多軸力規開發與以力與位置複合控制實現六足機器人動態步態

本論文致力於設計應用於六足機器人髖關節上之自製多軸力規，並將力規應用於機器人動態步態之調控。透過重新設計多軸力規，搭配FEM分析了解力規應變狀況，使圓形力規在同樣受力下有產生更大的應變訊號。從四分之一橋改為半橋設計，不但增加量測應變，且解決溫度飄移效應。採用創新的固定馬達方式，使得自製力規框架不與馬達直接接觸，達到阻隔馬達電位雜訊的功能，不導電之樹脂螺絲也不易斷裂。種種新設計使得力規校正從最大誤差10 N降至2 N，故可將圓形自製力規之量測值做為回授進行機器人動態步態控制。模擬上以PR-SLIP模型（具有位置控制之R-SLIP模型）為基礎，加入模型當時受力做為力回授訊號，建構HybridR-SLIP模型，為一具有力與位置複合控制模型。HybridR-SLIP模型以被動動態R-SLIP髖關節軌跡為位置目標、R-SLIP地面作用力為受力目標，分別計算應給予髖關節自由度力矩，混合後控制模型運動。給予一有偏差的初始狀況，在模擬上驗證了使用力與位置複合控制可以使得模型更快的收斂至目標被動動態上。設計與製作FORHex機器人，與六足型態的TWIX相比有更好的剛性，減少自製力規受到機身變形的影響。以R-SLIP所計算出之穩定點進行Tripod步態實驗，誘發FORHex機器人進行被動動態運動。在觸地速度角度大的穩定點中，FORHex機器人與R-SLIP模型存在較大的受力差異。透用力與位置複合控制使其受力輪廓更貼近R-SLIP被動動態，電能消耗因此降低，機器人運動動態更貼近圓弧形腳本身之被動動態。在模擬中觀察到HybridR-SLIP暫態收斂性提高，在實驗中觀察到FORHex穩態貼近被動動態，雙方面驗證力與位置複合控制可改善機器人步態。

關鍵字

多軸力規；六足機器人；動態步態；力與位置複合控制；力控制模型

並列摘要

This research is dedicated to improve performance of self-made multi-axis force/torque sensor embedded on hip actuator of hexapod robot and apply it to control dynamic gaits of robot. By utilizing finite element analysis to help us understanding mechanism under force/torque sensor stress/strain behavior, new force/torque sensor design produces larger strain signal under same load than last version. Strain gauges temperature drift problem is solved and measured signal is larger by changing quarter bridge to half bridge design. A novel motor housing method is applied to stop direct connection between self-made sensor and motor, making sure that electrical voltage potential of motor would not influence the measuring signal of half bridge. It also decrease possibility of reny screws’ fracture. Overall, these improvements reduce the calibration error of force/torque sensor from 10N maximum to 2N. Hence, measurement values of self-made force/torque sensor can be used as feedback signal to control dynamic gaits of robot. In simulation, HybridR-SLIP model is proposed, which use PR-SLIP model as foundation, adding ground reaction force feedback to achieve force control. Hip trajectory and ground reaction force profile in R-SLIP model are used as position control target and force control target. After calculating torque requirements in each controller, hybrid controller sums up position and force control results to control hip DoF of the model. Given a deviation in initial touchdown condition, force and position hybrid control making model converging to passive dynamics of target fixed points faster is verified in simulation. Design and manufacturing Hexapod FROHex, which is more rigid than TWIX, reduces the influence of strain signal of force/torque sensor when deformation of robot is occurred. Results of fixed points in R-SLIP model are used to induce passive dynamics of FROHex. It exists about 100N difference between FROHex and R-SLIP model in high touchdown speed angle fixed point targets. Through force and position hybrid control, measuring force profiles are closer to those of R-SLIP model. Because of smaller difference between dynamics of robot and real passive dynamics of circular legs, electrical consumption are reduced under hybrid control strategy. In simulation, HybridR-SLIP shows greater converge ability in transient state. In experiments, force feedback control strategy induced passive dynamics in force profile. Force and position hybrid control is verified to improve dynamics of robot in both way.

並列關鍵字

multi-axis force/torque sensor ； hexapod ； RHex ； force and position hybrid control ； force control simulation ； dynamic gait

參考文獻

[2] F. Beyeler, S. Muntwyler, and B. J. Nelson, "A Six-Axis MEMS Force-Torque Sensor With Micro-Newton and Nano-Newtonmeter Resolution," Journal of Microelectromechanical Systems, vol. 18, pp. 433-441, 2009.

[3] F. Beyeler, S. Muntwyler, and B. J. Nelson, "Design and calibration of a microfabricated 6-axis force-torque sensor for microrobotic applications," in IEEE International Conference on Robotics and Automation, pp. 520-525, 2009.

[4] S. Hirose and K. Yoneda, "Development of optical six-axial force sensor and its signal calibration considering nonlinear interference," in IEEE International Conference on Robotics and Automation, pp. 46-53, 1990.

[5] J. D. Goldberg and R. S. Fearing, "Force Sensing Shell using a Planar Sensor for Miniature Legged Robots," in IEEE/RSJ International Conference on Intelligent Robots and Systems, 2015.

[6] X. A. Wu, T. M. Huh, R. Mukherjee, and M. Cutkosky, "Integrated Ground Reaction Force Sensing and Terrain Classification for Small Legged Robots," IEEE Robotics and Automation Letters, vol. 1, pp. 1125-1132, 2016.

國際替代計量

多軸力規開發與以力與位置複合控制實現六足機器人動態步態

全文下載

主題瀏覽