Telescopic Legs Research Articles

Development of a novel quadruped hybrid wheeled-legged mobile robot with telescopic legs

Development of a novel quadruped hybrid wheeled-legged mobile robot with telescopic legs

An agile monopedal hopping quadcopter with synergistic hybrid locomotion.

Nature abounds with examples of superior mobility through the fusion of aerial and ground movement. Drawing inspiration from such multimodal locomotion, we introduce a high-performance hybrid hopping and flying robot. The proposed robot seamlessly integrates a nano quadcopter with a passive telescopic leg, overcoming limitations of previous jumping mechanisms that rely on stance phase leg actuation. Based on the identified dynamics, a thrust-based control method and detachable active aerodynamic surfaces were devised for the robot to perform continuous jumps with and without position feedback. This unique design and actuation strategy enable tuning of jump height and reduced stance phase duration, leading to agile hopping locomotion. The robot recorded an average vertical hopping speed of 2.38 meters per second at a jump height of 1.63 meters. By harnessing multimodal locomotion, the robot is capable of intermittent midflight jumps that result in substantial instantaneous accelerations and rapid changes in flight direction, offering enhanced agility and versatility in complex environments. The passive leg design holds potential for direct integration with conventional rotorcraft, unlocking seamless hybrid hopping and flying locomotion.

Development of a rimless wheel robot with telescopic legs for step adaptability

AbstractIn this study, we developed a rimless wheel robot with elastic telescopic legs that can overcome steps. Numerical studies have shown that a rimless wheel robot with elastic telescopic legs has high adaptability to steps. However, rimless wheel robots that can walk in environments with steps have not yet been developed. To develop a rimless wheel robot that could overcome the steps, we initially developed a three-dimensional model of the robot through Unity software and simulated its walking on level ground and surfaces with steps. Then, we determined the optimal elasticity of the elastic telescopic legs through numerical simulation and constructed a model with optimized parameters. Finally, we conducted the walking experiments employing the developed robot. The robot can walk on level ground and surfaces with steps.

High Dynamic Bipedal Robot with Underactuated Telescopic Straight Legs

Bipedal robots have long been a focal point of robotics research with an unwavering emphasis on platform stability. Achieving stability necessitates meticulous design considerations at every stage, encompassing resilience against environmental disturbances and the inevitable wear associated with various tasks. In pursuit of these objectives, here, the bipedal L04 Robot is introduced. The L04 Robot employs a groundbreaking approach by compactly enclosing the hip joints in all directions and employing a coupled joint design. This innovative approach allows the robot to attain the traditional 6 degrees of freedom in the hip joint while using only four motors. This design not only enhances energy efficiency and battery life but also safeguards all vulnerable motor reducers. Moreover, the double-slider leg design enables the robot to simulate knee bending and leg height adjustment through leg extension. This simulation can be mathematically modeled as a linear inverted pendulum (LIP), rendering the L04 Robot a versatile platform for research into bipedal robot motion control. A dynamic analysis of the bipedal robot based on this structural innovation is conducted accordingly. The design of motion control laws for forward, backward, and lateral movements are also presented. Both simulation and physical experiments corroborate the excellent bipedal walking performance, affirming the stability and superior walking capabilities of the L04 Robot.

Design and modeling of hexapod robot using telescopic legs connected to pivot joints at the hips

Hexapod robots are widely used in applications such as search and rescue, exploration, and surveillance due to their improved mobility and stability on uneven terrain. However, conventional hexapod robots typically suffer from issues such as heavy weight and complex design, which limits their effectiveness in certain scenarios. In this paper, we propose a new hexapod robot that addresses the issues of weight and complexity often associated with conventional hexapod robots. Our proposed design uses telescopic legs connected to pivot joints at the hips, resulting in a two-DOFs-leg configuration. The robot’s six legs are aligned with a parallelepiped body, with each leg configured with a revolute joint and a prismatic joint. With a total of twelve degrees of freedom (DOFs), the proposed robot can move in a straight line or turn. Our solution for stabilizing the robot’s horizontally oriented body on uneven terrain, using analytical kinematics, inverse kinematics, and geometric analysis, is a valuable contribution. Additionally, we present simulation of path generation and gait design for various inclined planes and stairs using a virtual prototype modeled in MATLAB/Simulink Simscape Multibody. The results of our simulated and physical prototype experiments demonstrate that the proposed design and body control algorithm effectively maintain the orientation of the robot’s body usually stable while it moves on different types of surfaces. Overall, our proposed hexapod robot using telescopic legs offers a promising solution for achieving improved mobility and stability on uneven terrain, with reduced weight and complexity compared to conventional hexapod robots.

Prediction of optimum tilt angle of Flat-plate solar collector in Abia State Nigeria

Most solar collectors in Nigeria are mounted without consideration of optimum tilt angle for maximum solar radiation. To address the gap, a flat plate surface solar collector of area 0.15 m2, hinged on horizontal support for quick adjustment of inclination between 0 to 90o was fabricated marked out at 1o intervals on a telescopic leg graduated in degrees. Measurement of the solar radiation at varying degrees of inclination was taken between 12:00 noon and 2.00 pm for 4 days at clear sky hours, within the week of nth day of the year. The measurements were taken for each month of the year at Michael Okpara University of Agriculture, Umudike. Umuahia, Abia State, Nigeria, at each degree of inclination. The result showed that the optimum angle of inclination of a flat plate for maximum collection of solar radiation intensities for January to December were 9.5, 9.1, 3.0, 6.4, 9.9, 11.8, 9.0, 7.3, 3.1, 7.0, 10.2, and 11.8o respectively. The study also revealed that the average angle of inclination at which a flat surface solar collector can be mounted at a fixed position in Umudike is 8.14o. The analysis indicated that solar energy gain of 123,314.79 MJm-2, 39,041.24 MJm-2, and 25,610.84 MJm-2 for horizontal, Latitude angle of location and calculated fixed angle of inclination of the solar collector respectively. Comparison of the measured and calculated optimum values of angle of inclination of a flat plate surface for trapping maximum solar radiation intensity indicated a high correlation ( R2 ) of 0.97.

Kinematics of a 5-axis hybrid robot near singular configurations

• A method based on kinematics modification for singularity avoidance is proposed. • A criterion for choosing the appropriate inverse kinematic solution is presented. • A semi-analytical algorithm for forward kinematic analysis is developed. • An algorithm is developed by modifying C -axis instructions. • Both simulations and experiments are carried out to verify the proposed approach. This paper proposes a method for non-singular tool path generation based on inverse kinematics modification in joint space to deal with the singularity problem of a 5-axis hybrid robot in machining process. Firstly, a criterion for choosing the appropriate solution of inverse displacement analysis is presented, that enables the avoidance of mechanical interference and enlargement of the task workspace. As a counterpart of inverse displacement analysis, a semi-analytical algorithm for forward displacement analysis is developed with high computational efficiency. These works lay a comprehensive and solid foundation for motion control and tool path simulation of the hybrid robot. Then, it reveals that at a singular configuration that varies with the system configurations, sudden changes occur in both rotation of the C -axis of the 2-DOF wrist and lengths of three telescopic legs within the 3-DOF parallel mechanism. This finding leads to an effective method for non-singular tool path planning by directly modifying the C -axis commands in the joint space using linear interpolation technique. Finally, both simulation and experimental results on a prototype machine show that in the neighborhood of singularity, continuous and smooth joint motions and acceptable tracking accuracy can be ensured after the modification.

Walking dynamics for an ascending stair biped robot with telescopic legs and impulse thrust

<abstract><p>In this study, an ascending stair biped robot model with impulse thrust is presented. The biped robot contains a hip joint and two legs with massless telescoping actuator. Impulse thrust is applied at the ankle joint of robot's stance leg to simulate the forward push-off of the ankle during human walking. The nonlinear ascending stair biped model is linearized and a discrete map is obtained. The conditions for the existence and stability of period-1 gait are obtained by means of this discrete map. The expressions of torques to ensure robot walking are derived and Flip bifurcation is investigated. Numerical simulations, such as phase diagram of period-1, 2, 4 gaits and bifurcation diagram, are given in an example. Theoretical analysis and numerical results obtained in this study provide a theoretical basis for stable walking of ascending stair biped robot with periodic gaits.</p></abstract>

Revisiting Stewart–Gough platform applications: A kinematic pavilion

Stewart–Gough platforms are well known for their extraordinary kinematic motion and therefore they are widely used as devices, ranging from flight simulators to microsurgical manipulators. However, they have not yet been explored much as architectural objects and transformable spaces with regards to irregular arrangements of legs and their associate structural performance. In the current study, an innovative architectural and structural application of the Stewart–Gough platform, implemented as full-scale kinematic pavilion, namely the Zero Gravity pavilion, at Aalto University, Finland, is presented. During the design process a Stewart–Gough 3–3 configuration was rearranged to an irregular 6–6 configuration. The architectural freedom in the arrangement of columns was guided by its immanent effect on the structure’s motion, stability, and strength. We opted for one telescopic leg only and its selection is based on four main criteria. Firstly, for each telescopic leg the stability of the different configurations is investigated. Secondly, the self-collision of leg–leg, leg–roof, and roof–floor was investigated by means of physical and computational models as well as through the full-scale pavilion. Thirdly, the selection process is influenced by the force distribution on the six legs. Fourthly, the path trajectory of the kinematic structure is examined in terms of magnitude and type of motion as an architectural feature. The final choice of the telescopic leg was based on the conclusions drawn from the parametric architectural and structural studies. The overall spatial and structural qualities of the system was validated by the full-scale Zero Gravity pavilion.

Design and analysis of a new frame-foot wall-climbing robot

This paper designs and develops a new type of frame-foot wall-climbing robot structure. According to the bionic principle, a new parallel telescopic leg structure is proposed, and the 3D design of the overall structure of the wall-climbing robot is completed. Secondly, the kinematics analysis of the robot is carried out, and the forward and inverse solution models of the leg structure position are completed to verify the feasibility of the leg structure stability. Based on the polynomial motion equations, the robot motion planning and gait design are established, and the speed and acceleration change graphs of the leg structure slider are obtained, which avoids the rigid impact between the parts, and realizes the alternate adsorption and continuous movement of the robot legs, which the rationality of the legs structure design and the stability of the movement are verified. Through simulation and experimental results, it is shown that during the robot’s movement, the leg structure can adjust the step distance and step height according to obstacles, so as to achieve the expected obstacle crossing goal. The leg structure is adjusted according to the working environment to ensure that the fuselage and the working surface are always kept parallel to improve the stability of the overall structure.

Design and Isokinetic Training Control Method of Leg Press Training Device

Lower-limb function in elderly people gradually degenerates with age, and poor rehabilitation conditions preventing the elderly from receiving scientific rehabilitation training result in the decline of social labor force and the increased economic burden of the elderly. Aiming at the characteristics of the single function and the complex structure of an existing telescopic leg trainer combined with the needs of the application group, a new type of leg-stretching training device with multiple training modes for lower extremity extension and flexion of the elderly is proposed. A new mechanical structure and electrical system is designed. At the same time, the anti-resistance training man–machine model is analyzed, aiming at the isokinetic resistance training mode, and a training controller strategy based on a fuzzy synovial algorithm is proposed. Finally, the feasibility of the designed controller strategy and the proposed leg training device are verified by prototype experiments, which will guide further research.

A New 4-DOF Fully Parallel Robot With Decoupled Rotation for Five-Axis Micromachining Applications

We present a novel 4-DOF (degrees of freedom) parallel robot designed for five-axis micromachining applications. Two of its five telescoping legs operate simultaneously, thus acting as an extensible parallelogram linkage, and in conjunction with two other legs control the position of the tooltip. The fifth leg controls the tilt of the end-effector (a spindle), while a turntable fixed at the base of the robot controls the swivel of the workpiece. The robot is capable of tilting its end-effector up to 90 deg, for any tooltip position. In this paper, we study the mobility of the new parallel kinematic machine (PKM), describe its inverse and direct kinematic models, then study its singularities, and analyze its workspace. Finally, we propose a potential mechanical design for this PKM utilizing telescopic actuators as well as the procedure for optimizing it. In addition, we discuss the possibility of using constant-length legs and base-mounted linear actuators in order to increase the volume of the workspace.

Finite-time control strategy for the running of a telescopic leg biped robot

Designing stable and efficient control methods for walking and running of biped robots has been a challenge over the past years. The goal of this paper is to design a finite-time controller to stabilize the running gait of a compliant leg biped robot. The biped model consists of two springy telescopic legs with flat feet. The robot model has five actuators including a torque actuator at the hip joint, two torque actuators at the ankle joints and two force actuators at the legs prismatic joints parallel to the springs. Dynamic equations of stance phase, flight phase and touchdown event are derived to build the dynamic model of a complete step of running. This robot model has passive periodic running gaits which are unstable. The controller aims to stabilize the gaits around the desired limit cycles and reject disturbances. Finite-time sliding mode control is used to design controller for the stance phase; the flight phase remains passive. Starting from various deviated initial conditions, the state space trajectory of the system with the designed control law is derived and its convergence to the desired trajectory is shown. The result of the controller is also compared with an event-based linear controller from previous references.

Development of Mechanism to Estimate the Amount of Contraction in Wire-Driven Telescopic Leg

Development of Mechanism to Estimate the Amount of Contraction in Wire-Driven Telescopic Leg

Efficiency analysis of telescopic-legged bipedal robots

This paper investigates the stability of underactuated bipedal walking incorporating telescopic-leg actuation. In human walking, knee joints of swing and support legs are bent and stretched. The telescopic legs mimic the motion of the center of mass of human legs via their telescopic motion during the stance phase. First, underactuated telescopic-legged biped robot models are introduced. Second, an output-following control law is applied to the linearized equation of motion of the robot, and the controlled robot’s equation is then specified as a linear time-varying system. The error transition equation is developed to evaluate the stability during the stance phase. Numerical calculations are performed to show the influences of leg telescopic motion on the stability.

Inverse kinematics of a 5-axis hybrid robot with non-singular tool path generation

Abstract This paper deals with non-singular tool path generation of a 5-axis hybrid robot named TriMule, which is designed for large part machining in situ. It is observed that at a singularity pose sudden changes occur in rotation of the C-axis and lengths of three telescopic legs. It is found that when the tool axis rotates about the axis normal to the plane expanded by the tool axis and the singular axis, the singular axis itself is forced to rotate simultaneously about the same axis in the opposite direction. This exploration enables the minimum rotation angle of the tool axis to be determined accurately for avoiding singularity and reducing machined surface errors caused by tool axis modification, leading to the development of an algorithm for non-singular tool path generation by modifying a partial set of the control points of B-splines. Both simulation and experiment on a prototype machine are carried out to verify the effectiveness of this approach.

Development of a Quickly Erectable Prefabricated Collapsible Construction System for Temporary Accommodation

This paper considers the importance of quickly erectable construction systems, as well as their main purpose and applicability in various situations. Based on the analysis of scientific publications and the results of patent search, the authors suggest the structural features and technological solutions for installation of a new small-size quickly erectable collapsible construction system. The system is designed for temporary accommodation of a group of people involved in construction, geological exploration and other works in hard-to-reach areas, for tourists etc. Such a collapsible construction system can be adapted to serve as a temporary shelter for people surviving natural calamities. The foundation of the suggested system is an enclosed three-dimensional structure (crate) where the necessary structural elements are kept pending the assembly of the construction system, including telescopic legs and other tubular framing structures, rolls of tent covering, set of coupling elements, and supports. The specific features of this new system, as compared to similar space planning solutions, are low labor costs involved in its assembly and dismantling, small weight ensuring transportability of a collapsed and packed system, and reusability. Other benefits of the new small-size construction system include its low overall cost, environmental safety and energy efficiency.

Control oriented model-based simulation and experimental studies on a compliant legged quadruped robot

Quadruped robots offer better maneuverability over wheeled mobile robots. However, a quadruped robot contains many joint actuators which have to operate in a coordinated fashion to achieve the desired locomotion. Joint actuations cause various degrees of disturbance on the robot body and may even destabilize the system. Thus, prior dynamic analysis plays an important role for development of control laws for quadruped locomotion. Here, a three dimensional dynamic model of a quadruped has been developed using the bond graph technique which can be interfaced with various controller models. This model contains a detailed sub-model for telescopic compliant legs. Results from simulations, animations and experiments are discussed. Turning motion at various leg speeds is studied for dynamic stability of the robot. The effect of leg compliance on locomotion parameters is studied which helps in selecting a suitable compliance. Performance measure is carried out using energy efficiency as deciding criteria. Study on energy efficient quadruped structure, energy efficient locomotion gait and foot trajectory have been carried out for designing an efficient quadruped.

A Modified Kneed Biped Real Robot Based on Parametric Excitation Principle

Parametric excitation walking is one of the bipedal gait generation methods on level ground. This method was first applied to a biped robot with telescopic legs and later to a kneed biped robot. An experimental robot with telescopic legs was also developed and it was verified that the robot could walk more than eight steps by the parametric excitation walking. Recently, we have developed an experimental kneed biped robot and have shown the robot can walk more than fifteen steps stably in inverse bending fashion. But the robot has a deficiency in that the robot does not have a ground sensor and the robot is controlled only in open-loop fashion. In this paper, we modify and improve the robot by using a ground sensor and shock absorbing material to enable to control in closed-loop fashion and hence, to improve the gait performance. The experiments are performed and the walking performance of the robot is investigated. The experimental results are compared with the numerical results, and the validity of the numerical simulation is verified.

The dynamic optimization approach to locomotion dynamics: human-like gaits from a minimally-constrained biped model

This work presents a unifying framework to study energy-efficient optimal gaits for a bipedal model without elastic elements. The model includes a torso, flat feet, and telescoping legs, equipped with rotational hip and ankle joints. Two general types of gaits are studied: with and without a flight phase. The support surface can be level ground, sloped, or staircase. The algorithm achieves the optimum within the admissible space by using a minimal set of realistic physical constraints, and avoiding a priori assumptions on kinetic and kinematic parameters such as extended or instantaneous double-support, collisional or collisionless foot-ground contact, step length, step period, etc. The gait optimization for this simple model predicts many features of human locomotion including the optimality of pendular walking and impulsive running at slow and fast progression speeds, ankle push-off prior to touch-down, swing leg retraction, landing on a near vertical leg in gaits with flight phase, and burst hip torques at both ends of the swing phase.