Magnification of energy transmission ratio using miniature cycloidal gear box for humanoids

Abstract

Design challenges arise in applications like humanoids where high torque is required to move and self-balance the bot. Present research focuses on development of a cycloidal gearbox for humanoid shoulder joints. Light weight gear box assembly was designed with mass of 360g. Structural design and analysis of cycloidal gearbox is carried out. A 3D printed prototype is developed to validate motion analysis. It was actuated by NEMA 17 step motor (0.45 N-m) which is controlled by A4988 motor driver module on the Arduino platform. The speed reduction ratio is achieved 20:1 in a very small space of 60 x 60 x 20mm. Motor torque 0.45Nm is magnified up to 8.82Nm. Result shows proposed cycloidal gearbox satisfies requirement of humanoid shoulder joints such as high torque, light weight and compact assembly. Additional features noticed are back drivable, vibration and noise free transmission which are highly desirable for humanoid shoulder joints.

Multibody Dynamics Model of the Cycloidal Gearbox, Implemented in Fortran for Analysis of Dynamic Parameters Influenced by the Backlash as a Design Tolerance

“…( 16). The linear velocity (17) of the Q point can be computed by differentiating Eq. ( 13) and substituting Eq.…”

“…Studies in the field of cycloidal gearbox engineering deal with the subject of design issues [7][8][9][10][11][12][13], finite element analysis of the cycloidal gearbox parts [7,[13][14][15][16][17], kinematical analysis [16,18], applications in robotics [12,16,17,19], friction, lubrication and machining [20][21][22][23][24], measurements [25], efficiency [26,27], optimisation [8,28], contact modelling [29][30][31][32], backlash and design tolerances [9,30,[33][34][35] or vibration and dynamics [31,32,[36][37][38][39][40].…”