Electromechanical Servo System High Overload Harmonic Gear Bearing Characteristics

The harmonic drive used in servo drive system of aerocrafts works for a short time, and at a high overload, and is requested to be small and light. Therefore, common harmonic drive is hard to meet the requirements. This paper focused on the bearing characteristic and inactivation forms of harmonic drive, for the purpose of improving its load capacity, and finding new design methods.First, according to the particularity of harmonic drive this paper researched, this paper expounded the weak part and major inactivation forms in the special condition. Second, on the base of classical theory, this paper analyzed the deformation and stress of flexspline under load, and found the dangerous cross-section which influenced loading ability, and then proposed the method for calculating the strength of dangerous cross-section. Next, this paper analyzed the deformation and stress of flexspline both in no-load and under-load condition by using ABAQUS FEA software, and found the stress distribution regularity of flexspline under different load. The influences of some structure parameters such as depth-diameter aspect ratio and thickness were compared by changing parameters. On the basis of above analyses, some optimal structure parameters that not only met the requirements of miniaturization and light weight, but also met the design demand. To enhance the harmonic drive's loading ability, this paper introduced a new teeth profile named STS profile, and presented its derivation. The research results provided theoretical references for improving load capacity of harmonic drive and designing this type of harmonic drive.