Distance calculation

CoppeliaSim can measure the minimum distance between two measurable entities in a flexible way. The calculation is an exact minimum distance calculation.

[Minimum distance calculation between two manipulators]

Using the API function sim.checkDistance, one can easily calculate the minimum distance between entities, for instance between a robot and its environment, from within a simulation script, in each simulation step:

#python

def sysCall_init():
    sim = require('sim')
    robotBase = sim.getObject('/robotModelAlias')
    self.robotCollection = sim.createCollection(0)
    sim.addItemToCollection(self.robotCollection, sim.handle_tree, robotBase, 0)

def sysCall_sensing():
    result, distData, objectPair = sim.checkDistance(self.robotCollection, sim.handle_all)
    if result > 0:
        txt = 'Robot clearance is ' + str(distData[6]) + 'm, minimum distance object pair is ' + str(objectPair)
        print(txt)

--lua

function sysCall_init()
    sim = require('sim')
    local robotBase = sim.getObject('/robotModelAlias')
    robotCollection = sim.createCollection(0)
    sim.addItemToCollection(robotCollection, sim.handle_tree, robotBase, 0)
end

function sysCall_sensing()
    local result, distData, objectPair = sim.checkDistance(robotCollection, sim.handle_all)
    if result > 0 then
        local txt = 'Robot clearance is '..distData[7]
        txt = txt..'m, minimum distance object pair is '..getAsString(objectPair)
        print(txt)
    end
end

One can also display the measured minimum distance, as a colored segment in the scene:

#python

def sysCall_init():
    sim = require('sim')
    robotBase = sim.getObject('/robotModelAlias')
    self.robotCollection = sim.createCollection(0)
    sim.addItemToCollection(self.robotCollection, sim.handle_tree, robotBase, 0)
    self.distanceSegment = sim.addDrawingObject(sim.drawing_lines, 4, 0, -1, 1, [0, 1, 0])

def sysCall_sensing():
    result, distData, objectPair = sim.checkDistance(self.robotCollection, sim.handle_all)
    if result > 0:
        sim.addDrawingObjectItem(self.distanceSegment, None)
        sim.addDrawingObjectItem(self.distanceSegment, distData)

--lua

function sysCall_init()
    sim = require('sim')
    local robotBase = sim.getObject('/robotModelAlias')
    robotCollection = sim.createCollection(0)
    sim.addItemToCollection(robotCollection, sim.handle_tree, robotBase, 0)
    distanceSegment = sim.addDrawingObject(sim.drawing_lines, 4, 0, -1, 1, {0, 1, 0})
end

function sysCall_sensing()
    local result, distData, objectPair = sim.checkDistance(robotCollection, sim.handle_all)
    if result > 0 then
        sim.addDrawingObjectItem(distanceSegment, nil)
        sim.addDrawingObjectItem(distanceSegment, distData)
    end
end

CoppeliaSim's distance calculation functionality is also available as stand-alone routines via the Coppelia geometric routines.