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Classical straight-line mechanisms are one of the most interesting, both from a theoretical and practical point of view. In many cases, those mechanisms frequently produce a nearly straight trajectory rather than one perfectly straight. In compliant form, those mechanisms can produce even better results. Compliant mechanism joints' deformability allows engineers to make further modifications. These modifications may improve the mechanism's ability to follow a straight path even further. This paper will provide an analysis of different hinge sizes, thicknesses, shapes, and overall geometrical characteristics. Their influence on the straightness of the mechanism trajectory will be analyzed and quantified.

Classical straight-line mechanisms are one of the most interesting, both from a theoretical and practical point of view. In many cases, those mechanisms frequently produce a nearly straight trajectory rather than one perfectly straight. In compliant form, those mechanisms can produce even better results. Compliant mechanism joints' deformability allows engineers to make further modifications. These modifications may improve the mechanism's ability to follow a straight path even further. This paper will provide an analysis of different hinge sizes, thicknesses, shapes, and overall geometrical characteristics. Their influence on the straightness of the mechanism trajectory will be analyzed and quantified.

For the synthesis problems of the approximate straight-line mechanism with instantaneous center at infinity, a universal synthesis method is proposed in this paper. Given the overall design requirements: the expected straight-line and one fixed pivot, the mathematical model is established to determine the mechanism with the offset as the design variables, through which the infinite straight-line mechanisms are generated with the offset change, including second-order and third-order osculation four-bar linkage. Moreover, the model is also suitable for the synthesis of mechanism with a sliding pair; the second-order osculation slider and rocking-block linkage and third-order osculation slider linkage are gained, which makes a beneficial exploration for the mechanism synthesis with a sliding pair. The robustness is one of the essential indicators to evaluate the motion output of mechanism in this paper, and a robust model of the approximate straight-line mechanism with instantaneous center at infinity is established. Then, the mechanisms are screened by geometric and kinematic constraints and robustness constraints, and the final optimal solution that meets all the constraints is found according to the optimization aim. This method allows the designer to rapidly discover the optimal robust mechanism from an infinite number of straight-line mechanisms, reducing design time substantially and making up for the deficiency of the current synthesis theory of approximate straight-line mechanism in the mechanism with instantaneous center at infinity.

Unmanned aerial vehicles (UAVs) are widely used for monitoring and payload transport; however, their application in autonomous physical interaction remains limited due to payload constraints, stability challenges, and the complexity of integrating manipulation systems. This study presents the design and development of a lightweight foldable robotic arm based on the ten-bar Kempe Kite Inversor II linkage for UAV aerial manipulation. The mechanism generates precise straight-line motion using a single degree of freedom. Kinematic modeling and simulation validated a maximum end-effector reach of approximately 0.42 m. Structural optimization using additive manufacturing and honeycomb cellular architectures significantly reduced system weight while maintaining mechanical reliability. A passive compliant gripper, counterbalance mechanism, onboard storage net, and landing gear were integrated to evaluate the arm in a practical harvesting scenario using cherries as the test object. The final integrated system weighs 0.351 kg during operation, remaining approximately 16% below the experimentally determined UAV payload limit of 0.4185 kg. Proof-of-concept flight demonstrations confirmed successful aerial grasping of cherries, validating the feasibility of the proposed lightweight manipulation approach for agricultural applications.

Face hobbing is a continuous indexing and double-flank cutting process whose high productivity and precision has made it one of the leading methods for fabricating spiral bevel and hypoid gears. The current method is inappropriate, however, for cutting straight bevel gears (SBGs) because it generates extended epicycloidal flanks. Nonetheless, a mathematical model of a face-hobbed SBG was successfully established in earlier research that enables straight cutting paths to cut straight tooth spaces based on a hypocycloidal straight-line mechanism in which the rolling circle radius equals half the base circle radius. This mathematical model, however, is based on a virtual universal cradle-type bevel gear cutting machine that has not yet been developed. This paper therefore proposes another mathematical model of face-hobbed SBG based on a modern six-axis computer numerical control (CNC) bevel gear cutting machine. The six-axis nonlinear machine settings are derived through conversion from the cradle-type machine settings. Meanwhile, the usage of electric gearbox (EGB) for bevel gear cutting is not revealed because of commercial consideration. Therefore, we also provide a solution to use EGB of Fanuc 16i CNC controller. A cutting experiment validates the proposed mathematical models using our developed six-axis CNC bevel gear cutting machine to cut the face-hobbed SBGs. Finally, a flank topographic correction is made that, according to postcorrection simulated topographic errors, can effectively reduce manufacturing errors. This paper successfully implements a face-hobbing process for manufacturing SBGs on a modern six-axis CNC bevel gear cutting machine.

Small precise robotic devices, working on principle of compact compliant mechanisms, must meet the conditions to high positioning accuracy what mean moving in straight-line too. But, compliant mechanisms are usually produced by equivalent of revolute joints, therefore in design of small robotic devices is necessary apply knowledge from design of one type of specialized mechanisms – straight-line mechanisms. This paper presents some straight-line mechanism and its applications to design of some small precise robotic devices. According to kinematics analysis most known straight-line mechanisms are evaluated for their application in compliant mechanisms. Such devices are transformed to flexure structures. Consequently, these devices are important building blocks to design some linear-motion stages and/or micro-grippers.

A new type of walking mechanism for middle- and low-speed maglev vehicle, including a single anti-roll beam placed at the middle of each suspension frame, a big air spring placed at the middle of each longitudinal beam of each suspension module, and a forced steering mechanism canceled, was proposed to improve the comprehensive competitiveness of the middle- and low-speed maglev vehicle in the field of urban rail transit. The dynamic characteristics of a new-type maglev vehicle were investigated by dynamics simulation analysis. The following conclusions are drawn based on the obtained results: the new-type maglev vehicle meets the operational requirements at the running speed of 160 km/h on the straight line and at the running speed of 30 km/h on the curved track of radius 75 m.

Compliant translational joints (CTJs) have been extensively used in precision engineering and microelectromechanical systems (MEMS). There is an increasing need for designing higher-performance CTJs. This paper deals with the conceptual design of CTJs via three approaches: parallelogram based method, straight-line motion mechanism based method and combination based method. Typical emerging CTJ designs are reviewed by explaining their design principles and qualitatively analyzing their characteristics. New CTJs are proposed using three approaches, including an asymmetric double parallelogram mechanism with slaving mechanism, several compact and symmetric double parallelogram mechanisms with slaving mechanisms and a general CTJ using the center drift compensation and a CTJ using Roberts linkage and several combination designs. This paper provides an overview of the current advances/progresses of CTJ designs and lays the foundation for further optimization, quantitative analysis and characteristic comparisons.

This article deals with the kinematics and dynamics of a novel leg based on the Peaucellier–Lipkin mechanism, which is better known as the straight path tracer. The basic Peaucellier–Lipkin linkage with 1 degree of freedom was transformed into a more skillful mechanism, through the addition of 4 more degrees of freedom. The resulting 5-degree-of-freedom leg enables the walking machine to move along paths that are straight lines and/or concave or convex curves. Three degrees of freedom transform the leg in relation to a reachable center of rotation that the machine walks around. Once the leg is transformed, the remaining 2 degrees of freedom position the foot at a desirable Cartesian point during the transfer or support phase. We analyzed the direct and inverse kinematics developed for the leg when the foot describes a straight line and found some interesting relationships among the motion parameters. The dynamic model equations of motion for the leg were derived from the Lagrangian dynamic formulation to calculate the required torques during a particular transfer phase.

Aerospace represents the development of national science and technology. It is an important foundation for exploring space and an important guarantee for the construction of aerospace power. There are many large workpieces in the aerospace field. The box insulation layer of large workpieces is an important processing problem. A new thick processing equipment is proposed to process the box insulation layer of large workpieces. The thick processing equipment consists of the XYZ shaft long guide rail and five degrees of freedom (5-DOF) RAPA. The mechanical structure of the 5-DOF RAPA is a redundantly actuated parallel mechanism (RAPM). Meanwhile, this paper proposes a new method to design 5-DOF redundantly actuated parallel mechanisms (RAPMs) with large output rotational angles. Based on configuration evolution and Li group, two articulated moving platforms (AMPs) and four kinds of limbs are designed, and a series of 3T2R (T represents translation, R represents rotation) RAPMs and 2T3R RAPMs are synthesized. To verify the designed RAPMs with large angle, an example of RAPMs, 4UPS-{2UPR}-R is analyzed. To ensure that the RAPM has no mechanism vibration impact in movement, this paper represents the RAPM adopts a newly proposed trajectory planning method. The results show that the 4SPU-(2UPR)R mechanism possesses large angles and verifies the efficiency of the new proposed trajectory planning method in simplified trajectories. This work lays the foundation for processing the box insulation layer of large workpieces with straight lines and arcs paths.