提出三阶段框架,让悬空双足机器人精准复现人体运动,安全评估外骨骼。
A Three-Stage Offline SDRE-Based Control Framework for Human Motion Reproduction on a Suspended Bipedal Robot
- 分三步生成可执行指令:先算参考力矩,再转为速度指令,最后用实测数据优化。
- 重复试验中关节角度误差均值低于3°,标准差小于0.15°,表现稳定。
- 适合外骨骼研发前的机器人预测试,避免人体直接暴露于故障风险。
直接用人进行下肢外骨骼评估存在风险,尤其在驱动器故障、关节错位或辅助不当的情况下。因此,需将人体运动数据转换为可由机器人硬件执行且可重复的指令。本文提出一种三阶段离线指令生成框架,用于在悬空双足机器人平台上重现下肢运动与力矩,作为外骨骼评估的机器人试验平台。第一阶段,基于状态依赖黎卡提方程(SDRE)控制机器人动力学模型,获取与实测下肢运动对应的参考力矩轨迹;第二阶段,通过参数化优化,将参考力矩转化为满足电机速度和加速度限制的梯形关节速度指令;第三阶段,利用实验跟踪数据,采用比例-积分-微分线性二次调节器(PID-LQR)对指令进行补偿修正。使用Vicon运动捕捉系统采集的行走与下蹲动作在悬空机器人上重现,评估跟踪精度与可重复性。结果显示,重复试验中关节角度的平均均方根误差(RMSE)和标准差(STD)分别低于3°和0.15°。与两个基线控制器相比,本文方法在所有情况下均实现了更低的最大RMSE和STD值。结果表明,该三阶段控制框架能在悬空双足机器人平台上实现可重复、执行可行的运动再现,适用于外骨骼研究中的人体试验前预测试。
原文摘要 · Abstract (English)
Evaluating lower limb exoskeletons directly with human subjects can expose users to risk when actuator faults, joint misalignment, or unsuitable assistance occur. Therefore, captured human motion must first be converted into commands that are executable by the robot hardware and repeatable across trials. This paper presents a three-stage offline command generation framework for reproducing lower limb motion and torque on a suspended bipedal robot platform used as a robotic bench system for exoskeleton evaluation. First, State-Dependent Riccati Equation control is applied to the robot dynamic model to obtain a reference torque trajectory associated with measured lower limb motion. Second, parameterized optimization converts this reference into trapezoidal joint velocity commands subject to motor speed and acceleration limits. Third, a proportional-integral-derivative linear quadratic regulator (PID-LQR) compensation refines the command profiles using experimental tracking data. Walking and squatting motions recorded by a Vicon motion capture system are reproduced on the suspended robot to evaluate tracking accuracy and repeatability. The results show that the average root mean square error (RMSE) and standard deviation (STD) of joint angles across repeated trials remain below 3° and 0.15°, respectively. Comparisons of joint angles and torques further show that the proposed method achieves lower maximum RMSE and STD values than the two baseline controllers in all reported cases. These results indicate that the proposed three-stage control provides repeatable and actuator-feasible motion reproduction on a suspended bipedal robot platform as a preliminary test environment for lower limb exoskeleton research before tests involving human subjects.
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