Gearbox | |||||
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# MotorsHow many motors do you have in total for this mechanism (assuming they're identical, and geared together) | |||||

EfficiencyEfficiency of the transmission | Speed LossMagical "Speed Loss Constant" from the JVN-calcs. Doesn't impact simulation, only used to compute "JVN adjusted speed". |

Free SpeedThe maximum RPM of the motor | [RPM] | |
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Stall TorqueThe maximum torque of the motor, occurring at 0 RPM | ||

Free CurrentThe current drawn when the motor is unloaded | [A] | |

Stall CurrentThe current drawn at 0 RPM / Max Torque | [A] |

Gear RatioThe overall gear ratio. Larger than 1 is a reduction, smaller is a RPM increase. Empty cells are assumed to be 1. You can either blank out all the cells, and plug in a number in the top right one, or build a ratio by typing in the number of teeth on each gear (or belts/sprockets) starting from the motor.

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Encoder(Optional) Where is the encoder placed - on (or in) the motor, or on the output shaft?

CPREncoder Counts Per Revolution (you can also put ticks, and ticks will be computed. Math is the same) |
C/xEncoder Counts Per Distance Traveled (how many encoder counts per unit distance traveled) |
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ReductionAdditional reduction applied between the shaft and the encoder | Max CPSMaximum Counts per Second, at free speed |

Interface | |||||
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Radius Radius of the output. If this is an arm, input the length of the arm. If this is an elevator, input the radius of the spool. If this is a drivetrain, input the radius of the wheel. |
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Mass[Equivalent] Mass. If you're running a linear device, just put its mass in here. If you are analyzing a rotational device, put the moment of inertia, divided by the radius squared here. |
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Load(Optional) Load. | |||||

Override dt=(Optional) Timestep override. Default is to auto-time-step. This doesn't work well for mechanisms that are extremely quick. | [s] | ||||

End Condition(Optional) End condition. Must be an expression that logically evaluates. You can use any javascript operators/comparators (+,-,*,/,>,<,Math.sin(...),...). You can use any variables described in the pullout below. |

Basic Calculations | ||||
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JVN Adjusted SpeedAdjusted speed; computed like in the JVN calc. | ||||

No LoadSpeed without any load on the system. Equivalent to the JVN calc. |
[A] | |||

RunningSpeed and current while running at steady-state, ASSUMING THAT ALL TRANSIENT VARIABLES (v,x,omega,theta) ARE ZERO. Equivalent to the JVN calc. |
[A] | |||

StallForce produced while at stall (ignoring external load/mass) Equivalent to the JVN calc. |
[A] | |||

Traction Limit | [A] | |||

Simulation Results | ||||

Time To EndWhen simulation terminated if the end condition was met. If not, it will tell you the end condition was unmet. Auto-time-stepping may cause runs with high initial accelerations to have very short runtimes. | [s] | |||

Current UsedTotal electrical consumption in the simulation period | [A-s] |

The calculator can be used for any mechanism. For a drivetrain, plug in wheel radius, robot mass, and nothing for load (unless you're pushing something). For an arm, plug in the radius to the center of mass, arm's mass, and the effective load at the center of gravity. For an elevator, plug in pulley radius, elevator mass, and the elevator load (weight minus any counterbalancing). Reverse the load to go 'down'.

Click on the chart to probe points!

The gear ratio has a dropdown that can be used to compute ratios from gearsets. Otherwise you can collapse it and plug in a gear ratio directly.

The simulator uses auto-time-stepping based on the initial acceleration. It's best to specify an end condition. If your mechanism is extremely snappy, it's probably geared really, really low- so it will put the motor near free speed, which is generally undesirable.

You can input arithmetic anywhere. But only input symbolic math (with variables) in the end condition and load equation boxes.

G | [-] | Overall gear ratio |
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m | [kg] | Mass |

I | MOI | |

r | Radius | |

t | [s] | Time |

v | Lin. Velocity | |

x | Lin. Position | |

omega | Rot. Velocity | |

theta | Rot. Position | |

omega_m | Rot. Motor Velocity | |

theta_m | Rot. Motor Position |