There is a problem with non-contact measurement and detection, which reduces its measurement accuracy. Methods developed for measuring and inspecting screw thread characteristic parameters usually using a camera, which is controlled to scan the projection of thread in the parallel optical field to obtain thread images. However, with the block of screw line on the projection of the real thread form, it is impossible to acquire the real thread form from images. The traditional way is adjusting the optical axis to a suitable angle with the thread axis to acquire the real thread form projection, which has some problems, such as time consuming, high skill of operator, high-precision equipment for adjustment, inaccuracy, and so on. Hence, a new method through digital image calibration is presented. The results of relevant simulation indicated the feasibility of this new method, which improves thread measurement and detection accuracy.

Underwater manipulator as efficient tools plays important roles in ocean exploitation. Because of its specificity for underwater operations, the structure of an underwater manipulator should be designed compactly with light weight and small size. Structure of a 7-function underwater manipulator is designed here. Except forearm rotation and wrist rotation which use hydraulic motors, other functions are driven by hydraulic cylinders, whose parameters are determined by force analysis and limit positions. The hydraulic pipelines from the elbow joint to the end are passed through the forearm, and the hydraulic cylinder of the jaw is integrated into the wrist motor. Built-in pipelines are achieved in the designed structure and the whole weight and volume are greatly reduced by integrated and optimized design.

A new type of reducer based on traveling wave driver principle was put forward. The initial structure of the reducer was designed and the theoretical model was built up. An initial reducer was manufactured and some performances were tested. The experiment results illustrated that the new type reducer has a feature of large ratio, and the testing results accord with the theoretical model through adjusting some test parameters.