigidity adjusting medium (481) and a wrapping layer (482) wrapping the rigidity adjusting medium (481); the rigidity adjusting medium comprises a plurality of fiber cloth layers which are sequentially stacked; the arrangement direction of each fiber cloth layer is consistent with the bending direction of the variable-stiffness soft finger (4); the inner cavity of the wrapping layer (482) is connected to an air suction port of the negative pressure generating device (5) through an air duct (47); when the pressure in the wrapping layer (482) is reduced, the gap between the fiber cloth layers is reduced, and the rigidity of the rigidity adjusting device (48) as a whole is increased.
2. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: an opening degree adjusting mechanism is arranged between the grabbing unit and the base (7); the opening degree adjusting mechanism is arranged on the base (7); the opening degree adjusting mechanism comprises a range adjusting motor (1), a bevel gear set (6) and a radial transmission assembly (2); the radial transmission assembly (2) comprises a slideway (21), a radial lead screw (22), a radial slider (23), a roller (24) and a bevel gear set (6); the base (7) is provided with n slide ways (21) arranged along the radial direction of the base (7); n is the number of grabbing units; the n slide ways (21) are sequentially arranged along the circumferential direction of the central axis of the base (7); the n slideways (21) are internally and rotatably connected with radial lead screws (22) and are connected with radial slide blocks (23) in a sliding way; a roller (24) is arranged at the position where the radial slide block (23) is connected with the base (7); the threaded holes on the n radial sliding blocks (23) and the n radial lead screws (22) respectively form a screw pair; the bevel gear set (6) comprises a driving bevel gear and n driven bevel gears; the range adjusting motor (1) is fixed at the central position of the base (7); a driving bevel gear is fixed on an output shaft of the range adjusting motor (1); the inner ends of the n radial lead screws (22) are all fixed with driven bevel gears; the n driven bevel gears are all meshed with the driving bevel gear; the inner ends of the n grabbing units are respectively arranged on the n radial sliding blocks (23).
3. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: the bending driving mechanism (3) comprises a bidirectional screw rod (31), a clamping driving motor (33), a bracket (34), a first sliding block (35) and a second sliding block (36); the bidirectional screw rod (31) is rotationally connected to the bracket (34); the bidirectional screw rod (31) is driven to rotate by a clamping driving motor (33); the first sliding block (35) and the second sliding block (36) are both connected to the bracket (34) in a sliding manner and form a screw pair with two screw thread sections with opposite rotation directions on the bidirectional screw rod (31) respectively; the soft finger base (45) is fixed with the outer end of the bracket (34); two muscle ropes (46) in the same variable stiffness soft finger (4) are respectively fixed with a first slide block (35) and a second slide block (36) on the corresponding bending driving mechanism (3).
4. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: protective plates are arranged on two sides of the rigidity adjusting device (48); gaps are arranged between the rigidity adjusting device (48) and the protection plates on the two sides.
5. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: v-shaped grooves are formed in the two sides of the connecting block (43); an annular groove is formed in the middle of the connecting block (43) in the thickness direction; the end part of the inner cavity of the clamping outer sleeve (49) is provided with a bulge corresponding to the V-shaped groove and the annular groove of the connecting block (43); the protrusions are inserted into the V-shaped groove and the annular groove of the connecting block (43).
6. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: the inner side surface and the outer side surface of the clamping outer sleeve (49) are both wavy; the tip of the variable-rigidity soft finger (4) is of a solid structure, and the longitudinal section of the variable-rigidity soft finger is in an isosceles triangle shape; resistance type force sensors (42) are bonded on two sides of the tip of the variable stiffness soft finger (4); a force transmission sheet (41) is fixed in a thin film sensing area outside the resistance type force sensor (42).
7. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: independent on-off valves are arranged between the rigidity adjusting device (48) in each rigidity-variable soft finger (4) and the negative pressure generating device 5.
8. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: the number of the negative pressure generating devices (5) fixed on the base (7) is three; the three grabbing units are uniformly distributed along the circumferential direction of the central axis of the base (7).
9. The muscle rope driven variable stiffness soft manipulator of claim 1, wherein: the elastic sheet (44) is made of nickel-titanium alloy and has a thickness of 0.3mm.
10. The muscle rope driven variable stiffness soft manipulator grabbing method according to claim 2, wherein the muscle rope driven variable stiffness soft manipulator grabbing method comprises the following steps: comprises the following steps:
step one, according to the external dimension or the inner hole size of a grabbed object; a range adjusting motor (1) in the opening degree adjusting mechanism rotates to adjust the distance of the inner end of each grabbing unit;
moving the variable-rigidity soft fingers (4) to the periphery of the grabbed object or extending into an inner hole of the grabbed object;
thirdly, if the variable-rigidity soft fingers (4) are positioned around the grabbed object, the bending driving mechanism (3) drives the variable-rigidity soft fingers (4) to bend inwards to clamp the outer side surface of the grabbed object; if the variable stiffness soft fingers (4) are positioned in the inner hole of the object to be grabbed, the bending driving mechanism (3) drives the variable stiffness soft fingers (4) to bend outwards to abut against the side wall of the inner hole of the object to be grabbed;
fourthly, starting the negative pressure generating device (5), and pumping out the gas in the rigidity adjusting device (48) to increase the rigidity of the rigidity adjusting device (48) and improve the clamping stability; after the rigidity-variable soft manipulator transfers the clamped object to the target position, the negative pressure in the rigidity adjusting device (48) is released, and each rigidity-variable soft finger (4) resets to release the clamping of the clamped object.
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| CN116171732A (en) * | 2023-02-09 | 2023-05-30 | 浙江理工大学 | Fruit and vegetable picking hand with flexible fingers and bionic adsorption function |
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| CN115592672B (en) | 2024-06-25 |
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