TURTLE 8-Wheeled Base
|CST Group, TU/e|
|Software Flow Charts|
As an alternative for the three-wheeled base of the RoboCup Middle Size League soccer robots of Tech United Eindhoven, an eight-wheeled version was designed consisting of four wheel sets, each having two hub-drive wheels. Figure 1 depicts such a wheel set, whereas the realization of the system is shown in Figure 2. The main advantages compared to the three-wheeled platform are the possibility to apply the torque delivered by the motors in the desired direction in order to achieve a higher acceleration in this direction.
- Author: Group, TU/e
- License: CERN OHL v.1.1
- Software: https://gitlab.tue.nl/tech-united-eindhoven/Turtle3
- Simulink Control Implementation: low_level_control_lib.slx. Chose the "Turtle8W" subsystem to find the implementation of the control architecture of the 8-wheeled base.
Contributions in publications about this platform can be found in
Houtman W. et al. (2019) Tech United Eindhoven Middle-Size League Winner 2019. In: Chalup S., Niemueller T., Suthakorn J., Williams MA. (eds) RoboCup 2019: Robot World Cup XXIII. RoboCup 2019. Lecture Notes in Computer Science, vol 11531. Springer, Cham
Douven Y. et al. (2019) Tech United Eindhoven Middle Size League Winner 2018. In: Holz D., Genter K., Saad M., von Stryk O. (eds) RoboCup 2018: Robot World Cup XXII. RoboCup 2018. Lecture Notes in Computer Science, vol 11374. Springer, Cham
The eight-wheels system is a redesign of the three wheeled version of the Tech United RoboCup Team Limited Edition (TURTLE) robots. As such, the base has been reconsidered, while the the upper body and the the ball handling and kicking mechanism have been reused. Therefore, the focus of the hardware elaborated on this page is on the wheel sets and the assembly of the entire system.
This platform consists of four wheel sets, each having two hub-drive wheels. As such, the platform is five times over-constrained. To avoid an over-constrained design, each wheel set has an internal degree of freedom. This degree of freedom is visualized in Figure 1 by the white lines. The last platform-constraint is addressed by a hinging axle at the back of the robot, which is shown in Figure 3. By using slip rings for powering the wheel sets and communicating the control signals, the rotation of the wheels is unconstrained in both directions.
• Wheel radius: 0.056 meter
• Lateral wheel distance: 0.056 meter
• Motor velocity constant: 135 revolutions per minute per volt
• Motor torque constant: 135 Newton meter per ampere
• Motor resistance: 0.072 Ohm
Custom EtherCat module consisting of
• Measured orientation of the wheel set (19 bit encoder)
• Measured position of each wheel (16 bit encoder)
• Measured velocity of each wheel
• Safe torque off status
• Warning & error statuses
• Measured Negative Temperature Coefficient (NTC) resistor for temperature observations
• Control Mode: position, velocity or current control
• Corresponding setpoint
The video on the left indicated the first match appearance of the Eight-wheeled system at the RoboCup Portuguese Open 2019. The eight-wheeled system, indicated with number 7, can be discriminated from the other robots based on its square base. The video on the right demonstrates the functionalities of the system on the practice field of Tech United Eindhoven.
Copyright Eindhoven University of Technology 2020.
This documentation describes Open Hardware and is licensed under the CERN OHL v. 1.1.
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