Disclosure of Invention
The invention solves the technical problem of providing the exoskeleton lower limb power-assisted robot which is convenient to use, simple to operate and capable of assisting a patient to stand again.
The exoskeleton lower limb assisting robot comprises a hip support, a waist backboard, a knapsack support, two waist bundle fixing frames, four skeleton slide bar outer plug-ins, four skeleton slide bar inner plug-ins, four joint coaxial connecting rod driving mechanisms, four leg binding bands, two damping shoes, two ankle fixing straps, two corresponding damping shoes, two control shoes and two ankle fixing straps, wherein the waist backboard is fixedly arranged on the hip support, the knapsack support is fixedly arranged on the hip support, the waist bundle fixing frames are fixedly arranged on the hip support, the four leg binding bands are fixedly connected with the four skeleton slide bar outer plug-ins, the four leg binding bands are fixedly connected with the four skeleton outer plug-ins, the two ankle fixing straps are fixedly arranged on the two corresponding damping shoes, the two ankle fixing straps are fixedly arranged on the two control shoes, and the two control shoes are fixedly arranged on the two ankle fixing supports.
Preferably, the joint coaxial connecting rod driving mechanism comprises a leg adjustable slide bar, a flange, a pressing sheet, a deep groove ball bearing, a rotating shaft, a connecting sheet, a servo motor, a planetary reducer and a right-angle reducer, wherein the leg adjustable slide bar is fixedly connected with the hip support, the flange is fixedly arranged on the leg adjustable slide bar through a screw, the pressing sheet is fixedly connected with the flange, the deep groove ball bearing is positioned in the pressing sheet and is rotationally sleeved on the outer side of the rotating shaft, the connecting sheet is sleeved on the outer side of the rotating shaft and is fixedly connected with the pressing sheet, the right-angle reducer is sleeved on the outer side of the rotating shaft, the planetary reducer is fixedly arranged on the right-angle reducer, and the servo motor is fixedly arranged on the planetary reducer.
Preferably, the right-angle speed reducer is fixedly provided with an angle sensor base, the angle sensor base is provided with an angle sensor, and the outer side of the angle sensor is sleeved with an angle sensor protective cover fixedly connected with the angle sensor base.
Preferably, the ankle damper comprises an ankle inner shell, a rotary main shaft, a first torsion spring, a first gasket, a second torsion spring, a shaft sleeve, a second gasket, a first spring gasket, a second spring gasket, a sole plate, a hexagonal nut, an ankle outer shell and an inner hexagonal screw.
Compared with the related art, the exoskeleton lower limb power-assisted robot provided by the invention has the following beneficial effects:
The invention provides an exoskeleton lower limb power-assisted robot, which adopts a three-in-one driving mode of a joint coaxial connecting rod driving mechanism, uses a servo motor as a power source, is matched with a planetary reducer and a right angle reducer, has double reduction and double effects, increases moment, simultaneously selects a concentric rotating shaft and four longer screws in a coaxial connection mode, sequentially connects all parts in series, avoids the problems of unsmooth operation and the like caused by angle deviation, simultaneously adopts a flange and tab design to connect, ensures that the mechanical structure is more stable and compact, avoids the problems of loosening, sliding and the like of the mechanism caused by long-time operation, ensures that the whole mechanism can be accurately restored to an initial position before executing a command, ensures the accuracy of mechanical structure transmission, is more convenient to wear, ensures that a user can stop in time when encountering any problem during use, can autonomously and accurately reset after being electrified again, and executes a motion command again.
Drawings
FIG. 1 is a schematic structural view of a first embodiment of an exoskeleton lower limb assist robot provided by the present invention;
FIG. 2 is a schematic view of an exploded view of the articulated coaxial link drive mechanism shown in FIG. 1;
FIG. 3 is a schematic view of the ankle damper shown in FIG. 1;
FIG. 4 is a remote block diagram of the control assembly shown in FIG. 1;
FIG. 5 is a flow chart of the process of the present invention employing modularization;
FIG. 6 is a force diagram of a robot of the present invention;
FIG. 7 is a schematic illustration of a human gait cycle of the present invention;
FIG. 8 is a graph showing the change in angle and moment of each joint of the lower limb during one gait cycle of the present invention;
FIG. 9 is a lower limb planar coordinate system of the present invention;
fig. 10 is a schematic diagram of a second embodiment of an exoskeleton lower limb assist robot provided by the present invention.
Reference numerals 1, lumbar backboard, 2, backpack support, 3, hip support, 4, joint coaxial link driving mechanism, 401, leg adjustable slide bar, 402, flange, 403, tabletting, 404, deep groove ball bearing, 405, rotation shaft, 406, tab, 407, servo motor, 408, planetary reducer, 409, right angle reducer, 410, angle sensor base, 411, angle sensor, 412, angle sensor protective cover, 5, lumbar strap mount, 6, adjustable lumbar strap, 7, bone slide bar outer insert, 8, bone slide bar inner insert, 9, leg strap, 10, shoe, 11, damper ankle, 1101, ankle inner shell, 1102, rotation spindle, 1103, first torsion spring, 1104, first shim, 1105, second torsion spring, 1106, bushing, 1107, second shim, 1108, first spring shim, 1109, second spring shim, 1110, plantar plate, 1111, hexagonal nut, 1112, ankle outer shell, 1113, inner hexagonal screw, 12, control assembly.
Detailed Description
The invention will be further described with reference to the drawings and embodiments.
First embodiment
Referring to fig. 1-9 in combination, in a first embodiment of the present invention, the exoskeleton lower limb booster robot includes a hip support 3, a waist back plate 1 fixedly mounted on the hip support 3, a backpack support 2 fixedly mounted on the hip support 3, two waist-harness fixing frames 5 fixedly mounted on the hip support 3, an adjustable waist-harness 6, four skeleton-slide-bar outer plug-ins 7 fixedly connected with the hip support 3, four skeleton-slide-bar inner plug-ins 8 respectively connected with the four skeleton-slide-bar outer plug-ins 7 by screws, four joint coaxial-link driving mechanisms 4 fixedly mounted on the four skeleton-slide-bars 7, four leg-pieces 9 fixedly mounted on the two shoe-outer plug-ins 7, four leg-pieces 9 fixedly mounted on the two ankle-support frames 11 respectively, two ankle-strap assemblies 11 fixedly mounted on the two ankle-support frames 11, and two ankle-strap assemblies 11 fixedly mounted on the two ankle-support members 11.
The joint coaxial connecting rod driving mechanism 4 comprises a leg adjustable sliding rod 401, a flange 402, a pressing sheet 403, a deep groove ball bearing 404, a rotating shaft 405, a joint piece 406, a servo motor 407, a planetary reducer 408 and a right-angle reducer 409, wherein the leg adjustable sliding rod 401 is fixedly connected with the hip support 3, the flange 402 is fixedly arranged on the leg adjustable sliding rod 401 through a screw, the pressing sheet 403 is fixedly connected with the flange 402, the deep groove ball bearing 404 is positioned in the pressing sheet 403 and is rotationally sleeved on the outer side of the rotating shaft 405, the joint piece 406 is sleeved on the outer side of the rotating shaft 405 and is fixedly connected with the pressing sheet 403, the right-angle reducer 409 is sleeved on the outer side of the rotating shaft 405, the planetary reducer 408 is fixedly arranged on the right-angle reducer 409, and the servo motor 407 is fixedly arranged on the planetary reducer 408.
The right angle speed reducer 409 is fixedly provided with an angle sensor base 410, the angle sensor base 410 is provided with an angle sensor 411, and the outer side of the angle sensor 411 is sleeved with an angle sensor protective cover 412 fixedly connected with the angle sensor base 410.
The ankle 11 includes an ankle inner housing 1101, a rotation main shaft 1102, a first torsion spring 1103, a first washer 1104, a second torsion spring 1105, a boss 1106, a second washer 1107, a first spring washer 1108, a second spring washer 1109, a sole plate 1110, a hexagonal nut 1111, an ankle outer housing 1112, and an socket head cap screw 1113.
According to gait movement and calculation of ankle part torque and elasticity, the following is adopted:
When the spring has elastic requirements. In order to ensure the torque at the designated torsional deformation angle, the working deformation angles phi 1 and phi 2 of the springs should be between 20% and 80% of the test angle phi 3, or the working torques T1 and T2 should be between 20% and 80% of the test torque T3.
D-diameter of spring material (mm), medium, inner and outer diameters (mm) of D, D and D2 springs, T1-test torque (N mm) which is the maximum torque allowed to be born by the springs, T1 and T2-working torque (N mm), phi 1, phi 2 and phi 3-deformation angles under the action of T1, T2 and T3, H-free length and phi-pitch (mm) and is calculated by the following steps:
sigmaB in the formula-bending stress (MPa);
σBp —allowable bending stress (MPa);
t-working torque (N mm);
-deformation angle (°) at the working torque;
Kappa-torque spring rate (N mm/(°);
k1 —the camber coefficient of the torque spring, defined by the convolution ratio c=d/D;
Calculated as follows:
The ankle structure is designed, and the applicable force and structure are finally obtained through multiple times of calculation and practice from the original common spring to the torsion spring damping structure used at present. The whole structure is composed of the following 11 parts to realize the self-adjusting function.
The control component 12 adopts a high-speed Bluetooth transmission module, is stable in transmission, responds in real time, has no delay trouble and is provided with a one-key restoration function, and the robot can be quickly restored to a wearing state from any placement posture. The three closed-loop negative feedback PID regulating systems of position, speed and current are adopted, the gait movement angle of a human body is taken as input, the joints can be accurately controlled to walk smoothly and smoothly like a human body in real time, and the incremental photoelectric encoder is adopted to realize the acquisition and accurate control of the position information of the joints. The acquisition of human gait movement angles is realized by utilizing the avionic sensor MPU6050, and the absolute positions of all joints of the exoskeleton robot are acquired by utilizing the related characteristics of the avionic sensor MPU, so that the initialization and origin location are facilitated. STM32F103ZET6 is adopted as a main control, a high-performance ARM Cortex-M3 kernel is adopted, the working frequency is 72MHz, a built-in high-speed memory (flash memory up to 128K bytes and SRAM of 20K bytes) is rich in enhanced IO ports and peripherals (2 12-bit ADC, 8 16-bit timers and other communication interfaces such as standard I2C, SPI, RS232, RS485,5 UART and 1 CAN buses) connected to two APB buses are provided, the energy consumption is low, the working stability is high, and the performance is high. The program regulates the advancing speed, so that the patient has an adaptation process, gradually learns and gradually recovers, and the limitation of the speed can meet the requirements of patients of any age group. More importantly, the exoskeleton robot is provided with the scram button, accidental injury caused by emergency is prevented, the scram button achieves safety protection to a patient, family members of the patient and the patient can use the exoskeleton robot safely, and the patient can walk freely, sit down, stand up, squat and other activities through simple training and adaptation after wearing the exoskeleton robot. The patient can complete the activities independently, which is beneficial to promoting the blood circulation of the body, increasing the heart and lung functions, solving the physical complications caused by long-term non-exercise of the patient, solving the personal physiological problems and psychological problems of the patient.
The controller in the control assembly 12 selects STM32 microprocessor, the touch screen is connected with the controller through an RS485 bus, and the gait, the movement speed and the information such as power supply voltage and movement state can be set through the touch screen. Be provided with bluetooth module on the walking stick, can carry out man-machine interaction through USART serial ports, the user can select required motion state (standing up, walking, squatting, scram) through the button on the walking stick according to the intention. The PUS+DIR ports of the four servo drivers are respectively connected to four input comparison ports (CH 1, CH2, CH3 and CH 4) of the controller TIM3, the servo motors are connected to the servo drivers through UVW, the position and the speed of each joint are obtained in real time through the photoelectric encoder behind the servo motors, and the positions and the speeds are adjusted in real time through a PID control algorithm with speed position current three loops connected in series, so that the gait operation of a person can be simulated. In addition, the four attitude sensors are connected with the controller through the IIC bus, so that initialization and dynamic searching of the original position are facilitated, as shown in fig. 4.
(1) And (3) programming:
The program adopts modularized programming steps, firstly, all GPIO ports are initialized, then key scanning is performed, an LED indicator lamp is initialized, then communication (USART and IIC) and an analog-to-digital conversion port are configured, finally, interruption distribution is performed, a timer input comparison channel is started, and dead circulation is entered. The wearer can press the keys on the crutch to form preset actions according to the needs of the wearer, as shown in fig. 5.
(2) System overview:
A control system:
Control principle the exoskeleton device is run by a pre-numbered procedure, with limited intervention by the operator. Lower limb motion correction devices are used to help paralytic patients recover motion ability. The motion trail of the device is designed in advance, and the design is designed according to the motion gait of a normal person and is changed to adapt to the correction device. The mechanical joint is controlled to simulate the walking gait of a normal person through a pre-programmed program, so that the patient is driven to move, and the patient is helped to train and recover.
The control system of the exoskeleton lower limb assisting robot mainly adopts an STM32 chip as a main control, and a drive signal is sent to a driver of a motor through the main control, so that the motor is controlled to move to achieve the purpose of assisting walking.
B driving system:
The driving system of the exoskeleton lower limb power-assisted robot is the core of a robot hardware system, the system consists of 4 servo motors and a planetary reducer, the rated voltage of the motors is 36V, the rated power is 200W, the rated output torque is 0.637NM, the maximum output torque is 1.9NM, the rated rotating speed is 3000RPM, and the maximum rotating speed is 5000RPM. The driver selects the encoders of DMS-055A, mounted at each active joint. Meanwhile, for the four drivers, function call and programming are carried out by adopting Keil software by utilizing serial communication.
C mechanical structure:
The main technical indexes are that the robot can bear a load of about 100KG, and the main actions which can be realized by the robot are standing, sitting down, advancing and stopping. The robot is able to reach a speed of 1.08 Km/h.
The mechanism body of the exoskeleton power-assisted robot consists of mechanical legs, feet and a back. The mechanical legs are used to provide assistance, the feet and back are used to secure the robot and wearer, and the back is also used primarily to store power devices and control systems for the overall system.
(3) Core technology:
torque and power calculations;
The method is characterized in that stress analysis is firstly carried out on gait movement of the joint, and under the condition that the robot moves at a low speed, statics analysis is directly carried out on the rod piece, so that the value of the joint driving force can be accurately calculated. Secondly, when static analysis is carried out, a moment with the largest stress or driving force required by the robot joint is selected for calculation, so that the driving moment of the joint can be ensured sufficiently, and at the moment, the driving of the supporting legs of the single-leg supporting phase is selected;
The joints were the target of the analysis. Thirdly, aiming at the power-assisted index of the robot, the power-assisted target carries a load of 30Kg, and the driving moment of the skeleton joint and the knee joint is calculated. As shown in fig. 6.
T1 and T2 are driving moments of the skeleton joint and the knee joint, the instantaneous maximum moment of the skeleton joint and the knee joint of the robot is T1=T2=60 Nm, the moment only exists for a short time, and when a single leg stands, the whole gravity center of a human body can incline forwards, namely, the load is smaller than 200mm relative to the moment arm generated by the skeleton joint and the knee joint, so that the driving moment requirement on the joint is further reduced. At this time, the maximum moment is output by the driving joint of the robot, and the average moment of the robot should be less than 60Nm.
The power-assisted robot active joint is designed on the skeleton joint and the knee joint, and adopts a direct current motor for driving, and the direct current motor has the characteristics of convenient control and lower driving moment and power. Aiming at the problems of efficiency and the like generated by motor driving, and referring to the precedent of using a motor driving robot abroad, the working efficiency, motor power and torque of the robot under the motor driving are analyzed. First, after the motor is powered on, electrical energy will be consumed in several forms, including useful work, work consumed by mechanical friction and work consumed by the motor copper wire heating, respectively. Wherein the useful power des of the motor is represented by the following formula:
Pdes=Tdesdes;
tdes in the formula is one-to-one expected moment;
des one-to-one desired speed;
The work produced by friction is also large, and the motor needs to consume additional power D, which is a damping coefficient, when overcoming static friction and dynamic friction. Meanwhile, the inertia of transmission elements such as a motor rotor, a gear and the like also consumes energy I in the acceleration process, and finally, heat emitted by a machine consumes energy T2/KM2, and finally, the power consumed by a robot joint is as follows:
P=Tdesdes+D+I+T2/KM;
From the data obtained by motor drive, the average output of the knee joint is 17w, the negative work is performed, the efficiency is 21.2%, when the swing phase is reached, the moment is smaller than the no-load moment of the motor, the energy is mainly consumed to overcome friction and inertia force, the power required by the skeleton joint is 81w, and the efficiency of useful work is 7.7w is 9.5%.
1) From the CGA data of the knee joint, the average power of walking on level ground was 16.01w, the average torque was 40.5Nm, and the joint average speed was 56. The average power of knee joint when climbing stairs is 35.3, the average moment is 87.0Nm, and the joint moment calculated by statics is 60Nm. Because the design objective of the exoskeleton power-assisted robot can only complete gait movement of flat ground walking, the exoskeleton power-assisted robot can be solved according to the power and the moment of flat ground walking. The rated power of the motor is approximately calculated as:
P knee = X100%76W;
2) From the CGA data of the skeleton joint, the average power of the skeleton joint when climbing stairs was 16.23W, the average power of walking was 7.03W, the maximum power was 97.3W, and the moment of walking on the flat ground was 60.0nm. The average moment to climb stairs was 84.7Nm, as was the moment calculated by statics. Although the power of the bone joint is small, its torque output is large, indicating that the bone joint is at a lower speed. To ensure output torque, te=60 Nm, the rated power of the motor is calculated approximately as:
p hip = X100% = 74W;
(4) Human gait analysis;
The gait analysis of healthy people can be used as a necessary basis for the design of the lower limb assisting exoskeleton robot, and is also a precondition for the system dynamics analysis. The movement of the lower limbs of human needs the unified coordination of bones, muscles and the nervous system controlling the muscles, so that the lower limbs are very complex and have automatic adjustment capability. The system is controlled by a nervous system, muscle contraction provides power, bones are used as exercise levers, and joints are used for connecting the movement of the parts, so that the normal movement of the lower limbs of the human is realized. The normal gait walking is the main movement of the lower limbs of the human beings and is also the primary simulation and evaluation standard of the lower limb assistance exoskeleton robot.
As shown in fig. 7 and 8, one gait cycle of human walking is from the contact of the heel of a lower limb on one side with the ground to the end of the secondary touchdown of the heel on the same side. In one gait cycle, there are two states for one lower limb, the supportive phase and the oscillatory phase. The support phase is the period from heel strike to toe off, i.e., the foot is in contact with the ground for 60% of the total length of a cycle, and the swing phase is the period from toe off to heel strike again, i.e., the foot is off the ground for about 40% of the total cycle. The supporting phase has the characteristic of bearing the weight of a human body, can be divided into a double supporting phase and a single supporting phase, wherein the double supporting phase refers to a double-foot equal-contact stage, and the single supporting phase is opposite to the single supporting phase. The dual support phase occurs at the beginning and end of the support phase and has a duration that is related to the pace, the faster the pace, the shorter the duration. The swing phase can be divided into three stages of early swing, middle swing and later swing.
The clinical gait analysis database collects the motion information of each joint of the lower limb of the healthy human body in one gait cycle. The CGA database contains the measurement results of gait data of different subjects by different researchers, and is quite comprehensive. As shown in FIG. 8, the data were from subjects weighing 70Kg in the CGA database, walking at a speed of 1.3 m/s.
The maximum movement range of each joint of the lower limb is obtained through the analysis of the physiological structure of the lower limb of the human body, and the movement angles of each joint when the human body walks in normal gait are known through the analysis of the gait of the human body. Therefore, the maximum movement range of the robot active joint is preliminarily designed, and the maximum movement range is between the maximum movement range of a human body and the movement range during walking. Again this is one of the basis for actuator selection, as shown in fig. 9.
c=-15。~+30。
k=+5。~+55。
Second embodiment:
Referring to fig. 10 in combination, according to the exoskeleton lower limb assist robot provided by the first embodiment of the present invention, the exoskeleton lower limb assist robot provided by the second embodiment of the present invention further includes a first connection plate 13, the first connection plate 13 is fixedly installed at the top of the sole plate 1110, a cavity 14 is provided on the first connection plate 13, a rotating rod 15 is rotatably installed in the cavity 14, two support blocks 16 are sleeved on the outer side of the rotating rod 15 in a threaded manner, clamping blocks 17 are fixedly installed on the sides, far away from each other, of the two support blocks 16, a second connection plate 20 is sleeved on the outer side of the first connection plate 13, the second connection plate 20 is in contact with the top of the sole plate 1110, the second connection plate 20 is fixedly installed at the bottom of the shoe 10, a positioning groove 18 is provided on the second connection plate 20, the tops of the two support blocks 16 all extend into the positioning groove 18, clamping grooves 19 are provided on the inner walls of the two sides of the positioning groove 18, and the two clamping blocks 17 are located on the sides, far away from each other, respectively.
Two sections of external threads are arranged on the outer side of the rotating rod 15, and the rotation directions of the two sections of external threads are opposite.
The top inner wall of the cavity 14 is provided with a sliding hole, and the supporting block 16 penetrates through the corresponding sliding hole and is slidably connected with the inner wall of the sliding hole.
The bottom of the second connecting plate 20 is provided with a mounting groove with one side being an opening, and the first connecting plate 13 is positioned in the mounting groove.
The rotary groove is formed in one side of the first connecting plate 13, the rotary block is rotatably mounted in the rotary groove, the hexagonal groove is formed in one side of the rotary block, and the other side of the rotary block is fixedly connected with one end of the rotary rod 15.
A rotating hole is formed in one side, close to the rotating groove, of the cavity 14, and the rotating rod 15 penetrates through the rotating hole and is in rotating connection with the inner wall of the rotating hole.
When the shoe 10 is disassembled, only the rotation stop block is required to rotate, the rotation block drives the rotation rod 15 to rotate in the cavity 14, the rotation rod 15 drives the two support blocks 16 to be close to each other, the support blocks 16 drive the clamping blocks 17 to move, the two clamping blocks 17 are close to each other until the two support blocks 16 are contacted, the clamping blocks 17 are moved out of the clamping grooves 19 at the moment, and the shoe 10 with the second connecting plate 20 can be disassembled from the sole plate 1110 at the moment, so that the shoe 10 is convenient to replace, and the cleaning work of the shoe 10 is also convenient.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.