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Motion Control Cheat Sheet & Unit Conversions

  • Common Engineering Unit Conversions – Basic Units
    Parameter (Basic Units) SI Units English/American Units
    mass (m) kilogram (kg) pound mass (lbm)
    length – distance (L) meter (m) foot or inch (ft or in)
    time (t) second (s)
    current (I) Ampere (A)
  • Derived Units
    Parameter (Derived Units) SI Units English/American Units
    Force – weight (F or W) Newton (N) pound or ounce (lbf or oz)
    Torque (T) Newton-meter (Nm) foot-pound (ft-lb or in-lb)
    Work – energy (W or E) Joule (J) foot-pound (ft-lb or in-lb
    Power (P) Watt (W) horsepower (hp or W)
    Voltage, EMF (V) Volt (V)
    Resistance (R) ohms (Ω)
    Inertia (J) kilogram-meter2 (kg-m2) inch-pound-second2 (in-lb-s2)
    plane angle (α, β, γ, etc.) radian (rad) degree or radian (deg or rad)
    rotation (Ө) revolution (rev)
    velocity – linear (v) meter per sec. (m/s) inch per second (in/s)
    acceleration (a) meter per second2 (m/s2) inch per second2 (in/s2)
    velocity – angular (ω) rad per second (rad/s)
    velocity – rotational (ω) rev per minute (rpm)
    accel – angular (α) rad per second2 (rad/s2)
  • Basic Definitions & Formulae
    Parameter Formula SI Units Formula English/American Units Formula
    Force – accel (F = m * a) 1 N = 1 kg * 1 m / s2 1 lbf = 1 lbf / (386 in / s2) * 386 in / s2
    Torque – accel (T = J * α) 1 Nm = 1 kg-m2 * 1 rad / s2 1 in-lb = 1 in-bl-s2 * 1 rad / s2
    Voltage, EMF (V = I * R) 1 V = 1 A * 1 Ω
    Work – Energy (E = F * L) 1 J = 1 N * 1 m 1 in-lb = .113 Nm = .113 Ws = .113 J
    Energy – elect (E = V * I * t) 1 J = 1 V * 1 A * 1 s
    Power (P = F * v) 1 W = 1 N * 1 m / s 1 hp = 550 ft-lb / s = 745.7 W
    Power (P = T * ω) 1 W = 1 Nm * 1 rad / s (note: radians have no units)
    Power (P = V * I) 1 W = 1 V * 1 A
    Power (P = E / t) 1 W = 1 J / 1 s
    Power (P = I2 * R) 1 W = 1 A2 * 1 Ω
  • Motor Constants
    Parameter Formula SI Units Formula English/American Units Formula
    Torque const (Kt = T / I) Kt = Nm / A Kt = in-lb / A
    Voltage const (Ke = V / ω) Ke = V / (rad / s) Ke = V / krpm
  • Servo Motor Formulae
    Parameter Formula SI Units Formula English/American Units Formula
    Current Draw (I + T / Kt) 1 A = 1 Nm / (Nm / A) 1 A = 1 in-lb / (in-lb / A)
    Voltage Required (V = IRa + Ke * ω) 1 V = AΩ + V / (rad / s) * (rad / s) 1 V = AΩ + V / (krpm) * (krpm)

 

Conversions

To convert from units of A to units of B, find the value at the intersection of A and B, then multiply your number by this value. Example: to convert from cm to microns, multiply value in cm by 1.00E+04.

  • Length Conversion
    A (below) B (right) micron (µm) mm cm m in ft
    micron (µm) 1 0.001 1.00E-04 1.00E-06 3.94E-05 3.28E-06
    mm 1000 1 0.1 0.001 0.03937 3.28E-03
    cm 1.00E+04 10 1 0.01 0.3937 0.03281
    m 1.00E+06 1000 100 1 39.37 3.281
    in 2.54E+04 25.4 2.54 0.0254 1 0.0833
    ft 3.05E+05 304.8 30.48 0.3048 12 1
  • Mass Conversion
    A (below) B (right) g kg slug ozm lbm
    g 1 0.001 6.85E-05 0.0353 2.20E-03
    kg 1000 1 6.85E-02 35.274 2.2046
    slug 1.46E+04 14.59 1 514.78 32.17
    ozm 28.35 0.0284 1.94E-03 1 0.0625
    lbm 453.6 0.4536 0.0311 16 1
  • Force Conversion
    A (below) B (right) N kgf gf ozf lbf
    N 1 0.102 101.97 3.596 0.225
    kgf 9.81 1 1000 35.274 2.205
    gf 9.81E-03 0.001 1 0.0353 2.21E-03
    ozf 0.28 0.0283 28.35 1 0.0625
    lbf 4.45 0.4536 453.6 16 1
  • Torque Conversion
    A (below) B (right) g-cm kg-cm kg-m N-m oz-in lb-in lb-ft
    g-cm 1 0.001 1.00E-05 9.81E-05 0.014 8.68E-04 7.23E-05
    kg-cm 1000 1 0.01 0.098 13.89 0.868 0.072
    kg-m 1.00E+05 100 1 9.81 1389 86.8 7.23
    N-m 1.02E+04 10.2 0.102 1 141.6 8.85 0.738
    oz-in 72.01 0.072 7.21E-04 7.06E-03 1 0.063 5.21E-03
    lb-in 1.15E+03 1.152 0.012 0.113 16 1 0.083
    lb-ft 1.38E+04 13.83 0.138 1.356 192 12 1
  • Power Conversion
    A (below) B (right) Watts kW Horsepower in-lb/s ft-lb/s
    Watts 1 100E-03 1.34E-03 8.85 0.74
    kW 1000 1 1.34 8851 738
    Horsepower 746 0.746 1 6600 550
    in-lb/s 0.113 1.13E-04 1.52E-04 1 0.083
    ft-lb/s 1.35 1.36E-03 1.82E-03 12 1
  • Linear Velocity Conversion
    A (below) B (right) mm/s cm/s m/s in/s ft/s in/min ft/min
    mm/s 1 0.1 0.001 0.0394 3.28E-03 2.362 0.1968
    cm/s 10 1 0.01 0.394 0.0328 23.62 1.97
    m/s 1000 100 1 39.37 3.281 2362.2 196.9
    in/s 25.4 2.54 0.0254 1 0.083 60 5
    ft/s 304.8 30.48 0.3048 12 1 720 60
    in/min 0.423 0.0423 4.23E-04 0.0167 1.39E-03 1 0.0833
    ft/min 5.08 0.508 5.08E-03 0.2 0.0167 12 1
  • Angular Velocity Conversion
    A (below) B (right) deg/s rad/s rpm rps
    deg/s 1 0.0175 0.167 2.78E-03
    rad/s 57.3 1 9.55 0.159
    rpm 6 0.105 1 0.0167
    rps 360 6.28 60 1
  • Rotary Inertia Conversion
    A (below) B (right) g-cm2 kg-cm2 g-cm-s2 kg-cm-s2 kg-m2 lb-in-s2 lb-ft-s2 lb-in2 lb-ft2 oz-in2 oz-in-s2
    g-cm2 1 0.001 0.001 1.02E-06 1.00E-07 8.85E-07 7.38E-08 3.42E-04 2.37E-06 5.50E-03 1.42E-05
    kg-cm2 1000 1 1.02 0.001 0.0001 8.85E-04 7.38E-05 0.342 2.40E-03 5.47 0.014
    g-cm-s2 981 0.981 1 0.001 9.81E-05 8.68E-04 7.23E-05 0.335 2.30E-03 5.36 0.014
    kg-cm-s2 9.81E+05 981 1000 1 0.0981 0.868 0.072 335.1 2.33 5362 13.89
    kg-m2 1.00E+07 10000 10190 10.19 1 8.85 0.738 3417.74 23.734 54675 141.6
    lb-in-s2 1.13E+06 1130 1.15E+03 1.152 0.113 1 0.083 386.1 2.68 6177 16
    lb-ft-s2 1.36E+07 1.36E+04 1.38E+04 13.83 1.36 12 1 4633 32.2 7.41E+04 192
    lb-in2 2926 2.93 2.98 0.003 2.93E-04 2.60E-03 2.16E-04 1 6.90E-03 16 0.041
    lb-ft2 4.21E+05 421.4 429.7 0.43 0.0421 0.373 0.031 144 1 2304 5.97
    oz-in2 182.9 0.183 0.187 1.87E-04 1.83E-05 1.62E-04 1.35E-05 0.0625 4.34E-04 1 2.60E-03
    oz-in-s2 7.06E+04 70.62 72 0.072 0.007 0.063 5.20E-03 24.13 0.168 386.1 1

Download Unit Conversions in PDF Format

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