Exoskeleton robot with motor and center of gravity of lower limb of exoskeleton in line and control method thereof

Abstract

The present invention belongs to the field of lower limb exoskeleton robots, and specifically relates to an exoskeleton robot and a control method in which a motor and the center of gravity of the lower limb of the exoskeleton are colinear. The robot comprises a back frame mechanism and two groups of lower limb mechanisms, wherein the lower limb mechanisms include a hip joint transmission mechanism, a thigh mechanism, a knee joint transmission mechanism, and a calf mechanism; the knee joint transmission mechanism includes a motor, a group of helical gear transmission mechanisms, and a group of planetary gear train reduction mechanisms. The motor is connected to the helical gear set through a coupling for transmission, and the helical gear set and the sun gear of the planetary gear train are coaxially connected, thereby connecting the planetary gear train for transmission. The present invention has a compact structure, wherein the motor is installed inside the main body of the lower limb of the exoskeleton, the transmission is completed by the helical gears, and the reduction is completed by the planetary gear train, which can effectively reduce the torque applied by the exoskeleton to the wearer, and can also effectively avoid the sudden change of joint movement caused by the moment of starting or shutting down the motor, and has better human-machine coordination and wearing comfort.

Description

Technical Field

[0001] The present invention belongs to the field of lower limb exoskeleton robots, and in particular relates to an exoskeleton robot in which a motor and the center of gravity of an exoskeleton lower limb are colinear, and a control method thereof. Background Art

[0002] With the progress of science and technology in human society, people are no longer satisfied with breaking through the limits of their bodies, and have turned to developing auxiliary facilities that can enhance human performance. Therefore, exoskeletons have gradually come into people's view. From the perspective of engineering mechatronics, the exoskeleton system is an electromechanical wearable device that enhances the physical ability of its wearer. In the military field, this kind of equipment can enable soldiers to carry more weapons and equipment, enhance the soldiers' athletic ability, and effectively improve the combat capability of individual soldiers; in the civilian field, it can be widely used in firefighting, disaster relief and other situations where vehicles cannot pass and need to carry heavy supplies or transport the wounded; in the medical field, lower limb exoskeleton robots can also assist disabled people and the elderly in walking, and can also help patients who have temporarily lost their ability to move to perform human function recovery training, so it has broad prospects. Regarding active exoskeleton robots, the more famous ones include the exoskeleton robot HULC developed by Lockheed Martin in the United States and the robotic exoskeleton IHMC developed by the Institute of Human-Machine Cognition at the Florida Institute.

[0003] The motor installation position at the knee joint of the above-mentioned active lower limb exoskeleton robot will cause the center of gravity of the motor and the center of gravity of the exoskeleton lower limb to be not in the same straight line, or even in the same plane. In addition, the coordination structure of the reducer and the motor is complex, difficult to install and too large.

[0004] In existing active lower limb exoskeleton robot products, the center of gravity of the motor is inconsistent with the center of gravity of the exoskeleton lower limb. The motor reducer causes the joint to be too large, which brings the following problems:

[0005] (1) The existing mechanism will add excess torque to the lower limbs of the exoskeleton, causing the wearer to be subjected to excess pressure when wearing the exoskeleton, affecting the comfort of the human body and the exoskeleton during exercise.

[0006] (2) The existing mechanism has a large knee joint. When the wearer wears the exoskeleton and exercises, the knee joint does not coordinate well with the human body, which affects the coordination between the human body and the exoskeleton during exercise.

[0007] (3) The existing mechanism is directly driven by a motor. When the motor is just started, it may cause a sudden change in joint movement. When the wearer starts to run, he will suddenly be subjected to a large force, affecting the comfort of the human body and the exoskeleton movement. If the initial torque is too large, it may cause injury. Summary of the invention

[0008] The purpose of the present invention is to provide a lower limb exoskeleton robot in which the center of gravity of the motor is colinear with the center of gravity of the lower limb of the exoskeleton, thereby solving the problem that the existing exoskeleton knee joint power-assisting transmission mechanism cannot well match the human knee joint movement and reduce the excess torque exerted on the human body when wearing it.

[0009] The technical solution to achieve the purpose of the present invention is: a lower limb exoskeleton robot with a motor center of gravity co-linear with the center of gravity of the lower limb of the exoskeleton, comprising a back frame mechanism and two groups of lower limb mechanisms, the two groups of lower limb mechanisms are symmetrically arranged on both sides of the back frame mechanism, each group of the lower limb mechanisms comprises a hip joint transmission mechanism, a thigh mechanism, a knee joint transmission mechanism, and a calf mechanism;

[0010] The knee joint transmission mechanism is equipped with a motor, the thigh mechanism and the calf mechanism form an exoskeleton lower limb, and the center of gravity of the motor and the center of gravity of the exoskeleton lower limb are on the same straight line.

[0011] Further, the thigh mechanism includes a thigh shell I and a thigh shell II;

[0012] The knee joint transmission mechanism also includes a coupling, a helical gear set, a planetary gear train and a shank connecting piece;

[0013] The motor and coupling are arranged in the space formed by the thigh shell I and the thigh shell II. The output shaft of the motor is connected to the bevel gear set through the coupling. The bevel gear set changes the transmission direction. The bevel gear set is connected to the planetary gear train. The calf connecting piece connects the planetary gear train with the calf mechanism.

[0014] Furthermore, the helical gear set includes two meshing helical gears, one large and one small, and the planetary gear train (4-4) includes four external meshing gears and one internal meshing gear, the central external meshing gear is the sun gear, the three surrounding external meshing gears are planetary gears, and the internal meshing gear is a planetary disk; the planetary disk is arranged on the upper part of the shank connecting member;

[0015] The small bevel gear is connected to the driven shaft of the coupling, and the large bevel gear is coaxially driven with the sun gear of the planetary gear system; the sun gear is meshed with the three planetary gears, and the positioning parts of the three planetary gears are connected to the shaft connecting the large bevel gear and the sun gear through bearings; the three planetary gears are meshed with the planetary disk, thereby completing the transmission from the motor (4-1) to the shank connecting part.

[0016] Furthermore, the thigh shell I and thigh shell II are connected by screws and nuts.

[0017] Furthermore, the length of the calf mechanism is adjustable, and the length range of the calf mechanism is 30-150 mm.

[0018] Furthermore, it also includes an ankle joint transmission mechanism and a sole mechanism;

[0019] The calf mechanism comprises a calf outer tube and an ankle joint connector;

[0020] The calf connecting piece is provided with a plurality of vertically arranged holes, and the calf outer tube is provided with a plurality of vertically arranged holes. The calf connecting piece and the calf outer tube are connected by a pin shaft, and the connection between different holes realizes the adjustable length of the calf mechanism; the other end of the calf outer tube is connected to the ankle joint connecting piece by a pin shaft, and the other end of the ankle joint connecting piece is connected to the ankle joint transmission mechanism, and the other end of the ankle joint transmission mechanism is connected to the sole mechanism.

[0021] Furthermore, the hip joint transmission mechanism and the knee joint transmission mechanism are both provided with encoders;

[0022] An inertial measurement unit is provided on the outside of the back frame mechanism and located at the back of the human body, an inertial measurement unit is provided on the outside of the thigh mechanism and located at the back of the human body, and an inertial measurement unit is provided on the outside of the calf mechanism and located at the back of the calf of the human body;

[0023] The back frame mechanism is equipped with a microprocessor, a CAN communication module, a circuit board and a power supply.

[0024] A control method for the above-mentioned lower limb exoskeleton robot comprises the following steps:

[0025] Step (1): The inertial measurement unit on the outside of the back frame mechanism is used as a fixed reference point to construct a mathematical model of the lower limb exoskeleton robot. The posture change of the inertial measurement unit installed on the lower limb relative to the reference point can be calculated through the change in relative position, thereby obtaining the motion information of the human joint;

[0026] Step (2): After the wearer puts on the lower limb exoskeleton robot, he or she remains stationary for a certain period of time to collect initial information from each active joint encoder and each inertial measurement unit;

[0027] Step (3): When the wearer is exercising, the inertial measurement unit is configured to collect the wearer's lower limb movement data, and the data is transmitted to the microprocessor. The human joint movement information is obtained through data processing, and the drive mechanism of the corresponding exoskeleton joint is controlled to output, so as to realize the movement of the lower limb exoskeleton. The exoskeleton movement will drive the joint encoder to start recording, and the kinematic information of the exoskeleton joint can be measured in real time. It is monitored whether the movement of the lower limb exoskeleton mechanism is correct, and it is input into the processor as feedback to complete the closed-loop control of the joint drive mechanism.

[0028] Compared with the prior art, the present invention has the following significant advantages:

[0029] (1) The present invention connects the thigh shell to the knee joint, and the motor of the lower limb exoskeleton robot is inside the thigh shell, so that the center of gravity of the motor is consistent with the center of gravity of the lower limb of the lower limb exoskeleton, reducing the excess torque added by the motor to the lower limb of the exoskeleton, reducing the pressure added to the wearer when wearing the exoskeleton, and better fitting the human body movement.

[0030] (2) The present invention wraps the motor inside the thigh shell, and the knee joint and the thigh exoskeleton are integrated, so that the motor is less affected by the outside world during movement, and the influence of external factors on the motor when in use can be reduced.

[0031] (3) The present invention uses a helical gear set to change the transmission direction, a planetary gear system to reduce speed, and a reasonable arrangement of the mechanical mechanism to make the knee joint structure more compact and further improve the comfort of human wear.

[0032] (4) In the process of assisting the knee joint, the present invention drives the helical gear through the motor, and the helical gear drives the planetary gear train to rotate, thereby driving the calf to rotate; such a transmission mechanism can effectively avoid the sudden force caused by the initial torque brought to the joint by the motor when it is just started, so that the wearer can move more smoothly when wearing the exoskeleton and reduce the impact of the sudden movement of the motor on the movement of the exoskeleton.

[0033] (5) The calf mechanism of the present invention can adjust the length of the calf. The calf connector and the calf outer tube, and the calf outer tube and the ankle joint connector are connected by a pin shaft, making the calf easier to install and disassemble, and also making it easier to adjust the length of the calf. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the lower limb exoskeleton robot of the present invention.

[0035] Figure 2 It is a schematic diagram of the explosion of the thigh mechanism of the present invention.

[0036] Figure 3 It is an exploded schematic diagram of the knee joint mechanism of the present invention.

[0037] Figure 4 It is a schematic diagram of the explosion of the calf mechanism of the present invention.

[0038] Figure 5 It is a schematic diagram of the knee joint mechanism of the present invention.

[0039] Figure 6 It is a schematic diagram of the interior of the knee joint mechanism of the present invention.

[0040] Figure 7 It is a flow chart of the control method of the present invention.

[0041] Description of reference numerals:

[0042] 1-back frame mechanism, 2-hip joint mechanism, 3-thigh mechanism, 3-1-thigh shell I, 3-2-thigh shell II, 4-knee joint mechanism, 4-1-motor, 4-2-coupling, 4-3-helical gear set, 4-4-planetary gear train, 4-5-calf connector, 5-calf mechanism, 5-1-calf outer tube, 5-2-ankle joint connector, 6-ankle joint mechanism. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0044] Combination Figure 1 , an exoskeleton knee joint whose motor center of gravity is co-linear with the lower limb of the exoskeleton, comprising a back frame mechanism 1 and two sets of lower limb mechanisms, the two sets of lower limb mechanisms are symmetrically arranged on both sides of the back frame mechanism 1, wherein the lower limb mechanism comprises a hip joint transmission mechanism 2, a thigh mechanism 3, a knee joint transmission mechanism 4, a calf mechanism 5, an ankle joint transmission mechanism 6 and a sole mechanism;

[0045] The knee joint transmission mechanism connects the thigh mechanism 3 and the calf mechanism 5 together and completes the power-assisted transmission movement.

[0046] Combination Figure 2 , Figure 3 and Figure 6 The lower limb exoskeleton robot, a knee joint transmission mechanism, includes a thigh shell, a motor 4-1, a bevel gear set 4-3, a planetary gear train 4-4, and a calf connector 4-5; the knee joint can make the center of gravity of the motor 4-1 and the center of gravity of the lower limb of the exoskeleton be in the same straight line.

[0047] Combination Figure 2 The described knee joint, the thigh shell includes a thigh shell Ⅰ3-1 and a thigh shell Ⅱ3-2, the thigh shell Ⅰ3-1 and the thigh shell Ⅱ3-2 are fixed with screws and nuts, the thigh shell wraps the motor 4-1 and the coupling 4-2 inside, and can fix the motor.

[0048] Combination Figure 3 , Figure 6 , the shank connecting member 4-5, the shank connecting member 4-5 connects the shank rod and the planetary disk of the planetary gear train 4-4 into one.

[0049] Combination Figure 3 , Figure 6 , the bevel gear set 4-3 changes the transmission direction and is connected to the planetary gear train.

[0050] Combination Figure 3 The planetary gear train 4-4 connects the bevel gear 4-3 and the shank connector 4-5 to achieve the purpose of speed reduction.

[0051] The planetary gear system consists of 4 external gears and one internal gear. The central external gear is the sun gear, the surrounding 3 external gears are planetary gears, and the internal gear is the planetary disk. Figure 3 The output shaft of motor 4-1 is connected to coupling 4-2, which serves as the driving shaft of coupling 4-2. The driven shaft of the coupling is connected to the helical gear set. The helical gear set consists of two meshing helical gears, one large and one small. The small helical gear is connected to the driven shaft of the coupling. The large helical gear is coaxially driven with the sun gear of the planetary gear train. The sun gear is meshed with three planetary gears. The positioning parts of the three planetary gears are connected to the shaft connecting the large helical gear and the sun gear through bearings. The three planetary gears are meshed with the planetary disk. The planetary disk and the shank connector are made into an integrated mechanism, namely 4-5, thereby completing the transmission from motor 4-1 to shank connector 4-5.

[0052] Combination Figure 4 The calf length adjustment mechanism includes a calf connector 4-5, a calf outer tube 5-1, and an ankle joint connector 5-2.

[0053] Combination Figure 4 The calf connector 4-5 is connected and fixed to the calf outer tube 5-1 through a pin, and the calf outer tube 5-1 is connected to the ankle connector 5-2 through a pin, wherein the length can be changed from 30 to 150 mm, and can be adjusted for different users.

[0054] Combination Figure 3 , Figure 6 It can be seen that when the knee joint is assisting, first, the coupling 4-2 is driven to rotate by the rotation of the motor 4-1, and then the transmission direction is changed through the helical gear to connect with the planetary gear train, and finally the assisting movement of the entire joint is completed.

[0055] Combination Figure 1 The wearer's thigh is connected to the thigh mechanism 3 of the lower limb exoskeleton with a thigh strap, and the human calf is connected to the calf mechanism 5 through the calf strap. When the exoskeleton is to assist the human body in movement, the motor 4-1 rotates, changes the transmission direction through the bevel gear, and then decelerates through the planetary gear train, and finally transmits the force to the calf, so that the exoskeleton calf mechanism 5 has a forward or backward force, thereby assisting the human body to move forward.

[0056] Combination Figure 1 In the lower limb exoskeleton robot, the hip joint transmission mechanism 2 and the knee joint transmission mechanism 4 are both equipped with encoders, and the back frame mechanism 1 is equipped with a microprocessor, a CAN communication module, a circuit board, and a power supply.

[0057] In order to obtain the motion information of the knee joint of the human lower limb during movement, an inertial measurement unit needs to be installed. An inertial measurement unit is installed on the outside of the back frame mechanism 1 and located on the back of the human body, an inertial measurement unit is installed on the outside of the thigh 3 and located on the back of the human body, and an inertial measurement unit is installed on the outside of the calf 5 and located on the back of the human calf. In order to accurately measure the angle of rotation of the exoskeleton knee joint, it is necessary to install sensors at the joints.

[0058] Combination Figure 7 First, a mathematical model of the mechanism of the lower limb exoskeleton robot of the present invention is constructed. After the wearer puts on the lower limb exoskeleton robot of the present invention, the robot remains stationary for a certain period of time, and the initial information of each active joint sensor and the inertial measurement unit is collected. During the movement, the posture change of the inertial measurement unit installed at the lower limb strap relative to the reference point of the inertial measurement unit on the outside of the back frame is obtained through coordinate transformation, and then the movement information of the human lower limb knee joint is obtained. According to the information, the exoskeleton knee joint actuator is controlled to output, and the exoskeleton joint movement information obtained by the encoder is used as feedback to complete the closed-loop control, so as to achieve the movement matching between the present invention and the wearer.

Claims

1. An exoskeleton robot in which a motor and the center of gravity of the lower limbs of the exoskeleton are colinear, comprising a back frame mechanism (1) and two sets of lower limb mechanisms, the two sets of lower limb mechanisms being symmetrically arranged on both sides of the back frame mechanism (1), each set of the lower limb mechanisms comprising a hip joint transmission mechanism (2), a thigh mechanism (3), a knee joint transmission mechanism (4), and a calf mechanism (5); It is characterized in that The knee joint transmission mechanism (4) is equipped with a motor (4-1), the thigh mechanism (3) and the calf mechanism (5) form an exoskeleton lower limb, and the center of gravity of the motor and the center of gravity of the exoskeleton lower limb are on the same straight line; The thigh mechanism (3) comprises a thigh shell I (3-1) and a thigh shell II (3-2); The knee joint transmission mechanism (4) further comprises a coupling (4-2), a helical gear set (4-3), a planetary gear train (4-4) and a calf connecting piece (4-5); The motor (4-1) and the coupling (4-2) are arranged in a space formed by the thigh shell I (3-1) and the thigh shell II (3-2); the output shaft of the motor (4-1) is connected to the bevel gear set (4-3) through the coupling (4-2); the bevel gear set (4-3) changes the transmission direction; the bevel gear set (4-3) is connected to the planetary gear train (4-4); and the calf connecting piece (4-5) connects the planetary gear train (4-4) to the calf mechanism (5); The helical gear set (4-3) comprises two meshing helical gears, one large and one small; The planetary gear train (4-4) comprises four external meshing gears and one internal meshing gear, the central external meshing gear is the sun gear, the three surrounding external meshing gears are planetary gears, and the internal meshing gear is a planetary disk; the planetary disk is arranged on the upper part of the shank connecting member; The small helical gear is connected to the driven shaft of the coupling (4-2), and the large helical gear is coaxially driven with the sun gear of the planetary gear train (4-4); the sun gear is meshed with the three planetary gears, and the positioning parts of the three planetary gears are connected to the shaft connecting the large helical gear and the sun gear through bearings; the three planetary gears are meshed with the planetary disk, thereby completing the transmission from the motor (4-1) to the shank connecting part (4-5); It also includes an ankle joint transmission mechanism (6) and a sole mechanism; The calf mechanism (5) comprises a calf outer tube (5-1) and an ankle joint connector (5-2); The calf connecting piece (4-5) is provided with a plurality of vertically arranged holes, the calf outer tube (5-1) is provided with a plurality of vertically arranged holes, the calf connecting piece (4-5) and the calf outer tube (5-1) are connected via a pin shaft, and the connection between different holes enables the length of the calf mechanism to be adjustable; the other end of the calf outer tube (5-1) is connected to the ankle joint connecting piece (5-2) via a pin shaft, the other end of the ankle joint connecting piece (5-2) is connected to the ankle joint transmission mechanism (6), and the other end of the ankle joint transmission mechanism (6) is connected to the sole mechanism; The thigh shell I (3-1) and the thigh shell II (3-2) are connected by screws and nuts.

2. The exoskeleton robot according to claim 1, characterized in that: The length of the calf mechanism (5) is adjustable, and the length variation range of the calf mechanism (5) is 30-150 mm.

3. The exoskeleton robot according to claim 2, characterized in that: The hip joint transmission mechanism (2) and the knee joint transmission mechanism (4) are both provided with encoders; An inertial measurement unit is provided on the outside of the back frame mechanism (1) and located at the back of the human body, an inertial measurement unit is provided on the outside of the thigh mechanism (3) and located at the back of the human body, and an inertial measurement unit is provided on the outside of the calf mechanism (5) and located at the back of the calf of the human body; The back frame mechanism (1) is provided with a microprocessor, a CAN communication module, a circuit board and a power supply.

4. A control method for an exoskeleton robot according to claim 3, characterized in that: The steps include: Step 1: Take the inertial measurement unit on the outside of the back frame as a fixed reference point to build a mathematical model of the lower limb exoskeleton robot. The posture change of the inertial measurement unit installed on the lower limb relative to the reference point can be calculated through the change in relative position, and then the motion information of the human joint can be obtained; Step 2: After the wearer puts on the lower limb exoskeleton robot, he / she stays still for a certain period of time to collect initial information from each active joint encoder and each inertial measurement unit; Step 3: When the wearer is exercising, the inertial measurement unit is used to collect the wearer's lower limb movement data, and the data is transmitted to the microprocessor. The human joint movement information is obtained through data processing, and the drive mechanism of the corresponding exoskeleton joint is controlled to output to achieve the movement of the lower limb exoskeleton. The exoskeleton movement will drive the joint encoder to start recording, which can measure the kinematic information of the exoskeleton joint in real time, monitor whether the movement of the lower limb exoskeleton mechanism is correct, and input it into the processor as feedback to complete the closed-loop control of the joint drive mechanism.

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