Variable structure trunk rehabilitation training robot and exercise training method

Abstract

The invention belongs to the technical field of robots, and provides a structure-variable trunk rehabilitation training robot and an exercise training method.The structure-variable trunk rehabilitation training robot comprises a binding device, a rope traction system and a sliding rail; the binding device is worn on the trunk of a human body; the sliding rail is annularly arranged on the waist of a human body; the rope traction system comprises a driving device and a corresponding Bowden cable; the driving device can be limited on the sliding rail or can slide relative to the sliding rail, the configuration change of the robot is achieved by changing the distribution position of the driving device on the sliding rail, one end of a sheathing canal of the Bowden cable is connected with the driving device, and the other end of the sheathing canal is connected to an anchor point on the binding device. And the trunk is dragged to move through the rope for winding and unwinding the Bowden cable. According to different rehabilitation training requirements, the distribution positions of the driving units on the waist of the human body can be adjusted in a stepless mode, personalized and targeted rehabilitation training is achieved, and meanwhile the wearing comfort is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology and relates to a rehabilitation training robot, specifically a variable-structure trunk rehabilitation training robot and a motor training method. Background Technology

[0002] Neurological disorders such as stroke, spinal cord injury, and Parkinson's disease often lead to trunk motor dysfunction, manifested as core muscle weakness, abnormal postural control, and loss of balance. As the center of the body, the trunk not only maintains balance in sitting and standing postures but also forms the biomechanical basis for functional movements such as upper limb extension and lower limb walking. Scientific and systematic trunk rehabilitation training can significantly improve patients' motor learning abilities and promote limb functional recovery.

[0003] Currently, clinical trunk rehabilitation primarily relies on manual training by rehabilitation therapists. However, this "one-on-one" or even "many-to-one" manual training method has many drawbacks: First, it is physically demanding, requiring prolonged assistance to patients in repetitive movements, resulting in significant energy expenditure. Second, it lacks quantitative standards; the training effect is highly dependent on the therapist's personal experience and professional skills, making it difficult to accurately quantify and adjust the applied assistance or resistance in real time. Finally, it is inefficient and cannot meet the needs of the large rehabilitation patient population.

[0004] To address the shortcomings of manual training, various trunk rehabilitation robots have emerged in recent years. However, existing technologies still suffer from the following significant drawbacks. Current rigid exoskeleton robots typically employ a metal linkage structure connected in parallel with the human body. Because the human torso (especially the spine) is a complex, flexible structure containing multiple joints, its center of motion changes instantaneously. The fixed center of rotation of a rigid robot is difficult to keep aligned with the instantaneous center of rotation of the human spine (i.e., the "human-machine joint axis mismatch" problem). This not only causes additional pressure and discomfort for the patient during training but can also potentially lead to secondary injuries in severe cases. Furthermore, rigid structures are usually bulky and have high inertia, limiting the patient's natural freedom of movement.

[0005] To overcome the drawbacks of rigid structures, researchers have developed flexible rehabilitation robots based on rope traction. These robots utilize the flexibility of ropes to improve wearing comfort. However, most existing flexible trunk rehabilitation robots employ a fixed configuration design, meaning the position of the drive unit (motor or guide wheel) fixed to the body (anchor point) is not adjustable. This design presents serious adaptability problems: First, it has poor adaptability to individual differences; patients of different heights and body types have different optimal lever arm lengths. Fixed anchor points result in low torque output efficiency. Second, it limits targeted training; trunk movements include various modes such as flexion / extension (sagittal plane), lateral bending (coronal plane), and axial rotation (horizontal plane). When performing "axial rotation" training, the drive point needs to be located on the side of the body to provide the maximum lever arm; while for "flexion / extension" training, the drive point is more efficient when located on the anterior or posterior side of the body. Existing fixed-configuration robots cannot adjust the drive layout according to specific training goals, making it difficult for a single configuration to accommodate multiple complex trunk rehabilitation movements.

[0006] In view of the above, there is an urgent need for a rehabilitation device that can adapt to different patient body types and flexibly adjust the drive layout according to the training movement requirements. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention proposes a variable-structure trunk rehabilitation training robot and a motor training method.

[0008] The robot uses a circular slide rail as its base and flexible Bowden wire as its transmission medium. It can steplessly adjust the distribution of the drive unit on the waist according to different rehabilitation training needs, such as flexion, extension, lateral bending or rotation, so as to achieve personalized and targeted rehabilitation training while ensuring wearing comfort.

[0009] A variable-structure trunk rehabilitation training robot includes a restraint device, a rope traction system, and a slide rail; The binding device is worn on the human torso; The slide rail is arranged in a ring around the waist of the human body; The rope traction system includes a drive unit and a corresponding Bowden line; The drive device can be confined to the slide rail or can slide relative to the slide rail. The configuration of the robot can be changed by changing the distribution position of the drive device on the slide rail. One end of the Bowden cable sheath is connected to the drive device, and the other end of the sheath is connected to the anchor point on the binding device. The torso is pulled by the rope of the Bowden cable to generate movement.

[0010] Furthermore, the rope traction system includes four sets of drive devices: a left front rope traction drive device, a right front rope traction drive device, a left rear rope traction drive device, and a right rear rope traction drive device, and the four sets of drive devices are independently controlled.

[0011] Furthermore, the driving device includes a housing, a motor, a gearbox, and a winding wheel; the motor, gearbox, and winding wheel are arranged inside the housing, the output shaft of the motor is connected to the input end of the gearbox, the output shaft of the gearbox is equipped with a winding wheel, the rope is wound on the winding wheel, one end of the sheath is fixed to the housing, and the other end extends to connect to the binding device, the housing can be confined to the slide rail or can slide relative to the slide rail.

[0012] Furthermore, the binding device includes a shoulder binding strap and an abdominal binding strap; the abdominal binding strap is bound to the waist of the human body, and the slide rail is located on the outside of the abdominal binding strap; the shoulder binding strap is bound to the chest and shoulders of the human body, and the shoulder binding strap has symmetrically distributed chest anchor points and back anchor points, and the ends of the Bowden ropes are connected to the chest anchor points or back anchor points respectively.

[0013] A motion training method for a variable-structure trunk rehabilitation training robot, defining a left anterior rope traction drive device, a right anterior rope traction drive device, a left posterior rope traction drive device, and a right posterior rope traction drive device as corresponding to the left anterior Bowden line, the right anterior Bowden line, the left posterior Bowden line, and the right posterior Bowden line, respectively. Simultaneously tighten the left and right anterior Bowden lines to generate a downward pull; at the same time, release the left and right posterior Bowden lines, ultimately pulling the shoulders forward and downward, causing the spine to flex forward; simultaneously tighten the left and right posterior Bowden lines, while simultaneously releasing the left and right anterior Bowden lines, shortening the posterior rope, pulling the shoulders backward and downward, causing the spine to extend backward. Simultaneously tighten the left front and left rear Bowden lines while releasing the right front and right rear Bowden lines, shortening the left rope as a whole and pulling the left shoulder down, causing the torso to tilt to the left. Simultaneously tighten the right front and right rear Bowden lines while releasing the left front and left rear Bowden lines, shortening the right rope as a whole and pulling the right shoulder down, causing the torso to tilt to the right. Tighten the left rear and right front Bowden lines while simultaneously loosening the left front and right rear Bowden lines. The left rear line pulls the left shoulder backward, and the right front line pulls the right shoulder forward. This pair of forces creates a counterclockwise torque on the horizontal plane, driving the torso to rotate to the left. Tighten the right rear and left front Bowden lines while simultaneously loosening the right front and left rear Bowden lines. The right rear line pulls the right shoulder backward, and the left front line pulls the left shoulder forward. This pair of forces creates a clockwise torque on the horizontal plane, driving the torso to rotate to the right.

[0014] The advantages of this invention compared to the prior art are: 1. Flexible and Adjustable Configuration (Variable Configuration): This is the core advantage of this invention. Traditional rope-guided robots have fixed anchor points, making it difficult to accommodate multiple motion modes. This invention, through a ring-shaped slide rail design, allows the position of the drive unit to be flexibly adjusted according to the training objectives. For example, during trunk rotation training, the drive unit can be moved to the side of the body to obtain the maximum lever arm; during flexion and extension training, it can be moved to the front or back. This design greatly improves the robot's versatility and training efficiency.

[0015] 2. Smooth and Safe Human-Computer Interaction: Utilizing Bowden cables as a flexible transmission medium avoids the mechanical restrictions and forced alignment issues of rigid exoskeleton linkages on human joint movement, thus eliminating the risk of "joint axis mismatch." The flexible cables allow patients to retain a certain degree of natural freedom of movement, significantly improving wearing comfort and preventing secondary injuries.

[0016] 3. Compact and lightweight structure: Heavy components such as the motor and reducer are concentrated on the waist rail (such as near the body's center of gravity), and power is transmitted to the shoulders through the lightweight Bowden cable. This layout reduces the additional inertia of the moving limbs (such as the upper body) and reduces the physical burden on the patient.

[0017] The present application will be further described below with reference to the accompanying drawings and embodiments: Attached Figure Description

[0018] Figure 1 This is a dihedral view of a flexible-driven, variable-structure trunk rehabilitation training robot according to the present invention. Figure 2 This is a left view of a flexible-driven, variable-structure trunk rehabilitation training robot according to the present invention. Figure 3 This is a rear view of a flexible-driven, variable-structure trunk rehabilitation training robot according to the present invention. Figure 4 This is a schematic diagram of the drive device and slide rail installation according to the present invention; Figure 5 This is a perspective view of the driving device of the present invention; Figure 6 This is a schematic diagram of the human body rotation axis coordinate system used for motion and illustration in this invention.

[0019] In the picture: 1. Drive unit; 1-1. Left front rope traction drive unit; 1-2. Right front rope traction drive unit; 1-3. Left rear rope traction drive unit; 1-4. Right rear rope traction drive unit; 2. Slide rail; 3. Slide rail buckle; 4-1. Left front Bowden line; 4-2. Right front Bowden line; 4-3. Left rear Bowden line; 4-4. Right rear Bowden line; 5. Shoulder binding strap; 6. Chest anchor point; 7. Abdominal binding strap; 8. Back anchor point; 9. Set screw; 10. Slider; 11. Pulley; 12. Bowden line sheath; 13. Gearbox; 14. Motor; 15. Winding reel; 16. Housing. Detailed Implementation

[0020] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by those skilled in the art.

[0021] Existing rigid exoskeleton robots typically use metal linkage structures connected in parallel with the human body. The fixed rotation center of a rigid robot is difficult to align with the instantaneous rotation center of the human spine, which not only causes additional pressure and discomfort for patients during training but may also lead to secondary injuries in severe cases. Furthermore, rigid structures are usually bulky and have high inertia, limiting the patient's natural freedom of movement. Existing fixed-configuration robots cannot adjust their drive layout according to specific training goals, making it difficult for a single configuration to accommodate multiple complex trunk rehabilitation movements.

[0022] In view of this, this application provides a rehabilitation device that can adapt to different patient body types and flexibly adjust the drive layout according to the training movement requirements.

[0023] Example 1, Reference Figure 1 and Figure 2 This embodiment provides a variable-structure trunk rehabilitation training robot, which includes a binding device, a rope traction system, and a slide rail; The binding device is worn on the human torso; The rope traction system includes a drive unit 1 and a corresponding Bowden line 4; The slide rail 2 has a ring structure and is worn on the waist of the human body as the base of the robot. The slide rail 2 is provided with a groove for installing and fixing the drive device of the rope traction system.

[0024] The drive unit is mounted on the slide rail 2 via a slider 10 and is equipped with a tightening mechanism (such as a set screw 9). Each drive unit is engaged in a groove in the slide rail 2 via the slider 10 on its back. A pulley 11 is installed in the groove and the slider 10 is equipped with a set screw 9 or a quick clamp. When the screw is loosened, the drive unit can slide circumferentially along the slide rail 2. At this time, the pulley 11 rolls on both sides of the groove, which on the one hand positions the slider 10 to prevent it from derailing, and on the other hand improves the movement capability of the slider 10, thereby changing its orientation relative to the human torso. When the screw is tightened, the drive unit is locked in the current position, thus determining the current drive configuration. By adjusting the tightening mechanism, the slider 10 can be confined to the slide rail 2 or can slide relative to the slide rail 2.

[0025] This design allows for adjustment of the distribution angles of the four drive units according to training needs. For example, moving the drive units to the side increases the rotational lever arm, while moving them to the front or back optimizes flexion and extension efficiency. By changing the distribution of the drive units on the slide rail 2 (e.g., concentrated on the front and back sides or distributed on the left and right sides), the application point of traction force can be reconfigured to adapt to different muscle group training needs. One end of the sheath 41 of the Bowden line 4 is connected to the drive unit, and the other end of the sheath 41 is connected to the anchor point on the binding device. Movement is generated by pulling the torso through the rope 40 of the Bowden line.

[0026] This embodiment, by introducing a ring-shaped slide rail 2 and a movable mechanism, achieves for the first time stepless adjustment of the drive device at the circumference of the human waist. This "variable configuration" characteristic allows the robot to reconfigure the traction anchor points at different locations according to the rehabilitation prescription, thereby providing precise and compliant rehabilitation training to the patient with the optimal mechanical configuration. The robot is worn on the human torso, outputting power through the lumbar base, and tractioning the shoulders via flexible Bowden cables, thereby driving the spine to produce multi-degree-of-freedom movements.

[0027] The rope traction system comprises four drive units: a left front rope traction drive unit 1-1, a right front rope traction drive unit 1-2, a left rear rope traction drive unit 1-3, and a right rear rope traction drive unit 1-4. These four drive units are independently controlled and can collaboratively output torque to drive the human torso in flexion, extension, lateral bending, and axial torsion movements. Figure 1 and Figure 4 As shown, to achieve flexible adjustment of the drive configuration, this invention designs a slide rail 2 that surrounds the waist. The slide rail 2 is C-shaped, with two slide rails 2 joined together to form a ring and connected by a slide rail buckle 3. The front half of the slide rail 2 is equipped with a left front rope traction drive device 1-1 and a right front rope traction drive device 1-2; the rear half of the slide rail 2 is equipped with a left rear rope traction drive device 1-3 and a right rear rope traction drive device 1-4. Alternatively, the slide rail 2 can be a one-piece rigid ring structure. The slide rail 2 is fixedly installed on the outside of the abdominal binding strap 7.

[0028] Example 2, Reference Figure 4 and Figure 5 This embodiment defines a driving device, which includes a housing 16, a motor 14, a reduction gearbox 13, and a winding wheel 15. The motor 14, reduction gearbox 13, and winding wheel 15 are arranged inside the housing 16. The output shaft of the motor 14 (preferably a brushless DC motor) is connected to the input end of the reduction gearbox 13 to provide high torque output. The output shaft of the reduction gearbox 13 is equipped with a winding wheel 15 for winding or releasing the rope. The rope 40 is wound around the winding wheel 15, passes through a sheath 12, and the other end is fastened to a chest anchor point 6 or a back anchor point 8. One end of the sheath 41 is fixed to the outlet of the housing 16, and the other end extends to the binding device and abuts against the anchor point guide seat of the shoulder binding. The sheath 41 bears pressure but does not transmit tension. The housing 16 can be limited to the slide rail 2 or can slide relative to the slide rail 2 by a slider 10.

[0029] Example 3, referring to Figures 1-3 The binding device includes a shoulder binding strap 5 and an abdominal binding strap 7. The abdominal binding strap 7 is a wide waistband structure, bound to the waist of the body, used to support the annular slide rail and transmit the reaction force to the pelvic area, ensuring the stability of the base during training. The slide rail 2 is located on the outside of the abdominal binding strap 7. The shoulder binding strap 5 is a vest-style structure, worn on the patient's chest and shoulders. The shoulder binding strap 5 has symmetrically distributed front chest anchor points 6 and back anchor points 8, used to receive the traction force from the Bowden line. The ends of the Bowden line ropes 40 are connected to the front chest anchor point 6 or the back anchor point 8 respectively.

[0030] Furthermore, the restraint device is used to achieve a tight coupling between the robot and the human body. The shoulder restraint 5 is a vest-style structure made of flexible and breathable material, worn on the patient's chest and back. Its key design features four force transmission anchor points: two front anchor points 6 located below the front of both shoulders, and two back anchor points 8 located near the scapulae on the back of both shoulders (e.g., Figure 3 (As shown). These anchor points are used to connect the inner core of the Bowden line and are the points of application of traction force. The abdominal binding strap 7 is a widened semi-rigid waist belt that is tightly bound to the patient's waist and pelvic area. Its function is to serve as the "foundation" of the robot, bearing the weight of the slide rails and drive unit, and evenly transmitting the traction reaction force to the pelvis to avoid local compression of the lumbar spine.

[0031] Example 4, Reference Figures 1-6 It also relates to a motion training method for a variable-structure trunk rehabilitation training robot based on any of the above embodiments, which synthesizes torques in different directions in space by coordinating the changes in the length of four Bowden lines (winding in / winding out), driving the trunk to perform three-dimensional motion around the waist (similar to a ball-and-socket joint).

[0032] The flexion / extension and x-axis rotation movements primarily occur in the sagittal plane. Forward flexion (bending over): Simultaneously tighten the ropes on the left anterior Bowden line 4-1 and right anterior Bowden line 4-2 (motor 14 rotates forward), generating a downward pull; simultaneously, release the ropes on the left posterior Bowden line 4-3 and right posterior Bowden line 4-4 (motor 14 rotates in reverse or follows) to avoid generating opposing resistance. This ultimately pulls the shoulders forward and downward, leading to spinal flexion. Back extension (chest extension / backward lean): Simultaneously tighten the ropes on the left posterior Bowden line 4-3 and right posterior Bowden line 4-4; simultaneously, release the ropes on the left anterior Bowden line 4-1 and right anterior Bowden line 4-2, shortening the posterior ropes and pulling the shoulders backward and downward, leading to spinal extension.

[0033] Lateral bending movements (left and right lateral flexion, y-axis rotation) primarily occur in the coronal plane. To bend to the left: Simultaneously tighten the ropes along the left anterior Bowden line 4-1 and the left posterior Bowden line 4-3; simultaneously, release the ropes along the right anterior Bowden line 4-2 and the right posterior Bowden line 4-4. The left rope shortens overall, pulling the left shoulder downwards, causing the torso to tilt to the left. To bend to the right: Simultaneously tighten the ropes along the right anterior Bowden line 4-2 and the right posterior Bowden line 4-4; simultaneously, release the ropes along the left anterior Bowden line 4-1 and the left posterior Bowden line 4-3. The right rope shortens overall, pulling the right shoulder downwards, causing the torso to tilt to the right.

[0034] Torsional movements (z-axis rotation) occur in the transverse plane and are among the most complex and difficult movements to achieve in rehabilitation training. This embodiment achieves efficient torsion through diagonal synergy. Torso to the left: Tighten the ropes on the left posterior Bowden line 4-3 and the right anterior Bowden line 4-2; simultaneously, loosen the left anterior Bowden line 4-1 and the right posterior Bowden line 4-4 appropriately. The left posterior rope pulls the left shoulder backward, and the right anterior rope pulls the right shoulder forward. This pair of forces creates a counterclockwise torque (viewed from above) in the transverse plane, driving the torso to rotate to the left. Torso to the right: Tighten the ropes on the right posterior Bowden line 4-4 and the left anterior Bowden line 4-1; simultaneously, loosen the right anterior Bowden line 4-2 and the left posterior Bowden line 4-3 appropriately. The right posterior rope pulls the right shoulder backward, and the left anterior rope pulls the left shoulder forward. This pair of forces creates a clockwise torque in the transverse plane, driving the torso to rotate to the right.

[0035] This application has disclosed the preferred embodiments as above, but it is not intended to limit this application. Any person skilled in the art who can make some changes or modifications to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A variable-structure trunk rehabilitation training robot, characterized in that, Includes binding devices, rope traction systems, and slide rails; The binding device is worn on the human torso; The slide rail (2) is arranged in a ring around the waist of the human body; The rope traction system includes a drive unit and a corresponding Bowden line; The drive device (1) can be limited to the slide rail (2) or can slide relative to the slide rail (2). The configuration change of the robot can be achieved by changing the distribution position of the drive device on the slide rail (2). One end of the sheath (41) of the Bowden line (4) is connected to the drive device, and the other end of the sheath (41) is connected to the anchor point on the binding device. The torso is pulled by the rope (40) of the Bowden line to generate movement.

2. The variable-structure trunk rehabilitation training robot according to claim 1, characterized in that: The rope traction system includes four sets of drive devices: a left front rope traction drive device (1-1), a right front rope traction drive device (1-2), a left rear rope traction drive device (1-3), and a right rear rope traction drive device (1-4). The four sets of drive devices are independently controlled.

3. A flexible-driven, variable-structure trunk rehabilitation training robot according to claim 1 or 2, characterized in that: The drive device includes a housing (16), a motor (14), a gearbox (13), and a winding wheel (15); the motor (14), the gearbox (13), and the winding wheel (15) are arranged inside the housing (16), the output shaft of the motor (14) is connected to the input end of the gearbox (13), the output shaft of the gearbox (13) is equipped with the winding wheel (15), the rope (40) is wound on the winding wheel (15), one end of the sheath (41) is fixed to the housing (16), and the other end extends to the binding device. The housing (16) can be confined to the slide rail (2) or can slide relative to the slide rail (2).

4. The variable-structure trunk rehabilitation training robot according to claim 3, characterized in that: The slider (10) on the back of the housing (16) is inserted into the groove of the slide rail (2). The slider (10) is provided with a tensioning mechanism. By adjusting the tensioning mechanism, the slider (10) can be limited to the slide rail (2) or slide relative to the slide rail (2).

5. The variable-structure trunk rehabilitation training robot according to claim 1, characterized in that: The binding device includes a shoulder binding strap (5) and an abdominal binding strap (7); the abdominal binding strap (7) is bound to the waist of the human body, and the slide rail (2) is located on the outside of the abdominal binding strap (7); the shoulder binding strap (5) is bound to the chest and shoulders of the human body, and the shoulder binding strap (5) is provided with symmetrically distributed chest anchor points (6) and back anchor points (8), and the ends of the Bowden ropes are connected to the chest anchor points (6) or the back anchor points (8) respectively.

6. A method for motor training of a variable-structure trunk rehabilitation training robot as described in claim 2, characterized in that: By coordinating the changes in the length of the four Bowden lines, torques in different directions are synthesized in space, driving the human torso to perform forward flexion, extension, lateral bending, and torsional movements.

7. The motion training method for a variable-structure trunk rehabilitation training robot according to claim 6, characterized in that: Define the left front rope traction drive device (1-1), right front rope traction drive device (1-2), left rear rope traction drive device (1-3) and right rear rope traction drive device (1-4) as corresponding to the left front Bowden line (4-1), right front Bowden line (4-2), left rear Bowden line (4-3) and right rear Bowden line (4-4), respectively. Simultaneously tighten the ropes along the left anterior Bowden line (4-1) and the right anterior Bowden line (4-2) to generate a downward pull; at the same time, simultaneously release the ropes along the left posterior Bowden line (4-3) and the right posterior Bowden line (4-4), ultimately pulling the shoulders forward and downward, causing the spine to flex forward; simultaneously tighten the ropes along the left posterior Bowden line (4-3) and the right posterior Bowden line (4-4), while simultaneously releasing the ropes along the left anterior Bowden line (4-1) and the right anterior Bowden line (4-2), shortening the posterior ropes, pulling the shoulders backward and downward, causing the spine to extend backward; Simultaneously tighten the ropes on the left front side (4-1) and the left rear side (4-3), while releasing the ropes on the right front side (4-2) and the right rear side (4-4). The rope on the left side shortens as a whole, pulling the left shoulder down and causing the torso to tilt to the left. Simultaneously tighten the ropes on the right front side (4-2) and the right rear side (4-4), while releasing the ropes on the left front side (4-1) and the left rear side (4-3). The rope on the right side shortens as a whole, pulling the right shoulder down and causing the torso to tilt to the right. Tighten the ropes on the left rear Bowden line (4-3) and the right front Bowden line (4-2), while simultaneously loosening the left front Bowden line (4-1) and the right rear Bowden line (4-4). The left rear rope pulls the left shoulder backward, and the right front rope pulls the right shoulder forward. This pair of forces creates a counterclockwise torque on the horizontal plane, driving the torso to rotate to the left. Tighten the ropes on the right rear Bowden line (4-4) and the left front Bowden line (4-1), while simultaneously loosening the right front Bowden line (4-2) and the left rear Bowden line (4-3). The right rear rope pulls the right shoulder backward, and the left front rope pulls the left shoulder forward. This pair of forces creates a clockwise torque on the horizontal plane, driving the torso to rotate to the right.

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