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Robot Arm Torque Calculator Posted: 07 Mar 2013 05:45 PM PST The Robot Torque Arm Calculator is intended to help you choose the right motor for each joint of your robotic arm. The torque (T) required at each joint is calculated as a worst case scenario (lifting weight at 90 degrees). Ensure your units are consistent. Most common units are kg-cm and oz-in. Take a look at the Robot Arm Torque Tutorial for more information. L: length from pivot to pivot. M: link mass A: Actuator (servo or other) mass. Note: same units as for link masses. A1: can represent the load being lifted. Robot Arm Torque Calculator Use the image above to help you determine which torque corresponds to which joint. Note the numbering starts with the extremity of the arm, so the final torque is the one lifting the entire arm (start from A1 being the load you wish to carry at full reach.). The torque shown is the STALL TORQUE you can use for your search. L: [cm] M: [Kg] A: [Kg] T: [Kg-cm] L1: M1: A1: T1: L2: M2: A2: T2: L3: M3: A3: T3: L4: M4: A4: T4: L5: M5: A5: T5: L6: M6: A6: T6:

Drive Motor Sizing Tool Posted: 07 Mar 2013 12:51 PM PST Drive Motor Sizing The Drive Motor Sizing Tool is intended to give an idea of the type of drive motor required for your specific robot by taking known values and calculating values required when searching for a motor. DC motors are generally used for continuous rotation drive systems, though can be used for partial (angle to angle) rotation as well. They come in an almost infinite variety of speeds and torques to suite any need. Without a geardown, DC motors turn very fast (thousands of revolutions per minute (rpm)), but have little torque. To get feedback of the angle or the speed of the motor, consider a motor with an encoder option. Gear motors are essentially DC motors with an added geardown. Adding a geardown both reduces the speed and increases the torque. For example, an unloaded DC motor might spin at 12000 rpm and provide 0.1 kg-cm of torque. A 225:1 geardown is added to proportionally reduce the speed and increase the torque: 12000 rpm / 225 = 53.3 rpm and 0.1 x 225 = 22.5 kg-cm. The motor will now be able to move significantly more weight at a more reasonable speed. If you are not certain about what value to enter, try to make a good “educated” guess. Click each link for more explanation about the effect of each input value. You are also encouraged to look at the Drive Motor Sizing Tutorial, where you will find all the equations used in this tool complete with explanations. Input Total mass: Kg lbs g Number of drive motors: [#] Radius of drive wheel: m in ft Robot Velocity: m/s ft/s Maximum incline: [deg] Supply voltage: [V] Desired acceleration: m/s2 ft/s2 Desired operating time: min hs Total efficiency: [%] Output (for each drive motor) Angular Velocity: rad/s rev/min Torque*: Nm kgf-cm ozf-in Total Power: W hp Maximum current: [A] Battery Pack [Ah] * Note: Although kg-cm is used throughout the RobotShop site, it is actually kgf-cm. Similarly, oz-in should actually read ozf-in throughout the site.

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