Jumping Leg Research Articles

Kinematic synthesis and mechanism design of a six-bar jumping leg for elastic energy storage and release based on dead points

Small jumping robots widely adopt complex catapult mechanisms. This paper presents a novel jumping strategy using dead point instead of traditional catapult mechanisms, achieving efficient energy storage and release without increasing mechanical complexity. Single degree-of-freedom (DOF) planar six-bar linkages are widely used in bionic mechanism design due to their simple control and strong design flexibility. However, their complex configuration and numerous parameters make it challenging to carry out multi-objective and multi-constraint designs. In this paper, a design method of single DOF six-bar linkages based on dead-point constraints is proposed to design a frog-inspired leg mechanism. By enumerating the basic configuration atlas and using a stepwise closed-loop method, initial value screening is completed to improve the efficiency of objective function optimization. The dead-point constraints are simplified with graphical geometric properties. The resulting mechanism satisfies multiple objectives and constraints, including shape, motion posture and trajectory, demonstrating the feasibility of the method. Simulations and experiments confirmed the excellent jumping performance of the 147.1-g prototype, with a jump height of 8.55 times leg length and an energy-storing capacity of 35.39 J/kg.

Design and Optimisation of Bionic Frog Hind Limbs

With the deepening of human exploration of the Earth, more and more survey tasks are being carried out in unstructured environments. Biomimetic robots that can replace humans in completing related tasks under harsh conditions have gradually become a hot topic in robot development. Therefore, developing a biomimetic robot with a wide range of activities, strong mobility, excellent obstacle crossing ability, and rapid avoidance response has important theoretical research significance and broad application prospects. This paper focuses on frogs as the research object,research is conducted from the perspective of institutional design, aiming to design a frog like jumping robot with strong obstacle crossing ability and good environmental adaptability. In terms of overall structural design, a M-shaped structure based on linear bearings was proposed to ensure the stability of the robot during takeoff and landing; In terms of leg structure design, C-shaped flexible springs are used to integrate the calf, ankle joint, and foot into one, which can play a buffering role when the robot lands; In terms of transmission structure design, Propose to control the compression cycle of the jumping leg through a cam to achieve continuous jumping of the robot. The relevant research results indicate that the structural principle of the designed frog like jumping robot is correct, and the jumping effect is relatively good.For the sake of ideals, this paper provides a certain theoretical basis and basis for further research on bionic jumping robots.

Structural design and jumping motion planning of the jumping leg inspired by a goat's hindlimb

Abstract. At present, research on bionic jumping robots mainly focuses on imitating various jumping animals, such as kangaroos, frogs, or locusts. These bionic objects have good jumping ability. The goat, as one of these with a moderate size and a strong jumping ability, is very suitable as a prototype to imitate jumping. In this study, first, a simplified serial joint model that imitates a goat's hindlimb is proposed with a comparison analysis of its physiological structure. Then, a jumping leg mechanism that imitates a goat's hindlimb was designed. Second, the kinematics of the goat-inspired jumping leg were constructed to describe the relationship between joint angles and foot positions. Additionally, we used a cubic polynomial to plan the trajectory of the jumping process to achieve a smooth jumping movement based on the characteristics of the goat's jumping, with position and speed constraints during the jump. Thus, we established a smooth jumping trajectory model of the goat-inspired jumping leg. Finally, experiments on the jumping of the goat-inspired jumping leg were conducted. The goat-inspired jumping leg has good jumping performance. In this study, we took the goat's hindlimbs as the bionic model, proposed the goat-inspired jumping leg mechanism, and presented the jumping trajectory planning theory for smooth jumping of the goat-inspired jumping leg. These provide new ideas for the study of bionic jumping legs and can effectively promote further development of bionic jumping robots.

Iranotrichus crassisetosus gen. nov., sp. nov. (Acari: Oribatida: Zetomotrichidae) from central Iran

A new genus and species of oribatid mites (Oribatida) of the family Zetomotrichidae are described from soil in the Central Plateau of Iran, Yazd Province. Iranotrichus gen. nov., with type species Iranotrichus crassisetosus sp. nov., differs from all other genera of the family by a combination of the following character states: large body size; denticulate rostrum; dorsosejugal furrow medially interrupted; divided posterior margin of notogaster; prodorsal, notogastral and ventral plates ornamented with fine, fragmented longitudinal striae; large, thick notogastral seta c2; presence of notogastral lyrifissures ia and im, humeral sac and pyriform organ; absence of custodium; barbed epimeral setae, 1a and 1c longer than others, 1a longest; four pairs of genital, two pairs of anal and three pairs of adanal setae; tarsus I with 20 setae; presence of thick setae on genua I and II, tibia II and tarsi II–IV, with seta tc″ on tarsus IV slightly enlarged but not a thick spine; leg IV enlarged, acetabulum not dorsally displaced. Leg IV representing an intermediate stage between the genera with a well-developed jumping leg and those without a jumping leg. In addition, data on geographic distribution and some information about all known genera of Zetomotrichidae are given.

Jumping mechanism in the marsh beetles (Coleoptera: Scirtidae)

The jumping mechanism with supporting morphology and kinematics is described in the marsh beetle Scirtes hemisphaericus (Coleoptera: Scirtidae). In marsh beetles, the jump is performed by the hind legs by the rapid extension of the hind tibia. The kinematic parameters of the jump are: 139–1536 m s−2 (acceleration), 0.4–1.9 m s−1 (velocity), 2.7–8.4 ms (time to take-off), 0.2–5.4 × 10–6 J (kinetic energy) and 14–156 (g-force). The power output of a jumping leg during the jumping movement is 3.5 × 103 to 9.6 × 103 W kg−1. A resilin-bearing elastic extensor ligament is considered to be the structure that accumulates the elastic strain energy. The functional model of the jumping involving an active latching mechanism is proposed. The latching mechanism is represented by the conical projection of the tibial flexor sclerite inserted into the corresponding socket of the tibial base. Unlocking is triggered by the contraction of flexor muscle pulling the tibial flexor sclerite backwards which in turn comes out of the socket. According to the kinematic parameters, the time of full extension of the hind tibia, and the value of the jumping leg power output, this jumping mechanism is supposed to be latch-mediated spring actuation using the contribution of elastically stored strain energy.

Design and Joint Position Control of Bionic Jumping Leg Driven by Pneumatic Artificial Muscles

Using the skeletal structure and muscle distribution of the hind limbs of a jumping kangaroo as inspiration, a bionic jumping leg was designed with pneumatic artificial muscles (PAMs) as actuators. Referring to the position of biarticular muscles in kangaroos, we constructed a bionic joint using biarticular and monoarticular muscle arrangements. At the same time, the problem of the joint rotation angle limitations caused by PAM shrinkage was solved, and the range of motion of the bionic joint was improved. Based on the output force model of the PAM, we established a dynamic model of the bionic leg using the Lagrange method. In view of the coupling problem caused by the arrangement of the biarticular muscle, an extended state observer was used for decoupling. The system was decoupled into two single-input and single-output systems, and angle tracking control was carried out using active disturbance rejection control (ADRC). The simulation and experimental results showed that the ADRC algorithm had a better decoupling effect and shorter adjustment time than PID control. The jumping experiments showed that the bionic leg could jump with a horizontal displacement of 320 mm and a vertical displacement of 150 mm.

Resisted Sprint Training in Youth: The Effectiveness of Backward vs. Forward Sled Towing on Speed, Jumping, and Leg Compliance Measures in High-School Athletes.

Uthoff, A, Oliver, J, Cronin, J, Winwood, P, Harrison, C, and Lee, JE. Resisted sprint training in youth: the effectiveness of backward vs. forward sled towing on speed, jumping, and leg compliance measures in high-school athletes. J Strength Cond Res 35(8): 2205-2212, 2021-Resisted sprinting (RS) is a popular training method used to enhance sprinting performance in youth. However, research has only explored the effects of forward RS (FRS) training. We examined the effects of FRS and backward RS (BRS) and compared these with a traditional physical education curriculum (CON). One hundred fifteen boys (age 13-15 years) were matched for maturity and allocated to either an FRS (n = 34), BRS (n = 46), or CON (n = 35) group. Training groups towed progressively overloaded sleds (20-55% body mass) 2 d·wk-1 for 8 weeks. Pre-training and post-training data were collected for sprinting times over 10 and 20 m, countermovement jump (CMJ) height, and leg stiffness (KN). Performance remained unchanged for the CON group (all p > 0.05), whereas all variables significantly improved (p < 0.05) after BRS, and all but 10-m performance improved after FRS. Compared with the CON, BRS and FRS significantly (p > 0.05) improved CMJ (Effect size [ES] = 0.67 and 0.38) and KN (ES = 0.94 and 0.69), respectively. No differences were found between training groups. The probabilities of improving sprinting performance after BRS (∼70%) were on average ∼10 and ∼8% better than the FRS and CON groups, respectively. The BRS and FRS showed similar probabilities of improving CMJ (75 and 79%) and KN (80 and 81%), respectively, over the CON group. It seems that BRS may be a means to improve sprint performance, and regardless of direction, RS seems to be a beneficial method for improving jumping height and leg stiffness in youth male athletes.

Modeling, comparison and evaluation of one-DOF six-bar bioinspired jumping leg mechanisms

One degree-of-freedom (DOF) jumping leg has the advantages of simple control and high stiffness, and it has been widely used in bioinspired jumping robots. Compared with four-bar jumping leg, six-bar jumping leg mechanism can make the robot achieve more abundant motion rules. However, the differences among different configurations have not been analyzed, and the choice of configurations lacks basis. In this study, five Watt-type six-bar jumping leg mechanisms were selected as research objects according to the different selection of equivalent tibia, femur and trunk link, and a method for determining the dimension of the jumping leg was proposed based on the movement law of jumping leg of locust in take-off phase. On this basis, kinematics indices (sensitivity of take-off direction angle and trunk attitude angle), dynamics indices (velocity loss, acceleration fluctuation, and mean and variance of total inertial moment) and structure index (distribution of center of mass) were established, and the differences of different configurations were compared and analyzed in detail. Finally, according to the principal component analysis method, the optimal selection method for different configurations was proposed. This study provides a reference for the design of one DOF bioinspired mechanism.

The jumping mechanism of flea beetles (Coleoptera, Chrysomelidae, Alticini), its application to bionics and preliminary design for a robotic jumping leg.

Flea beetles (Coleoptera, Chrysomelidae, Galerucinae, Alticini) are a hyperdiverse group of organisms with approximately 9900 species worldwide. In addition to walking as most insects do, nearly all the species of flea beetles have an ability to jump and this ability is commonly understood as one of the key adaptations responsible for its diversity. Our investigation of flea beetle jumping is based on high-speed filming, micro-CT scans and 3D reconstructions, and provides a mechanical description of the jump. We reveal that the flea beetle jumping mechanism is a catapult in nature and is enabled by a small structure in the hind femur called an ‘elastic plate’ which powers the explosive jump and protects other structures from potential injury. The explosive catapult jump of flea beetles involves a unique ‘high-efficiency mechanism’ and ‘positive feedback mechanism’. As this catapult mechanism could inspire the design of bionic jumping limbs, we provide a preliminary design for a robotic jumping leg, which could be a resource for the bionics industry.

Design, Optimization, and Experiment on a Bioinspired Jumping Robot with a Six-Bar Leg Mechanism Based on Jumping Stability

A jumping leg with one degree of freedom (DOF) is characterized by high rigidity and simple control. However, robots are prone to motion failure because they might tip over during the jumping process due to reduced mechanism flexibility. Mechanism design, configuration optimization, and experimentation were conducted in this study to achieve jumping stability for a bioinspired robot. With locusts as the imitated object, a one-DOF jumping leg mechanism was designed taking Stephenson-type six-bar mechanism as reference, and kinematic and dynamic models were established. The rotation angle of the trunk and the total inertia moment were used as stability criteria, and the sensitivity of different links to the target was analyzed in detail. With high-sensitivity link lengths as the optimization parameters, a configuration optimization method based on the particle swarm optimization algorithm was proposed in consideration of the different constraint conditions of the jumping leg mechanism. Optimization results show that this method can considerably improve optimization efficiency. A prototype of the robot was developed, and the experiment showed that the optimized trunk rotation angle and total inertia moment were within a small range and can thus meet the requirements of jumping stability. This work provides a reference for the design of jumping and legged robots.

Coordinated Allocation of Driving Forces for Bioinspired Robot With One-DOF Jumping Leg on Rough Terrain

Bioinspired jumping robots need to be able to move on rough terrain. Despite the high rigidity and low control difficulty of robots with one-DOF jumping legs, they are more prone to losing stability than robots with multi-DOF series legs due to the varying attitudes of bilateral jumping legs in the initial state, thereby further causing motion failure. For keeping the jumping stability of robots with one-DOF jumping legs, a coordinated allocation method of driving forces is proposed in this paper. On the basis of an analysis of the instability of a locust in the take-off phase, kinematics and dynamics models were established for a robot with active and passive driving modes, respectively. Unlike active driving, passive driving means that the driving forces cannot be adjusted in real time during the take-off phase, and the randomness of the terrain needs to be considered. With the forces of the bilateral jumping legs to the trunk, take-off velocity, and take-off time of the equivalent center of mass as target values, the difference of target values on both sides should be approximately equal. Results show that with the driving forces obtained by the method proposed in this paper as the input, the effect of the rough terrain on the trunk is reduced, and the robot has good jumping stability. This study provides a theoretical basis for the application of jumping robots in complex environments.

Kinematic synthesis method for the one-degree-of-freedom jumping leg mechanism of a locust-inspired robot

The one-degree-of-freedom (DOF) mechanism has a simple structure, convenient control, and high stiffness, and it has been applied in many micro jumping robots. Meanwhile, the six- and eight-bar mechanisms can satisfy more complex motion requirements than the four-bar jumping leg mechanism and they have good application prospects. However, the lack of effective design methods limits the application range of these mechanisms. In this work, a type and dimensional integration synthesis method was proposed with the one-DOF six-bar leg mechanism as the research object. The initial tibia and femur were determined based on the kinematic chain atlas, and configuration design was implemented through the superposition of links. When a closed chain was formed in the superposition process, the feasible range of the link length was analyzed by considering the constraint conditions. The proposed method innovatively establishes the relationship between the kinematic chain atlas and the configuration, and the feasible length ranges of the links can be quickly obtained simultaneously. Several examples were provided to prove the feasibility of the kinematic synthesis method. This method provides a useful reference for the design of one-DOF mechanisms.

Modeling, analysis, and experiments of a pause-and-leap jumping robot during takeoff, flight, and landing buffering

Jumping robots can overcome obstacles strongly and are suitable for complex terrain environments. However, the takeoff parameters of most jumping robots, especially pause-and-leap jumping robots, cannot be changed accurately. Moreover, the stability of the flight and landing of these robots needs to be improved. On the basis of observations of the jumping process of a locust, leg mechanisms, including one-degree-of-freedom jumping leg and series buffering leg, are designed. Then, dynamic models for takeoff, flight, and landing buffering are established and combined with Lagrange/Newton-Euler dynamic modeling methods and conservation of momentum moment. For the former, the effects of structural parameters, including position of the driving spring, absolute position of the center of mass, and stiffness coefficient of the driving spring, on takeoff velocity and acceleration can be obtained. The takeoff parameters can also be changed accurately. For the flight phase, the relationship between the relative position of the center of mass and the stability of flight is revealed. For the latter, the effects of two buffering modes on the supporting forces and energy storage capacity are analyzed. On the basis of the parameters determined by the abovementioned modeling method, a prototype is developed, and an experiment is conducted to verify the rationality of the modeling method. Experimental results show that the prototype can acquire accurate takeoff parameters and achieve stable flight and landing buffering. This study provides a useful reference for the design and control of jumping robots.

Dynamic model and performance analysis of rigid-flexible coupling four-bar leg mechanism for small scale bio-inspired jumping robot

Bio-inspired jumping robot can imitate the jumping process of creatures, and can move in environment with large obstacles. This type of robot can be applied to complex situations such as earthquakes and landslides, and has a broad application prospect. Aiming at the problems of the existing micro bionic jumping robots, such as the simple dynamic model and the unclear rigid-flexible coupling characteristics, the dynamic modeling and performance analysis of rigid-flexible coupling jumping leg is conducted in this paper. Based on the analysis of the jumping mechanism of stick insect, a design method of four-bar jumping leg mechanism under multiple constraint conditions is put forward. Then the dynamic model of the rigid-flexible coupling four-bar jumping leg with flexible equivalent tibia and elastic joint is established combining with Lagrange and Newton–Euler dynamic modeling methods, which can describe the dynamic characteristics of the robot quantitatively during jumping. The relationship between the stiffness of flexible tibia and jumping performance is analyzed, which includes energy storage capacity, take-off velocity/acceleration and jumping stability. The analysis results show that proper reduction of stiffness of flexible tibia can improve the dynamic performance of small scale bio-inspired jumping robot. This study offers primary theories for design and analysis of rigid-flexible coupling four-bar jumping leg with flexible equivalent tibia and elastic joint, and it establishes a theoretical basis for studies and engineering applications.

Mechanism design for locust-inspired robot with one-DOF leg based on jumping stability

The good jumping stability of a robot prevents the robot from turning over in the jumping process and is the basis for achieving good jumping performance. This study investigates stability assurance for a locust-inspired jumping robot from the perspective of mechanism design. A mechanism design method for a locust-inspired robot with one-degree-of-freedom jumping leg is proposed based on the jumping stability mechanism of locusts. Jumping stability includes kinematic and dynamic stability. Kinematic stability focuses on the attitude change of a robot in the take-off process and determines the dimension of each link. The smaller the changes in attitude are, the better the kinematic stability is. Dynamic stability focuses on the relationship between the center of mass position and the total inertia moment. The smaller the changes in the total inertia moment are, the better the dynamic stability is; that is, the robot has a low tendency to turn over in the flight phase. Simulation results show that the examined robot demonstrates good jumping stability when the developed mechanism design method is used.

Analysis and Comparison of Two Jumping Leg Models for Bioinspired Locust Robot

Bionic jumping robot can cross the obstacles by jumping, and it has a good application prospect in the unstructured complex environment. The less Degree of Freedom (DOF) jumping leg, which has the characteristics of simple control and high rigidity, and is very important in research. Based on the experimental observation of leg physiological structure and take-off process of locust, two 1 DOF jumping leg models, which includes four-bar jumping leg model and slider-crank jumping leg model, are established, and multi objective optimization is conducted to deduce the motion law of two 1 DOF jumping leg models and jumping leg of locust is closer. Then the jumping performance evaluation indices are proposed, which include the mechanical property, body attitude, jumping distance and environmental effect. According to these evaluation indices, the jumping performances of the two jumping leg models are analyzed and compared, and the simulation is conducted for further explanations. The analysis results show that the four-bar jumping leg has smaller structural size and its motion law is closer to the hindleg of locust. The slider-crank jumping leg has better mechanical property, stronger energy storage capacity and the rough ground has less effect on it. This study offers a quantitative analysis and comparison for different jumping leg models of bionic locust jumping robot. Furthermore, a theoretical basis for future research and engineering application is established.

Jumping mechanisms and performance in beetles. I. Flea beetles (Coleoptera: Chrysomelidae: Alticini).

The present study analyses the anatomy, mechanics and functional morphology of the jumping apparatus, the performance and the kinematics of the natural jump of flea beetles (Coleoptera: Chrysomelidae: Galerucinae: Alticini). The kinematic parameters of the initial phase of the jump were calculated for five species from five genera (average values from minimum to maximum): acceleration 0.91-2.25 (×10(3))ms(-2), velocity 1.48-2.80ms(-1), time to take-off 1.35-2.25 ms, kinetic energy 2.43-16.5 µJ, G: -force 93-230. The jumping apparatus is localized in the hind legs and formed by the femur, tibia, femoro-tibial joint, modified metafemoral extensor tendon, extensor ligament, tibial flexor sclerite, and extensor and flexor muscles. The primary role of the metafemoral extensor tendon is seen in the formation of an increased attachment site for the extensor muscles. The rubber-like protein resilin was detected in the extensor ligament, i.e. a short, elastic element connecting the extensor tendon with the tibial base. The calculated specific joint power (max. 0.714 W g(-1)) of the femoro-tibial joint during the jumping movement and the fast full extension of the hind tibia (1-3 ms) suggest that jumping is performed via a catapult mechanism releasing energy that has beforehand been stored in the extensor ligament during its stretching by the extensor muscles. In addition, the morphology of the femoro-tibial joint suggests that the co-contraction of the flexor and the extensor muscles in the femur of the jumping leg is involved in this process.

Jumping Robot with Initial Body Posture Adjustment and a Self-Righting Mechanism

To improve jumping performance, this paper presents a jumping robot with initial body posture adjustment and a self-righting mechanism. A segmental gear, stretching and triggering a spring for the storage and rapid release of energy, is used for the jumping mechanism. Pairs of front and hind supporting legs are used for the initial body posture adjustment. One end of each jumping leg is connected to a spring, while the other end is connected to the necessary wiring. In this way, the robot can correct its orientation from an upside down posture upon landing, simultaneously recovering its jumping legs and storing energy. Experimental results indicate that a jumping robot with a size of 78 mm × 43 mm × 40 mm and a weight of 30 g can jump across an obstacle with a controlled trajectory. It can also control its air pitching posture using the initial body posture adjustment. In addition, the robot can recover its body posture on the ground and store energy for a second jump. This work may provide useful data for further research into take-off posture control mechanisms.

The Relationship Between Hip Extensor Strength, Jump Height and External Hip Flexion Moments During Jumping

External hip flexion moments have been reported as the biomechanical variable most predictive of maximal jump height (MJH) during a drop vertical jump, however, this relationship has not yet been established during more basketball-specific tasks, such as a one-step countermovement jump (CMJ). Additionally, the extent to which the strength of the hip extensors influence external hip flexion moments and MJH during a one-step CMJ are unknown. Identifying the relationship between MJH, external hip flexion moments, and hip extensor strength during a one-step CMJ may be valuable to optimize MJH performance. PURPOSE: To identify the relationship between MJH, external hip flexion moments, and hip extensor strength during a one-step CMJ. METHODS: Twenty-three Division-1 collegiate basketball players (11M, 12F) participated in the study. Established 3D motion analysis techniques were utilized to collect three trials each of a one-step CMJ while leading with the preferred and non-preferred jumping leg. Hip extensor strength was measured as the average of the middle 3 of 5 isokinetic, concentric hip extensor strength trials performed at 60º/sec and normalized to body mass. Pearson product-moment correlations were performed to identify relationships between MJH, external hip flexion moment and hip extensor strength (p<0.05). RESULTS: There was a significant positive correlation between MJH and external hip flexion moment of both legs measured during the one-step CMJ when leading with the preferred (Lead: r=0.90, p=<0.001; Trail: r=0.66, p=0.001) and non-preferred (Lead: r=0.85, p=<0.001; Trail: r=0.53, p=0.01) jumping leg. Concentric hip extensor strength was not significantly correlated to either MJH or external hip flexion moment. CONCLUSIONS: External hip flexion moments explain up to 81% of the variance of MJH values during a one-step CMJ, yet concentric hip extensor strength measured at 60º/sec was not related to MJH or hip flexion moments. Further examination of hip extensor function (e.g. activation, strength at higher speeds) may warrant further investigation.

Effects of life history on oxygen delivery in the grasshopper jumping leg (879.22)

Although the insect tracheal system is extremely efficient, oxygen delivery is reduced during the intermolt period. Intermolt growth results in compressed tracheae, reduced tracheal volume, and reduced femoral air sac ventilation rates. Gravidity reduces tracheal volume in adult female grasshoppers; however, it is unknown whether gravid grasshoppers also have lower ventilation rates. Using micro‐dissections and video analysis, we examined the tracheal system of the abdomen and femur of ten (5 females; 5 males) American locust grasshoppers (Schistocerca americana). We found that abdominal compression rates correlated with the inflation of proximal and distal femoral air sacs. Females (1.99 to 2.95 g) had higher compression rates in both their abdomens (36.2 ± 3.62 min‐1; mean ± s.e.m.) and femoral air sacs (36.8 ± 3.73 min‐1) than male grasshoppers (1.07 to 1.27 g; abdomen 28.6 ± 2.04 min‐1 and femoral air sacs 26.8 ± 1.85 min‐1). The most gravid females showed the highest abdominal and femoral air sac compression rates. These findings suggest that gravid females will compensate for reduced tracheal volumes by increasing tracheal ventilation rates. Current research is examining how gravidity affects tibial and tarsal air sac compression rates.Grant Funding Source: Supported by Union College Undergraduate Research Grants