Kinematic Tool-Path Smoothing for 6-Axis Industrial Machining Robots
Kinematic Tool-Path Smoothing for 6-Axis Industrial Machining Robots
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DOI：
10.20965/ijat.2021.p0621
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Shingo Tajima;Satoshi Iwamoto;Hayato Yoshioka
中科院分区：
文献类型：
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作者：
Shingo Tajima;Satoshi Iwamoto;Hayato Yoshioka
由于工业机器人安装成本低、灵活性高，对工业机器人加工的需求不断增加。本文提出了一种用于工业机器人高速高精度加工的新型轨迹生成算法。工作空间中的线性插补和拐角处的平滑轨迹生成对于工业加工机器人来说非常重要。由于工业机器人由旋转关节组成，关节空间与工作空间存在非线性关系。因此，传统机床中广泛采用的关节空间线性插补并不能保证实际加工工作空间中的线性插补。这导致加工表面退化。所提出的基于解耦方法的轨迹生成算法可以通过将位置命令分离为笛卡尔坐标并将方向命令分离为球坐标来实现工作空间中的线性插值。此外，本文提出了一种新颖的角平滑方法，可以从离散命令生成平滑且连续的轨迹。所提出的运动学局部角平滑通过在关节空间的角处使用 3 段恒定急动度曲线来生成平滑轨迹。从而可以用平滑的曲线代替尖角。通过改变转弯持续时间来控制由此产生的转弯误差。仿真结果证明了所提出的运动平滑算法在直线部分实现线性刀具运动以及在用户定义的公差范围内的拐角部分生成平滑轨迹方面的有效性。
The demands for machining by industrial robots have been increasing owing to their low installation cost and high flexibility. A novel trajectory generation algorithm for high-speed and high-accuracy machining by industrial robots is proposed in this paper. Linear interpolation in the workspace and smooth trajectory generation at the corners are important in industrial machining robots. Because industrial robots are composed of rotational joints, the joint space has a nonlinear relationship with the workspace. Therefore, linear interpolation in the joint space, which has been widely used in conventional machine tools, does not guarantee linear interpolation in the actual machining workspace. This results in the degradation of the machining surface. The proposed trajectory generation algorithm based on the decoupled approach can achieve linear interpolation in the workspace by separating the position commands into Cartesian coordinates and the orientation commands into spherical coordinates. In addition, a novel corner smoothing method that generates a smooth and continuous trajectory from discrete commands is proposed in this paper. The proposed kinematic local corner smoothing generates a smooth trajectory by using a 3-segmented constant jerk profile at the corners in the joint space. The sharp corners can thereby be replaced by smooth curves. The resulting cornering error is controlled by varying the cornering duration. The simulation results demonstrate the effectiveness of the proposed kinematic smoothing algorithm in achieving linear tool motion in straight sections and in generating smooth trajectories at corner sections within the user-defined tolerance.