Singh Amanpreet, Singla Ekta, Soni Sanjeev, Singla Ashish
1 Department of Mechanical Engineering, Thapar University, Patiala, India.
2 Mechanical Engineering Department, IIT Ropar, Rupnagar, India.
Proc Inst Mech Eng H. 2018 Jan;232(1):12-23. doi: 10.1177/0954411917741331. Epub 2017 Nov 15.
The prime objective of this work is to deal with the kinematics of spatial hybrid manipulators. In this direction, in 1955, Denavit and Hartenberg proposed a consistent and concise method, known as D-H parameters method, to deal with kinematics of open serial chains. From literature review, it is found that D-H parameter method is widely used to model manipulators consisting of lower pairs. However, the method leads to ambiguities when applied to closed-loop, tree-like and hybrid manipulators. Furthermore, in the dearth of any direct method to model closed-loop, tree-like and hybrid manipulators, revisions of this method have been proposed from time-to-time by different researchers. One such kind of revision using the concept of dummy frames has successfully been proposed and implemented by the authors on spatial hybrid manipulators. In that work, authors have addressed the orientational inconsistency of the D-H parameter method, restricted to body-attached frames only. In the current work, the condition of body-attached frames is relaxed and spatial frame attachment is considered to derive the kinematic model of a 7-degree of freedom spatial hybrid robotic arm, along with the development of closed-loop constraints. The validation of the new kinematic model has been performed with the help of a prototype of this 7-degree of freedom arm, which is being developed at Council of Scientific & Industrial Research-Central Scientific Instruments Organisation Chandigarh to aid the surgeon during a medical surgical task. Furthermore, the developed kinematic model is used to develop the first column of the Jacobian matrix, which helps in providing the estimate of the tip velocity of the 7-degree of freedom manipulator when the first joint velocity is known.
这项工作的主要目标是研究空间混合机器人的运动学。在这个方向上，1955年，丹纳维特（Denavit）和哈滕贝格（Hartenberg）提出了一种连贯且简洁的方法，即D-H参数法，用于处理开式串联链的运动学。通过文献综述发现，D-H参数法被广泛用于对由低副组成的机器人进行建模。然而，当应用于闭环、树形和混合机器人时，该方法会导致模糊性。此外，由于缺乏对闭环、树形和混合机器人进行建模的直接方法，不同的研究人员不时地对该方法进行修正。作者成功地提出并实现了一种利用虚拟框架概念的修正方法，并将其应用于空间混合机器人。在那项工作中，作者解决了仅局限于固连于物体的坐标系的D-H参数法的方向不一致问题。在当前的工作中，放宽了固连于物体的坐标系的条件，并考虑了空间坐标系的附着，以推导一个7自由度空间混合机器人手臂的运动学模型，同时建立了闭环约束。借助于这个7自由度手臂的原型对新的运动学模型进行了验证，该原型由位于昌迪加尔的科学与工业研究理事会-中央科学仪器组织开发，用于在医疗手术任务中辅助外科医生。此外，所开发的运动学模型用于推导雅可比矩阵的第一列，这有助于在已知第一个关节速度时估计7自由度机器人末端的速度。
