Performance measurement of mobile manipulators

An advanced approach to flexible manufacturing is to move robotic manipulators, using anAGV or mobile robot, called mobile manipulators, between workstations. The use ofmobile manipulators can be advantageous in a number of situations. It can result in costsavings when a single mobile manipulator can be used to replace several stationarymanipulators. However, mobile manipulators are “a relatively young discipline withinrobotics.” An extensive literature review of the research leading to commercial mobilemanipulators and mobile robots was performed. The performance measurement of mobilemanipulators, including a mobile base with an onboard robot arm, is virtually non-existent.However, mobile manipulators are beginning to appear in manufacturing, healthcare, andpossibly other industries and therefore, a method to measure their performance is critical toboth manufacturers and users of these relatively complex systems. Measurements of mobilemanipulators performing standard tasks (poses and motions) are also non-existent except forsimply ensuring that the task has been more or less completed. The task chosen for thisthesis is assembly due to its requirement for relatively precise system posing.Performance test methods have lagged behind safety test methods for mobile manipulatorswhich is progressing towards development of a new safety standard in the US. Metrics forsafety and performance of mobile manipulators include many areas, such as: safe operation,task completion, time to complete the task, quality, and quantity (i.e., accuracy andrepeatability, respectively) of tasks completed. Prior to industrial acceptance and standardsdevelopment for mobile manipulators, users of these new systems will expect manufacturersto provide real performance data to guide their procurement and assure suitability for givenapplication tasks. Due to the relatively high cost to procure and setup motion tracking systemsto measure systems performance, an alternative method for use by manufacturers and users isideal. A new test method concept that uses an artifact, called the Reconfigurable MobileManipulator Artifact (RMMA), is described in this thesis and compared to an optical trackingsystem that was used as ground truth for the RMMA and mobile manipulator.System modeling the mobile manipulator system, components, and the associatedmeasurements can help to improve the understanding of these relatively complex systems.Systems Modeling Language (SysML) was chosen and used throughout this thesis becauseof SysML has reusable software modules for structure, behavior, requirements andparametrics off the mobile manipulator. The models describe the many aspects ofmeasuring mobile manipulator performance also as new research area. The models wereevaluated through experiments on an example mobile manipulator components and the entiresystem. SysML was used to describe the theoretical basis of the performance throughpropagation of uncertainty where mathematical equations are also modeled.A use case is modeled and described where the concepts researched to measure mobilemanipulator performance are applied to a manufacturing implementation. The simplisticnature of the measurement process using the RMMA can be directly applied to today’smanufacturing processes, and extended beyond the contributions of this research to othereven more complex measurement needs. The research is also discussed to even apply tocross-industry test methods for exoskeletons worn by humans.