Autonomous snooker robot

We had the following initial data from the Customer: mass of the cue - 0,52 kg, speed of the cue at the moment of contact with the ball - 5 m/s, path of the cue with the sticker to the moment of impact with the ball - 250-300 mm, path of the tip of the cue with the sticker after impact with the ball (puncture) - 200 mm, speed of the cue after impact with the ball - 3 m/s. 

In order to develop an impact mechanism of the smallest possible size, our team needed to select or develop an optimum servo drive.

Since most servo drives are made for quick, accurate displacements with little load, high impact loads on the servo will shorten its lifespan. After 5 iterations of testing, we have found one that can withstand the loads over time and move the cue quickly along a given trajectory. 

The use of non-standard gears and auxiliary mechanisms can reduce the cost of the device many times over. By using this method, we were able to lower the price of shoulder assemblies for the robot by a factor of 10.

The next step is to develop a layout solution for the impact mechanism. We looked at 5 alternative variations and contrasted the sizes and masses of the solutions among them. We chose the following option:

• Aligning the driving mechanism of the cue grip and the carriage plates. We flipped the device's main units by 90°. The overall dimensions in this layout are 80*130 mm. 

We took the Customer's suggestion to create the kinematics that would allow the robot to reach a specific spot on the table without toppling over. The idea was to use a gyro platform. The centre of gravity of the robot changes its position over a wide range. Standard gyroscooters cannot compensate for this tipping moment, so we needed a custom scooter with high performance.

A 10*2.15 inch 1000W 205 40H V2 wheel motor with MTSVESC7.5R motor control was the one we chose. The undercarriage had to perform the following actions: moving, maneuvering, docking with the table, pulling away from the table and moving away from the table.

Gyroscopes are installed inside the gyroplatform’s undercarriage. They maintain the robot's upright posture while establishing the location of the base of the undercarriage in relation to the floor surface. The gyroscopes transmit this information to the control board, which is located on the chassis. The control board issues orders to the motor wheels based on this data. The power component at the bottom of the chassis is the lithium-ion battery. It provides energy for the entire robot. The battery has enough charge for 8-12 hours of operation. The large weight of the battery and its location on the bottom of the device increases its stability.

The allowable swing angle of the robot in an equilibrium position was +-10 degrees with a wheel diameter of 300 mm. We worked to lessen the robot's moment of inertia in relation to the wheel axis in order to boost the balance angle of the robot during design.