Acceleration controls for a mobile drive unit
Motion controls for a mobile drive unit adjust linear acceleration for laden mobile drive units to decrease the likelihood of the payload tipping or bouncing off the mobile drive unit and adjust angular acceleration to reduce the risk of the drive wheels slipping while the casters align with the direction of travel.
1. A mobile drive unit having a linear acceleration value and an angular acceleration value, the mobile drive unit comprising:
a chassis assembly including a pair of drive wheel assemblies, each drive wheel assembly comprising a motor;
a front caster and a rear caster each connected to the chassis assembly;
a support structure mounted on the chassis assembly;
a payload housing mounted on the support structure, the payload housing comprising a top surface;
a controller communicatively coupled to the pair of drive wheel assemblies; and
memory storing instructions that cause the controller to effectuate operations, the operations comprising:
determining a mass of a payload located on the top surface;
defining a permissible maximum linear acceleration based on the linear acceleration value and the mass of the payload;
determining a prior directional movement of the mobile drive unit, the prior directional movement indicative of a direction of the front caster and the rear caster;
determining a next directional movement of the mobile drive unit, the next directional movement indicative of a travel direction;
defining a permissible maximum angular acceleration and a maneuver angle based on the prior directional movement and the next directional movement, wherein determination of the maneuver angle is based at least in part on the front caster and the rear caster aligned with the travel direction after completion of the maneuver angle;
if the next directional movement comprises a turn, causing the mobile drive unit to operate at the permissible maximum angular acceleration for at least the maneuver angle; and
if the next direction movement comprises a linear movement, causing the mobile drive unit to operate under the permissible maximum linear acceleration.
2. The mobile drive unit of claim 1 , wherein the permissible maximum angular acceleration is at least fifty percent (50%) of the angular acceleration value.
3. The mobile drive unit of claim 1 , wherein the prior directional movement and the next directional movement are both turns in a same direction and the maneuver angle is zero (0) degrees.
4. The mobile drive unit of claim 1 , wherein the prior directional movement is a first turn and the next directional movement is a second turn in an opposite direction as the first turn and the maneuver angle is twenty (20) degrees.
5. The mobile drive unit of claim 1 , wherein the prior directional movement is linear, the maneuver angle is ten (10) degrees.
6. The mobile drive unit of claim 1 , wherein the payload housing comprises a sensor and the determining the mass is based on receiving data from the sensor.
7. The mobile drive unit of claim 1 , wherein the permissible maximum linear acceleration equals the linear acceleration value where the mass does not exceed 270 kilograms.