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For equine-assisted therapy, a bionic horse configuration is presented. A bionic horse's single leg system has two degrees of freedom (DOFs), which is driven by a cam-linkage mechanism and can adjust the leg's endpoint trajectory. Based on analyzing the motion law of the bionic horse and the foot trajectory's requirements of the leg system, a multi-objective optimization model is established based on the foot trajectory performance index. To determine the objective function, the errors between the ideal foot trajectory and the mechanism motion model's foot trajectory, and the errors between the actual adjustable values and the target values for the motion range are taken as the optimization objective. In terms of the constraint conditions, the structural constraints, kinematic feasible region conditions, pressure angle requirements, et al., are considered. The ideal mechanism parameters are obtained by the intelligent optimization method. The results are verified by simulation modeling and experimental prototype, and the relevant ideas can provide a reference for the research of similar problems. [ABSTRACT FROM AUTHOR]

The cam-linkage mechanism is a typical transmission mechanism in mechanical science and is widely used in various automated production equipment. However, conventional modeling methods mainly focus on the design and dimensional synthesis of the cam-linkage mechanism in the slow-speed scenario. The influence of component dimensions is not taken into consideration. As a result, the model accuracy dramatically falls when analyzing large-size cam-linkage mechanisms, especially in high-speed environments. The kinematic aspects of cam design have been investigated, but there are few studies discussing the motion characteristic and accuracy analysis models of the large-size cam-linkage mechanism under high-speed scenarios. To handle such issues, this paper proposes a parameter optimization methodology for the design analysis of the large-size high-speed cam-linkage mechanism considering kinematic performance. Firstly, the mathematical model of the cam five-bar mechanism is presented. The cam curve and motion parameters are solved forward with linkage length and output speed. Then, a particle swarm-based multi-objective optimization method is developed to find the optimal structure parameters and output speed curve to minimize cam pressure angle and roller acceleration and maximize linkage mechanism drive angle. A Monte Carlo-based framework is put forward for the reliability and sensitivity analysis of kinematic accuracy. Finally, a transverse device of a sanitary product production line is provided to demonstrate the applicability of the proposed method. With the parameter optimization, the productivity of the transverse device is doubled, from 600 pieces per minute (PPM) to 1200 PPM. [ABSTRACT FROM AUTHOR]

Exact 3D path generation is a fundamental problem of designing a mechanism to make a point exactly move along a prescribed 3D path, driven by a single actuator. Existing mechanisms are insufficient to address this problem. Planar linkages and their combinations with gears and/or plate cams can only generate 2D paths while 1-DOF spatial linkages can only generate 3D paths with rather simple shapes. In this paper, we present a new 3D cam-linkage mechanism, consisting of two 3D cams and five links, for exactly generating a continuous 3D path. To design a 3D cam-linkage mechanism, we first model a 3-DOF 5-bar spatial linkage to exactly generate a prescribed 3D path and then reduce the spatial linkage's DOFs from 3 to 1 by composing the linkage with two 3D cam-follower mechanisms. Our computational approach optimizes the 3D cam-linkage mechanism's topology and geometry to minimize the mechanism's total weight while ensuring smooth, collision-free, and singularity-free motion. We show that our 3D cam-linkage mechanism is able to exactly generate a continuous 3D path with arbitrary shape and a finite number of C0 points, evaluate the mechanism's kinematic performance with 3D printed prototypes, and demonstrate that the mechanism can be generalized for exact 3D motion generation. [ABSTRACT FROM AUTHOR]

In this paper, a cam-linkage mechanism with a swing follower with variable pivot has been studied. In this mechanism, the pivot of the swing follower is installed on a slider with an adjustable track direction, the follower performs a complex planar motion, and the motion range of the output angle can be adjusted according to the output requirements. In order to synthesize this mechanism, firstly, the relevant model is established and the basic structural parameters are optimized by considering the assembly conditions and the pressure angle under the limit position of the movement track of the follower mounting slider. Subsequently, the inverse method and the envelope theory are employed to derive the cam contour coordinates. Finally, the corresponding follower motion law is selected, the corresponding cam contour coordinates are calculated, and the entire cam contour curve is obtained using spline interpolation. An automatic design system for cam contours is developed. The processes are carried out through design examples and verified through motion simulations and prototype experiment. The present work can enrich the design theory of cam-linkage mechanisms. [ABSTRACT FROM AUTHOR]

The cam-linkage mechanism is a typical transmission mechanism in mechanical science and is widely used in various automated production equipment. However, conventional modeling methods mainly focus on the design and dimensional synthesis of the cam-linkage mechanism in the slow-speed scenario. The influence of component dimensions is not taken into consideration. As a result, the model accuracy dramatically falls when analyzing large-size cam-linkage mechanisms, especially in high-speed environments. The kinematic aspects of cam design have been investigated, but there are few studies discussing the motion characteristic and accuracy analysis models of the large-size cam-linkage mechanism under high-speed scenarios. To handle such issues, this paper proposes a parameter optimization methodology for the design analysis of the large-size high-speed cam-linkage mechanism considering kinematic performance. Firstly, the mathematical model of the cam five-bar mechanism is presented. The cam curve and motion parameters are solved forward with linkage length and output speed. Then, a particle swarm-based multi-objective optimization method is developed to find the optimal structure parameters and output speed curve to minimize cam pressure angle and roller acceleration and maximize linkage mechanism drive angle. A Monte Carlo-based framework is put forward for the reliability and sensitivity analysis of kinematic accuracy. Finally, a transverse device of a sanitary product production line is provided to demonstrate the applicability of the proposed method. With the parameter optimization, the productivity of the transverse device is doubled, from 600 pieces per minute (PPM) to 1200 PPM.

• Forward and inverse cam generation methods for cam-linkage mechanism. • Cam-rocker-slider mechanism for function generation. • Forward method specifies cam shape, inverse method specifies linkage output. • Evaluation of cam profiles for the design of hydraulic motor. • Case study of hydraulic motor with radially spaced linkage mechanisms. This paper presents a comparison between the forward and inverse cam generation methods applied to the design of a multi-lobed cam-rocker slider mechanism for function generation. In the forward method, the cam profile is specified directly and then the linkage output is determined using kinematics. In the inverse method, the trajectory of the output link is specified first and then the cam profile is determined using inverse linkage kinematics. First, the cam-linkage mechanism is introduced, and relevant kinematic equations are presented. Then, the cam generation methods are thoroughly explained. The two cam generation methods are applied to a case study of a hydraulic motor using a multi-lobed cam and multiple linkage mechanisms. While the forward method has direct control of the cam shape, the inverse method has direct control of the linkage output and offers an advantage in calculation speed. For the mechanism selected, the cam designed with the inverse method achieved a reduction of at least 50.97% in the torque ripple when compared to the cam designed with the forward method. [ABSTRACT FROM AUTHOR]

In order to overcome the drawbacks of traditional gait training methods, gait rehabilitation robotized systems have been developed to provide a consistent, labor-saving and efficient treatment. However, the high cost of these systems makes them impracticable for home healthcare. This paper deals with the conceptual design and dimensional synthesis of cam-linkage mechanisms for gait rehabilitation. First, a two degrees of freedom seven-bar crank-slider mechanism is selected as the original mechanism, of which the displacement of the slider is formulated as a function of the crank angle to achieve the target trajectory by using the inverse kinematics. A cam is then designed to reduce the mobility of the mechanism to one. Moreover, a constant speed motor is sufficient for the control of the mechanism. For the dimensional synthesis, a goal function is proposed based on the kinematic performance criteria and constraints, and the genetic algorithm is employed for global searching. Two target trajectories are used for the dimensional synthesis of the mechanism. The results show the generated trajectories match well with the desired ones, which illustrates the feasibility of the methodology. [ABSTRACT FROM AUTHOR]

This work synthesizes the topological structures of the lost Zhang Heng's seismoscope, which was invented in ancient China in 132 AD, with cam-linkage mechanisms. Based on the study of the literature and seismology, the design specifications of Zhang Heng's seismoscope are defined and concluded. According to the concepts of generalization and specialization subject to the concluded design specifications, all feasible interior mechanisms with cams and links that meet science theories and techniques of the subject's time period are receated. Two examples, one with five members and six joints and the other with six members and eight joints, of the interior mechanism of Zhang Heng's seismoscope are derived with 2 and 11 feasible designs, respectively.