Standard Practice for Grasp-Type Robot End-Effectors: Split Force Measurement Apparatus

Abstract

5.1 To design relevant performance metrics and methods for characterizing grasp-type end-effectors, this practice helps to understand the contextual or application-specific issues surrounding robotic grasping and manipulation. Characterization of an end-effector should not be thought of in terms of a single value or dimension. Rather, a full characterization that involves a range of metrics is needed to guide selection of appropriate end-effectors for a particular application and to direct research and development advancements. 5.2 Regardless of the task, any grasping and manipulation problem can be broken down into its first principles: kinematics and kinetics, or more simply, motion and effort. Kinematics is the geometry of motion of bodies or particles, disregarding the forces that cause such motion. Therefore, any kinematic metric or test method will be concerned with evaluating positions, velocities, or accelerations of bodies or particles, and will typically be expressed in units of length and time. Kinetics are the forces acting on bodies or particles that are responsible for causing their motion. Any kinetic metric or test method will be evaluating force, torques, and any other measure of effort, such as electrical current. Evaluation areas of interest include palms, fingers, points of contact, or objects under grasp. Building test methods using the first principles approach will ultimately lead to relevant performance capture and will span from lower-level capabilities, including primitive sensing and control, to higher-level capabilities including manipulation, perception, and decision making. 5.3 When evaluating the capabilities of a grasp-type end-effector, performance tests should be agnostic to the other system components such as the robot arm and perception system. While it is possible to access data directly from a robotic hand and derive the defined metrics, these measurements would be based on the inherent properties of the system under test. Therefore, independent measurement systems must be developed to support testing to allow for comparative metrics between systems to establish extrinsic ground truths.