TY - JOUR
T1 - Balance control of a biped robot on a rotating platform based on efficient reinforcement learning
AU - Xi, Ao
AU - Mudiyanselage, Thushal Wijekoon
AU - Tao, Dacheng
AU - Chen, Chao
PY - 2019/7/1
Y1 - 2019/7/1
N2 - In this work, we combined the model based reinforcement learning (MBRL)and model free reinforcement learning (MFRL)to stabilize a biped robot (NAO robot)on a rotating platform, where the angular velocity of the platform is unknown for the proposed learning algorithm and treated as the external disturbance. Nonparametric Gaussian processes normally require a large number of training data points to deal with the discontinuity of the estimated model. Although some improved method such as probabilistic inference for learning control (PILCO)does not require an explicit global model as the actions are obtained by directly searching the policy space, the overfitting and lack of model complexity may still result in a large deviation between the prediction and the real system. Besides, none of these approaches consider the data error and measurement noise during the training process and test process, respectively. We propose a hierarchical Gaussian processes (GP)models, containing two layers of independent GPs, where the physically continuous probability transition model of the robot is obtained. Due to the physically continuous estimation, the algorithm overcomes the overfitting problem with a guaranteed model complexity, and the number of training data is also reduced. The policy for any given initial state is generated automatically by minimizing the expected cost according to the predefined cost function and the obtained probability distribution of the state. Furthermore, a novel Q (3BB)based MFRL method scheme is employed to improve the policy. Simulation results show that the proposed RL algorithm is able to balance NAO robot on a rotating platform, and it is capable of adapting to the platform with varying angular velocity.
AB - In this work, we combined the model based reinforcement learning (MBRL)and model free reinforcement learning (MFRL)to stabilize a biped robot (NAO robot)on a rotating platform, where the angular velocity of the platform is unknown for the proposed learning algorithm and treated as the external disturbance. Nonparametric Gaussian processes normally require a large number of training data points to deal with the discontinuity of the estimated model. Although some improved method such as probabilistic inference for learning control (PILCO)does not require an explicit global model as the actions are obtained by directly searching the policy space, the overfitting and lack of model complexity may still result in a large deviation between the prediction and the real system. Besides, none of these approaches consider the data error and measurement noise during the training process and test process, respectively. We propose a hierarchical Gaussian processes (GP)models, containing two layers of independent GPs, where the physically continuous probability transition model of the robot is obtained. Due to the physically continuous estimation, the algorithm overcomes the overfitting problem with a guaranteed model complexity, and the number of training data is also reduced. The policy for any given initial state is generated automatically by minimizing the expected cost according to the predefined cost function and the obtained probability distribution of the state. Furthermore, a novel Q (3BB)based MFRL method scheme is employed to improve the policy. Simulation results show that the proposed RL algorithm is able to balance NAO robot on a rotating platform, and it is capable of adapting to the platform with varying angular velocity.
KW - Biped robot
KW - Gaussian processes (GP)
KW - Reinforcement learning
KW - Temporal difference
UR - http://www.scopus.com/inward/record.url?scp=85068790252&partnerID=8YFLogxK
U2 - 10.1109/JAS.2019.1911567
DO - 10.1109/JAS.2019.1911567
M3 - Article
AN - SCOPUS:85068790252
SN - 2329-9266
VL - 6
SP - 938
EP - 951
JO - IEEE/CAA Journal of Automatica Sinica
JF - IEEE/CAA Journal of Automatica Sinica
IS - 4
M1 - 8753751
ER -