Model Predictive Obstacle Avoidance and Wheel Allocation Control of Mobile Robots Using Embedded CPU

In this study, we propose a real-time model predictive control method for leg/wheel mobile robots which simultaneously achieves both obstacle avoidance and wheel allocation at a flexible position. The proposed method generates both obstacle avoidance path and dynamical wheel positions, and controls the heading angle depending on the slope of the predicted path so that the robot can keep a good balance between stability and mobility in narrow and complex spaces like indoor environments. Moreover, we reduce the computational effort of the algorithm by deleting usage of mathematical function in the repetitive numerical computation. Thus the proposed real-time optimization method can be applied to low speed on-board CPUs used in commerciallyproduced vehicles. We conducted experiments to verify efficacy and feasibility of the real-time implementation of the proposed method. We used a leg/wheel mobile robot which is equipped with two laser range finders to detect obstacles and an embedded CPU whose clock speed is only 80 MHz. Experiments indicate that the proposed method achieves improved obstacle avoidance comparing with the previous method in the sense that it generates an avoidance path with balanced allocation of right and left side wheels.

[1]  Oliver Brock,et al.  High-speed navigation using the global dynamic window approach , 1999, Proceedings 1999 IEEE International Conference on Robotics and Automation (Cat. No.99CH36288C).

[2]  Gen Endo,et al.  Study on Roller-Walker - Adaptation of characteristics of the propulsion by a leg trajectory - , 2008, 2008 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[3]  Gabriel Hugh Elkaim,et al.  Obstacle avoiding real-time trajectory generation and control of omnidirectional vehicles , 2009, 2009 American Control Conference.

[4]  R. Rockafellar The multiplier method of Hestenes and Powell applied to convex programming , 1973 .

[5]  Hiroaki Seki,et al.  Practical Obstacle Avoidance for a Nonholonmic Vehicle Considering Its Shape , 2008 .

[6]  H. Harry Asada,et al.  Design of a Holonomic Omnidirectional Vehicle Using a Reconfigurable Footprint Mechanism and Its Application to a Wheelchair , 1998 .

[7]  O. Khatib,et al.  Real-Time Obstacle Avoidance for Manipulators and Mobile Robots , 1985, Proceedings. 1985 IEEE International Conference on Robotics and Automation.

[8]  Kenichiro Nonaka,et al.  Optimal online generation of obstacle avoidance trajectory running on a low speed embedded CPU for vehicles , 2010, 2010 IEEE International Conference on Control Applications.

[9]  Masaki Takahashi,et al.  Obstacle avoidance considering robot's size for an autonomous omni directional mobile robot by simultaneous control of translational and rotational motions , 2010 .

[10]  Eiji Nakano,et al.  Mechanism and Control of a Reconfigurable Footprint Omni-Directional Vehicle , 2001 .

[11]  Tatsuo Arai,et al.  Hybrid Locomotion of Leg-Wheel ASTERISK H , 2008, J. Robotics Mechatronics.

[12]  Stephen P. Boyd,et al.  Fast Model Predictive Control Using Online Optimization , 2010, IEEE Transactions on Control Systems Technology.

[13]  Toshiyuki Ohtsuka,et al.  A continuation/GMRES method for fast computation of nonlinear receding horizon control , 2004, Autom..

[14]  Stephen P. Boyd,et al.  Receding Horizon Control , 2011, IEEE Control Systems.

[15]  Stavros G. Vougioukas Reactive Trajectory Tracking for Mobile Robots based on Non Linear Model Predictive Control , 2007, Proceedings 2007 IEEE International Conference on Robotics and Automation.