A strategy for transporting tall objects with a swarm of miniature mobile robots

Jianing Chen, Melvin Gauci and Roderich Groß

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Abstract

This research proposes a strategy for transporting a tall, and potentially heavy, object to a goal using a large number of miniature mobile robots.

The robots move the object by pushing it, and hence, are not required to have any manipulation capabilities (eg gripping).

The direction in which the object moves is controlled by the way in which the robots distribute themselves around its perimeter. If the robots dynamically reallocate themselves around the section of the object's perimeter that occludes their view of the goal, then the object will eventually be transported to the goal.

This strategy is fully distributed, and makes no use of communication between the robots.

A controller based on this strategy was implemented on a swarm of 12 physical e-puck robots. A systematic experiment with 30 randomised trials was performed. The object was successfully transported to the goal in all the trials.

On average, the path the object was moved was about 7.7% longer than the shortest path.

Highlight video

State flow diagram

In this strategy, making more robots push along the occluded side of the object does not only increase the pushing power, it also stabilises the moving direction of the object. These four movements are the key motions to achieve a uniform and tight pushing formation.

Motion controller

Block diagram

Weight matrices

S1. Search object (avoiding)

n_S	0.7
n_D	0
S_R	-0.25	-0.25	0	0	0	0	-0.25	-0.25
S_A	-0.125	-0.125	0	0	0	0	-0.125	-0.125
D_R	4.25	3.75	1	2	-2	-1	-3.25	-3.5
D_A	2.125	1.875	0.5	1	-1	-0.5	-1.625	-1.75

S2. Move to object (avoiding)

n_S	0.7
n_D	0
S_R	-0.75	-0.25	0	0	0	0	-0.25	-0.625
S_A	-0.25	-0.25	0	0	0	0	-0.25	-0.25
D_R	-0.75	-0.25	0	0	0	0	-0.25	-0.625
D_A	4.25	3.75	1	2	-2	-1	-3.25	-3.5

S3. Close in on object (robot avoiding and object following)

n_S	0.6
n_D	0
S_R	-0.75	-0.25	0	0	0	0	-0.25	-0.625
S_A	-0.25	-0.25	0	0	0	0	-0.25	-0.25
D_R	-3.25	-2.25	-1	0	0	0.25	0.75	2.625
D_A	4.25	3.75	1	2	-2	-1	-3.25	-3.5

S5. Push object (robot avoiding and object following)

n_S	0.5
n_D	0
S_R	-0.125	0	0	0	0	0	0	-0.125
S_A	-0.25	-0.375	0	0	0	0	-0.375	-0.25
D_R	-1.875	-1	0	0	0	0	1	1.875
D_A	1.5	0.125	0	0	0	0	-0.125	-1.5

S6. Move around object (left-hand wall following)

n_S	0.1
n_D	0.7
S_R	0	0	0	0	0	2.375	1.5	0
S_A	0	0	0	0	0	1.5	0.5	0
D_R	0	0	0	0	-1	-3.625	-6	-5
D_A	0	0	0	0	-1	-1.5	-2.5	-3

S7. Evade (repulsive motion)

n_S	0
n_D	0
S_R	-0.75	-0.375	0	0.625	0.625	0	-0.375	-0.75
S_A	-0.75	-0.375	0	0.625	0.625	0	-0.375	-0.75
D_R	0.25	0.125	0	0.125	-0.125	0	-0.125	-0.25
D_A	0.25	0.125	0	0.125	-0.125	0	-0.125	-0.25