Time-optimal trajectory planning method for six-legged robots under actuator constraints

Current studies on time-optimal trajectory planning centers on cases with fixed base and only one end-effector. However, the free-floating body and the multiple legs of the legged robot make the current methods inapplicable. This paper proposes a time-optimal trajectory planning method for six-legged robots. The model of the optimization problem for six-legged robots is built by considering the base and the end-effectors separately. Both the actuator constraints and the gait cycle constraints are taken into account. A novel two-step optimization method is proposed to solve the optimization problem. The first step solves the time-optimal trajectory of the body and the second step solves the time-optimal trajectory of the swinging legs. Finally, the method is applied to a six-parallel-legged robot and validated by experiments on the prototype. The results show that the velocity of the optimized gait is improved by 17.8% in contrast to the non-optimized one.

[1]  Jan Swevers,et al.  Time-Optimal Path Tracking for Robots: A Convex Optimization Approach , 2009, IEEE Transactions on Automatic Control.

[2]  Feng Gao,et al.  Obstacle avoidance for a hexapod robot in unknown environment , 2017 .

[3]  Alessandro Gasparetto,et al.  Optimal trajectory planning for nonlinear systems: robust and constrained solution , 2014, Robotica.

[4]  Xilun Ding,et al.  Gait analysis of a radial symmetrical hexapod robot based on parallel mechanisms , 2014 .

[5]  Kalyanmoy Deb,et al.  Optimal path and gait generations simultaneously of a six-legged robot using a GA-fuzzy approach , 2002, Robotics Auton. Syst..

[6]  Goele Pipeleers,et al.  Time-Optimal Path Following for Robots With Convex–Concave Constraints Using Sequential Convex Programming , 2013, IEEE Transactions on Robotics.

[7]  Saeed Behzadipour,et al.  Time-optimal trajectory planning in cable-based manipulators , 2006, IEEE Transactions on Robotics.

[8]  Feng Gao,et al.  Energy Expenditure of Trotting Gait Under Different Gait Parameters , 2017 .

[9]  Jean-Jacques E. Slotine,et al.  Improving the Efficiency of Time-Optimal Path-Following Algorithms , 1988, 1988 American Control Conference.

[10]  Ming-Chuan Leu,et al.  Optimal trajectory generation for robotic manipulators using dynamic programming , 1987 .

[11]  Qiang Zhang,et al.  Time-optimal path tracking for robots under dynamics constraints based on convex optimization , 2015, Robotica.

[12]  Olivier Stasse,et al.  Time-Optimal Path Parameterization for Redundantly Actuated Robots: A Numerical Integration Approach , 2015, IEEE/ASME Transactions on Mechatronics.

[13]  Feng Gao,et al.  Efficient motion generation for a six-legged robot walking on irregular terrain via integrated foothold selection and optimization-based whole-body planning , 2017, Robotica.

[14]  Qiang Zhang,et al.  An efficient stochastic approach for robust time-optimal trajectory planning of robotic manipulators under limited actuation , 2017, Robotica.

[15]  Feng Gao,et al.  Novel Door-opening Method for Six-legged Robots Based on Only Force Sensing , 2017 .

[16]  Friedrich Pfeiffer,et al.  A concept for manipulator trajectory planning , 1987, IEEE J. Robotics Autom..

[17]  E. Croft,et al.  Smooth and time-optimal trajectory planning for industrial manipulators along specified paths , 2000 .