Enhanced D-H : an improved convention for establishing a robot link coordinate system fixed on the joint

Purpose: Robot kinematic modeling needs to be based on clear physical concepts. The widely used Denavit–Hartenberg (D–H) convention requires the coordinate system to be established on an extension of the axis. This leads to non-trivial problems which this study seeks to address by developing an improved convention. Design/methodology/approach: First, the problems associated with the traditional D–H convention are systematically analyzed. Then, pursuant of solving these problems, an enhanced Denavit–Hartenberg (ED–H) convention is proposed, and a procedure is delineated for establishing the coordinate frame and obtaining the associated parameters. The transformation equations are derived based on a homogeneous matrix. The characteristics of traditional D–H and ED–H with regard to kinematics and dynamics are comprehensively compared. Finally, an application of dynamics for lead-through programming and collision protection is undertaken to validate the proposed ED–H method. Simulations and experiments are carried out using the Tiansui-One cooperative robot platform with the aim of exploring the merits of the proposed convention. Findings: The proposed convention is compatible with traditional methods and can solve the problems inherent in these methods. The main characteristic of ED–H is that the coordinate system is fixed on the joint, which is a general modeling method. Originality/value: An enhanced D–H convention is proposed to establish a unified, intuitive and accurate link model that exhibits stronger adaptability than traditional D–H and can be used effectively in kinematic and dynamic modeling of mechanical arms.