CN211806192U - Five-finger dexterous hand based on force and displacement fuzzy hybrid control - Google Patents
Five-finger dexterous hand based on force and displacement fuzzy hybrid control Download PDFInfo
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- CN211806192U CN211806192U CN202020121336.4U CN202020121336U CN211806192U CN 211806192 U CN211806192 U CN 211806192U CN 202020121336 U CN202020121336 U CN 202020121336U CN 211806192 U CN211806192 U CN 211806192U
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Abstract
A five-finger dexterous hand based on force and displacement fuzzy mixed control comprises a palm main body, four single fingers and a thumb, wherein the four single fingers and the thumb are arranged on the palm main body; each single finger comprises a near knuckle, a middle knuckle, a far knuckle and a driving mechanism, the driving mechanism comprises a first tendon rope for driving the knuckles to bend, a second tendon rope for resetting the knuckles, a first motor and a second motor, the first motor and the second motor are installed in the palm main body, the thumb does not comprise the middle knuckle, and the other structures are the same as those of each single finger; the tension sensor and the encoder are both connected with the controller. The utility model provides a dexterous hand of five fingers based on power and the fuzzy hybrid control of displacement realizes dexterous hand power and displacement hybrid control, and this dexterous hand outside does not have any naked sensor, and all sensors are all integrated inside the palm, have further improved dexterous hand's protection level and stability can.
Description
Technical Field
The utility model belongs to the technical field of the robotechnology and specifically relates to a dexterous hand of five fingers based on power and fuzzy hybrid control of displacement is related to.
Background
With the development of industry, industrial robots have been developed vigorously in recent decades, and industrial manipulators have been widely studied as an emerging end effector. The traditional robot end effector has poor flexibility and can only grab or operate specific objects, such as a sucker, a welding gun and the like. The bionic dexterous hand is close to a human hand in shape and high in operation dexterous degree, is not comparable to the traditional mechanical clamp holder, can be used for replacing the work environment in which people are dangerous again to carry out more complex operation, saves manpower resources and ensures personal safety. However, due to the complex structure and high cost, no bionic dexterous hand which can be widely applied to the production line exists in the market. When the bionic dexterous hand grabs an irregular object, the bionic dexterous hand has obvious advantages compared with other two-finger and three-finger grippers due to the fact that the bionic dexterous hand has more freedom of movement.
Most of the dexterous five-finger hands researched and produced at present are provided with various sensors, so that the protection level IP value of the whole hand is low and the hand is easy to be damaged.
Disclosure of Invention
In order to overcome the defect that current dexterous hand of five fingers has the structure complicacy and the cost is expensive, the utility model provides a dexterous hand of five fingers based on power and the fuzzy hybrid control of displacement realizes dexterous hand power and displacement hybrid control, and this dexterous hand outside does not have any naked sensor, and all sensors are all integrated inside the palm, have further improved dexterous hand's protection level and stability can.
The utility model provides a technical scheme that its technical problem adopted is:
a five-finger dexterous hand based on force and displacement fuzzy mixed control comprises a palm main body, four single fingers and a thumb, wherein the four single fingers and the thumb are arranged on the palm main body;
each single finger comprises a near knuckle, a middle knuckle, a far knuckle and a driving mechanism, the near knuckle and the middle knuckle are hinged, the middle knuckle and the far knuckle are hinged, two sides of the palmar and hand backs of the middle knuckle and the near knuckle are respectively provided with a first tendon sheath and a second tendon sheath, the driving mechanism comprises a first tendon rope for driving the knuckles to bend, a second tendon rope for resetting the knuckles, a first motor and a second motor, the first motor and the second motor are installed in a palm main body, one end of the first tendon rope is connected with the far knuckle, the other end of the first tendon rope sequentially penetrates through the first tendon sheath of the middle knuckle and the first tendon sheath of the near knuckle and extends into a palm main body cavity to be connected with a tension motor shaft of the first motor, a tension sensor is further arranged on the tension first tendon rope, and the tension sensor is arranged in the palm main body cavity; one end of the second tendon rope is connected with the far knuckle, the other end of the second tendon rope sequentially penetrates through a second tendon sheath of the middle knuckle and a second tendon sheath of the near knuckle and extends into the cavity of the palm main body to be connected with a motor shaft of a second motor, and the second motor is further provided with an encoder for measuring the angular displacement and the rotating speed of the second motor;
the thumb does not comprise the middle knuckle, and the other structures are the same as that of each single finger; the tension sensor and the encoder are both connected with the controller.
Furthermore, the four single fingers and one thumb are all provided with a silica gel finger sleeve.
Still further, all hinge joint through the hinge between two adjacent knuckles and between nearly knuckle and the palm main part to both ends interference fit has the jump ring about the hinge.
The beneficial effects of the utility model are that: the hybrid control of the force and the displacement of the dexterous hand is realized, the outside of the dexterous hand is not provided with any exposed sensor, all the sensors are integrated in the palm, and the protection grade and the stability of the dexterous hand are further improved
Drawings
Fig. 1 is a schematic view of a single finger of a dexterous hand at the view angle of the palm of the hand of the present invention.
Figure 2 is a cross-sectional view of a single finger of a dexterous hand at a side hand view angle.
Fig. 3 is a schematic diagram of single finger driving in view of palm.
Figure 4 is a cross-sectional view of a dexterous hand from a side-by-hand perspective.
Fig. 5 is an overall appearance diagram of the dexterous hand under the view angle of the palm of the hand.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
Referring to fig. 1 to 5, a five-finger dexterous hand based on force and displacement fuzzy mixed control comprises a palm main body 23, four single fingers and a thumb which are arranged on the palm main body 23;
each single finger comprises a near knuckle 7, a middle knuckle 4, a far knuckle 1 and a driving mechanism, the near knuckle 7 and the middle knuckle 4 are hinged, the middle knuckle 4 and the far knuckle 1 are hinged, a first tendon sheath and a second tendon sheath are respectively arranged on the two sides of the palm and the back of the hand of the middle knuckle 4 and the near knuckle 7, the drive mechanism comprises a first tendon rope for driving knuckle bending, a second tendon rope 25 for knuckle resetting, a first motor 21 and a second motor 18, the first motor 21 and the second motor 18 are arranged in the palm main body 23, one end of the first tendon rope is connected with the far knuckle 1, the other end of the first tendon rope sequentially passes through the first tendon sheath 10 of the middle knuckle and the first tendon sheath 8 of the near knuckle and extends into the cavity of the palm main body to be connected with a motor shaft of the first motor 21, a tension sensor 19 is also arranged on the first tendon rope, and the tension sensor 19 is arranged in the palm main body cavity; one end of the second tendon rope 25 is connected with the far knuckle, the other end of the second tendon rope 25 sequentially penetrates through the second tendon sheath 12 of the middle knuckle and the second tendon sheath 13 of the near knuckle and extends into the cavity of the palm main body to be connected with a motor shaft of the second motor 18, and the second motor 18 is further provided with an encoder 22 for measuring the position and the rotating speed of the second motor;
the thumb does not comprise the middle knuckle, and the other structures are the same as that of each single finger; therefore, the first tendon rope and the second tendon rope of the driving mechanism of the thumb respectively penetrate through the first tendon sheath and the second tendon sheath on the proximal knuckle and then are connected with the corresponding motors. The tension sensor and the encoder are both connected with the controller.
Furthermore, silica gel finger sleeves 14 are arranged outside the four single fingers and the thumb.
Still further, all hinge joint through the hinge between two adjacent knuckles and between nearly knuckle 7 and palm main part 23 to both ends interference fit has the jump ring about the hinge.
The palm body 23 includes a palm face 26, which is a cavity structure.
First tendon rope includes two sections, and the one end and the far knuckle of first section 17 are connected, and the other end and the one end of force sensor of first section 17 are connected, and force sensor 19's the other end is connected with the one end of second section 20, and the other end of second section 20 is connected with the motor shaft of first motor 21, the utility model discloses mainly be by first tendon rope and second tendon rope as drive mechanism, first tendon rope can drive dexterous hand and take place bending motion, the dexterous hand can be driven to the second tendon rope, makes it reset. The tendon sheath has the beneficial effects of avoiding the direct contact of the tendon rope with other components of the dexterous hand, reducing the friction force of the tendon rope moving components, helping to reduce the power of the driving force and protecting the tendon rope from other components which may contact.
A revolute pair is formed between the far knuckle 1 and the middle knuckle 4 through a hinge 2, and a clamp spring 11 and a clamp spring 3 are assembled at two ends of the hinge 2 in an interference mode. Similar to the above connection structure, a rotation pair is formed between the middle knuckle 4 and the near knuckle 7 through the hinge 5, and the clamp springs 9 and 6 are assembled at two ends of the hinge 5 in an interference manner. The proximal knuckle 7 and the palm main body 23 form a revolute pair through the hinge 3, and the two ends of the hinge 3 are assembled with the clamp springs 24 and 15 in an interference manner. The silica gel finger stall has the advantages that the friction force for grabbing the dexterous hand is increased, and the flexibility for contacting the dexterous hand and an object is improved.
A first motor 21 and a second motor 18 are arranged in the palm main body, the first motor 21 is used for driving the first tendon rope, and the second motor 2 is used for driving the second tendon rope. And the encoder is used for measuring the angular displacement and the rotating speed of the second motor and is used for realizing the position control of the dexterous hand. And a tension sensor 19 is arranged on the first tendon rope and is used for realizing the force control of the dexterous hand.
The utility model discloses realize power and the fuzzy hybrid control strategy of displacement mainly by two kinds of control algorithm and a switching face and constitute, before dexterous hand contact object, carry out the hand eye through visual system and mark to carry out the boundary detection, regard its contact cartesian coordinate system as the kinematics input, make it be close to the switching face. And after the controller passes through the switching surface, the control strategy is switched from motion control to the fuzzy controller. The switching surface mainly functions as an algorithm selector and is a main judgment basis for algorithm switching. After the dexterous hand enters the fuzzy controller, the product of the displacement of the tendon rope passing through the switching surface and the rigidity of the finger is used as rigidity matrix input, and the pressure trend of the finger is represented by a tendon rope tension sensor. The sensor information is used as two-dimensional input, is mapped to a corresponding region of a discourse domain, and is fuzzified through a Gaussian function so as to perform fuzzy reasoning and finally realize fuzzy solution. The design of the fuzzy controller has great significance for realizing the mixed control of force and displacement. The important theoretical preparation basis that the fuzzy controller can realize is that a certain positive correlation distribution of the tendon rope tension sensor and the actual fingertip pressure can be obtained by constructing a covariance matrix of the tendon rope tension sensor and the actual fingertip pressure, and similarly, a correlation coefficient between the tendon rope displacement and the rigidity matrix after passing through the switching surface can be proved.
Taking the example of clever hand grasping the cuboid on the desktop, the specific method comprises the following steps:
firstly, calibrating the position of an object by hands and eyes through a vision system, and searching the boundary of the object through a related algorithm to enable a dexterous hand to gradually approach the boundary. Firstly, according to the Riemann spatial color difference principle, introducing HVS color masking characteristics to carry out gray processing on the HVS color masking characteristics, and bringing pixel points into the following mathematical model:
I(x,y)＝(0.30×R(x,y)+0.59×G(x,y)+0.11×B(x,y))/3 (1)
in order to reduce the influence caused by factors such as camera and light source arrangement in the holding process, the original gray level histogram data is subjected to accumulative probability distribution to realize the remapping of pixel points and gray levels, and the mapping equation is as follows:
wherein k is 0, 1, 2., L-1, in order to improve the contrast between the object and the background, a small template gaussian filter is used to process the image single-pixel noise, and the equalized gray pixels are substituted into a gaussian formula:
after the previous image processing is completed, different methods for detecting the boundary of the object are different. Taking a cuboid on a desk as an example, the image information is processed and collected by adopting a Hough transform algorithm, and the planar image pixel problem is converted into a statistically accumulated extreme value problem. The parameter equation for converting the pixel points is as follows:
p＝x×cos(θ)+y×sin(θ) (4)
the distance delta x of the x axis on the image is calculated by adopting a vertical projection method, based on the perspective principle, the parameter of the camera is h, and the distance of the x axis on the image can be mapped to the actual distance l:
l＝f(h)*Δx (5)
in combination with the relative relationship of the camera and the object, the position of the gripping boundary can be found:
pi(i∈(1,n)) (6)
step two: the first step is mainly to determine the object holding boundary, and the second step is mainly to realize the motion control of the dexterous hand on the basis of finishing the calibration of the hands and the eyes until the dexterous hand contacts the holding boundary obtained in the first step. Obtaining the holding boundary of the object from the step one, wherein the position of the holding boundary is pi. The encoder is an absolute value encoder, the number of the collected current pulses is C, the total number of pulses in one circle is T, and the gyration radius of the tendon rope on the motor is R. Displacement of tendon-recording rope and angle theta of proximal knuckle joint1Is k1(ii) a Displacement of tendon-recording rope and angle theta of proximal knuckle joint2Phase ofThe parameter is k2(ii) a Displacement of tendon-recording rope and angle theta of proximal knuckle joint3Is k3To obtain the equation set:
the lengths of the proximal knuckle, the middle knuckle and the distal knuckle of the dexterous hand are respectively l1、l2、l3A DH parameter table is established according to the link length and joint variables, as shown in table 1:
TABLE 1
Four transition matrices are obtained:
obtaining a transfer matrix from the base joint coordinate system to the fingertip coordinate system as follows:
0T4＝0T1 1T2 2T3 3T4(8)
according to the hand shape of the human hand when holding the object, let:
bringing the above formula into0T4The method comprises the following steps:
different with the dexterous hand of full drive, the three joint of the dexterous hand of underactuated have the coupling characteristic, consequently not only can by the value of encoder feedback combines above-mentioned formula to calculate the cartesian coordinate, also can be by step one produced position pi of grabbing the border and reversely solve the controlled quantity of encoder. Important data tools required for inverse solution are a double angle formula and a triple angle formula.
Step three: the tension sensor monitors a first tendon tension trend. When the dexterous hand is close to the grasping boundary and the tension change gradient monitored by the tension sensor exceeds a threshold value, the control algorithm is switched to the fuzzy controller to perform force and displacement hybrid control on the object.
Step four: and after entering the fuzzy controller, calculating the increment of the encoder and the tension sensor by taking the switching surface as reference, and taking the two-dimensional increment as the input of the fuzzy controller. The tension delta and the encoder delta are mapped to between the domains of discourse [ -5,5 ]. Fuzzifying the mapped two-dimensional increment value through a Gaussian function:
according to the actual variation characteristic of the force displacement, the basic idea of the fuzzy control rule is as follows: after algorithm switching, the reference value is placed on a switching surface, and tendon rope tension and encoder increment are calculated. When the tension of the tendon rope and the bending degree of the dexterous hand represented by the encoder have larger deviation from the expected value, the value of the output control quantity is mainly to eliminate the deviation as soon as possible; when tendon tensions and dexterous hand curvatures characterized by the encoder are small, the output control should be taken care to prevent overshoot to keep the system stable.
When the material of the contact object is soft, the input of the encoder is large, the input of the tension sensor is small, the motor needs to generate large angular displacement to meet the requirement of sufficient gripping force, but when the angular displacement is gradually increased, the output of the control quantity is gradually reduced so as to avoid damaging the shape of the object; when the contact material is hard, the input change of the encoder is small, the input change of the tension sensor is large, and the output of the control quantity is gradually reduced to prevent the smart hand and the object from being damaged. The fuzzy rule base is thus shown in table 2:
TABLE 2
Claims (3)
1. The utility model provides a dexterous hand of five fingers based on force and displacement fuzzy hybrid control which characterized in that: comprises a palm main body, four single fingers and a thumb, wherein the four single fingers and the thumb are arranged on the palm main body;
each single finger comprises a near knuckle, a middle knuckle, a far knuckle and a driving mechanism, the near knuckle and the middle knuckle are hinged, the middle knuckle and the far knuckle are hinged, two sides of the palmar and hand backs of the middle knuckle and the near knuckle are respectively provided with a first tendon sheath and a second tendon sheath, the driving mechanism comprises a first tendon rope for driving the knuckles to bend, a second tendon rope for resetting the knuckles, a first motor and a second motor, the first motor and the second motor are installed in a palm main body, one end of the first tendon rope is connected with the far knuckle, the other end of the first tendon rope sequentially penetrates through the first tendon sheath of the middle knuckle and the first tendon sheath of the near knuckle and extends into a palm main body cavity to be connected with a tension motor shaft of the first motor, a tension sensor is further arranged on the tension first tendon rope, and the tension sensor is arranged in the palm main body cavity; one end of the second tendon rope is connected with the far knuckle, the other end of the second tendon rope sequentially penetrates through a second tendon sheath of the middle knuckle and a second tendon sheath of the near knuckle and extends into the cavity of the palm main body to be connected with a motor shaft of a second motor, and the second motor is further provided with an encoder for measuring the angular displacement and the rotating speed of the second motor;
the thumb does not comprise the middle knuckle, and the other structures are the same as that of each single finger; the tension sensor and the encoder are both connected with the controller.
2. The five-finger dexterous hand based on force and displacement fuzzy hybrid control as claimed in claim 1, characterized in that: and silica gel finger sleeves are arranged outside the four single fingers and the thumb.
3. A dexterous five-finger hand based on force and displacement fuzzy hybrid control as claimed in claim 1 or 2, characterized in that: all articulated through the hinge between two adjacent knuckles and between nearly knuckle and the palm main part to both ends interference fit has the jump ring about the hinge.
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| CN111098323A (en) * | 2020-01-19 | 2020-05-05 | 浙江工业大学 | Five-finger dexterous hand based on force and displacement fuzzy hybrid control and control method thereof |
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| CN111098323A (en) * | 2020-01-19 | 2020-05-05 | 浙江工业大学 | Five-finger dexterous hand based on force and displacement fuzzy hybrid control and control method thereof |
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