Surface roughness has an important influence on the service performance and life of parts. Areal surface roughness has the advantage of accurately and comprehensively characterizing surface microtopography. Understanding the relationship and distinction between profile and areal surface roughness is conducive to deepening the study of areal surface roughness and improving its application. In this paper, the concepts, development, and applications of surface roughness in the profile and the areal are summarized from the aspect of evaluation parameters. The relationships and differences between surface roughness in the profile and the areal are analyzed for each aspect, and future development trends are identified.

Surface roughness is an important indicator in the evaluation of machining and product quality, as well as a direct factor affecting the performance of components. A rapidly developing filtering technology has become the main means of extracting surface roughness. The International Organization for Standardization (ISO) is constantly updating and improving the standard system for filtering technology in order to meet the requirements of technological development. Based on the filters already accepted by the international standard ISO 16610, this study briefly introduces the filtering principle of each filter, reviews the development of each filter in the application of surface roughness, and compares the advantages and limitations of their individual performances. The application range of each filter is summarized and, finally, the future direction of the digital filtering used in surface roughness is extrapolated.

While cycloid pin-wheel precision reducers (referred to as RV reducers) are widely used in industrial robots, a widely accepted design standard or verification method of their test platforms is not available. In this study, a comprehensive sliding-separation test platform of RV reducers was developed. The test platform can test various measurement items such as transmission error, static measurement of lost motion, dynamic measurement of lost motion, torsional rigidity, no-load running torque, starting torque, backdriving torque, and transmission efficiency of the RV reducer for robots. The principle and method of dynamic measurement of lost motion tests based on the two-way transmission error method were studied and this test function was successfully integrated with the comprehensive test platform in order to increase the test items of the dynamic performance parameters of RV reducers. The measurement results of the no-load running torque of the RV reducer were consistent with the Stribeck curve. Based on the concept of optimal measurement speed, a decomposition test method of the geometric component of the dynamic measurement of lost motion and the elastic component of the dynamic measurement of lost motion was proposed in the dynamic measurement test of lost motion. Through precision calibration, function test and repeatability test, the results were compared with the data of enterprise’s samples. The consistent results have proved that the test platform met engineering requirements and measurement accuracy requirements. Based on the new test principle, the developed platform can test more parameters of RV reducers with high precision and display the comprehensive test performance.