Water distribution systems are critical infrastructure that are expected to supply healthy water. Deliberate or accidental incidents such as terrorist attacks or pipe breaks can contaminate potable water in pipelines. Inline mobile sensors are promising solutions which have been designed and developed to monitor water quality and detect leaks in water pipelines. These mobile sensors can move towards the location of contamination or leak and provide more timely and accurate measurements. However, these sensors, which are often free-swimming spheres and move by water flow, have two problems: instability and passiveness. In this research, we designed a robot that stabilizes and automates our previously fabricated spherical mobile sensor. The robot empowers a water utility operator to control the mobile sensor motion in a pressurized environment with a high-speed flow. The robot has three spring-based adjustable arms for stability in pipes with diameters between 22.86 (cm)-9 (in) and 55.88 (cm)-22 (in). Each arm is actuated with a motor and a wheel at its end. The wheels are in contact with a pipe wall, and the motors keep the robot moving. Each motor is customized with a gearhead that provides required torque at its wheel for motion. A lithium battery attached to the sphere supplies electricity for motors and sensors. The proposed design is characterized and prototyped in this paper. To evaluate the controllability and observability of the robot, we have linearized governing equations. Results show the successful performance of the robot in pipes.