Most motion simulators manufactured today benefit from the use of electric actuators. The common solution to a heavier payload is a larger actuator. However, this results in higher power consumption and expenses. Furthermore, the electric actuators continue to use power in stationary positions as well as low platform speeds. To overcome these drawbacks, a combination of passive pneumatic actuators may be supplemented with the electric actuators to allow the motion simulators to sustain equipment weight. However, it is challenging to design a weight compensation system so that it could be efficient throughout the entire workspace. In this paper, kinematics and dynamics of the six axis FUM Stewart robot with three passive redundant pneumatic actuators are investigated. Six independent trajectories using maximum allowed velocity and accelerations are defined and the trajectory containing maximum actuator force is selected. A genetic algorithm is used to optimize the power consumption for the worst-case trajectory. A cost function is defined to minimize the absolute value of average as well as maximum actuator forces by identifying a structural kinematics arrangement of the passive pneumatic actuators. Results indicate that the weight compensation implemented on the FUM Stewart successfully decreased actuator forces in static positions as well as dynamics trajectories by at least 29% and 37.1%, respectively. Furthermore, maximum actuators’ forces during both outstroke and instroke are mostly balanced which helps improve the life expectancy of the mechanical system. The procedures outlined in this paper are general and may be applied to any existing Stewart robot.

今天制造的大多数运动模拟器都受益于电动执行器的使用。较重有效载荷的常见解决方案是使用更大的执行器。然而，这会导致更高的功耗和费用。此外，电动执行器在静止位置和低平台速度下继续使用动力。为了克服这些缺点，可以将被动气动执行器与电动执行器相结合，以允许运动模拟器承受设备重量。然而，设计一个重量补偿系统以使其在整个工作空间内都有效是具有挑战性的。在本文中，研究了具有三个被动冗余气动执行器的六轴 FUM Stewart 机器人的运动学和动力学。定义了使用最大允许速度和加速度的六个独立轨迹，并选择了包含最大致动器力的轨迹。遗传算法用于优化最坏情况轨迹的功耗。成本函数被定义为通过识别被动气动致动器的结构运动学布置来最小化平均和最大致动器力的绝对值。结果表明，在 FUM Stewart 上实施的重量补偿成功地将静态位置和动态轨迹中的致动器力分别降低了至少 29% 和 37.1%。此外，外冲程和内冲程期间的最大执行器力大多是平衡的，这有助于提高机械系统的预期寿命。