Research Article

Calibrating initial position of manipulator via ultrasound transducer

¹ School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144, PR China
² Department of Mechanical and Aerospace Engineering, Brunel University London, Uxbridge UB8 3PH, UK

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 21 August 2025
Accepted: 1 October 2025

Abstract

Before a manipulator begins operation, its initial position needs to be confirmed. The manipulator will work more accurately after eliminating offsets in the initial position. Though some measuring devices have been widely used to calibrate the initial position, they are generally used to measure absolute position and featured with high cost and complex operation. Considering that ultrasonic testing system has measurement capability, we proposed a calibration method based on ultrasonic theory. This method employs relative position to calibrate the initial position of the manipulator, which can avoid complex process in measuring absolute position. According to reflection characteristics existing in ultrasonic theory, we find that the initial position of the manipulator can be calculated according to the relative position and posture between an ultrasonic transducer and a reflective surface. Firstly, D-H parameters are introduced to build kinematic model. Then, the model is rewritten according to Taylor series. The first order of Taylor series is retained to estimate relative relationship between joint angle and spatial position of the end-effector. The positioning error in X, Y and Z direction is increased by 85.8%, 69.2% and 81.4% respectively, demonstrating that this method can calibrate initial position effectively.