Study on Coordinated Control of Two Arm Robots

从系统论的观点出发，在位置和力的混合控制框架下，研究了两臂机械手握持并搬运同一物体的运动学和静力学问题。从理论上定义了代表混合控制工作空间坐标的内力空间和外力空间，并对每个空间的位置、速度和力进行了一致的推导。此外，还从理论上讨论了对象的鲁棒保持问题，并给出了确定两臂载荷合理分担的算法。这些理论结果得到了实验的证实。1.从理论上分析了两个机械手握持同一物体形成的闭环链的运动学和静力学，定义了内力空间和外力空间。在这种分析中，引入了虚拟杆的概念，并利用它统一地定义了内外空间中的位置、速度和力。提出了一种以位置、速度和力为任务向量的位置和力混合控制方案，为协作两机械手的控制提供了一种新的方案。在上述框架中，讨论了两机械手之间的载荷分担问题，提出了一种新的考虑载荷分担的理论框架，其中定义了一种新的以载荷分担系数为参数的广义逆矩阵来计算外力。从合理确定载荷分担系数的角度出发，讨论了对象的鲁棒保持问题，并给出了相应的启发式算法。用具有两个四自由度笛卡尔臂的工业双臂机器人进行的实验验证了上述理论结果。

From the point of view of systems theory, kinematics and statics of two arm manipulators holding a common object and carrying it has been studied in the framework of hybrid control of positions and forces. Internal and external force spaces to represent the workspace coordinates for the hybrid control are defined theoretically, and positions, velocities and forces for each space are derived consistently. Moreover, robust holding of the object is discussed theoretically and, for the robust holding, algorithms to determine proper sharing of loads between the two arms are presented. These theoretical results have been corroborated experimentally. The results of this study are summarized as follows:1. After kinematics and statics of the closed loop chain formed by two manipulators holding a common object is analyzed systems theoretically, internal and external force spaces are defined. In this analysis, a new concept called a virtual stick is introduced and by using it positions, velocities and forces in the internal and external spaces are defined consistently.2. A hybrid control scheme of positions and forces which uses those positions, velocities and forces as task vectors is formulated as a new scheme for the control of cooperating two manipulators.3. In the above framework, load sharing between the two manipulators is discussed, and a new theoretical framework to take the load sharing into account is formulated, in which a new generalized inverse matrix that is parameterized by load sharing coefficients is defined to calculate external forces.4. Robust holding of the object is discussed from the point of view of proper determination of the load sharing coefficients, and heuristic algorithms for it are derived.5. The above theoretical results have been corroborated by experiments using an industrial two arm robot having two 4-DOF Cartesian type arms.