Robo-Erectus Senior – I (RESr-I)

Robo-Erectus Senior I (RESr-I) is a human sized humanoid robot completely fabricated and developed at Singapore Polytechnic. RESr-I gave an outstanding exhibition in the Humanoid League of RoboCup 2007 and won the 4th place in the penalty kick competition of Humanoid TeenSize League. It was also featured in CNN Live and TIME magazine. Modular design concept is employed in the development of RESr-I. The modular biped robot system of RESr-I consists of a set of independently designed modules, such as actuators, passive joints, rigid links (connectors) that can be rapidly assembled into a complete robot with various configurations having different kinematics and dynamic characteristics. Off-the-shelf intelligent mechatronic drives, PowerCube, are selected as actuator modules for rapid deployment. Each of the actuator modules is a self-contained drive unit with a built-in motor, a controller, an amplifier, and the communication interface. It has a cubic or double-cube design with multiple connecting sockets so that two actuator modules can be connected in many different orientations. To facilitate the forward kinematics analysis, an angular displacement sensor is built into each of the passive rotary and pivot joint modules. A set of rigid links with various geo-metrical shapes and dimensions has been custom-designed to connect joint modules. Torque and power requirements of the actuators (brushless servo motor) used in RESr-I were carefully chosen to enable walking, playing soccer and climbing stairs.

Table I shows the physical specifications of RESr-I. It has 22 Degrees Of Freedom (DOFs). They are powered by rechargeable lithium-polymer battery matrix that can support biped walking as long as half an hour. Robot is controlled by an onboard computer and a Sony VAIO ultra portable PC, which are incharge of robot navigation and localization and vision processing respectively. Because the active modules are self-contained mechatronic units, the control loop of the robot is closed at the joint level. Each actuator module has its own individual motion controller. The inter-module communication is through the CAN-bus protocol and the RS-485 serial interface. Based on hierarchical control concept, low-level trajectory generation and control are developed. Once the robot is fully constructed, configured and initialized, the artificial intelligence PC is able to identify the configuration of the robot, generate the necessary models, and coordinate the motion control of the robot.

The USB camera is a 640x480 (VGA) progressive scan CMOS with a standard miniature lenses. The frame rate is 30Hz for 640×480 with automatic control of exposure, gain and black level. Multiple color objects can be detected in one image. From the parameters of the objects in the image (x, y, coordinates and objective size) and the known orientation of the cameras, physical position of the objects relative to the robot can be calculated. Besides visual sensor, tilt sensor and an electronic compass is set in upper body to get the tilt information and to measure the moving direction.



Physical Specifications of Robo-Erectus Senior – I (RESr-I)




Untitled Document © Advanced Robotics & Intelligent Control Centre 2009