A foot-type robot

Abstract

This application discloses a legged robot for reducing the risk of stalling during forward rolls and minimizing the impact of ground contact on movement safety and stability. The legged robot provided in this application includes: a torso, comprising an upper torso and hips; a head connected to the upper torso; two upper limbs, each connected to the upper torso and each including a corresponding distal end; two lower limbs, each connected to the hips and each including a corresponding distal end; at least one processor; and at least one storage medium storing instructions that, when executed by the at least one processor, cause the legged robot to: respond to a forward roll trigger instruction, control the legged robot to enter a preparatory posture, and perform a forward roll sequence based on the preparatory posture.

Description

Technical Field

[0001] This application relates to the field of robot control technology, and in particular to a legged robot. Background Technology

[0002] Legged robots can establish contact with surfaces such as the ground through their limbs and perform actions such as walking, turning, and posture adjustment. With the development of the mobility of legged robots, some application scenarios have put forward higher requirements for the dynamic movements of robots, such as requiring robots to perform continuous movements similar to forward rolls.

[0003] During a legged robot's forward roll, the robot body needs to rotate forward, bringing the head, torso, or limbs sequentially towards the contact surface. When the robot's head approaches the contact surface, it easily bears the weight of the body and the inertial load of the roll within a short period, resulting in a significant impact upon landing. Furthermore, the head of a legged robot is typically used to house functional components, making its outer shell structure relatively fragile. If the head experiences a large localized load during the forward roll, it can easily damage the head shell, internal components, or the connection structure between the head and torso, thus affecting the reliability of the legged robot's ability to continue performing the forward roll and subsequent motion control. Summary of the Invention

[0004] This application provides a legged robot for reducing the risk of stalling during forward rolls and minimizing the impact of ground impact on motion stability.

[0005] This application provides a legged robot, comprising:

[0006] The trunk, including the upper torso and hips; The head is connected to the upper torso; Two upper limbs, each connected to the upper torso, each upper limb including a corresponding distal end; Two lower limbs are connected to the hip, and each lower limb includes a corresponding lower limb end; At least one processor; And, at least one storage medium storing instructions that, when executed by the at least one processor, cause the legged robot to: In response to a forward roll trigger command, the legged robot is controlled to enter a preparatory posture, and a forward roll sequence is executed based on the preparatory posture; In the preparatory posture, the distance between the hip and the contact surface is a first distance, and the ratio of the first distance to the length of the lower leg is 0.2-0.9; The forward roll sequence includes at least a roll phase, which includes: The head is controlled to move towards the contact surface, and the head and the first of the two upper limbs jointly establish contact with the contact surface to form an initial contact area; the legged robot is controlled to tumble around the initial contact area, and during the tumbling phase, the contact area between the legged robot and the contact surface transitions sequentially from the initial contact area, the back of the upper torso, the hip to the first of the two lower limbs, with the first lower limb and the first upper limb located on different sides of the torso; The rolling phase further includes, after the head and the first upper limb establish contact with the contact surface, controlling the first upper limb to output a force to the contact surface, wherein the reaction force of the contact surface acting on the first upper limb is used to drive the contact area between the legged robot and the contact surface to the first lower limb.

[0007] As can be seen from the above technical solutions, this application has the following advantages: The legged robot responds to the forward roll trigger command by entering a preparatory posture, maintaining the ratio of the initial distance between the hip and the contact surface to the lower leg length at 0.2-0.9. This ensures the robot is in a relatively low position before initiating the forward roll, while also reserving space for the lower limbs to store power and for the torso to lean forward. During the roll phase, the legged robot controls its head to move closer to the contact surface, establishing initial contact with the surface through both the head and the first upper limb. This allows the head and the first upper limb to share the initial ground load of the forward roll. The participation of the first upper limb in contact support reduces the local impact on the head, protecting its structure. Furthermore, as the head and the first upper limb jointly establish the initial contact area, the legged robot's center of gravity can shift towards the side where the first upper limb is located. This allows the legged robot to overcome the critical roll position in the initial stage of the forward roll even with high torso rigidity or insufficient waist folding capacity, thanks to a lateral support posture. During the legged robot's roll around the initial contact area, the contact area transitions sequentially from the initial contact area to the back of the upper torso, the hips, and the first lower limb, allowing the main load-bearing position to continuously migrate along the body as the robot's posture changes. Simultaneously, since the first lower limb and the first upper limb are located on opposite sides of the torso, after the first upper limb exerts force on the contact surface, the reaction force from the contact surface on the first upper limb guides the contact area to shift towards the side where the first lower limb is located. Through this shift, the legged robot can first tilt towards the side where the first upper limb is located, and then transition the contact area towards the side where the first lower limb is located, thereby balancing the lateral deviation during the forward roll and making the robot's overall roll direction closer to straight ahead. This reduces the risk of the robot's roll direction deviating due to excessive unilateral deviation and minimizes the impact of ground impact on the safety and stability of the movement. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 A schematic diagram of the overall structure of a humanoid robot provided as an example of a legged robot for this application; Figure 2 A schematic diagram of the control flow for an embodiment of the legged robot performing a forward roll motion provided in this application; Figure 3 A schematic diagram of a support state of the legged robot provided in this application in a preparatory posture; Figure 4 A schematic diagram of a support state of the legged robot provided in this application during the tumbling phase; Figure 5 A schematic diagram showing the positional relationship between the head contact area of ​​the legged robot provided in this application and the projections of the elbow joints of the two upper limbs; Figure 6 A schematic diagram of the first posture of the legged robot provided in this application during the process of moving the distal end of the first lower limb toward the contact surface; Figure 7 A schematic diagram of the second posture of the legged robot provided in this application during the process of moving the distal end of the first lower limb toward the contact surface; Figure 8 A schematic diagram of a control process for the legged robot provided in this application during the landing phase; Figure 9 A planar schematic diagram of the legged robot provided in this application forming a first supporting polygon during the landing phase. Detailed Implementation

[0010] This application provides a legged robot for reducing the risk of stalling during forward rolls and minimizing the impact of ground impact on motion safety and stability.

[0011] The legged robot provided in this application includes a torso, a head, two upper limbs, two lower limbs, at least one processor, and at least one storage medium. In some embodiments, the legged robot can be a humanoid robot, which is a specific implementation of the legged robot. For ease of description, the following description mainly uses a humanoid robot as an example. Please refer to... Figure 1The torso 3 includes an upper torso 31 and a hip 32, which are rotatably connected via a power module 33. The head 4 is connected to the upper torso 31, and the two upper limbs 1 are each connected to the upper torso 31. The two lower limbs 2 are each connected to the hip 32. For ease of description, the two upper limbs can be referred to as the first upper limb and the second upper limb, and the two lower limbs can be referred to as the first lower limb and the second lower limb. It should be noted that the terms "first upper limb," "second upper limb," "first lower limb," and "second lower limb" are only used to distinguish different limb structures and do not constitute a limitation on specific left and right positions.

[0012] Each upper limb includes an end effector for establishing supporting contact with a contact surface. Each upper limb may also include an upper arm and a forearm. The upper arm is connected to the upper torso, and the forearm is connected to the end effector. The upper arm and forearm are connected via an elbow joint. Each lower limb includes an end effector for establishing supporting contact with a contact surface. Each lower limb may also include a thigh and a lower leg. The thigh is connected to the hip, and the lower leg is connected to the end effector. The thigh and lower leg are connected via a knee joint, enabling the lower limb to adjust its posture between different support states. It should be noted that the contact surface can be the ground, platform surface, sports field surface, cushioning surface, or other bearing surface that can provide support for the legged robot; the end effector of the upper limb can be a hand, a robotic hand, or other end structure that can establish supporting contact with the contact surface; the end effector of the lower limb can be a foot, a foot actuator, or other end structure that can establish supporting contact with the contact surface. This application does not limit the scope of these claims.

[0013] It should be noted that, in the embodiments of this application, "contact" refers to the state in which the limbs, torso, or other body parts of the legged robot are in physical contact with the contact surface; "supporting contact" refers to the state in which the above-mentioned contact provides support to the legged robot, enabling the corresponding part to bear part of the load from the body. Specifically, when a part of the legged robot only makes slight contact, rubbing, or non-load-bearing contact with the contact surface, that part can be understood as having ordinary contact with the contact surface; when there is a contact between that part and the contact surface that can bear the weight of the body or participate in posture stability, that part can be understood as establishing supporting contact with the contact surface. Whether supporting contact is established can be determined by force sensors, tactile sensors, joint torque, motor current, contact pressure distribution, or posture changes.

[0014] Please see Figure 2 , Figure 2 This is a schematic diagram of the control flow for an embodiment of a legged robot performing a forward roll. In this embodiment, at least one storage medium stores instructions that, when executed by at least one processor, cause the legged robot to: 201. In response to the forward roll trigger command, control the legged robot to enter the ready posture; in the ready posture, the distance between the hip and the contact surface is the first distance, and the ratio of the first distance to the length of the lower leg is 0.2-0.9.

[0015] In this embodiment, the forward roll trigger command can be input by the user or automatically generated by the legged robot based on preset tasks, environmental conditions, or motion planning results. In the preparatory posture, the distance between the hip and the contact surface is the first distance. This first distance can be the minimum distance between the hip and the contact surface along the direction of gravity. The length of the lower leg can be the length of the link between the knee joint and the end of the lower limb. The ratio of the first distance to the length of the lower leg is 0.2-0.9, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. When the ratio of the first distance to the length of the lower leg is less than 0.2, the hip is too close to the contact surface, the legged robot has less space for pushing off the ground to store momentum, and the torso and head are easily subject to motion constraints when approaching the contact surface, making it difficult for the robot to generate sufficient initial momentum for a roll. When the ratio of the first distance to the length of the lower leg is greater than 0.9, the hip position is relatively high, and the center of gravity of the legged robot is relatively large, which easily leads to a large impact when the head and the first upper limb make contact with the contact surface. By limiting the first distance within the above ratio range, the hip can be kept in a relatively low position, giving the legged robot a low-position foundation for entering forward roll movements, while reserving the necessary movement space for the lower limbs to push off the ground, the upper body to lean forward, and the head to approach the contact surface.

[0016] 202. Execute a forward roll sequence based on the preparatory posture; the forward roll sequence includes at least a rolling phase, which includes: controlling the head to move towards the contact surface, and making the head and the first of the two upper limbs jointly contact the contact surface to form an initial contact area; controlling the legged robot to roll around the initial contact area, during the rolling phase, the contact area between the legged robot and the contact surface transitions sequentially from the initial contact area, the back of the upper torso, the hip to the first of the two lower limbs, with the first lower limb and the first upper limb located on different sides of the torso; wherein, after the head and the first upper limb establish contact with the contact surface, the rolling phase also includes: controlling the first upper limb to output a force to the contact surface, and the reaction force of the contact surface acting on the first upper limb is used to drive the contact area between the legged robot and the contact surface to transfer to the first lower limb.

[0017] In this embodiment, during the rolling phase, the legged robot first controls its head to move towards the contact surface. Specifically, this can be achieved by adjusting the posture of the upper torso relative to the hips, or by controlling the change in the support height of the two lower limbs to gradually bring the head closer to the contact surface. As the head approaches the contact surface, the legged robot controls the head and the first of the two upper limbs to jointly establish contact with the contact surface, forming an initial contact area. This initial contact area can include the contact area formed between the head and the contact surface, and the contact area formed between the first upper limb and the contact surface. The head and the first upper limb jointly establishing contact with the contact surface can mean that the head and the first upper limb contact the contact surface simultaneously, or that they contact the contact surface sequentially and maintain contact simultaneously for at least a period of time. The head of a legged robot is typically used to mount vision sensors, communication devices, or shell components, and its impact resistance is generally lower than that of the limb structures used to support movement. If only the head establishes contact with the contact surface in the initial stage of the forward roll, the head is easily subjected to concentrated forces, thereby increasing the risk of damage to the head shell, internal components, or connecting structures. In this embodiment, by having the head and the first upper limb jointly establish contact with the contact surface, the ground contact load during the initial stage of the forward roll can be shared by the head and the first upper limb. As a limb support structure, the first upper limb can output force to the contact surface and bear the support reaction force generated by the contact surface, thus sharing the load acting on the head and reducing the local impact on the head.

[0018] After forming an initial contact area, the legged robot rolls around this area. This rolling around the initial contact area can be understood as the legged robot using the initial contact area as the initial load-bearing area for a forward roll, causing the upper torso, hips, and lower limbs to undergo continuous rolling motion relative to the initial contact area. During this process, the contact area between the legged robot and the contact surface sequentially transitions from the initial contact area to the back of the upper torso, then from the back of the upper torso to the hips, and finally to the first of the two lower limbs. It should be noted that this sequential transition of contact areas does not require that only one contact area exists at any given time. When two adjacent contact areas switch, both can maintain contact with the contact surface simultaneously for a period of time. This sequential transition can be understood as the contact area bearing the main load-bearing function migrating sequentially along the body of the legged robot. For example, when transitioning from the initial contact area to the back of the upper torso, the head or the first upper limb may still maintain brief contact with the contact surface; when transitioning from the back of the upper torso to the hips, the back of the upper torso and the hips may also have continuous or overlapping contact.

[0019] In this embodiment, the first lower limb and the first upper limb are located on different sides of the torso. For example, the first upper limb can be the right upper limb and the first lower limb can be the left lower limb; alternatively, the first upper limb can also be the left upper limb and the first lower limb can be the right lower limb. By positioning the first lower limb and the first upper limb on different sides of the torso, after the first upper limb participates in the initial contact support, the legged robot can transfer the subsequent contact area to the first lower limb on the other side of the torso, thereby forming a forward roll path with lateral transition.

[0020] After the head and first upper limb establish contact with the contact surface, the tumbling phase also includes controlling the first upper limb to output force towards the contact surface. After the first upper limb outputs force towards the contact surface, the contact surface generates a support reaction force on the first upper limb. Since the first upper limb is located on one side of the torso, and the first lower limb is located on a different side of the torso, this support reaction force can cause the legged robot's body to move towards the side where the first lower limb is located. Thus, during the process of the legged robot tumbling around the initial contact area, the support reaction force of the contact surface acting on the first upper limb can drive the contact area between the legged robot and the contact surface to shift towards the first lower limb. For legged robots with high torso rigidity or insufficient waist folding ability, it is difficult for the body to complete the initial tumbling of the forward roll by relying on the large flexible bending of the torso itself. In this embodiment, when the head and first upper limb jointly establish contact with the contact surface, the legged robot can form a support posture tilted towards the side where the first upper limb is located, causing the center of mass to shift relative to the contact area between the head and the contact surface towards the side where the first upper limb is located, thereby assisting the body to pass the critical tumbling position in the initial tumbling phase. After the robot completes the initial roll using the lateral support of the first upper limb, if the contact area remains on the side of the first upper limb, the overall rolling direction of the legged robot is prone to deviate to that side, affecting the orientation of the roll. Therefore, this embodiment further utilizes the reaction force received by the first upper limb to guide the contact area from the initial contact area to the back of the upper torso, the hip, and the first lower limb. Since the first lower limb and the first upper limb are located on different sides of the torso, the transfer of the contact area to the first lower limb can compensate for the lateral deviation formed in the initial movement towards the side of the first upper limb. This allows the legged robot to tilt towards the side of the first upper limb first, and then complete the contact with the side of the first lower limb, thus making the overall rolling path closer to the front. Furthermore, the sequential transition of the contact area from the initial contact area to the back of the upper torso, the hip, and the first lower limb allows the supporting effect applied to the legged robot by the contact surface to gradually shift with the robot's posture changes, avoiding a large abrupt change in posture when the robot directly switches from a head-to-ground state to a lower limb-to-ground state. In this way, the joint support of the first upper limb and the head helps to reduce the impact of the head hitting the ground. The shift of the center of mass to the side where the first upper limb is located helps the legged robot to pass the critical rolling position in the early stage of the forward roll. The support reaction force on the first upper limb further guides the contact area to the first lower limb, thereby improving the continuity and stability of the forward roll action and ensuring that the direction of the forward roll action does not deviate.

[0021] In some embodiments, when the head and the first upper limb jointly establish contact with the contact surface, the projection point of the legged robot's center of mass onto the contact surface along the direction of gravity is located on the side of the contact area between the head and the contact surface closer to the first upper limb. In some embodiments, when the head and the first upper limb jointly establish contact with the contact surface, the distal end of the second upper limb does not contact the contact surface, and the center of mass of the legged robot shifts towards the side where the first upper limb is located.

[0022] Please see Figure 3 , Figure 3 This is a schematic diagram of a support state in a preparatory posture. Figure 3 In the illustrated embodiment, the knee joint of the first lower limb of the legged robot establishes supporting contact with the contact surface, and the distal end of the second lower limb establishes supporting contact with the contact surface. By having both the knee joint of the first lower limb and the distal end of the second lower limb participate in the support, the legged robot can maintain a low hip height in the preparatory posture. Thus, after triggering the forward roll sequence, the legged robot can first obtain initial rolling momentum through the reaction force between the lower limbs and the contact surface, and then control the head and first upper limb to move closer to the contact surface and form an initial contact area. It should be noted that... Figure 3 Only one support state in the preparatory posture is shown. In other embodiments, the preparatory posture can also be a support state with both hands and feet on the ground, one knee on the ground, both knees on the ground, or a combination of knees and lower limbs on the ground. As long as the first distance between the hip and the contact surface and the length of the lower leg meet the above-mentioned proportional relationship, and can provide an initial support foundation for the subsequent forward roll sequence, it can be applied to the embodiments of this application. Specific details are not limited here.

[0023] Please see Figure 4 , Figure 4 This is a schematic diagram of a legged robot's support state during the tumbling phase. Figure 4 In the embodiment shown, the legged robot is composed of Figure 3 After entering the tumbling phase from the preparatory posture, the upper torso rotates towards the contact surface, and the head gradually approaches the contact surface, establishing contact with the first upper limb together, thus forming the initial contact area. After the head and the first upper limb jointly form the initial contact area, the legged robot can continue to tumble around this initial contact area. At this time, at least one of the two lower limbs can be in a state of being detached from the contact surface, and the other can also gradually detach from the contact surface after outputting force, so as to reduce the constraint of the lower limbs on the forward tumbling motion of the body. As the body continues to tumble, the contact area can transition from the initial contact area formed by the head and the first upper limb to the upper torso and back, providing a motion basis for the subsequent transfer of the contact area to the hips and the first lower limb. Figure 4 Only one posture is shown where the head and first upper limb establish contact during the rolling phase. In other embodiments, the contact point between the first upper limb and the contact surface, the swinging posture of the two lower limbs, etc., can be adjusted according to the structural dimensions and motion control parameters of the legged robot, as long as the head and first upper limb can jointly form an initial contact area and support the legged robot to continue performing forward rolls around this initial contact area.

[0024] In this embodiment, the legged robot responds to a forward roll trigger command and enters a preparatory posture, maintaining the ratio of the first distance between the hip and the contact surface to the length of the lower leg at 0.2-0.9. This ensures the robot is in a relatively low position before initiating the forward roll, while simultaneously reserving space for the lower limbs to store power and for the torso to lean forward. During the roll phase, the legged robot controls its head to move closer to the contact surface, establishing initial contact with the surface through both the head and the first upper limb. This allows the head and the first upper limb to share the initial ground load of the forward roll. By participating in contact support with the first upper limb, the local impact on the head is reduced, protecting the head structure. Furthermore, when the head and the first upper limb jointly establish the initial contact area, the legged robot's center of gravity can shift towards the side where the first upper limb is located. This allows the legged robot to overcome the critical roll position in the initial stage of the forward roll even when the torso rigidity is high or the waist folding capacity is insufficient, thanks to a lateral support posture. During the legged robot's roll around the initial contact area, the contact area transitions sequentially from the initial contact area to the back of the upper torso, the hips, and the first lower limb, allowing the main load-bearing position to continuously migrate along the body as the robot's posture changes. Simultaneously, since the first lower limb and the first upper limb are located on opposite sides of the torso, after the first upper limb exerts force on the contact surface, the reaction force from the contact surface on the first upper limb guides the contact area to shift towards the side where the first lower limb is located. Through this shift, the legged robot can first tilt towards the side where the first upper limb is located, and then transition the contact area towards the side where the first lower limb is located, thereby balancing the lateral deviation during the forward roll and making the robot's overall roll direction closer to straight ahead. This reduces the risk of the robot's roll direction deviating due to excessive unilateral deviation and minimizes the impact of ground impact on the safety and stability of the movement.

[0025] In some embodiments, during the tumbling phase, at least one of the forearm, the distal end of the forearm, and the elbow joint of the first upper limb, together with the head, makes contact with the contact surface.

[0026] In this embodiment, the first upper limb can establish contact with the contact surface through its forearm, its distal end, its elbow joint, or a combination of these multiple points. After the head and the first upper limb jointly establish contact with the contact surface, the first upper limb can output force to the contact surface through its contact point, and the contact surface will correspondingly generate a support reaction force on the first upper limb. This support reaction force can be transmitted to the upper torso via the first upper limb, thereby participating in the posture adjustment and tumbling actuation of the legged robot. Thus, regardless of whether the first upper limb establishes contact with the contact surface through its forearm, distal end, or elbow joint, as long as the first upper limb can form an effective force transmission at the contact point, it can be used to share the load of the head touching the ground and assist the legged robot in continuing to tumble around the initial contact area.

[0027] In one embodiment, the forearm or elbow joint of the first upper limb can be used to jointly establish contact with the contact surface with the head. Since the upper limb end effector can be a dexterous hand, a robotic hand, or other end-effector, it may contain internal actuators or sensors, and may also include a plastic shell or other structures with relatively weak impact resistance. If the upper limb end effector directly establishes supporting contact with the contact surface during the initial stage of a forward roll, the shell, internal components, or connecting structures are easily damaged by the impact upon ground contact. Therefore, based on this embodiment, by having the forearm or elbow joint of the first upper limb participate in the contact, the direct impact on the upper limb end effector can be reduced, thereby protecting the upper limb end effector structure.

[0028] When the forearm of the first upper limb is used to establish contact with the contact surface along with the head, the forearm, which typically has a large length and contact area, can form a relatively stable support area when in contact with the contact surface. This disperses the load during the initial stage of the forward roll over a wider area, further reducing the impact on the head. Furthermore, after the forearm establishes contact with the contact surface, the first upper limb can output force to the contact surface via the forearm, and the contact surface correspondingly provides a reaction force to the forearm. This reaction force can be transmitted to the upper torso via the first upper limb and participates in guiding the transfer of the contact area between the legged robot and the contact surface to the first lower limb. Since the first lower limb and the first upper limb are located on different sides of the torso, this contact area transfer allows the legged robot to first form lateral support on the side where the first upper limb is located, and then transition the contact area to the side where the first lower limb is located, thereby improving the continuity and directional stability of the forward roll.

[0029] When the elbow joint of the first upper limb and the head jointly establish contact with the contact surface, the first upper limb can be in a bent state, so that the head and the first upper limb form a relatively concentrated initial contact area, which is conducive to the legged robot entering a rolling state around the initial contact area.

[0030] In some embodiments, during the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, the maximum support reaction force exerted by the contact surface on the first upper limb is greater than the maximum support reaction force exerted by the contact surface on the head.

[0031] In this embodiment, since the head of a legged robot is typically equipped with visual sensors, shell components, or other functional devices, by controlling the first upper limb to bear a greater support reaction force during the joint contact process, the main ground contact load in the initial stage of the forward roll is borne more by the first upper limb, thereby reducing the risk of damage to the head structure or internal components. Simultaneously, after the first upper limb bears a larger support reaction force, this force can be transmitted to the upper torso and used to drive the contact area between the legged robot and the contact surface towards the first lower limb. Because the first lower limb and the first upper limb are located on different sides of the torso, in the initial stage of the forward roll, the legged robot can use the initial contact area formed by the head and the first upper limb to first establish a support posture shifted towards the side of the first upper limb, assisting the body in entering the roll state; subsequently, through the larger support reaction force received by the first upper limb, the contact area is guided to the side of the first lower limb, allowing the contact area to transition sequentially from the initial contact area to the back of the upper torso, the hips, and the first lower limb. The maximum support reaction force here can be the peak value of the support reaction force at the corresponding contact point during the duration of contact between the head and the first upper limb and the contact surface.

[0032] This control method allows the first upper limb to bear a greater supporting force, which on the one hand reduces the impact of the head hitting the ground, and on the other hand guides the contact area to transition continuously to the first lower limb, thereby improving the directional stability and continuity of the forward roll.

[0033] Specifically, the contact area relationship between the first upper limb and the head can be adjusted so that the maximum support reaction force exerted by the contact surface on the first upper limb is greater than the maximum support reaction force exerted by the contact surface on the head. In some embodiments, during the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, a first contact area is formed between the head and the contact surface, and a second contact area is formed between the first upper limb and the contact surface, wherein the area of ​​the first contact area is smaller than the area of ​​the second contact area.

[0034] Because the area of ​​the second contact area is larger than that of the first contact area, a larger load-bearing range can be formed between the first upper limb and the contact surface. In some embodiments, the second contact area can be formed by the forearm of the first upper limb contacting the contact surface. Since the forearm has a certain length along the extension direction of the first upper limb, compared with the local contact area formed between the head and the contact surface, the contact area formed by the forearm and the contact surface can be distributed along the extension direction of the forearm, thus making the area of ​​the second contact area larger than that of the first contact area. When the legged robot controls the first upper limb to output force to the contact surface, the first upper limb can transmit the force to the contact surface through the larger area of ​​the second contact area, and the contact surface correspondingly provides a support reaction force to the first upper limb. Compared with the first contact area formed by the head, the larger area of ​​the second contact area can reduce the force concentration per unit area, making the first upper limb more suitable for bearing the main support load in the initial stage of forward roll.

[0035] In some embodiments, during the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, a first contact area is formed between the head and the contact surface, the elbow joint of the first upper limb forms a first projection on the contact surface along the direction of gravity, the elbow joint of the second upper limb forms a second projection on the contact surface along the direction of gravity, and the minimum distance between the first projection and the first contact area is greater than the minimum distance between the second projection and the first contact area.

[0036] Please see Figure 5 , Figure 5 This is a schematic diagram showing the positional relationship between the head contact area and the projections of the elbow joints of both upper limbs. (Example:) Figure 5 As shown, during the process of the head and the first upper limb jointly establishing contact with the contact surface, a first contact area A1 is formed between the head and the contact surface. The elbow joint of the first upper limb forms a first projection P1 on the contact surface along the direction of gravity, and the elbow joint of the second upper limb forms a second projection P2 on the contact surface along the direction of gravity. The first minimum distance between the first projection P1 and the first contact area A1 is d1, and the second minimum distance between the second projection P2 and the first contact area A1 is d2, where d1 is greater than d2.

[0037] Under the aforementioned positional relationship, the first projection P1 is further away from the first contact area A1 relative to the second projection P2, indicating that the first upper limb extends outward relative to the head. After the first upper limb extends outward, a large lateral gap is formed between the contact positions of the head and the first upper limb on the contact surface, meaning that the contact position of the first upper limb has a large lateral lever arm relative to the contact position of the head. When the legged robot continues to roll forward during the initial stage of the forward roll, the weight of the body and the inertial load of the roll are transmitted to the head and the first upper limb through the upper torso. Since the first upper limb extends outward relative to the head, it can bear part of the body load on the side of the head and provide lateral support to the upper torso through the large lateral lever arm. Under this lateral support, one side of the upper torso is constrained by the support of the first upper limb, causing the upper torso to tilt towards the side where the first upper limb is located. During the tilting process of the upper torso towards the side where the first upper limb is located, the projection point of the legged robot's center of mass will move towards the side where the first upper limb is located relative to the first contact area A1 formed by the head. For legged robots with high torso rigidity or insufficient waist folding ability, after the head establishes contact with the contact surface, the contact area near the head becomes a temporary fulcrum during the initial stage of forward roll. Because the torso cannot continue to bend forward sufficiently, the forward movement of the hips and upper torso relative to this temporary fulcrum is limited, and the center of mass projection point cannot move in time to a position that can drive the robot to continue rolling. The robot easily remains in a state of head or upper torso contact. By having the first upper limb participate in support on the side of the head, the upper torso can be tilted towards the side where the first upper limb is located, and the center of mass projection point can be laterally offset relative to the contact area near the head, thus providing attitude space and torque conditions for the robot to continue rolling.

[0038] Furthermore, the first upper limb outputs a force to the contact surface, and the reaction force exerted by the contact surface on the first upper limb can be transmitted to the upper torso via the first upper limb. The direction and location of this reaction force can cause the contact area between the legged robot and the contact surface to shift towards the side where the first lower limb is located. Since the first lower limb and the first upper limb are located on different sides of the torso, after the contact area transitions to the first lower limb, it can balance the lateral displacement formed by the first upper limb side in the early stage, so that the legged robot first tilts towards the side where the first upper limb is located, and then transitions to the side where the first lower limb is located, thereby making the overall rolling path closer to the front.

[0039] Through the aforementioned control method, the first minimum distance d1 between the first projection P1 and the first contact area A1 is greater than the second minimum distance d2 between the second projection P2 and the first contact area A1, enabling the first upper limb to form a support position with a large lateral lever arm on the side of the head. This support position facilitates the tilting of the upper torso towards the side where the first upper limb is located, causing the center of mass to move towards the side where the first upper limb is located, thereby helping the rigid torso robot overcome the critical rolling position in the initial stage of the forward roll; subsequently, the reaction force received by the first upper limb guides the contact area to transfer towards the first lower limb, which helps improve the directional stability and continuity of the forward roll action.

[0040] In some embodiments, during the tumbling phase, before controlling the head to move towards the contact surface and making the head and the first upper limb jointly contact the contact surface, the legged robot is also controlled to: control at least one of the two lower limbs to output a force to the contact surface and then detach from the contact surface, and the support reaction force of the contact surface acting on at least one of the two lower limbs is used to drive the legged robot to tumble, so that the head and the first upper limb jointly contact the contact surface.

[0041] In this embodiment, before controlling the head to move towards the contact surface during the rolling phase and before the head and the first upper limb jointly establish contact with the contact surface, at least one of the two lower limbs can be controlled to output a force to the contact surface and then detach from the contact surface. Here, at least one of the two lower limbs can be the first lower limb, the second lower limb, or both the first and second lower limbs.

[0042] Specifically, when the legged robot is in a ready position, at least one of its two lower limbs can establish supporting contact with the contact surface. The processor can control the joint output driving torque of the lower limb, causing the lower limb to output force to the contact surface through the corresponding lower limb tip, knee, or other contact point. The contact surface correspondingly applies a support reaction force to the lower limb, which can be transmitted through the lower limb to the hip and upper torso, thereby driving the legged robot to generate a tendency to move in the direction of forward roll. Subsequently, the lower limb that output the force disengages from the contact surface, so that the lower limb no longer restricts the body from continuing to roll forward, allowing the head and the first upper limb to continue to approach the contact surface and jointly establish contact with the contact surface, forming an initial contact area. In some embodiments, when the lower limb outputs force to the contact surface, the force can have a component along the direction of forward roll and a component along the side where the first upper limb is located. The support reaction force of the contact surface acting on the lower limb correspondingly drives the center of mass of the legged robot to move in the direction of forward roll and shifts the center of mass towards the side where the first upper limb is located. Thus, before the head and first upper limb jointly make contact with the contact surface, the legged robot has already formed a tendency to tilt towards the side where the first upper limb is located, making it easier for the head and first upper limb to approach the contact surface together and form an initial contact area.

[0043] It should be noted that controlling at least one of the two lower limbs to detach from the contact surface does not require the entire legged robot to be completely airborne. In some embodiments, after one lower limb exerts force and detaches from the contact surface, the other lower limb, upper limb, or part of the torso can continue to maintain contact with the contact surface for a period of time to maintain the controllability of the posture in the early stage of the roll. In other embodiments, the two lower limbs can exert force on the contact surface and detach from it sequentially, allowing the legged robot to obtain more sufficient rolling driving force. By causing at least one of the two lower limbs to exert force on the contact surface and detach from it before the head and the first upper limb jointly contact the contact surface, the reaction force between the lower limb and the contact surface can be used to pre-drive the legged robot into a forward roll motion state and shift the center of mass towards the side where the first upper limb is located. In this way, when the head and the first upper limb establish contact with the contact surface, they mainly receive and guide the already formed roll motion, reducing the possibility that the legged robot relies on the head to collide with the contact surface to initiate the roll, which helps to reduce the impact of the head hitting the ground and improves the continuity of the initial contact area formation process.

[0044] In some embodiments, during the tumbling phase, the distal end of the first lower limb first moves away from the contact surface and then moves towards the contact surface. As the distal end of the first lower limb moves towards the contact surface and the contact area between the legged robot and the contact surface is transferred from the hip to the first lower limb, a plane that intersects the geometrically enclosed area of ​​the thigh, knee joint, and lower leg of the first lower limb is used as a reference plane. The angle between the reference plane and the contact surface is less than 90 degrees and gradually decreases.

[0045] Please see Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the first posture of the distal end of the first lower limb as it moves towards the contact surface. Figure 7 This is a schematic diagram of the second posture of the distal end of the first lower limb as it moves towards the contact surface. Figure 6 and Figure 7 This illustrates the process by which the first lower limb of a legged robot gradually approaches the contact surface during the later stages of a tumbling maneuver, following the changes in the posture of the torso. Figure 6 In the posture shown, the contact area between the legged robot and the contact surface has transitioned from the back of the upper torso to near the hips; Figure 7 In the posture shown, as the first lower limb continues to move closer to the contact surface, the contact area between the legged robot and the contact surface further transitions from the hip to the first lower limb.

[0046] In this embodiment, during the transition of the legged robot from the initial contact area to the back and hips of the upper torso, the distal end of the first lower limb can move away from the contact surface as the lower limb swings, reserving space for relative tumbling between the torso, hips, and lower limbs, reducing the possibility of premature collision between the first lower limb and the contact surface in the first half of the tumbling process. When the contact area between the legged robot and the contact surface shifts from the hips to the first lower limb, the distal end of the first lower limb moves towards the contact surface. At this time, as... Figure 6 As shown, in the initial stage of the first lower limb moving towards the contact surface, the first lower limb can remain bent, and the thigh of the first lower limb has an external rotation posture relative to the hip, causing the side of the first lower limb to deflect towards the contact surface. Figure 7 As shown, as the legged robot continues to tumble, the lower end of the first lower limb moves closer to the contact surface, and the outer side of the first lower limb gradually approaches the contact surface, thus enabling the first lower limb to assume a posture for absorbing the load of the later stage of the tumble.

[0047] As the distal end of the first lower limb moves towards the contact surface, and the contact area between the legged robot and the contact surface shifts from the hip to the first lower limb, a plane that simultaneously intersects the geometrically enclosed areas of the thigh, knee joint, and lower leg of the first lower limb serves as a reference plane. This reference plane can pass through the thigh, knee joint, and lower leg of the first lower limb simultaneously. During this process, the angle between the reference plane and the contact surface is less than 90 degrees, and this angle gradually decreases as the distal end of the first lower limb moves towards the contact surface. This angle can be understood as the angle between the outer region of the first lower limb and the contact surface. Due to the external rotation or abduction of the thigh relative to the hip, the outer region of the first lower limb deflects towards the contact surface, allowing the angle between the reference plane and the contact surface to be less than 90 degrees. Please refer to [link to relevant documentation]. Figure 6 , Figure 6 The thigh of the first lower limb externally rotates relative to the hip, causing the thigh, knee joint, and lower leg of the first lower limb to tilt towards the contact surface A. An angle α is formed between the reference plane B and the contact surface A. This angle α can be an acute angle between the reference plane B and the contact surface A, i.e., angle α can be marked on the outer side of the thigh of the first lower limb. As the first lower limb continues to approach the contact surface, i.e., as... Figure 6 The posture transition shown is to Figure 7 As shown in the posture, the first lower limb continues to approach the contact surface, and the angle α between the reference plane B and the contact surface A further decreases.

[0048] Through the aforementioned posture control, the first lower limb, when approaching the contact surface, can use the outer thigh region, outer knee region, outer calf region, or the side of the lower limb's end as the area closer to the contact surface, allowing the contact area between the legged robot and the contact surface to transition continuously from the hip to the first lower limb. It should be noted that if the first lower limb contacts the contact surface with the sole of its foot early, the sole of the foot can easily form a more stable blocking support, causing the torso to be constrained by the lower limb's end before completing the roll, thus increasing the risk of roll stoppage or foot impact. This embodiment reduces the likelihood of the sole of the first lower limb establishing contact with the contact surface first by controlling the external rotation of the first lower limb and gradually decreasing the angle between the reference plane and the contact surface. Furthermore, as the side region of the first lower limb gradually approaches the contact surface, the first lower limb can coordinate with knee flexion, creating a folded posture between the thigh and calf suitable for close contact with the contact surface. Therefore, the first lower limb can bear the body load after the hip and provide a posture basis for subsequent lower limb end support contact, thereby improving the continuity of the forward roll and landing stability.

[0049] In some embodiments, when the distal end of the first lower limb establishes contact with the contact surface, the distal end of the first lower limb establishes contact with the contact surface through the side of the foot.

[0050] In this embodiment, as the distal end of the first lower limb moves towards the contact surface, the legged robot can control the thigh of the first lower limb to externally rotate or abduct relative to the hip, and coordinate with the knee joint flexion of the first lower limb to bring the distal end of the first lower limb closer to the contact surface in an inclined posture. In this way, the sole of the foot maintains a certain angle relative to the contact surface, making it easier for the side of the foot to establish contact with the contact surface first. By having the distal end of the first lower limb establish contact with the contact surface through the side of the foot, the possibility of the sole of the foot forming planar support too early in the later stages of the roll can be reduced. If the sole of the foot contacts the contact surface too early before the torso has completed the roll, the sole of the foot can easily form a stable obstruction to the distal end of the lower limb, restricting the continued rolling of the hip and torso, thus increasing the risk of roll stalling. In this embodiment, the side contact of the foot allows the distal end of the first lower limb to bear the load of the later stages of the roll with a smaller contact area or an inclined contact posture, allowing the contact area to transition further from the hip to the first lower limb, and reserving movement space for the distal end of the lower limb to adjust to a stable support posture later. Furthermore, side contact with the foot can reduce the collision between the bottom of the foot and the contact surface, allowing the lower limb end to roll or adjust its posture after contact, thus reducing the impact on the lower limb end and improving the continuity of the contact area from the hip to the first lower limb.

[0051] In some embodiments, during the tumbling phase, at the initial moment when the first lower limb establishes contact with the contact surface, the lower limb end of the second lower limb is suspended in the air, the knee joint angle of the first lower limb is 30° to 100°, and the knee joint angle of the second lower limb is greater than that of the first lower limb.

[0052] In this embodiment, at the initial moment when the first lower limb establishes contact with the contact surface, keeping the tip of the second lower limb suspended in the air prevents it from prematurely forming support with the contact surface. Since the legged robot is still in the later stages of a roll at this time, if the tip of the second lower limb touches the ground prematurely, it can easily constrain the body before the hip or the first lower limb has completed the contact transition, hindering the continued rolling motion of the torso and increasing the impact on the lower limb tip. By keeping the tip of the second lower limb suspended at this initial moment, the contact area can preferentially transition from the hip to the first lower limb, allowing the first lower limb to bear the brunt of the later stages of the roll, thereby improving the continuity of the contact area transition.

[0053] The knee angle of the first lower limb is between 30° and 100°, such as 30°, 45°, 60°, 75°, 90°, and 100°. This allows the first lower limb to maintain a relatively pronounced flexion. When the knee angle of the first lower limb is less than 30°, the degree of flexion is too great, and the distance between the thigh and lower leg is too small, which can easily cause movement interference between the structures of the first lower limb itself and reduce the effective space of the contact surface in the lateral area of ​​the first lower limb. When the knee angle of the first lower limb is greater than 100°, the first lower limb tends to extend, and the lower limb tip has a large swing radius relative to the hip. When the lower limb tip moves towards the contact surface, it is easy to impact the contact surface with a large speed or contact force, thereby increasing the risk of injury. At the same time, excessive extension of the first lower limb weakens the cushioning effect of the lateral thigh area, knee joint area, lateral lower leg area, or the lateral side of the lower limb tip, making the transition of the contact area from the hip to the first lower limb less smooth. By limiting the knee joint angle of the first lower limb to 30° to 100°, the first lower limb can maintain a flexed posture suitable for lateral contact while avoiding excessive folding. This facilitates the participation of the outer thigh area, knee joint area, outer calf area, or lower limb end side in the contact transition, reduces the possibility of the lower limb end contacting the contact surface with a large impact force, and improves the continuity of the contact area migration after the roll.

[0054] Furthermore, the knee angle of the second lower limb is greater than that of the first lower limb, placing the second lower limb in a more extended position relative to the first. This allows the second lower limb to maintain a larger support preparation posture while the first lower limb absorbs the load from the subsequent roll, enabling the distal end of the second lower limb to move more smoothly towards the contact surface and establish support contact during the landing phase. Consequently, the first and second lower limbs have distinct roles: the first lower limb participates in the contact area transition during the roll with a smaller knee angle, while the second lower limb prepares for subsequent landing support with a larger knee angle, thereby reducing the risk of roll stoppage and improving stability during landing.

[0055] In some embodiments, the forward roll sequence further includes a landing phase following the roll phase, the landing phase including: Control the lower limb end to establish contact with the contact surface, and control the center of mass of the legged robot to move along the direction of gravity to the projection point of the center of mass on the contact surface to the first support polygon defined by the contact area of ​​the two lower limbs on the contact surface.

[0056] At the initial moment when the first lower limb establishes contact with the contact surface in the aforementioned embodiment, the distal end of the second lower limb is suspended in the air. The knee joint angle of the first lower limb is 30° to 100°, and the knee joint angle of the second lower limb is greater than that of the first lower limb. In this embodiment, the forward roll sequence also includes a landing phase following the roll phase. In the later stage of the roll phase, the first lower limb participates in the transition of the contact area from the hip to the first lower limb in a bent posture, while the distal end of the second lower limb remains suspended in the air. This prevents the second lower limb from prematurely touching the ground before the first lower limb has completed its contact, thus avoiding hindering the continued roll of the torso. Simultaneously, because the knee joint angle of the second lower limb is greater than that of the first lower limb, the second lower limb is in a more extended state relative to the first lower limb. During the landing phase, the legged robot controls the distal end of the second lower limb to move towards the contact surface, establishing contact between the distal end of the second lower limb and the contact surface. At this point, the first lower limb has already established contact with the contact surface in the later stage of the tumbling phase. After the distal end of the second lower limb also establishes contact with the contact surface, the two lower limbs can jointly form a support area on the contact surface. This support area is jointly defined by the contact areas of the first lower limb and the second lower limb on the contact surface, forming a first support polygon.

[0057] The contact area of ​​the first lower limb on the contact surface includes the contact area formed by at least one of the following: the lateral thigh region, the knee joint region, the lateral calf region, the sole of the foot, and the side of the foot, and the contact area formed by the first lower limb with the contact surface. The contact area of ​​the second lower limb on the contact surface includes the contact area formed by the distal end of the second lower limb with the contact surface, such as the contact area formed by the toe region, the sole of the foot, and the side of the foot with the contact surface. The first supporting polygon can be defined by the outer boundaries of the contact areas of the first and second lower limbs on the contact surface, or it can be formed by connecting multiple support points selected in the aforementioned contact areas. In some embodiments, the first supporting polygon can be defined by the knee joint region of the first lower limb and the distal end of the second lower limb; in other embodiments, the first supporting polygon can be defined by the side of the foot of the distal end of the first lower limb and the distal end of the second lower limb; in still other embodiments, the first supporting polygon can be defined by the knee joint region of the first lower limb, the distal end of the first lower limb, and the distal end of the second lower limb. Depending on the actual contact state between the first lower limb and the contact surface, the outer thigh region or the outer calf region of the first lower limb may also participate in defining the first supporting polygon.

[0058] When the centroid projection point enters the first supporting polygon, the legged robot can stably transition from the late tumbling posture to the posture where both lower limbs are in contact with the contact surface, reducing the possibility of the robot continuing to tilt to one side, thereby improving the stability of the forward roll action from the tumbling phase to the landing phase.

[0059] In some embodiments, please refer to Figure 8 , Figure 8 This is a control flow diagram for the implementation phase, which specifically includes: 801. Control the lower limb end of the second lower limb to establish contact with the contact surface. The lower limb end of the second lower limb, the knee joint of the first lower limb, and the lower limb end of the first lower limb together form a first supporting polygon on the contact surface. Control the centroid projection point to move into the first supporting polygon. In the later stages of the tumbling phase, the first lower limb has already established contact with the contact surface in a flexed posture. At this point, the processor controls the lower limb tip of the second lower limb to move towards the contact surface and establish contact with the contact surface. After the lower limb tip of the second lower limb establishes contact, the lower limb tip of the second lower limb, the knee joint of the first lower limb, and the lower limb tip of the first lower limb form at least three support positions on the contact surface, thereby collectively constituting the first support polygon.

[0060] Please see Figure 9 , Figure 9 This is a planar schematic diagram illustrating the formation of the first supporting polygon by a legged robot during the landing phase. Figure 9In the illustrated embodiment, the knee joint of the first lower limb and the contact surface form a first lower limb knee support region 901, the lower limb distal end of the first lower limb and the contact surface form a first lower limb distal end support region 902, and the lower limb distal end of the second lower limb and the contact surface form a second lower limb distal end support region 903. The first lower limb knee support region 901, the first lower limb distal end support region 902, and the second lower limb distal end support region 903 together define a first support polygon 900.

[0061] Taking the understanding that the first supporting polygon is jointly determined by all supporting regions as an example, convex hull calculations can be performed on the outer boundaries of the first lower limb knee supporting region 901, the first lower limb end supporting region 902, and the second lower limb end supporting region 903. The smallest convex hull closed polygon including all supporting points is taken, and the outer contour region obtained from the convex hull calculation is taken as the first supporting polygon 900. At this time, the first supporting polygon 900 covers the first lower limb knee supporting region 901, the first lower limb end supporting region 902, the second lower limb end supporting region 903, and the area enclosed by the outer boundaries of the convex hulls between each supporting region. When the projection point of the legged robot's center of mass on the contact surface along the direction of gravity is located within the first supporting polygon 900, it can be considered that the center of mass of the legged robot falls within the stable supporting range jointly defined by the above three supporting regions.

[0062] Taking the understanding that the first supporting polygon is constructed from supporting points in the supporting regions as an example, at least one supporting point can be selected from the first lower limb knee supporting region 901, the first lower limb distal supporting region 902, and the second lower limb distal supporting region 903, and the first supporting polygon 900 can be constructed based on the selected supporting points. For example, a first supporting point can be selected from the first lower limb knee supporting region 901, a second supporting point can be selected from the first lower limb distal supporting region 902, and a third supporting point can be selected from the second lower limb distal supporting region 903. After connecting the first, second, and third supporting points, a triangular supporting region can be formed, and this triangular supporting region can be used as the first supporting polygon 900. In other embodiments, multiple supporting points can also be selected from any supporting region to form a convex-edge supporting polygon with more sides.

[0063] In some embodiments, the centroid projection point is considered to be within the first support polygon 900, calculated from the outer boundary convex hulls of the first lower limb knee support region 901, the first lower limb distal support region 902, and the second lower limb distal support region 903. In other embodiments, the centroid projection point is also considered to be within the first support polygon 900 when it is located within the convex edge support polygon constructed from the selected support points.

[0064] After the first supporting polygon is formed, the processor controls the legged robot's center of mass to move along the direction of gravity onto the contact surface, where the center of mass projection point is located, into the first supporting polygon. When the center of mass projection point enters the first supporting polygon, the legged robot can transition from a lateral support state in the later stages of tumbling to a relatively stable multi-point support state, reducing the possibility of the robot continuing to tip over in the tumbling direction.

[0065] 802. After the center of mass falls into the first supporting polygon, control the knee joint of the first lower limb to move away from the contact surface, and control the center of mass to rise. During the process of raising the center of mass, keep the projection point of the center of mass within the second supporting polygon formed by the lower limb ends of the first lower limb and the lower limb ends of the second lower limb on the contact surface.

[0066] After the center of mass projection point has entered the first supporting polygon, the legged robot has the stable conditions to switch from a knee-supported state to a dual-limb end-supported state. At this point, the processor can control the knee joint of the first lower limb to move away from the contact surface, gradually releasing the knee joint from the contact surface. Simultaneously, the processor controls the extension of the first and second lower limbs to move the hips and upper torso away from the contact surface, thereby raising the center of mass of the legged robot. After the knee joint of the first lower limb leaves the contact surface, the legged robot mainly relies on the distal ends of the first and second lower limbs to establish support with the contact surface. The contact areas of the distal ends of the first and second lower limbs on the contact surface together constitute the second supporting polygon. The understanding of the second supporting polygon is similar to that of the first supporting polygon, and will not be repeated here.

[0067] During the lifting of the center of mass, the processor maintains the projection point of the center of mass within the second support polygon. In this way, after the knee joint of the first lower limb is released from contact, the legged robot can still maintain stability by relying on the ends of the two lower limbs, reducing the risk of the robot tipping forward, backward, or sideways during the lifting of the center of mass.

[0068] Through steps 801 and 802 described above, the legged robot first utilizes the distal end of the second lower limb, the knee joint of the first lower limb, and the distal end of the first lower limb to form a first supporting polygon, allowing the body load during the later stages of the roll to enter a stable support range. Subsequently, with the center of mass projection point located within the first supporting polygon, the knee joint of the first lower limb is controlled to lift off the ground and the center of mass is raised, while simultaneously maintaining the center of mass projection point within the second supporting polygon formed by the distal ends of the two lower limbs. Thus, the legged robot can continuously transition from a roll-bearing state to a state supported by both distal ends of the lower limbs, improving the stability of the landing phase of the forward roll.

[0069] In some embodiments, in the preparatory posture, the knee joint of the first lower limb remains in contact with the contact surface, and the lower limb tip of the second lower limb remains in contact with the contact surface; before controlling the head to move towards the contact surface and making the head and the first upper limb jointly establish contact with the contact surface, the tumbling phase further includes: controlling the first lower limb to output a force to the contact surface and then detach from the contact surface; after the lower limb tip of the first lower limb detaches from the contact surface, the tumbling phase further includes: controlling the second lower limb to output a force to the contact surface and then detach from the contact surface, so as to drive the legged robot to tumble.

[0070] In the preparatory posture of this embodiment, the knee joint of the first lower limb remains in contact with the contact surface, and the lower limb tip of the second lower limb remains in contact with the contact surface. That is to say, before the legged robot enters the forward roll action, it can use the knee joint of the first lower limb and the lower limb tip of the second lower limb to jointly support the body, keep the hip in a low position, and give the upper torso a posture basis for tilting towards the contact surface.

[0071] Building upon this, before controlling the head to move towards the contact surface and establishing contact between the head and the first upper limb, the tumbling phase may further include: controlling the first lower limb to output a force towards the contact surface and then detach from it. Specifically, the processor can control the hip or knee joints of the first lower limb to output torque, causing the first lower limb to output a force towards the contact surface. The contact surface correspondingly applies a reaction force to the first lower limb, which is transmitted through the first lower limb to the hip and upper torso, thereby causing the legged robot to generate an initial tendency to tumble forward. After the first lower limb outputs a force towards the contact surface, the processor controls the knee joint of the first lower limb to detach from the contact surface. After the knee joint of the first lower limb detaches from the contact surface, the constraint of the first lower limb on the forward tumbling motion of the body is reduced, allowing the upper torso and head to continue moving towards the contact surface. After the contact between the first lower limb and the contact surface is released, the tumbling phase also includes controlling the second lower limb to output a force towards the contact surface and then detach from it, so as to continue driving the legged robot to tumble. Specifically, the second lower limb can output force to the contact surface through its distal end. The reaction force exerted by the contact surface on the second lower limb is transmitted through the second lower limb to the hip and upper torso, thereby further driving the legged robot to roll forward. After the second lower limb leaves the contact surface, the degree of constraint on the legged robot by the distal end of the lower limb is reduced, and the head and the first upper limb can continue to approach the contact surface and form an initial contact area, or the legged robot can continue to tumble around the already formed initial contact area. It should be noted that the moment when the second lower limb outputs force to the contact surface and leaves the contact surface can occur before the head and the first upper limb jointly establish contact with the contact surface, can overlap with the process of the head and the first upper limb establishing contact, or can occur after the head and the first upper limb jointly establish contact with the contact surface.

[0072] In one specific implementation, after the head and first upper limb jointly establish contact with the contact surface to form an initial contact area, the processor then controls the second lower limb to output force to the contact surface and then detach from the contact surface. The second lower limb can output force to the contact surface through its distal end, and the reaction force exerted by the contact surface on the second lower limb is transmitted through the second lower limb to the hip and upper torso to continue driving the legged robot to tumble around the initial contact area. By having the second lower limb output force after the head and first upper limb have jointly established contact with the contact surface, the legged robot can always maintain a load-bearing contact base in the initial stage of forward roll. That is, after the knee joint of the first lower limb detaches from the contact surface, the distal end of the second lower limb still maintains support, preventing the body from experiencing a large airborne state before the head and first upper limb touch the ground; after the head and first upper limb form the initial contact area, the second lower limb pushes off the ground to detach from the contact surface, which can further increase the tumbling driving force on the basis of the existing initial contact area.

[0073] In this way, even after the first lower limb detaches from the contact surface, the second lower limb can still provide support for the body, reducing the possibility of the legged robot becoming airborne before the head and first upper limb establish an initial contact area. Once the head and first upper limb have jointly established contact with the contact surface, the second lower limb then exerts force and detaches from the contact surface, supplementing the rolling drive force even when the initial contact area is already capable of bearing the body's load. This reduces the risk of the head bearing the impact alone, helps protect the head structure, and improves the continuity of the legged robot's transition from the preparatory posture to the rolling phase.

[0074] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0076] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0077] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0078] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A legged robot, characterized in that, include: The torso includes an upper torso and hips, the upper torso and the hips being rotatably connected via a power module; The head is connected to the upper torso; Two upper limbs, each connected to the upper torso, each upper limb including a corresponding distal end; Two lower limbs are connected to the hip, and each lower limb includes a corresponding lower limb end; At least one processor; And, at least one storage medium storing instructions that, when executed by the at least one processor, cause the legged robot to: In response to a forward roll trigger command, the legged robot is controlled to enter a preparatory posture, and a forward roll sequence is executed based on the preparatory posture; In the preparatory posture, the distance between the hip and the contact surface is a first distance, and the ratio of the first distance to the length of the lower leg is 0.2-0.

9. The forward roll sequence includes at least a roll phase, which includes: The head is controlled to move towards the contact surface, and the head and the first of the two upper limbs jointly establish contact with the contact surface to form an initial contact area; the legged robot is controlled to tumble around the initial contact area, and during the tumbling phase, the contact area between the legged robot and the contact surface transitions sequentially from the initial contact area, the back of the upper torso, the hip to the first of the two lower limbs, with the first lower limb and the first upper limb located on different sides of the torso; The rolling phase further includes, after the head and the first upper limb establish contact with the contact surface, controlling the first upper limb to output a force to the contact surface, wherein the reaction force of the contact surface acting on the first upper limb is used to drive the contact area between the legged robot and the contact surface to the first lower limb.

2. The legged robot according to claim 1, characterized in that, During the tumbling phase, at least one of the forearm, the distal end of the upper limb, and the elbow joint of the first upper limb, together with the head, makes contact with the contact surface.

3. The legged robot according to claim 2, characterized in that, During the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, the maximum support reaction force exerted by the contact surface on the first upper limb is greater than the maximum support reaction force exerted by the contact surface on the head.

4. The legged robot according to claim 2, characterized in that, During the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, a first contact area is formed between the head and the contact surface, and a second contact area is formed between the first upper limb and the contact surface. The area of ​​the first contact area is smaller than the area of ​​the second contact area.

5. The legged robot according to claim 2, characterized in that, During the tumbling phase, as the head and the first upper limb jointly establish contact with the contact surface, a first contact area is formed between the head and the contact surface. The elbow joint of the first upper limb forms a first projection on the contact surface along the direction of gravity. The elbow joint of the second upper limb forms a second projection on the contact surface along the direction of gravity. The minimum distance between the first projection and the first contact area is greater than the minimum distance between the second projection and the first contact area.

6. The legged robot according to claim 2, characterized in that, During the tumbling phase, before controlling the head to move towards the contact surface and before the head and the first upper limb jointly establish contact with the contact surface, the legged robot is also made to: After controlling at least one of the two lower limbs to output a force to the contact surface and then detach from the contact surface, the reaction force of the contact surface acting on at least one of the two lower limbs is used to drive the legged robot to roll, so that the head and the first upper limb jointly establish contact with the contact surface.

7. The legged robot according to claim 1, characterized in that, During the tumbling phase, the distal end of the first lower limb first moves away from the contact surface, and then moves towards the contact surface. As the distal end of the first lower limb moves towards the contact surface, and the contact area between the legged robot and the contact surface is transferred from the hip to the first lower limb, a plane that intersects the geometrically enclosed area of ​​the thigh, knee joint, and lower leg of the first lower limb is used as a reference plane. The angle between the reference plane and the contact surface is less than 90 degrees and gradually decreases.

8. The legged robot according to claim 1, characterized in that, When the lower limb tip of the first lower limb makes contact with the contact surface, the lower limb tip of the first lower limb makes contact with the contact surface through the side of the foot.

9. The legged robot according to claim 1, characterized in that, During the tumbling phase, at the initial moment when the first lower limb establishes contact with the contact surface, the lower limb end of the second lower limb is suspended in the air, the knee joint angle of the first lower limb is 30° to 100°, and the knee joint angle of the second lower limb is greater than that of the first lower limb.

10. The legged robot according to claim 9, characterized in that, The forward roll sequence also includes a landing phase following the roll phase, the landing phase including: Control the lower limb end of the second lower limb to establish contact with the contact surface, and control the center of mass of the legged robot to move along the direction of gravity to the projection point of the center of mass on the contact surface to the first support polygon defined by the contact area of ​​the two lower limbs on the contact surface.

11. The legged robot according to claim 10, characterized in that, The implementation phase includes: The lower limb of the second lower limb is controlled to establish contact with the contact surface. The lower limb of the second lower limb, the knee joint of the first lower limb, and the lower limb of the first lower limb together form a first supporting polygon on the contact surface. The centroid projection point is controlled to move into the first supporting polygon. After the center of mass falls into the first supporting polygon, the knee joint of the first lower limb is controlled to move away from the contact surface, and the center of mass is controlled to rise. During the rising of the center of mass, the projection point of the center of mass is maintained within the second supporting polygon formed by the lower limb ends of the first lower limb and the lower limb ends of the second lower limb on the contact surface.

12. The legged robot according to any one of claims 1 to 11, characterized in that, In the preparatory posture, the knee joint of the first lower limb remains in contact with the contact surface, and the lower limb tip of the second lower limb of the two lower limbs remains in contact with the contact surface; Before controlling the head to move towards the contact surface and making the head and the first upper limb jointly make contact with the contact surface, the tumbling phase further includes: controlling the first lower limb to output a force towards the contact surface and then detach from the contact surface; After the knee joint of the first lower limb disengages from the contact surface, the rolling phase further includes: controlling the second lower limb to output a force to the contact surface and then disengage from the contact surface, so as to drive the legged robot to roll.

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