Design and Implementation of a Simplified Humanoid Robot with 8 DOF

1. Design and Implementation of a Simplified Humanoid Robot with 8 DOF HariKrishnan R, PG Scholar, Department of ECE, Hindustan Institute Of Technology and Science, Chennai Vallikannu A.L. Assistant Professor, Department of ECE, Hindustan Institute Of Technology and Science, Chennai

2. An Overview on Humanoid robots • Humanoid Robots basically resembles Human physical characteristics. • Humanoid Robotics is an attempt to design a tool that works with human. • These robots are expected to co-exist and work together with humans, for this it should be able to recognize and perform human like action • Simulation of Human body gives a better idea about Humanoids

3. Why Minimalistic Approach to Humanoid Design? • Huge amount of money is spent for developing Humanoid robots. • Major aim is to put forward a design with- • Minimal Actuation. • Minimal Control. • Minimum Energy Utilization • Minimum Development Cost. • One such approach is to utilize springs and oscillatory motions of pendulum

4. Major limitation- Cannot be used for a productive application. Courtesy:-Leonid Paramonov. et. al.

5. Proposed Design • Minimal Actuator Design with only 8 Degrees of Freedom. • 1 DOF at each shoulders, elbows, hips and ankles. • Both the Elbows and Ankles exhibits Roll orientation. • Shoulders exhibits pitch orientation. • Hips exhibits Yaw orientation. • Simple Mechanical and Electrical design.

6. Mechanical Considerations Kinematic Model of Lower Limbs • The Orientation of foot frame of the biped structure is Where Ci=Cos(Ɵi) and Si =Sin(Ɵi)

7. Stability Issue and Biped logic Gait Phases • A biped walker undergoes 2 basic support phases. • Single Support Phase (SSP)- Only one feet of the robot is on ground. • Double Support Phase (DSP)- Both the feet are on ground. • To provide stability in SSP, concept of moving Dead Weight is used. • According to this concept, the upper body weight is moved, so as to bring the centre of gravity on the axis of the footing leg. • Proposed robot has 6 different walking phases for successful, stable walking.

8. Biped Logic Gait Phases

9. Structural Design • 4 Servo motors with double ball bearing and metal gears having stall Torque of 14 Kg/cm are used in lower body of the proposed design. • Large foot pads of 9x6.5 cm, makes the robot more stable in one foot phase. • The ankle motors are fixed on to the foot pads. • While walking, to ensure that the legs doesn’t hit each other, an optimal distance has been maintained. • The upper body of the robot consists of arms and torso that include 4 DOFs in total. • At shoulders servo motors with double ball bearing and plastic • gears , having stall torque of 5.5 Kg/cm are used. • Micro Servos of lesser size and stall Torque of about 1.8 Kg/cm • are employed at the elbows.

10. Electrical Design • Main Controller Board Consists of 2 processing elements, PIC 18F452. • Only one microcontroller will be active at a particular time. For this a Controller selection switch is provided. • The idea of implementing the design using two microcontrollers is to increase the number of applications, that can be performed by the robot. • A 4 pin DIP switch is provided to select a particular application embedded in each controller. • A Servo Extension board provides power and signals for the servo motors. • External power source is used to drive the robot

11. Firmware Development

12. Fabricated Model of the Robot

13. Video

14. Conclusion • The biped gait discussed is simple and could be implemented easily. • More applications like obstacle detection, Pick and Place and HRI could be embedded. • Making a humanoid to walk with lesser number of DOFs is a choice of interest, as it leads to energy efficient design. • This work proposes some foundations for further research and development of humanoid robots with minimum number of DOFs.

15. References [1] Leonid Paramonov, HenrikHautop Lund, “A Minimalistic Approach to Humanoids ,” in Proc. IEEE-RAS Int. Conf. on Humanoid Robots, 2001 [2] HanafiahYussof, Mitsuhiro Yamano, YasuoNasu, Masahiro Ohka, “Design of a 21-DOF Humanoid Robot to Attain Flexibility in Human – Like Motion,” in Proc 15th !EEE Int. Conf on Robot and Human Interactive Communication (RO-MAN06), 2006, pp.202-207. [3] Jung-Yup Kim, Ill-Woo Park, Jungho Lee, Min-Su Kim, Baek-kyu Cho, Jun-Ho Oh, “System Design and Dynamic Walking of Humanoid Robot KHR-2,” in Proc IEEE Int. Conf. on Robotics and Automation, 2005, pp.1443-1448. [4] AppuuKuttan K.K, Robotics, I.K International Publishing House Pvt. Ltd, India, 2007. [5] Kenji KANEKO1, Fumio KANEHIRO, Shuuji KAJITA, Kazuhiko YOKOYAMA, Kazuhiko AKACHI, Toshikazu KAWASAKI, Shigehiko OTA, Takakatsu ISOZUMI, “Design of Prototype Humanoid Robotics Platform for HRP,” in Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems, 2002, pp. 2431-2436. [6] Andre Senior, SabriTosunoglu, “Robust Bipedal Walking: The Clyon Project,” The 18th Florida Conf. on Recent Advances in Robotics, 2005. [7] Jacky Baltes, Sara McGrath , John Anderson, “Active Balancing Using Gyroscopes for a Small Humanoid Robot,” in Proc. 2nd Int. Conf. on Autonomous Robots and Agents, 2004, pp. 470-475. [8] Jens Christensen, JesperLundgaard Nielsen, Mads Solver Svendsen, Peter Flakesgaard Orts, “Development, Modelling and Control of a Humanoid Robot,” Technical report, Aalborg University, 2007

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