TENTH INTERNATIONAL CONGRESS ON SOUND AND VIBRATION , ICSV 10 DESIGN AND ANALYSIS OF A PARALLEL MECHANISM FOR THE GOLF INDUSTRY
Previous work done in the study of golf club dynamics professes dissatisfaction with robotic testing used to evaluate and compare golf equipment. The main complaint is that the club dynamics measured during a robot swing do not correlate with the same data in a human swing. This paper presents the design and analysis of an alternative to the current robotic testing systems. The viability of a parallel kinematic (two-arm) concept as a robotic testing machine for golf clubs and balls is demonstrated. Human biometric data was used as the basis for determining link geometry as well as motion planning for the swing. Models, simulations, and correlations with human test data were used for validating the design. A demonstration prototype was built to show the interactions and motions of the various components.
Impedance Control for a Golf Swing Robot to Emulate Different-Arm-Mass Golfers
Various golfers can play different golf swing motions even if they hold the same golf club. This phenomenon casts light on the significance of the dynamic interaction between the golfer's arm and golf club. The dynamic interaction results in different swing motions, even if the robot has the same input torque of the shoulder joint as that of a golfer. Unfortunately, such influence has not been considered in the conventional control of a golf swing robot. An impedance control method is proposed for a golf swing robot to emulate different-arm-mass golfers in consideration of the dynamic interaction between human arm and golf club. Based on the Euler-Lagrange principle and assumed modes technique, a mathematical model of golf swing considering the shaft bending flexibility is established to simulate the swing motions of different-arm-mass golfers. The impedance control method is implemented to a prototype of golf swing robot composed of one actuated joint and one passive joint. The comparison of the swing motions of the robot and different-arm-mass golfers is made and the results show that the proposed golf swing robot with the impedance control method can emulate different-arm-mass golfers.
Joint center longitudinal positions computed from a selected subset of Chandler's data.
Mathematical models of the human body are indispensable tools for studying the biomechanics of human movement. The geometrical centers of the 12 main joints (shoulders, elbows, wrists, hips, knees ankles), modeled as simple mechanical joints, are widely used as reference points for building mathematical models of the human body. These reference points, typically defined as "joint centers", are assumed to maintain a fixed 3D position relative to both the segments forming the joint, throughout the range of joint motion. No single point in a human joint perfectly meets this assumption, and no simple method is available for locating the points that are closest to meet it. Researchers often have recourse to subjective methods, based on their knowledge of anatomy. Objective estimates are easily attainable if the positions of a few bony landmarks can be measured on the subject, and the longitudinal distances of the joint centers from these landmarks are known. A subset of the anthropometric measurements performed by Chandler et al. (NTIS No. AD 710-622, 1975) on six cadavers was critically selected and utilized to compute the percent longitudinal distances of the 12 main joint centers from neighboring bony landmarks, relative to the lengths of the respective proximal and/or distal segments. Three-dimensional positions are attainable as well, by assuming joint centers lay on the respective segment longitudinal axes. The use of a method for accurately locating joint centers is recommended, particularly when they are used as reference points for defining a personalized geometrical model of a subject's body.