CAREER: Planning and Control for Overconstrained Mechanisms

职业：过度约束机制的规划和控制

• 批准号: 0951688
• 负责人: Todd Murphey
• 金额: $ 22.39万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0951688&HistoricalAwards=false
• 关键词: CAREER; Planning; Control; Overconstrained; Mechanisms; CAREER; Planning; Control; Overconstrained; Mechanisms

The goal of this Faculty Early Career Development (CAREER) Program research is to produce hybrid estimators, motion planning algorithms, and control strategies that will work in concert to guarantee performance and stability in the face of multiple contact interfaces in an unstructured environment. An overconstrained multiple point manipulator prototype will be developed and planning and control methods will be applied to this system to demonstrate manipulation that is not sensitive to the particulars of the frictional interfaces. Multiple point contact is common in many manipulation tasks. Examples include arrays for distributed or micro manipulation, vehicles, and traditional robotic grasping. Although all of these applications have received a great deal of attention, no previous works have provided an analytical approach capable of dealing with the inherent uncertainties in the contact state--the state that represents whether a given contact is sticking, slipping, or is out of contact. These nonsmooth transitions between contact states have a dramatic impact on the dynamics; hence, it is important to systematically mitigate the negative performance these nonsmooth effects induce. Moreover, these systems are often overactuated, so that each contact interface is independently articulated. This leads to mechanisms that are nominally kinematically overconstrained--that is, the kinematic relationships between all the point contacts cannot be simultaneously satisfied. Which constraint is broken is sensitive to details of friction and normal force modeling, so it is necessary to estimate the current contact state and incorporate the contact state into the motion planning and control.Manufacturing often involves the need to reposition and reorient objects for purposes of assembly. To accomplish this, multiple actuators are often used, and these actuators experience stick and slip contact with the object due to frictional interactions. The physics of the actuators and, in particular, their interaction with the object are notoriously difficult to model accurately. Hence, there is a strong need for manipulation strategies that are not sensitive to these low-level details. Moreover, many vehicles, such as the original Mars rover, have a mechanical design that guarantees that some of the wheels must slip during operation. However, which wheels slip is dependent on unknown environmental conditions. Hence, in this situation as well there is a need to develop motion planning strategies that are guaranteed to work even in the presence of substantial uncertainty arising from the environment. This project will contribute to these needs by developing strategies that have guaranteed performance in the face of inherent uncertainty. In the short term this project will contribute to macro-scale manufacturing and vehicle control, and in the long-term will likely impact micro-scale manufacturing.

这种教师早期职业发展（职业）计划研究的目的是生产混合估计器，运动计划算法和控制策略，这些策略将共同努力，以确保面对非结构化环境中多个接触接口的性能和稳定性。 将开发一个过度约束的多点操纵器原型，并将计划和控制方法应用于该系统，以证明对摩擦接口的细节不敏感的操作。 在许多操纵任务中，多点接触很常见。 示例包括用于分布式或微型操纵的阵列，车辆和传统的机器人抓钩。 尽管所有这些应用程序都受到了很多关注，但以前的工作都没有提供一种能够处理联系状态中固有的不确定性的分析方法 - 代表给定的联系人是粘住，滑倒还是失去联系的状态。接触状态之间的这些非平滑过渡对动态产生了巨大影响。因此，重要的是系统地减轻这些非平滑效应引起的负面性能。 此外，这些系统通常会被过度分流，因此每个接触界面都可以独立阐明。 这导致了名义上运动学过度约束的机制 - 即，无法同时满足所有点接触之间的运动学关系。 破坏了哪些约束对摩擦和正常力建模的细节敏感，因此有必要估计当前的接触状态并将接触状态纳入运动计划和控制中。制造通常涉及为组装目的重新定位和重新定位对象。 为此，经常使用多个执行器，并且由于摩擦相互作用，这些执行器会经历与物体的粘性和接触。 众所周知，执行器的物理学，尤其是它们与物体的相互作用很难准确地建模。因此，非常需要对这些低级细节不敏感的操纵策略。 此外，许多车辆，例如原始的火星漫游车，具有机械设计，可确保某些车轮在操作过程中必须滑动。 但是，车轮滑移取决于未知的环境条件。 因此，在这种情况下，有必要制定运动计划策略，即使在环境中引起的实质性不确定性的情况下，这些策略即使有效。 该项目将通过制定固有不确定性来确保绩效的策略来促进这些需求。在短期内，该项目将有助于宏观尺度的制造和车辆控制，从长远来看，可能会影响微型制造业。