Research On An Arm-Equipped Single-Wheeled Rover

Planetary exploration robots are becoming miniaturized and multi-robot cooperation of such small robots is the developing trend. Fewer tasks will be performed with robots becoming smaller. Thus, to maintain as many functions as possible while miniaturizing planetary robots is very important.Single-wheeled rover with an arm equipped, introduced and developed in this paper, has two working mode: manipulation mode and locomotion mode. The rover not only can work by itself as a single-wheeled robot, but also can be connected with another. Moreover, the single-wheeled rover can be connected to the mother rover as a driving child unit.First, the mechanical system of the prototype is introduced and developed. The mechanical system is composed of gripper unit, arm unit and wheel unit. The gripper unit, driven by a servo motor, has a sealed rolling bearing on it as the passive orientation wheel. Synchronous belt drive, gear drive and direct motor drive with protection are adopted in the design of the three joints of the arm unit. Gear drive is also adopted in the wheel unit, aiming to produce the eccentricity of the wheel unit and also to magnify the torque.Next, the rover controlling system is introduced. Its hardware is composed of DSP controlling board and motor driving board. There are two choices for the serial communication between the DSP board and the PC. Trapezoid curve method is adopted for frequency control of stepper motor. And a rough speed control method of servo motor is developed.Kinematics modeling of rover in manipulation is presented. Steering modeling of the prototype in locomotion is introduced and the relation between rover turning radius and its posture is derived. And obstacle surmounting ability of the prototype is modeled and analyzed. And working modes simulation is realized using Adams.Last, experiments of the working modes of the prototype are introduced, which validate the presented rover system.