1. From the Editor-in-Chief

   • Kimon P. Valavanis

   Editorial 01 July 2021 Article: 71

2. Robots Used Today that we Did Not Expect 20 Years Ago (from the Editorial Board Members)

   • Tauseef Gulrez

   Editorial 01 July 2021 Article: 70

3. Deep Reinforcement Learning for a Humanoid Robot Soccer Player

   • Isaac Jesus da Silva
   • Danilo Hernani Perico
   • Reinaldo Augusto da Costa Bianchi

   OriginalPaper 26 June 2021 Article: 69

4. Improving Control Performance of Unmanned Aerial Vehicles through Shared Experience

   • Peter Travis Jardine
   • Sidney Givigi

   Regular Paper 25 June 2021 Article: 68

5. PSO Based Optimal Gain Scheduling Backstepping Flight Controller Design for a Transformable Quadrotor

   • Saddam Hocine Derrouaoui
   • Yasser Bouzid
   • Mohamed Guiatni

   Regular Paper 24 June 2021 Article: 67

6. Whole-Body Control and Angular Momentum Regulation using Torque Sensors for Quadrupedal Robots

   • Young Hun Lee
   • Yoon Haeng Lee
   • Hyouk Ryeol Choi

   Regular Paper 18 June 2021 Article: 66

7. Fast Real-Time Control Allocation Applied to Over-Actuated Quadrotor Tilt-Rotor

   • M. F. Santos
   • L. M. Honório
   • V. F. Vidal

   Regular Paper 18 June 2021 Article: 65

8. Distributed Observer-Based Leader Following Consensus Tracking Protocol for a Swarm of Drones

   • Adeel Zaidi
   • Muhammad Kazim
   • Xu Zhang

   Regular Paper 18 June 2021 Article: 64

9. Lever Control for Position Control of a Typical Excavator in Joint Space Using a Time Delay Control Method

   • Dongik Sun
   • Seunghoon Hwang
   • Jeakweon Han

   Regular Paper 17 June 2021 Article: 63

10. Integration of a 4D-trajectory Follower to Improve Multi-UAV Conflict Management Within the U-Space Context

    • Hector Perez-Leon
    • Jose Joaquin Acevedo
    • Anibal Ollero

    Regular Paper 14 June 2021 Article: 62

11. Super Twisting Algorithm for Robust Geometric Control of a Helicopter

    • Akhil B. Krishna
    • Arijit Sen
    • Mangal Kothari

    Regular Paper 14 June 2021 Article: 61

12. Towards Hybrid Gait Obstacle Avoidance for a Six Wheel-Legged Robot with Payload Transportation

    • Zhihua Chen
    • Jiehao Li
    • Jing Li

    Regular Paper 11 June 2021 Article: 60

13. Formally-based Model-Driven Development of Collaborative Robotic Applications

    • Mehrnoosh Askarpour
    • Livia Lestingi
    • Federico Vicentini

    Regular Paper Open access 04 June 2021 Article: 59

14. Self-Selection Salient Region-Based Scene Recognition Using Slight-Weight Convolutional Neural Network

    • Zhenyu Li
    • Aiguo Zhou

    Regular Paper 03 June 2021 Article: 58

15. On the Optimal Adhesion Control of a Vortex Climbing Robot

    • Andreas Papadimitriou
    • George Andrikopoulos
    • George Nikolakopoulos

    Regular Paper Open access 03 June 2021 Article: 57

16. A Benchmarking Platform for Learning-Based Grasp Synthesis Methodologies

    • Jacques Janse van Vuuren
    • Liqiong Tang
    • Khalid Mahmood Arif

    Short Paper 03 June 2021 Article: 56

17. Image-Based Indoor Topological Navigation with Collision Avoidance for Resource-Constrained Mobile Robots

    • Suman Raj Bista
    • Belinda Ward
    • Peter Corke

    Regular Paper 03 June 2021 Article: 55

18. Learning Humanoid Robot Running Motions with Symmetry Incentive through Proximal Policy Optimization

    • Luckeciano C. Melo
    • Dicksiano C. Melo
    • Marcos R. O. A. Maximo

    Regular Paper 03 June 2021 Article: 54