how to simulate many balls walk

Question

I want to simulate and visualize some situation, there are many people walking inside a big room, with walls and doors. I simply model each person as a ball or a cylinder, and write python code to move it. the question is, how can I make the model (ball or cylinder) not going through the walls and each other? that is, they can have physics collision. I have set the feature of rigid body, active and passive, etc, not work. some suggest is using force, but it is difficult to control. have tried BGE/UPBGE, it is ok for one ball, but I do not know how to generate many balls which can "walk" by themselves.

snapshot, wall is passive rigid body

snapshot, ball is active rigid body the ball will fall, but not move video captured

if set animation, as this: then the ball will move, but it will not fall, and not stop at the wall (pass through):video captured

Answer 1

You can run the script to get scene

import bpy
from mathutils import Vector

# select and delete all object
if bpy.context.object:
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.select_all(action = "SELECT")
    bpy.ops.object.delete(use_global=True, confirm=False)

unit_settings = bpy.context.scene.unit_settings
unit_settings.system            = 'METRIC'
unit_settings.scale_length      = 1
unit_settings.length_unit       = 'METERS'
unit_settings.mass_unit         = 'KILOGRAMS'
unit_settings.time_unit         = 'SECONDS'
bpy.context.scene.use_gravity   = True
bpy.context.scene.gravity[0]    = 0
bpy.context.scene.gravity[1]    = 0
bpy.context.scene.gravity[2]    = -9.81
bpy.context.scene.render.fps    = 60
bpy.context.scene.frame_set(1)

bpy.ops.mesh.primitive_plane_add(size=5, enter_editmode=False, align='WORLD', location=(0, 0, 0), scale=(1, 1, 1))
bpy.context.object.name = "floor"
bpy.ops.rigidbody.object_add()
bpy.context.object.rigid_body.type = 'PASSIVE'
bpy.context.object.rigid_body.collision_shape = 'BOX'
bpy.context.object.rigid_body.friction = 0.02
bpy.context.object.rigid_body.restitution = 0.9

bpy.ops.mesh.primitive_cube_add(size=5, enter_editmode=False, align='WORLD', location=(5, 0, 0), scale=(1, 1, 1))
bpy.context.object.name = "wall_0"
bpy.ops.rigidbody.object_add()
bpy.context.object.rigid_body.type = 'PASSIVE'
bpy.context.object.rigid_body.collision_shape = 'BOX'
bpy.context.object.rigid_body.friction = 0.02
bpy.context.object.rigid_body.restitution = 0.9

bpy.ops.mesh.primitive_cube_add(size=5, enter_editmode=False, align='WORLD', location=(-5, 0, 0), scale=(1, 1, 1))
bpy.context.object.name = "wall_1"
bpy.ops.rigidbody.object_add()
bpy.context.object.rigid_body.type = 'PASSIVE'
bpy.context.object.rigid_body.collision_shape = 'BOX'
bpy.context.object.rigid_body.friction = 0.02
bpy.context.object.rigid_body.restitution = 0.9

bpy.ops.mesh.primitive_cube_add(size=5, enter_editmode=False, align='WORLD', location=(0, 5, 0), scale=(1, 1, 1))
bpy.context.object.name = "wall_2"
bpy.ops.rigidbody.object_add()
bpy.context.object.rigid_body.type = 'PASSIVE'
bpy.context.object.rigid_body.collision_shape = 'BOX'
bpy.context.object.rigid_body.friction = 0.02
bpy.context.object.rigid_body.restitution = 0.9

x = -1
balls = []
for r in range(10):
    bpy.ops.mesh.primitive_uv_sphere_add(radius=0.1, enter_editmode=False, align='WORLD', location=(x, 0, 0.101), scale=(1, 1, 1))
    bpy.context.object.name = f"ball_{r}"
    bpy.ops.object.shade_smooth()
    bpy.ops.rigidbody.object_add()
    oj = bpy.context.object
    balls.append(oj)
    oj.rigid_body.type = 'ACTIVE'
    oj.rigid_body.kinematic = True
    oj.rigid_body.collision_shape = 'MESH'
    bpy.context.object.rigid_body.collision_margin = 0.001
    bpy.context.object.rigid_body.friction = 0.02
    bpy.context.object.rigid_body.restitution = 0.9
    bpy.ops.rigidbody.mass_calculate(material='Iron', density=7874)
    oj.keyframe_insert(data_path="location", frame=1)
    oj.keyframe_insert(data_path="rigid_body.kinematic", frame=1)
    oj["control_by_rigid_body"] = False
    x += 0.2

def inside_room(x, y):
    if -2.3 < x < 2.3:
        if -2.5 < y < 2.3: return True
    return False


speed = 0.05
v = [
    Vector((-1.0, 0.0)).normalized() * speed,
    Vector((-0.9, 0.2)).normalized() * speed,
    Vector((-0.8, 0.4)).normalized() * speed,
    Vector((-0.6, 0.6)).normalized() * speed,
    Vector((-0.4, 0.7)).normalized() * speed,
    Vector((-0.1, 1.0)).normalized() * speed,
    Vector((0.1, 1.0)).normalized() * speed,
    Vector((0.3, 0.8)).normalized() * speed,
    Vector((0.5, 0.5)).normalized() * speed,
    Vector((1.0, 0.0)).normalized() * speed,
]


for r in range(2, 121):
    # bpy.context.scene.frame_set(r)
    for i, b in enumerate(balls):
        if b["control_by_rigid_body"] == False:
            b.location[0] += v[i][0]
            b.location[1] += v[i][1]
            if inside_room(b.location[0], b.location[1]):
                b.keyframe_insert(data_path="location", frame=r)
            else:
                b.rigid_body.kinematic = False
                b.keyframe_insert(data_path="rigid_body.kinematic", frame=r)
                b["control_by_rigid_body"] = True

To do this, first you need to know when to hit the wall. In my case, if location[0] of the ball > 2.4 will hit the right side (depends on the wall position).
if near the wall, keyframe the "rigid_body.kinematic". Then control by the Rigid Body.