Bionic bouncing robot for exploration and reconnaissance

Abstract

The invention discloses a bionic bouncing robot for exploration and reconnaissance, which comprises a tail driving assembly, a tail bionic structure, a series elastic driver, a leg bionic structure and an external framework, and is characterized in that the tail driving assembly controls the tail structure through a cable to adjust the bending degree of the tail so as to keep the stability of a machine body in a flying stage; the series elastic drivers are used for driving the leg bionic structures, the drivers have the effect of absorbing external impact, so that the stability of the robot is further improved, it is guaranteed that the motion trail of the tail ends of the connecting rods presents an approximate straight line through the leg structures of the bionic diving mouse, and the stability of the robot is improved. Inappropriate take-off angular momentum cannot be added to the whole robot, the motor adjusts the bending degree of the tail through the cable, the stability of the fuselage in the flying stage is more accurately and conveniently adjusted, and due to the fact that a spring is arranged in the driving device, the situation that a connecting rod mechanism is structurally damaged by huge ground counterforce can be prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of hopping robots, and specifically to a hopping mouse-like hopping robot. Background Art

[0002] With the increasing demands for tasks such as human interstellar exploration, rescue surveys, and military reconnaissance, higher requirements are put forward for the comprehensive performance of robots. Compared with tracked and wheeled mobile robots, the spatial range between consecutive landing points of hopping robots is large, the robot has good mobility, is flexible in movement, and can better adapt to changing complex environments. At the same time, due to the presence of an efficient energy storage mechanism, hopping robots have extremely strong motion burst capabilities and can cross extremely high obstacles. Therefore, hopping robots show great advantages in terms of movement flexibility, environmental adaptability, and energy utilization efficiency, and are widely used in various rescue survey tasks, which can effectively reduce the technical and economic costs of robots and fully and reasonably guide the development of robots towards health, environmental protection, and sustainability.

[0003] Traditional hopping robots have certain limitations in terms of hopping height and attitude stability due to problems such as less energy storage and unreasonable structures. With the development of bionics, many scholars are committed to integrating bionic principles with robot design technologies. By imitating the jumping mechanisms evolved by animals over thousands of years and drawing on their unique body structures and movement methods, it is ensured that hopping robots can jump over obstacles in complex unstructured environments.

[0004] Currently, the research on hopping bionic robots mainly focuses on the design of bionic mechanisms, efficient energy storage mechanisms, compliant control, etc. Mechanism bionics is guided by the bone structure of organisms and imitates the movement methods of each unit of organisms. Although there are jumping organisms as references, how to design an efficient energy storage mechanism to achieve the extremely high hopping performance of organisms remains a current research hotspot. Early research mainly tended to install energy storage components such as extension springs, compression springs, and torsion springs in leg joints, and at the same time used latching devices such as ratchet pawls, incomplete gears, and cams for the release and storage of spring energy. Since the release of this energy is difficult to control, it ultimately leads to unstable postures of hopping robots during the airborne phase. At the same time, the storage and release of hopping energy require the pre-closing and opening of latches, resulting in significant time delays, so that most hopping robots can only achieve intermittent jumps. Series elastic actuators can continuously amplify the output torque and buffer huge contact reaction forces by installing elastic elements between the motor and the load (Lee et al. 2019). Currently, series elastic actuators are widely used in the fields of rehabilitation and exoskeleton robots, and rich research results have been obtained (Ghidini et al. 2019).

[0005] In 1999, the California Institute of Technology and the Jet Propulsion Laboratory of the National Aeronautics and Space Administration jointly developed a hopping robot for planetary surface exploration, which is suitable for simple exploration tasks in low-gravity environments. The overall shape of the hopping robot is approximately eggshell-shaped and has the ability to self-right. The hopping motion is driven by the elastic energy stored in the spring, and the motor also provides the orientation of the body by moving the position of the center of gravity towards the direction of the next jump, enabling the robot to continuously adjust the takeoff attitude angle (Fiorini et al., 1999). In 2002, the University of Minnesota developed and designed a Scout robot based on the distributed robot system platform. The basic shape of the robot is cylindrical, and a ground wheel is installed at each end, allowing it to move on relatively flat surfaces. When the robot needs to cross an obstacle, the winch rotates rapidly, causing the cable to contract, which in turn drives the steel spring foot to bend to a certain angle. During this process, the steel spring continuously stores the huge energy required for jumping. When the winch is suddenly released, the stored energy is released instantaneously, causing the steel spring foot to hit the ground rapidly and generate a bouncing force (Stoeter et al., 2002).

[0006] In 2006, Umberto et al. (2007) from the IMT Lucca School of Advanced Studies in Italy developed a hopping robot, Grillo I. The frog-inspired Grillo I robot is a quadruped 50-mm robot with elastic elements in its front legs and inclined hind legs. Elastic energy is stored by loading two springs in the hind legs through a motor. Based on Grillo I, Li Fei et al. from Zhejiang University focused on the biological analysis of the hind legs of leafhoppers and found that a constant contact reaction force is generated when the leg structure contacts the ground. According to this discovery, the leg structure was designed as a spatial four-bar linkage mechanism, and the energy instantaneous release system was designed as a spring segmented gear mechanism. The spring is loaded during gear meshing and released after meshing, further developing the Grillo II hopping robot. Subsequently, Li Fei (2011) added a flexible wing to the Grillo II robot, which quickly unfolds after takeoff to improve flight stability, resulting in the Grillo III micro hopping robot.

[0007] In 2008, the École Polytechnique Fédérale de Lausanne conducted in-depth research on the hopping mechanism and hind leg structure of grasshoppers. The legs were designed as a four-bar linkage mechanism, and the power output by the motor was transmitted to the cam through gear reduction, enabling the torsion spring to store a huge amount of energy. The energy is locked and released through the cam structure. The robot is designed for intermittent hopping and weighs only 7 grams, with a jumping height of up to 1 m (M. Kovac et al., 2008).

[0008] In 2009, Wang Meng (2009) from Harbin Institute of Technology observed the jumping mechanism and movement trajectory of frogs and developed a jumping robot. The leg structure of the robot's hind legs is simplified to a five-bar mechanism, which can have a similar dynamic feedback when in contact with the ground as that of a frog during jumping.

[0009] Researchers at the University of California developed the jumping robots Salto and Salto-1p based on the bionic object of infant monkeys. The researchers found that infant monkeys would crouch for a long time after landing to prepare for the next jump. Inspired by this, Salto adopts the SE+MA concept, and the resulting takeoff power will be greater than the peak power provided by the motor. The robot also incorporates the variable mechanical advantage method into the design of the eight-link leg structure. The motor drives the series-connected torsion springs through a reduction gearbox to release the stored energy to the eight-bar mechanism. Based on Salto, Salto-1p adds a tail offset mass block on the side of the whole machine, and two small propellers can further control the attitude of the robot itself (Haldane etal. 2016).

[0010] Bai Long et al. (2018) from Northwestern Polytechnical University proposed a bouncing robot that uses a ten-bar mechanism as the bouncing execution device and stores energy in a linear spring and a coil through the rotation of the motor. Summary of the Invention

[0011] The present invention intends to design a bionic bouncing robot for reconnaissance and survey, which can carry lightweight survey instruments and perform long-term bouncing movements. Specifically, it includes a bionic leg mechanism, a joint-hinged tail, a SEA series elastic actuator, and an external support frame. The overall structure of the robot has a reasonable center of gravity and mass distribution. Key components and load-bearing parts have reasonable mechanical properties such as strength and stiffness. By studying the control algorithms of the bionic leg and tail motors, the leg driving ability and tail attitude adjustment effect are improved, enabling the robot to have excellent bouncing performance and accurately achieve attitude adjustment, which has very important scientific research significance and engineering application value in the field of mechanism bionics and rescue survey.

[0012] To achieve the above object, the present invention provides the following technical solutions: A bionic bouncing robot dedicated to exploration and reconnaissance, including: An external frame, which includes a motor fixing seat, a connecting rod support frame, an upper frame, a lower frame, a left frame, and a right frame. The rear ends of the left frame and the right frame are installed with connecting devices for the tail bionic structure and the leg bionic structure.

[0013] The series elastic actuator mainly consists of an end cover, an elastic element, a support ring, a left support cover, a thin-wall bearing, a deep groove ball bearing, an output end, a cycloid disc, a transmission plate, a cycloid pin wheel, a right support ring, a leg motor and a motor bracket. The support ring, the left support cover, the cycloid pin wheel, the thin-wall bearing, the cycloid disc, the deep groove ball bearing, the crankshaft, the output end, the transmission plate, the leg motor, the right support cover and the motor bracket form a reducer. The cycloid pin wheel reducer is adopted for the reducer. When transmitting power, it will not produce large deformation, is not easy to cause fatigue damage, and has the characteristics of shock resistance, large transmission ratio and high transmission accuracy. The elastic element includes an outer ring and an inner ring. The outer ring is connected to the link end, and the inner ring is connected to the output end of the reducer. The leg motor adopts a brushless motor, which has the advantages of high movement efficiency, low energy consumption, long service life, stable and reliable performance, and faster response speed.

[0014] The leg bionic structure includes an output rod, a single-degree-of-freedom Stephenson type six-bar mechanism, a frame and a link base. The frame is connected to the above-mentioned external frame. The output rod is connected to the above-mentioned leg motor. The link base is used to support the whole body. The six-bar mechanism imitates the leg structure of a jerboa. There is a certain proportional relationship between the rods, which can keep the movement trajectory of the link end approximately a straight line, avoiding the generation of unnecessary lateral momentum. Among them, the rod connected to the connection base mainly plays a role in supporting and buffering during the robot's jump.

[0015] The belt drive structure includes a synchronous belt, a small pulley and a large pulley. The synchronous belt transmission can ensure a strict transmission ratio, and the transmission is relatively stable, with the functions of buffering and vibration reduction, and is suitable for driving the tail release mechanism. The large pulley is fixed on the external frame through a coupling, and the wire winding wheel is coaxially fixed on the large pulley. Its diameter directly determines the speed of the cable elongation or contraction, thus affecting the bending angle of the tail joint. The small pulley is connected to the motor and is used for driving the belt drive structure. The motor is fixed on the external frame by the motor fixing seat in the above-mentioned external frame.

[0016] The tail bionic structure includes a tail connection base, a middle tail joint and a tail tip. The tail connection base is connected to the left frame and the right frame in the external frame. The middle tail joint has cable holes. A cable is inserted through the upper and lower holes and the left and right holes respectively, and each is driven by a motor. The above-mentioned belt drive structure contracts the cable to realize the control of each joint.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This bionic jumping robot has the following advantages: 1. Inspired by the hind limb structure of jerboas, a leg linkage mechanism with an approximately straight end trajectory is innovatively proposed, which avoids the horizontal component of the center of mass caused by the lateral movement of the legs, adding inappropriate take-off angular momentum to the whole robot, further improving the stability of the robot during the airborne phase and facilitating control, etc.

[0018] 2. An SEA series elastic actuator composed of a drive motor, a reducer and a special torsion spring is innovatively proposed for driving the leg bionic structure, which can fully amplify the driving force of the joint, buffer the additional ground forces during the rapid movement of the robot, and fully realize high-energy-efficient jumping motion; 3. An articulated tail mechanism is innovatively proposed, which has excellent attitude adjustment ability and can ensure that the robot can carry out survey operations maneuverably and stably during continuous jumping; 4. The tail is controlled by a belt-driven retractable cable, where the belt uses a synchronous belt. The synchronous belt drive can ensure a strict transmission ratio, and the transmission is relatively stable, with the functions of buffering and vibration reduction, and is suitable for driving the tail release mechanism; Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the bionic jumping robot of the present invention.

[0020] Figure 2 It is a schematic diagram of the tail bionic structure of the bionic jumping robot of the present invention.

[0021] Figure 3 It is a schematic diagram of the middle joint structure of the tail of the bionic jumping robot of the present invention.

[0022] Figure 4 It is a schematic diagram of the leg bionic structure of the bionic jumping robot of the present invention.

[0023] Figure 5 It is an exploded schematic diagram of the series elastic actuator structure of the bionic jumping robot of the present invention.

[0024] Figure 6 It is a schematic diagram of the elastic element of the bionic jumping robot of the present invention.

[0025] Figure 7 It is a schematic diagram of the belt drive structure of the bionic jumping robot of the present invention.

[0026] Figure 1 The reference numerals are as shown in the figure: Series elastic actuator, 2. External frame, 3. Belt drive structure, 4. Bionic tail structure, 5. Bionic leg structure.

[0027] Figure 2 The reference numerals are as shown in the figure: 41. Tail connection base, 42. Middle joint of the tail, 43. Tail tip.

[0028] Figure 5 The reference numerals are as shown in the figure: End cover, 12. Elastic element, 13. Support ring, 14. Left support cover, 15. Thin-walled bearing, 16. Deep groove ball bearing, 17. Output end, 18. Cycloid disc, 19. Transmission plate, 110. Cycloid pin wheel, 111. Right support ring, 112. Leg motor, 113. Motor bracket.

[0029] Figure 5 The reference numerals are as shown in the figure: 121. Outer ring, 122. Inner ring.

[0030] Figure 7 The reference numerals are as shown in the figure: 31. Synchronous belt, 32. Small pulley, 33. Large pulley. Specific implementation method

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] Embodiment 1, please refer to Figure 1 , 5, 6, 7. This embodiment provides a technical solution: A bionic jumping robot dedicated to exploration and reconnaissance, including a series elastic actuator 1, an external support frame 2, a belt transmission structure 3, a tail bionic structure 4, and a leg bionic structure 5; The series elastic actuator 1 mainly consists of an end cover 11, an elastic element 12, a support ring 13, a left support cover 14, a thin-walled bearing 15, a deep groove ball bearing 16, an output end 17, a cycloid disc 18, a transmission plate 19, a cycloid pin wheel 110, a right support ring 111, a leg motor 112, and a motor bracket 113; The support ring 13, the left support cover 14, the thin-walled bearing 15, the deep groove ball bearing 16, the output end 17, the cycloid disc 18, the transmission plate 19, the cycloid pin wheel 110, the right support ring 111, the leg motor 112, and the motor bracket 113 are assembled together to form a reducer, and this reducer adopts a cycloid pin wheel reducer; The elastic element 12 is cylindrical, including an outer ring 121 and an inner ring 122. The outer ring is connected to the link end, and the inner ring is connected to the output end of the reducer.

[0033] This drive scheme consists of a motor, a reducer, and a series spring. The series elastic actuator 1 can absorb part of the impact brought by the actuator and the landing process, and has the ability to store and release energy stably. In addition, the addition of the elastic element 12 can accurately control the torque acting on the load, and can also provide a large enough driving torque for the link actuator. Moreover, the storage of elastic potential energy can also maximize the output power of the actuator, making the peak power of the actuator much higher than the power provided by the motor alone.

[0034] The external support frame 2 includes a motor fixing base, a link support frame, an upper frame, a lower frame, a left frame, and a right frame. The connection devices of the tail bionic structure 4 and the leg bionic structure 5 are installed at the rear ends of the left frame and the right frame, and can also be used to install other accessory devices.

[0035] Example two, please refer to Figures 2 to 4 , this embodiment provides a technical solution: a bionic jumping robot dedicated to exploration and reconnaissance. This embodiment is a further explanatory description of the structure of Example one; The tail bionic structure 4 is a joint hinge structure, including a tail connection base 41, a middle tail joint 42, and a tail tip 43. The tail connection base 41 is connected to the above external support frame. The joint hinge structure can present an arc with a certain curvature in three-dimensional space. Driven by the power system, it can continuously change the overall bending angle in the tail space behind the robot. Since the tail connection base 41 hinges the tail to the external support frame, the continuous tail can generate forces of a certain magnitude in the X, Y, and Z directions, assisting the robot to achieve stable jumps in multiple directions and having a strong attitude adjustment ability; there is a hole on each of the upper, lower, left, and right sides of the middle tail joint 42, and the cable passes through the hole to control the joint. By driving the wire reel with a motor, the cable is wound and unwound, thereby driving the multi-joint tail to swing continuously at an angle in space and adjusting the bending degree of the tail to adjust the pitch, roll, and yaw attitude angles of the fuselage, making the machine have strong stability. When adjacent joints rotate, once the rotation angle reaches a certain threshold, contact will occur between the joints. The bending angle of adjacent joints of this structure can reach 20°, so theoretically the bending angle of the entire tail can reach 20°×4 = 80°.

[0036] This series elastic actuator drives the bionic leg structure so that the leg bionic structure obtains a vertically upward force, making the movement trajectory of the link end present an approximate straight line and not increasing the uncontrollable lateral momentum. Since the series elastic actuator contains an elastic element, the obstacle-crossing height of the bionic jumping robot is ≤0.6m.

[0037] The bionic leg structure 5 is evolved from a single-degree-of-freedom Stephenson type six-bar mechanism, and includes an output rod, a single-degree-of-freedom Stephenson type six-bar mechanism, a frame and a connecting rod base. This bionic leg structure imitates the leg structure of a jerboa. The length ratio of the femur, tibia-fibula and tarsal bone of the jerboa is 1:1.6:1.3. Therefore, the same proportional relationship also exists between the rods of this six-bar mechanism. This structure can keep the movement trajectory of the connecting rod end present an approximate straight line, without increasing the lateral uncontrollable momentum component. Among them, the rod connected to the connecting base mainly plays a role of support and buffering during the robot's jump. The frame is connected to the above-mentioned external frame. The output rod is connected to the leg motor, and the connecting rod base is used to support the whole body.

[0038] The single-cycle jump of this bionic jumping robot can be composed of two stages, including a standing stage and a flying stage. The standing stage can be further subdivided into a takeoff and a landing process.

[0039] In the standing stage, the connecting rod base contacts the ground, and at the same time the tail is in a hanging posture to keep the body stable.

[0040] In the flying stage, first, the leg mechanism is driven by the brushless motor in the series elastic actuator, and an upward flying force is obtained. After the mechanism leaves the ground, the belt transmission structure adjusts the bending degree of the tail by contracting the cable to control the forward direction of the bionic jumping robot and adjust the pitch, roll and yaw attitude angles of the body, so as to realize the stable flying stage of the machine. During the landing process of the mechanism, because the leg actuator contains an elastic element 12, it can buffer the huge external force during the landing process, and thus realizes the stable characteristics during landing. The tail structure still plays a role in adjusting the body attitude during this process, further improving the landing stability of the body.

[0041] Design features: 1. Compared with the prior art, the leg structure of this bionic jumping robot is inspired by the jerboa. The end trajectory of its leg link mechanism is approximately a straight line, avoiding the horizontal component of mass caused by the lateral movement of the legs, and adding inappropriate takeoff angular momentum to the whole robot, further improving the stability of the robot during the flying stage, and making it more convenient to control the movement of the robot.

[0042] 2. Compared with the prior art, the leg drive assembly of this bionic jumping robot is a SEA series elastic actuator composed of a drive motor, a reducer and a special torsion spring, which can fully amplify the driving force of the joint, buffer the additional ground forces during the rapid movement of the robot, and fully realize the high-energy-efficiency jumping motion.

[0043] 3. Compared with the prior art, the tail mechanism of this bionic jumping robot is a joint-linked tail mechanism, which has excellent attitude adjustment ability and can ensure that the robot conducts survey operations maneuverably and stably during continuous jumping.

[0044] 4. Compared with the prior art, the drive of the tail structure of this bionic jumping robot is completed by controlling the cable through a belt transmission structure. The synchronous belt transmission can ensure a strict transmission ratio, and the transmission is relatively stable, with the functions of buffering and vibration reduction, and is suitable for the drive of the tail release mechanism.

[0045] The bionic jumping robot for reconnaissance and survey of the present invention can carry lightweight survey instruments and conduct long-term jumping movements, specifically including a bionic leg mechanism, a joint-hinged tail, a SEA series elastic actuator, and an external support frame. The overall structure of the robot has a reasonable center of gravity and mass distribution. Key components and load-bearing parts, etc., have reasonable mechanical properties such as strength and stiffness. By studying the control algorithms of the bionic leg and tail motors, the leg driving ability and tail attitude adjustment effect are improved, enabling the robot to have excellent jumping performance and accurately achieve attitude adjustment, which has very important scientific research significance and engineering application value in the fields of mechanism bionics and rescue survey.

[0046] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0047] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A bionic jumping robot dedicated to reconnaissance and surveying, characterized in that It includes: A series elastic actuator (1), including an end cover 11, an elastic element 12, a support ring 13, a left support cover 14, a thin-walled bearing 15, a deep groove ball bearing 16, an output end 17, a cycloid disc 18, a transmission plate 19, a cycloid pin wheel 110, a right support ring 111, a leg motor 112 and a motor bracket 113; An external frame (2), including a motor fixing seat, a connecting rod support frame, an upper frame, a lower frame, a left frame and a right frame. A connecting device for a tail bionic structure and a leg bionic structure is installed at the rear ends of the left frame and the right frame; A belt drive structure (3), including a synchronous belt 31, a small pulley 32 and a large pulley 33. The synchronous belt transmission can ensure a strict transmission ratio, and the transmission is relatively stable, with the functions of buffering and vibration reduction, and is suitable for driving the tail bionic mechanism. The large pulley is fixed on the external frame through a coupling, and a wire winding wheel is coaxially fixed on the large pulley, and its diameter directly determines the speed of cable elongation or contraction, thereby affecting the bending angle of the tail joint. The small pulley is connected to the motor and is used to drive the belt transmission structure. The motor is fixed on the external frame with the motor fixing seat in the above external frame; A tail bionic structure (4), including a tail connection base 41, a middle tail joint 42 and a tail tip 43. The tail connection base 41 is connected to the left frame and the right frame in the external frame. The middle tail joint 42 has cable holes, and a cable is inserted through the upper and lower holes and the left and right holes respectively, and each is driven by a motor. The above belt drive structure contracts the cable to realize the control of each joint; A leg bionic structure (5), including an output rod, a single-degree-of-freedom Stephenson-type six-bar mechanism, a frame and a connecting rod base. The frame is connected to the above external frame. The output rod is connected to the above leg motor. The connecting rod base is used to support the entire fuselage.

2. The bionic jumping robot according to claim 1, wherein: The support ring 13, the left support cover 14, the thin-walled bearing 15, the deep groove ball bearing 16, the output end 17, the cycloid disc 18, the transmission plate 19, the cycloid pin wheel 110, the right support ring 111, the leg motor 112 and the motor bracket 113 form a reducer, and this reducer adopts a cycloid pin wheel reducer.

3. The bionic jumping robot according to claim 1, characterized in that: The elastic element 12 includes an outer ring and an inner ring. The outer ring is connected to the connecting rod end, and the inner ring is connected to the output end of the reducer. The leg motor adopts a brushless motor, which has the advantages of high motion efficiency, low energy consumption, long service life, stable and reliable performance, and faster response speed.

4. The bionic jumping robot according to claim 1, wherein: The series elastic actuator (1) includes a drive motor, a reducer and a special torsion spring to buffer the additional ground force during the rapid movement of the robot, and fully realize high-efficiency jumping motion.

5. The bionic jumping robot according to claim 1, characterized in that: The tail bionic structure (4) is a joint articulated tail mechanism, which can present continuous deformation and bending along the space of the robot's tail, has excellent attitude adjustment ability, and can ensure that the robot conducts survey operations maneuverably and stably during continuous jumping. The bending angle between adjacent joints can reach 20°, so theoretically the bending angle of the entire tail can reach 20° × 4 = 80°.

6. The bionic jumping robot according to claim 1, characterized in that: There is a certain proportional relationship among the rods of the six-bar mechanism in the leg bionic structure (5), which ensures that the component is a linkage mechanism with an approximately straight end trajectory, avoiding the horizontal component of the center of mass caused by the lateral movement of the leg and not adding inappropriate takeoff angular momentum to the overall robot.

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