Calculating Required Motor Torques
WIP for calculating the required torque, and modelling the 6-wheeled rocker bogie system.
| Variable | Known (assumed) /Unknown | Symbol | Value | Unit | Notes |
|---|---|---|---|---|---|
| Gross Weight | Known | Wg | TBD | Kg | |
| Wheel Diameters | Known | D | TBD | m | Assumed all wheel diameters are the same |
| Rolling Resistance Coefficient | Known | c | TBD | unitless | Assumed rubber tire on concrete |
| Time to accelerate | Known | t | TBD | s | Assuming linear acceleration, how long do we want it to take to accelerate? |
| Maximum speed | Known | Vmax | TBD | m/s | At the end of acceleration, how fast do we want our robot to be moving? |
| Slope Angle | Known | θ | TBD | degrees (or radians) | Angle of the slope that the robot is currently on |
Calculating Force to Accelerate
Faccel = Wg * Vmax / ta
Calculating Force due to Slope
Fslope = Wg*sinθ
Calculating Force due to Rolling Resistance
Froll = cWg
Total Tractive Force Required
Ftract = Faccel + Fslope + Froll
Since we have 6 wheels. We device Ftract by 6 to get the tractive force required per wheel, which is the required wheel torque.
21/08/27 Motor Torque Calculations
| Loading Condition | Notes | Minimum Torque, no SF (Nm) | Safety factor for torque | Minimum Torque, 1.25 SF (Nm) | Minimum Speed (RPM) |
|---|---|---|---|---|---|
Hill climb constant velocity |
| 8.67 | 1.4 | 12.1 | 87 |
flat ground constant velocity |
| 3.68 | 1.25 | 4.6 | 223 |