Wheel-legged robot and lower limb passive training coordination control method

Abstract

The application belongs to the technical field of lower limb training, and particularly discloses a wheel-leg robot and a lower limb passive training coordination control method. The wheel-leg robot comprises a wheeled mobile platform, an exoskeleton mechanical leg is connected to the wheeled mobile platform, the exoskeleton mechanical leg comprises a driving motor, a telescopic sleeve is connected to the shaft of the driving motor, an inner rod is slidingly connected to the telescopic sleeve, and the inner rod is connected to a leg supporting groove. A row of positioning grooves are arranged on the inner rod and are distributed along the sliding direction of the inner rod. A transverse insertion rod matched with the positioning grooves is slidingly connected to the telescopic sleeve, and a return spring is connected between the transverse insertion rod and the telescopic sleeve. The application provides a wheel-leg robot and a lower limb passive training coordination control method suitable for patients with different body types. The actual position of the foot is monitored to adjust the speed of the bottom wheel of the wheeled mobile platform, the coordination is improved, and the rehabilitation training needs of patients with lower limb movement dysfunction in various aspects can be met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lower limb training, and particularly relates to a wheel-leg robot and a lower limb passive training coordination control method. BACKGROUND

[0002] With the increasing aging society, more and more old people lose the lower limb self-standing function due to stroke, cardiovascular disease and other reasons, which brings great inconvenience to daily life, seriously reduces the quality of life, and needs lower limb training. The traditional wheeled lower limb rehabilitation robot cannot provide auxiliary force for the lower limb joint muscle of the rehabilitation training patient. For the patients who lack hip flexion ability or have abnormal joint phenomena such as knee hyperextension and foot drop, the robot cannot assist in improving gait and providing effective sit-to-stand training. The traditional leg-type lower limb rehabilitation robot often needs to be combined with an electric treadmill or an intelligent walking stick. The leg-type lower limb rehabilitation robot combined with the electric treadmill is bulky, and the rehabilitation training is limited by the site, which is contrary to the development trend of rehabilitation training community and family, and the price is often high. Due to the limitation of action, the patient is difficult to go up and down the electric treadmill. Moreover, the leg-type lower limb rehabilitation robot is difficult to adapt to patients with different body types. The control object of the exoskeleton mechanical leg is the thigh, and the user's foot and lower leg are not controlled, which will cause the problem of poor flexibility in human-computer interaction. SUMMARY

[0003] The application aims to provide a wheel-leg robot and a lower limb passive training coordination control method suitable for patients with different body types. The actual position of the foot is monitored to adjust the speed of the bottom wheel of the wheeled mobile platform, improve the coordination, and meet the rehabilitation training needs of patients with lower limb motor dysfunction in many aspects.

[0004] To achieve the above purpose, the application adopts the following technical scheme:

[0005] A wheel-leg robot comprises a wheeled mobile platform, a pair of symmetrical exoskeleton mechanical legs connected to the wheeled mobile platform, an exoskeleton mechanical leg comprising a driving motor, a shaft of the driving motor connected with a vertical telescopic sleeve, the telescopic sleeve slidingly connected with an inner rod in the same length direction, the sliding direction of the inner rod being consistent with the length direction, the inner rod connected with a leg holder slot perpendicular to the inner rod; a row of positioning grooves is arranged on the inner rod and distributed in the sliding direction of the inner rod, a transverse insertion rod slidingly connected with the positioning groove is arranged on the telescopic sleeve, the transverse insertion rod is perpendicular to the telescopic sleeve, and a return spring is connected between the transverse insertion rod and the telescopic sleeve. A torque sensor is arranged in the telescopic sleeve.

[0006] Further, a support is connected between the bottom end of the inner rod and the leg bracket, and the support is perpendicular to the inner rod; the support is rotationally connected to the leg bracket, and the rotation axis of the leg bracket is parallel to the inner rod; magnets are arranged on the leg bracket and the support to cooperate with each other; a vertical inserting rod is slidingly connected to the support, and a positioning inserting hole is connected to the leg bracket to cooperate with the vertical inserting rod.

[0007] During training, the leg bracket is connected to the thigh of the human body, and the leg bracket and the thigh are swung by the driving motor to perform lower limb training, and the upper body of the human body is supported by the wheel-leg robot.

[0008] A lower limb passive training coordination control method using the wheel-leg robot, comprising the following steps:

[0009] Step 1: fitting the hip joint rotation angle change curve and the center of gravity forward speed change curve according to the gait information of the human body;

[0010] Step 2: controlling the rotation of the exoskeleton motor using the gravity compensation PD control algorithm according to the hip joint rotation angle change curve; and controlling the rotation of the bottom wheel using the PI control algorithm according to the center of gravity forward speed change curve.

[0011] Further, in step 2, the method for controlling the rotation of the exoskeleton motor is: calculating the torque of the exoskeleton motor according to the following formula, and controlling the exoskeleton motor to rotate according to the torque;

[0012]

[0013] In the formula, e 单关节 is the difference between the value of the hip joint rotation angle change curve at the previous moment and the actual angle of the hip joint at the previous moment, K pDGJ is a proportional coefficient, K dDGJ is a differential coefficient, is the estimated value of the gravity torque.

[0014] Further, in step 2, the method for controlling the rotation of the bottom wheel is: calculating the forward speed of the bottom wheel according to the following formula, and then calculating the expected rotation speed of the bottom wheel according to the expected forward speed of the bottom wheel, and controlling the bottom wheel to rotate according to the expected rotation speed;

[0015] ω=K pD L·e 底轮 +K iDL ·∫e 底轮 dt

[0016] In the formula, ω is the expected forward speed of the bottom wheel, Kp DL is a proportional coefficient, K iDLis an integral coefficient; when calculating ω, firstly determine whether ω(t-1) has exceeded the limit value, if yes, only accumulate the negative deviation, if not, accumulate the positive deviation. 底轮 is the difference between the value of the center of gravity advancing speed change curve at the last moment and the actual center of gravity advancing speed at the last moment, or is obtained by the following method:

[0017]

[0018]

[0019] wherein ω d is the value of the center of gravity advancing speed change curve, y d足 is the expected foot position, y 足 is the actual foot position, K 协调 is an adjustment coefficient, and the adjustment coefficient is negative.

[0020] Further, in step 1, the method for fitting the hip joint rotation angle change curve is as follows: by combining the collected hip joint rotation angle change data through gait cycle analysis, the hip joint rotation angle change curve is fitted by using a sine function and the form:

[0021]

[0022] wherein f(T, h) is a function about gait cycle and height, T is the gait cycle, h is the height, a i , b i and c i are constant terms, and K is the number of the sine function.

[0023] Further, in step 1, the method for fitting the center of gravity speed change curve is as follows: by analyzing the collected human body center of gravity advancing speed change data, the center of gravity advancing speed change curve is fitted:

[0024]

[0025] wherein: B(T, h) and v avg (T, h) are functions about gait cycle T and height h, B(T, h) is the amplitude of the sine function, and v avg (T, h) is the mean value of the curve v comx .

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The present invention allows the horizontal insert rod to be inserted into different positioning slots, thereby adjusting the position of the inner rod and thus adjusting the distance between the telescopic sleeve and the leg support slot, making it suitable for patients of different heights; the torque sensor can measure the interactive force information of the user during the training process, which can be used to assess the patient's muscle strength and participation, and to implement corresponding control strategies based on the force information.

[0028] 2. The leg support and support are equipped with interlocking magnets. Before and after training, rotating the leg support to contact the support will attract the magnets, ensuring a stable connection between the leg support and the support, allowing the patient to smoothly enter and exit the wheel-leg robot. During training, inserting the vertical rod into the positioning hole will keep the leg support stable at a specific angle, ensuring a stable training process.

[0029] 3. Since the controlled object is the thigh angle, the lower leg cannot be controlled in practice. However, the distance a person walks is closely related to their foot position. Using the device's built-in lidar sensor and gait data calculation algorithm, the real-time position of the lower leg near the ankle is used to determine the patient's foot position. Based on the relationship between the wheeled mobile platform and the actual leg movement, the input error value of the bottom wheel PI controller is modified. The input PI error is the error between the desired and actual foot position multiplied by an adjustment coefficient. The adjustment coefficient is negative; that is, when the actual displacement in the forward direction of the center of gravity is less than the predefined displacement, the actual error is transformed into a coordination error. In the tracking controller, this manifests as the actual position exceeding the predefined tracking trajectory position, reducing the output speed to ensure tracking and thus coordination. Conversely, when the actual displacement in the forward direction of the center of gravity is greater than the predefined displacement, the actual error is transformed into a coordination error; in the tracking controller, this manifests as the actual position lagging behind the predefined tracking trajectory position, increasing the output speed to ensure tracking and thus ensuring the coordinated movement of the human body system.

[0030] 4. This invention features a lightweight structure, easy wear, safe and comfortable use, multifunctionality, and modularity. It meets the requirements for freedom of movement and range of motion of the hip joint and pelvis during human walking, while ensuring sufficient smoothness and comfort in human-machine interaction. The mechanism's dimensions can adapt to different body types. The lifting mechanism combined with a multi-degree-of-freedom pelvic support mechanism provides support for the body, reducing pressure on the patient's feet and limiting movement freedom to ensure dynamic balance. The robot has a small footprint, is mobile, and walking in a real-world environment, compared to walking on a treadmill, better stimulates the patient's proprioception, enhances visual feedback, and improves the effectiveness of rehabilitation training. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of Embodiment 1 of the present invention;

[0032] Figure 2 The schematic diagram of the wheeled mobile platform of the embodiment 1 of the present application;

[0033] Figure 3 The schematic diagram of the connection between the lifting mechanism and the pelvic support mechanism of the embodiment 1 of the present application;

[0034] Figure 4 The schematic diagram of the pelvic support mechanism of the embodiment 1 of the present application;

[0035] Figure 5 The schematic diagram of the exoskeleton mechanical leg of the embodiment 1 of the present application;

[0036] Figure 6 The schematic diagram of the connection between the inner rod and the transverse plug-in rod of the embodiment 1 of the present application;

[0037] Figure 7 The schematic diagram of the connection between the positioning groove and the transverse plug-in rod of the embodiment 1 of the present application;

[0038] Figure 8 The schematic diagram of the exoskeleton mechanical leg single-link model of the embodiment 2 of the present application;

[0039] Figure 9 The flow chart of the method for controlling the exoskeleton motor of the embodiment 2 of the present application;

[0040] Figure 10 The flow chart of the PI controller with anti-saturation design of the embodiment 2 of the present application;

[0041] Figure 11 The flow chart of the method for controlling the bottom wheel motor of the embodiment 3 of the present application;

[0042] Figure 12 The schematic diagram of the kinematic model of the wheeled mobile platform of the embodiment 4 of the present application.

[0043] In the figure: the upper computer tablet 1, the lifting mechanism 2, the pelvic mechanism 3, the exoskeleton mechanical leg 4, the control cabinet 5, the wheeled mobile platform 6, the electrical board 7, the universal caster 8, the lithium battery pack 9, the driver 10, the driving wheel 11, the driving motor 12, the suspension mechanism 13, the ball screw 14, the sliding module 15, the proximity switch 16, the potentiometer 18, the width adjustment knob 20, the yaw mechanism 21, the torque sensor 22, the telescopic cylinder 23, the tension and compression force sensor 24, the sliding block 25, the compression spring 26, the connecting block 27, the servo motor 28, the driving mechanism 29, the speed reducer 30, the synchronous pulley 31, the telescopic sleeve 32, the leg holding groove 33. The inner rod 17, the transverse plug-in rod 19, the positioning groove 34, the support 35, the magnet 36, the vertical plug-in rod 37, the handle 38 DETAILED DESCRIPTION

[0044] Embodiment 1

[0045] A wheel-legged robot, such as Figures 1-7 As shown in the figure, it comprises a motion unit and an information interaction unit, the motion unit comprises a gravity center moving subsystem, a passive support subsystem and a joint rotating subsystem, the information interaction unit comprises a control subsystem and a sensing subsystem and a power unit. The gravity center moving subsystem comprises a wheeled mobile platform 6, a lifting mechanism 2 is connected to the wheeled mobile platform 6, the passive support subsystem comprises a full-degree-of-freedom pelvis support mechanism 3 connected to the lifting mechanism 2, which provides lateral shift and lateral inclination direction passive support of the pelvis; the joint rotating subsystem comprises two modular hip joint exoskeleton mechanical legs 4, which provide auxiliary extension and flexion direction rotation of the hip joint.

[0046] The control subsystem comprises a host computer tablet 1 and a lower computer controller; the sensing subsystem comprises a safety protection module and an intention recognition module, the safety protection module comprises an obstacle avoidance detection submodule and a motion unit protection submodule; the intention recognition module comprises a mechanical information acquisition submodule and a position information acquisition submodule.

[0047] During rehabilitation training, the joint rotating subsystem drives the patient's thigh to move by two hip joint exoskeleton mechanical legs 4 through physical interaction methods such as magic tape belts, etc., to assist the lower limb hip joint, which is suitable for early, medium and bilateral hemiplegic patients; combined with the detachable modular design, it can be used for unilateral hemiplegic or late patients; the passive support subsystem, i.e. the full-degree-of-freedom pelvis support mechanism 3, is connected to the human body through physical interaction methods such as magic tape belts, etc., to provide the activity freedom degree of the human pelvis. The gravity center moving subsystem realizes the movement of the gravity center in the up-down direction by the lifting mechanism 2, i.e. the ball screw 14, transmits power to the multi-degree-of-freedom pelvis support mechanism 3, provides human body support, reduces the patient's lower limb weight, joint torque and foot pressure, and the movement freedom degree is physically limited to ensure the patient's dynamic balance; the omnidirectional wheeled mobile platform 6 realizes active transfer of the human body gravity center, meeting the patient's movement demand in any direction.

[0048] As shown in the figure, Figure 2 The wheeled mobile platform 6 specifically comprises: an electrical board 7 for installing an electrical control cabinet 5 and serving as a bearing; omnidirectional casters 8 located at the front of the wheeled mobile platform 6 to ensure smooth omnidirectional movement; drive wheels 11 located at the back of the wheeled mobile platform 6, which control the forward direction of the robot through differential rotation between the two drive wheels 11 to realize any radius rotation and movement on the ground, the drive wheels 11 being connected with drive motors 12. Suspension mechanisms 13 are mainly used to reduce the vibration generated during movement and training. The drive wheels 11 are symmetrically arranged on both sides of the center shaft of the extension arm of the pelvis support mechanism 3, ensuring that the center of the patient's pelvis is consistent with the turning center of the robot during turning. The design width is greater than the standard width of a conventional wheelchair under the condition that the movable space design meets the leg space demand of the human body when walking, sitting and standing, which is convenient for patients riding a wheelchair to get in and out of the robot working space.

[0049] As shown in Figure 3 , the lifting mechanism 2 specifically includes a servo motor 28, and a ball screw 14 that converts rotary motion into linear motion of the sliding module 15, providing a degree of freedom of motion in the vertical axis; the sliding module 15 is connected to the multi-degree-of-freedom pelvic support mechanism 3 on the ball screw 14, constituting a light weight reduction device. The lifting mechanism 2 has a physical height limit to ensure the safety of the patient during the use of the rehabilitation training, and to avoid secondary injury to the patient.

[0050] As shown in Figures 3-4 , the full-degree-of-freedom pelvic support subsystem specifically includes: extension arms, symmetrically located in front of the yaw mechanism 21, used to support the hip joint exoskeleton mechanical leg 4 mechanism and contact and fix with the patient's lower limb hip through physical interaction methods such as magic tape belts, etc.; the yaw mechanism 21 contains an encoder and two springs, providing the lateral displacement degree of freedom of the pelvis, the front end of the yaw mechanism 21 is connected with the sliding module 15 of the lifting mechanism 2, providing the vertical displacement degree of freedom of the pelvis; the roll unit is located at the junction of the yaw mechanism 21 and the two extension arms, and the roll degree of freedom of the pelvis rotating around the sagittal axis is realized through the meshing of the gears; the hinge is located at the end of the extension arm and is connected with the sliding block 25, providing the full degree of freedom of the pelvis, having a certain physical limit, improving the flexibility of the connection place on the premise of improving the reliability of the connection, and improving the patient's use experience; the telescopic cylinder 23 is located at the front end of the extension arm, cooperating with the width adjustment knob 20 to adjust the distance between the two arms, so as to adapt to patients of different body types; the connecting block 27 is divided into front and back parts, used for rigid connection with the extension arms of the multi-degree-of-freedom pelvic support mechanism 3, and the modular detachable design meets the use of patients of different degrees of hemiplegia in different periods.

[0051] As shown in Figures 5-7 , the exoskeleton mechanical leg 4 includes a housing connected with the extension arm, the top of the housing is a V-shaped structure, and the electrical equipment, synchronous pulley 31, synchronous belt, reducer 30, encoder and driving motor 12 in the housing together constitute a driving mechanism 29 to drive the patient's thigh movement; the driving motor 12 is connected with the height adjustable mechanism, and the extension of the inner rod 17 is used to adjust the extension of the thigh connecting rod, which conforms to the ergonomic design and selects the length according to the height of the patient by combining the height parameter conversion algorithm, so as to adapt to the needs of different thigh lengths. In order to reduce the occupied volume, the driving motor 12 is arranged on both sides of the hip joint, connected with the reducer on the thigh connecting rod through the synchronous pulley 31, and provides power for the leg lifting action of the patient.

[0052] The shaft of the driving motor 12 is connected with a vertically arranged telescopic sleeve 32, the telescopic sleeve 32 is provided with a torque sensor 22, the telescopic sleeve 32 is slidingly connected with an inner rod 17, the inner rod 17 and the telescopic sleeve are slidingly connected through a sliding rail and a sliding groove, the length direction of the inner rod 17 is consistent with the sliding direction of the inner rod 17; the inner rod 17 is connected with a leg supporting groove 33 which is perpendicular to the inner rod 17; a row of positioning grooves 34 are arranged on the inner rod 17, the positioning grooves 34 are distributed along the sliding direction of the inner rod 17, the telescopic sleeve 32 is slidingly connected with a transverse plug rod 19 which is matched with the positioning grooves 34, the transverse plug rod 19 is arranged perpendicularly to the telescopic sleeve 32, a reset spring is connected between the transverse plug rod 19 and the telescopic sleeve 32, one end of the transverse plug rod 19 which is located outside the telescopic sleeve 32 is connected with a handle 38, the reset spring is sleeved on the transverse plug rod 19, and the reset spring is arranged between the handle 38 and the telescopic sleeve 32; one end of the transverse plug rod 19 which is located inside the telescopic sleeve 32 is provided with a limiting structure, so that the transverse plug rod 19 cannot move out of the telescopic sleeve 32. By inserting the transverse plug rod 19 into different positioning grooves 34, the position of the inner rod 17 can be adjusted, and then the overall length of the exoskeleton mechanical leg 4 can be adjusted.

[0053] Further, a support piece 35 is connected between the bottom end of the inner rod 17 and the leg supporting groove 33, the support piece 35 is a longitudinally arranged plate-shaped structure, the support piece 35 is rotationally connected with the leg supporting groove 33, the rotation axis of the leg supporting groove 33 is parallel to the inner rod 17, and the leg supporting groove 33 and the support piece 35 are provided with magnets 36 which match with each other; a vertical plug rod 37 which is parallel to the telescopic sleeve 32 is slidingly connected with the support piece 35, and the leg supporting groove 33 is connected with a positioning insertion hole which matches with the vertical plug rod 37.

[0054] The upper computer tablet 1 is mainly used for bearing display rehabilitation robot interactive software and interacting through a humanized interactive interface; the lower computer controller is used for receiving the upper computer and sensing system input data and processing the data through an algorithm, and the motion control is performed on the motion unit in combination with the control algorithm.

[0055] The safety protection module specifically comprises: an obstacle avoidance detection submodule, such as an ultrasonic sensor, which is arranged on the front part of the outer side of the control cabinet 5 of the omnidirectional mobile wheeled platform mechanism electrical board 7, is used for detecting obstacles, and avoids faults; a motion unit protection submodule, such as a proximity switch 16, which is arranged in the shell and is used for marking the limit position and zero point position of the up-down displacement of the multi-degree-of-freedom pelvic support mechanism 3, so as to prevent hardware collision.

[0056] The mechanical information acquisition module specifically includes: inner rods symmetrically arranged in the telescopic sleeve 32 of the multi-degree-of-freedom pelvis supporting mechanism 3, used to detect the up-down swing moment of the pelvis when the human body walks, sits or stands; a patient front-rear direction movement intention detection sub-module, which obtains the human body movement intention by the elastic deformation extrusion of the compression spring 26 inside the front end of the extension arm of the multi-degree-of-freedom pelvis supporting mechanism 3 to the tension-compression force sensor 24; a patient pelvis transverse displacement detection sub-module, such as a potentiometer 18, located in the front part of the transverse swing mechanism 21 in the multi-degree-of-freedom pelvis supporting mechanism 3, used to detect the transverse displacement of the pelvis during the walking, sitting or standing of the human body; a patient pelvis inclination angle detection sub-module, such as a potentiometer 18, located in the middle part of the transverse swing mechanism 21 in the multi-degree-of-freedom pelvis supporting mechanism 3, used to detect the inclination angle of the pelvis during the walking, sitting or standing of the human body; and a patient hip joint movement intention detection sub-module, such as an inner rod, located inside the end of the thigh connecting rod of the hip joint exoskeleton mechanical leg 4 mechanism, used to detect the human-machine interaction moment to provide a hardware basis for robot control. The torque sensor 22 in the telescopic cylinder 23 is symmetrically arranged like the tension-compression force sensor 24, and is used to detect the up-down swing moment of the pelvis when the human body walks, sits or stands.

[0057] The position information acquisition sub-module specifically includes: a human body lower limb end position information acquisition sub-module, such as a laser radar scanner, located inside the rear of the omnidirectional mobile wheeled platform control cabinet 5, used to detect the position information of the lower leg and foot of the patient. Other sensors such as vision, wearable gyroscope and attitude sensor can also be used for measurement.

[0058] The power unit specifically includes: a driver 10, a lithium battery pack 9, a servo motor 28, and all movement units of the lower limb rehabilitation robot are driven in a motor driving mode.

[0059] Embodiment 2

[0060] A lower limb passive training coordination control method using the above wheel-leg robot, comprising the following steps:

[0061] Step 1, human gait information acquisition, mainly through the use of angle sensors and motor encoders of the wheel-leg combined lower limb rehabilitation robot to obtain the hip joint movement information (angular velocity) when the human body walks, and using sensors to obtain the front-rear direction movement information of the center of gravity; fitting the hip joint rotation angle change curve and the center of gravity forward speed change curve according to the gait information of the human body.

[0062] The method for fitting the hip joint rotation angle change curve is: combining the collected hip joint rotation angle change data through gait cycle analysis, and fitting the hip joint rotation angle change curve by using a sine function and form:

[0063]

[0064]

[0065] where f(T, h) is a function of gait cycle and height, T is gait cycle, h is height, a i , b i and c i are constant terms, K is the number of sine functions, v c is average walking speed, L s is step length.

[0066] The relationship between the amplitude of the hip joint rotation angle and height and gait cycle is analyzed by using multiple linear regression analysis method, and a regression model of the amplitude of the hip joint rotation angle is established:

[0067] f(T, h) = β0 + β1T + β2h (3)

[0068] The influence factor β

[0069]

[0070] According to the specific gait information data, the mathematical model of the hip joint rotation angle is finally obtained as follows:

[0071]

[0072] In the formula, the coefficients a1 = 0.0879 and a2 = 0.0281.

[0073] The method for fitting the center of gravity velocity variation curve is as follows: the center of gravity forward velocity variation data collected is analyzed, and the center of gravity forward velocity variation curve is fitted:

[0074]

[0075] In the formula: B(T, h) and v avg (T, h) are functions of gait cycle T and height h, B(T, h) is the amplitude of the sine function, and v avg (T, h) is the mean value of the curve v comx .

[0076] By combining the collected data of the average value of the center of gravity forward velocity of subjects with different heights walking at different speeds, and by using the same analysis method as that for obtaining the mathematical model of the amplitude of the hip joint rotation angle, the function fitting result is obtained as follows:

[0077] v avg (T, h) = -0.007585 * T * h + 0.02421 * h + 0.8926 * T - 2.57 (7)

[0078] In the formula, T is gait cycle, and h is height.

[0079] Step 2, according to the hip joint rotation angle change curve, the gravity compensation PD control algorithm is used to control the rotation of the exoskeleton motor; according to the center of gravity forward speed change curve, the PI control algorithm is used to control the rotation of the bottom wheel.

[0080] The method for controlling the rotation of the exoskeleton motor is as follows: as shown in Figures 8-9 , a single-link model of the exoskeleton mechanical leg is constructed, and the Lagrange function balance method is used to analyze the dynamics of the exoskeleton mechanical leg, to obtain the relationship between the hip joint torque and the hip joint activity angle:

[0081]

[0082] In the formula, θ1 is the included angle between the thigh connecting rod and the x axis; m1 is the total mass of the human lower limb thigh and the exoskeleton leg; d1 = l1 / 2, l1 is the length of the exoskeleton leg, which is adjusted to be consistent with the length of the patient's thigh during training, and it is assumed that the mass of the thigh connecting rod is uniformly distributed.

[0083] The torque of the exoskeleton motor is calculated according to the following formula, and the exoskeleton motor is controlled to rotate according to the torque;

[0084]

[0085] In the formula, e 单关节 is the difference between the value of the hip joint rotation angle change curve at the last time and the actual angle of the hip joint at the last time, K pDGJ is the proportional coefficient, K dDGJ is the differential coefficient, is the estimated value of the gravity torque, it is assumed that the human body completely follows the movement of the exoskeleton mechanical leg, and an online estimation method is used, and it is assumed that the gravity torque estimation is accurate, there is

[0086] The method for controlling the rotation of the bottom wheel is as follows: as shown in Figure 10 , the forward speed of the bottom wheel is calculated according to the following formula, and then the expected rotation speed of the bottom wheel is calculated according to the expected forward speed of the bottom wheel, and the bottom wheel is controlled to rotate according to the expected rotation speed;

[0087] ω = K pDL ·e 底轮 + K iDL ·∫e 底轮 dt (10)

[0088] In the formula, ω is the expected forward speed of the bottom wheel, K pDL is the proportional coefficient, K iDL is the integral coefficient, e 底轮 is the difference between the value of the center of gravity forward speed change curve at the last time and the actual forward speed of the center of gravity at the last time.

[0089] The integral saturation of the controller is dealt with by using the limited weakening method. The controller contains an output limiting module. The limiting module does not generate any new signal, but only performs integral weakening on the output of the controller after entering the saturation area (reaching the upper limit of the error). In the corresponding discrete system of PLC, when calculating ω, it is first judged whether ω(t-1) has exceeded the limiting value. If it exceeds the limiting value, only the negative deviation is accumulated. If it does not exceed the limiting value, the positive deviation is accumulated.

[0090] Since the control object is the thigh angle, the actual calf cannot be controlled, and the distance of human walking and the foot position are closely related. Through the built-in laser radar sensor and gait data calculation algorithm of the device, the real-time position of the calf near the ankle is obtained to judge the foot position of the patient. According to the relationship between the wheeled mobile platform and the actual movement of the leg, the error value of the input of the PI controller of the bottom wheel is modified. The error of the input PI is the error of the expected foot position and the actual foot position * the adjustment coefficient. The adjustment coefficient is a negative value, that is, after the actual center of gravity displacement in the forward direction is less than the predefined displacement, the actual error is transformed into a coordinated error. In the tracking controller, if the actual position exceeds the predefined tracking trajectory position, the output speed will be reduced to ensure tracking, thereby ensuring coordination. Conversely, when the actual center of gravity displacement in the forward direction is greater than the predefined displacement, the actual error is transformed into a coordinated error. In the tracking controller, if the actual position lags behind the predefined tracking trajectory position, the output speed will be increased to ensure tracking, thereby ensuring the coordinated movement of the human system.

[0091] Embodiment 3

[0092] The other parts of this embodiment are the same as those of embodiment 2, except that the method of controlling the rotation of the bottom wheel is different, as shown in Figure 11 The speed of the forward movement of the bottom wheel is calculated in real time by the coordination verification algorithm, and then the expected rotation speed of the bottom wheel is calculated according to the expected forward movement speed of the bottom wheel, and the bottom wheel is controlled to rotate at the expected rotation speed;

[0093]

[0094]

[0095] ω = K pDL · e 底轮 + K iDL · ∫ e 底轮 dt (13)

[0096] In the formula, ω is the expected forward movement speed of the bottom wheel, K pDL is the proportional coefficient, K iDL is the integral coefficient, ω d is the value of the center of gravity forward speed change curve, y d足 is the expected foot position, and y足 K is the actual foot position, K 协调 is the adjustment coefficient. The distance of the center of gravity advancing direction is calculated by using the velocity curve of the center of gravity advancing direction, and the distance of the expected foot position advancing; the actual foot position is measured and calculated by using the sensor. When calculating ω, first determine whether the ω of the last time has exceeded the limit value, if it exceeds the limit value, only accumulate the negative deviation, if it does not exceed the limit, accumulate the positive deviation.

[0097] Embodiment 4

[0098] The other parts of this embodiment are the same as embodiment 3, the difference is that when turning, according to the expected speed v comx of the center of gravity in the sagittal plane, the expected speed of the left and right drive wheels is calculated by the kinematics of the wheeled mobile platform. As shown in Figure 12 , the wheeled mobile platform model is established as a differential drive dolly model:

[0099]

[0100] In the formula, v p is the value of the center of gravity advancing speed change curve, v L and v R respectively represent the left and right drive wheel speed, the center point P is the midpoint of the left and right drive wheel line, L is the distance between the left and right drive wheels, and R is the turning radius.

Claims

1. A control method of a wheel-legged robot, characterized by, The method comprises the following steps: Step 1, fitting a hip joint rotation angle change curve and a center of gravity advancing speed change curve of a human body according to gait information of the human body; Step 2, controlling rotation of an exoskeleton motor according to the hip joint rotation angle change curve by using a gravity compensation PD control algorithm, and controlling rotation of a bottom wheel according to the center of gravity advancing speed change curve by using a PI control algorithm; In step 2, the method for controlling rotation of the exoskeleton motor is: calculating torque of the exoskeleton motor according to the following formula, and controlling the exoskeleton motor to rotate according to the torque; wherein e 单关节 is the difference between the value of the hip joint angle change curve at the previous time and the actual angle of the hip joint at the previous time, K pDGJ is a proportional coefficient, K dDGJ is a differential coefficient, is an estimated value of the gravity moment; The method for controlling rotation of the bottom wheel is: calculating a speed of advancing of the bottom wheel according to the following formula, then calculating an expected rotating speed of the bottom wheel according to an expected advancing speed of the bottom wheel, and controlling the bottom wheel to rotate according to the expected rotating speed; ω = K pDL · e 底轮 + K iDL · ∫ e 底轮 dt where ω is the desired forward speed of the base wheel, K pDL is a proportional coefficient, K iDL is an integral coefficient; when calculating ω, first determine whether the previous time's ω has exceeded the limit value, if it has exceeded the limit value, only accumulate the negative deviation, if it has not exceeded the limit, accumulate the positive deviation; wherein e 底轮 is the difference between the value of the center of gravity forward speed change curve at the previous time and the actual center of gravity forward speed at the previous time, or, is obtained by the following method: ω d is the value of the center of gravity forward velocity profile, y d足 is the desired foot position, y 足 is the actual foot position, K 协调 is the adjustment coefficient.

2. The method of claim 1, wherein, In step 1, the method for fitting the hip joint rotation angle change curve is: fitting the hip joint rotation angle change curve by combining collected hip joint rotation angle change data with gait cycle analysis and using a sine function and form: where f(T, h) is a function of gait cycle and height, T is gait cycle, h is height, a i , b i , and c i are constant terms, and K is the number of sinusoidal functions.

3. The method of claim 2, wherein, In step 1, the method for fitting the center of gravity speed change curve is: fitting the center of gravity advancing speed change curve by analyzing collected center of gravity advancing speed change data; and fitting the center of gravity advancing speed change curve by analyzing collected center of gravity advancing speed change data; and where: B(T, h) and v avg (T, h) is a function of the gait cycle T and the height h, B(T, h) is the amplitude of the sinusoidal function, v avg (T, h) is a curve v comx whose mean value is

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