When designing the form of the mechanism, in addition to meeting the specified motion form, motion law, or motion trajectory, the following criteria should also be followed:
　　
(l) The motion chain of the institution should be as short as possible. To complete the same action requirements, priority should be given to selecting mechanisms with fewer components and motion pairs, in order to simplify their structure, reduce weight, lower costs, and minimize cumulative errors in the motion chain caused by manufacturing errors of parts. A shorter motion chain is beneficial for improving the stiffness of the mechanism and reducing vibration.
　　
(2) In the selection of sports accessories, low accessories are preferred. The motion elements of the low pair mechanism are easy to process, ensuring precise coordination and high load-bearing capacity.
　　
(3) Properly selecting the prime mover to ensure good dynamic performance of the mechanism.
　　
Scale design principles for parallel robots:
　　
In the past, in the design phase, we mostly relied on experience and intuition to determine the size of the robot manipulator mechanism and the position and posture of the robot manipulator inside the workspace. Now, in order to develop high-precision, high-speed, and rate parallel robots, we need to consider the volume and shape of its workspace, singular configuration, and isotropic output conditions when designing the mechanism comprehensively. However, it is very difficult to consider all the above conditions in the comprehensive design of the global * mechanism scale. Domestic and foreign scholars have proposed many comprehensive standards for institutions, in order to achieve * performance under the design indicators that are met. Due to the smaller workspace of parallel robots compared to serial robots. Therefore, in order to meet the requirements of the assignment, it is crucial to first determine the workspace that can meet the performance indicators during design.
　　
In addition, in the design process of parallel mechanisms, it is necessary to consider avoiding configuration singularities. Unlike serial robots, parallel robots not only have kinematic singularities, but also configuration singularities caused by their configurations. Singular regions usually expand to the entire workspace or some significant subspaces, and are the most commonly used regions in practical operations. 0. M provides the conditions for determining the occurrence of configuration singularity in parallel mechanisms:
　　
(l) If the moving platform and the fixed platform are similar regular polygons, then the Jacobi matrix in the entire workspace is singular;
　　
(2) If the moving platform and the fixed platform are similar non regular polygons, and each pair of corresponding vertices is connected by a linkage, then the Jacobi matrix is singular in most areas of the workspace.
　　
The peculiar existence in this design will make parallel robots unable to work due to the inability to balance the load applied to the moving platform. In the region near the singularity of the configuration, even if no singularity occurs, it is possible to have a large condition number of the Jacobi matrix, which can also lead to poor transmission performance of motion and force. We call this region the pathological condition region. Therefore, when conducting scale synthesis design of parallel mechanisms, it is necessary to consider avoiding configuration singularities and pathological regions near singularities while meeting the requirements of workspace, motion transferability, and load capacity.