Real-Time Physics Simulation Forum 2020-03-23T17:38:41+00:00 https://pybullet.org/Bullet/phpBB3/app.php/feed/topic/12880 2020-03-23T17:38:41+00:00 2020-03-23T17:38:41+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42731#p42731 <![CDATA[Re: Maximum number of multibody links?]]>
The URDF file modelling our robot contains 333 links (output of getNumLinks) and thus the robot state won't compute due to:
https://github.com/bulletphysics/bullet ... .cpp#L7093

Locally I am able to change the value of MAX_DEGREE_OF_FREEDOM and it seems to work well in our case but I'd like to know if there is any better way to make it work ? or any known workaround ?

regards

Statistics: Posted by XavierB — Mon Mar 23, 2020 5:38 pm

]]> 2020-03-10T04:05:22+00:00 2020-03-10T04:05:22+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42681#p42681 <![CDATA[Re: Maximum number of multibody links?]]> The intention was for typical robots, which usually have only tens of links.

Statistics: Posted by Erwin Coumans — Tue Mar 10, 2020 4:05 am

]]> 2020-03-02T16:55:37+00:00 2020-03-02T16:55:37+00:00 https://pybullet.org/Bullet/phpBB3/viewtopic.php?p=42664#p42664 <![CDATA[Maximum number of multibody links?]]>
I have created a sample code that simulates a "string" as a chain of rigid bodies (spheres in this case). I programmatically create links along a profile curve by adding relative position of each link to the last in the array "linkPos". However, when I include more than 125 links, only the first ~125 seem to be registered. No errors are thrown and the simulation runs realistically, but as if the "string" were shortened to 125/n of its intended length of n links. Originally I thought it was a parsing issue with Python because the array was defined explicitly, and all on one line... so way more than the recommended max characters per line. But putting each vector on a new line didn't help. In the example below (should work as is), I made a circular loop of string with up to n=250 links, but it only ever makes 125 (a half circle). You can play with the value of n; if it's less than 125 you see a corresponding shortening of the arc, but if it's greater than or equal to 125, it maxes out at the half circle.

Code: 

import pybullet as pimport timeimport mathp.connect(p.GUI, options='--background_color_red=1.0 --background_color_green=1.0 --background_color_blue=1.0')p.configureDebugVisualizer(p.COV_ENABLE_SHADOWS,0)p.configureDebugVisualizer(p.COV_ENABLE_GUI,0)orientation = [0,0,0,-1]radius = 0.091mass = 0.0linkCol = p.createCollisionShape(  p.GEOM_SPHERE,  radius = radius)linkVis = p.createVisualShape(  p.GEOM_SPHERE,  radius = radius,  rgbaColor = [1,1,1,1],  specularColor = [1,1,1,1])n = 250link_Masses = []linkCollisionShapeIndices = []linkVisualShapeIndices = []linkPos = [[-0.002168,-0.002597,-0.269228],[-0.006504,-0.00779,-0.269058],[-0.010835,-0.012978,-0.268718],[-0.01516,-0.018157,-0.268209],[-0.019475,-0.023325,-0.26753],[-0.023778,-0.028479,-0.266681],[-0.028065,-0.033614,-0.265665],[-0.032335,-0.038728,-0.264481],[-0.036585,-0.043818,-0.263129],[-0.040811,-0.04888,-0.261611],[-0.045012,-0.053911,-0.259929],[-0.049184,-0.058908,-0.258082],[-0.053325,-0.063868,-0.256072],[-0.057433,-0.068787,-0.2539],[-0.061504,-0.073664,-0.251569],[-0.065536,-0.078493,-0.249077],[-0.069527,-0.083273,-0.246428],[-0.073474,-0.088,-0.243624],[-0.077375,-0.092672,-0.240667],[-0.081227,-0.097285,-0.237557],[-0.085028,-0.101837,-0.234297],[-0.088774,-0.106325,-0.230889],[-0.092465,-0.110745,-0.227335],[-0.096097,-0.115095,-0.223638],[-0.099669,-0.119373,-0.219799],[-0.103177,-0.123575,-0.215822],[-0.106621,-0.1277,-0.211708],[-0.109997,-0.131743,-0.20746],[-0.113303,-0.135703,-0.203082],[-0.116539,-0.139578,-0.198575],[-0.1197,-0.143365,-0.193943],[-0.122786,-0.147061,-0.189188],[-0.125794,-0.150664,-0.184314],[-0.128724,-0.154172,-0.179324],[-0.131571,-0.157582,-0.17422],[-0.134335,-0.160893,-0.169006],[-0.137015,-0.164103,-0.163685],[-0.139608,-0.167208,-0.158261],[-0.142113,-0.170208,-0.152737],[-0.144527,-0.1731,-0.147116],[-0.146852,-0.175884,-0.141403],[-0.149083,-0.178556,-0.1356],[-0.15122,-0.181116,-0.129712],[-0.153261,-0.183561,-0.123742],[-0.155206,-0.18589,-0.117693],[-0.157052,-0.188101,-0.111571],[-0.158799,-0.190194,-0.105377],[-0.160447,-0.192167,-0.099117],[-0.161992,-0.194018,-0.092795],[-0.163436,-0.195747,-0.086414],[-0.164776,-0.197352,-0.079978],[-0.166012,-0.198832,-0.073492],[-0.167143,-0.200187,-0.06696],[-0.168169,-0.201416,-0.060385],[-0.169088,-0.202517,-0.053772],[-0.169901,-0.20349,-0.047125],[-0.170606,-0.204335,-0.040448],[-0.171204,-0.205051,-0.033746],[-0.171693,-0.205637,-0.027022],[-0.172074,-0.206093,-0.020282],[-0.172347,-0.20642,-0.013528],[-0.17251,-0.206615,-0.006766],[-0.172564,-0.20668,-5.0191e-9],[-0.17251,-0.206615,0.006766],[-0.172347,-0.206419,0.013528],[-0.172075,-0.206094,0.020282],[-0.171693,-0.205637,0.027022],[-0.171204,-0.20505,0.033746],[-0.170606,-0.204335,0.040448],[-0.169901,-0.20349,0.047125],[-0.169088,-0.202517,0.053772],[-0.16817,-0.201417,0.060385],[-0.167143,-0.200187,0.06696],[-0.166012,-0.198832,0.073492],[-0.164776,-0.197352,0.079978],[-0.163435,-0.195746,0.086414],[-0.161993,-0.194019,0.092795],[-0.160446,-0.192166,0.099117],[-0.158799,-0.190194,0.105377],[-0.157052,-0.188101,0.11157],[-0.155206,-0.18589,0.117693],[-0.153261,-0.18356,0.123742],[-0.15122,-0.181116,0.129713],[-0.149083,-0.178556,0.1356],[-0.146852,-0.175884,0.141403],[-0.144528,-0.173101,0.147117],[-0.142113,-0.170208,0.152737],[-0.139608,-0.167208,0.158261],[-0.137015,-0.164102,0.163685],[-0.134335,-0.160893,0.169006],[-0.131571,-0.157582,0.174219],[-0.128723,-0.154172,0.179323],[-0.125794,-0.150664,0.184314],[-0.122786,-0.147061,0.189188],[-0.1197,-0.143365,0.193943],[-0.116539,-0.139579,0.198576],[-0.113304,-0.135704,0.203082],[-0.109997,-0.131743,0.207461],[-0.106621,-0.1277,0.211708],[-0.103177,-0.123575,0.215822],[-0.099669,-0.119373,0.219799],[-0.096097,-0.115095,0.223638],[-0.092464,-0.110744,0.227333],[-0.088774,-0.106325,0.230889],[-0.085027,-0.101837,0.234297],[-0.081227,-0.097285,0.237557],[-0.077375,-0.092672,0.240667],[-0.073474,-0.088,0.243624],[-0.069527,-0.083273,0.246429],[-0.065536,-0.078493,0.249077],[-0.061504,-0.073663,0.251568],[-0.057433,-0.068787,0.2539],[-0.053325,-0.063868,0.256072],[-0.049184,-0.058908,0.258082],[-0.045012,-0.053911,0.259929],[-0.040811,-0.04888,0.261611],[-0.036585,-0.043818,0.263129],[-0.032335,-0.038728,0.264481],[-0.028065,-0.033614,0.265665],[-0.023778,-0.028479,0.266682],[-0.019475,-0.023325,0.26753],[-0.01516,-0.018157,0.268209],[-0.010835,-0.012978,0.268718],[-0.006504,-0.00779,0.269058],[-0.002168,-0.002597,0.269228],[0.002168,0.002597,0.269228],[0.006504,0.00779,0.269058],[0.010835,0.012978,0.268718],[0.01516,0.018157,0.268209],[0.019475,0.023325,0.26753],[0.023778,0.028479,0.266681],[0.028065,0.033614,0.265665],[0.032335,0.038728,0.264481],[0.036585,0.043818,0.263129],[0.040811,0.04888,0.261611],[0.045012,0.053911,0.259929],[0.049184,0.058908,0.258082],[0.053325,0.063868,0.256072],[0.057433,0.068787,0.2539],[0.061504,0.073664,0.251569],[0.065536,0.078493,0.249077],[0.069527,0.083273,0.246428],[0.073474,0.088,0.243624],[0.077375,0.092672,0.240667],[0.081227,0.097285,0.237557],[0.085028,0.101837,0.234297],[0.088774,0.106325,0.230889],[0.092465,0.110745,0.227335],[0.096097,0.115095,0.223638],[0.099669,0.119373,0.219799],[0.103177,0.123575,0.215822],[0.106621,0.1277,0.211708],[0.109997,0.131743,0.20746],[0.113303,0.135703,0.203082],[0.116539,0.139578,0.198575],[0.1197,0.143365,0.193943],[0.122786,0.147061,0.189188],[0.125794,0.150664,0.184314],[0.128724,0.154172,0.179324],[0.131571,0.157582,0.17422],[0.134335,0.160893,0.169006],[0.137015,0.164103,0.163685],[0.139608,0.167208,0.158261],[0.142113,0.170208,0.152737],[0.144527,0.1731,0.147116],[0.146852,0.175884,0.141403],[0.149083,0.178556,0.1356],[0.15122,0.181116,0.129712],[0.153261,0.183561,0.123742],[0.155206,0.18589,0.117693],[0.157052,0.188101,0.111571],[0.158799,0.190194,0.105377],[0.160447,0.192167,0.099117],[0.161992,0.194018,0.092795],[0.163436,0.195747,0.086414],[0.164776,0.197352,0.079978],[0.166012,0.198832,0.073492],[0.167143,0.200187,0.06696],[0.168169,0.201416,0.060385],[0.169088,0.202517,0.053772],[0.169901,0.20349,0.047125],[0.170606,0.204335,0.040448],[0.171204,0.205051,0.033746],[0.171693,0.205637,0.027022],[0.172074,0.206093,0.020282],[0.172347,0.20642,0.013528],[0.17251,0.206615,0.006766],[0.172564,0.20668,5.0191e-9],[0.17251,0.206615,-0.006766],[0.172347,0.206419,-0.013528],[0.172075,0.206094,-0.020282],[0.171693,0.205637,-0.027022],[0.171204,0.20505,-0.033746],[0.170606,0.204335,-0.040448],[0.169901,0.20349,-0.047125],[0.169088,0.202517,-0.053772],[0.16817,0.201417,-0.060385],[0.167143,0.200187,-0.06696],[0.166012,0.198832,-0.073492],[0.164776,0.197352,-0.079978],[0.163435,0.195746,-0.086414],[0.161993,0.194019,-0.092795],[0.160446,0.192166,-0.099117],[0.158799,0.190194,-0.105377],[0.157052,0.188101,-0.11157],[0.155206,0.18589,-0.117693],[0.153261,0.18356,-0.123742],[0.15122,0.181116,-0.129713],[0.149083,0.178556,-0.1356],[0.146852,0.175884,-0.141403],[0.144528,0.173101,-0.147117],[0.142113,0.170208,-0.152737],[0.139608,0.167208,-0.158261],[0.137015,0.164102,-0.163685],[0.134335,0.160893,-0.169006],[0.131571,0.157582,-0.174219],[0.128723,0.154172,-0.179323],[0.125794,0.150664,-0.184314],[0.122786,0.147061,-0.189188],[0.1197,0.143365,-0.193943],[0.116539,0.139579,-0.198576],[0.113304,0.135704,-0.203082],[0.109997,0.131743,-0.207461],[0.106621,0.1277,-0.211708],[0.103177,0.123575,-0.215822],[0.099669,0.119373,-0.219799],[0.096097,0.115095,-0.223638],[0.092464,0.110744,-0.227333],[0.088774,0.106325,-0.230889],[0.085027,0.101837,-0.234297],[0.081227,0.097285,-0.237557],[0.077375,0.092672,-0.240667],[0.073474,0.088,-0.243624],[0.069527,0.083273,-0.246429],[0.065536,0.078493,-0.249077],[0.061504,0.073663,-0.251568],[0.057433,0.068787,-0.2539],[0.053325,0.063868,-0.256072],[0.049184,0.058908,-0.258082],[0.045012,0.053911,-0.259929],[0.040811,0.04888,-0.261611],[0.036585,0.043818,-0.263129],[0.032335,0.038728,-0.264481],[0.028065,0.033614,-0.265665],[0.023778,0.028479,-0.266682],[0.019475,0.023325,-0.26753],[0.01516,0.018157,-0.268209],[0.010835,0.012978,-0.268718],[0.006504,0.00779,-0.269058]]linkOrientations = []linkInertialFramePositions = []linkInertialFrameOrientations = []indices = []jointTypes = []axis = []for i in range(len(linkPos)):  link_Masses.append(mass)  linkCollisionShapeIndices.append(linkCol)  linkVisualShapeIndices.append(linkVis)  linkOrientations.append(orientation)  linkInertialFramePositions.append([0,0,0])  linkInertialFrameOrientations.append(orientation)  indices.append(i)  jointTypes.append(p.JOINT_FIXED)  axis.append([0,0,0])link_Masses = link_Masses[:n]linkCollisionShapeIndices = linkCollisionShapeIndices[:n]linkVisualShapeIndices = linkVisualShapeIndices[:n]linkPos = linkPos[:n]linkOrientations = linkOrientations[:n]linkInertialFramePositions = linkInertialFramePositions[:n]linkInertialFrameOrientations = linkInertialFrameOrientations[:n]indices = indices[:n]jointTypes = jointTypes[:n]axis = axis[:n]p.createMultiBody(  baseMass=mass,  baseCollisionShapeIndex=linkCol,  baseVisualShapeIndex=linkVis,  basePosition= [-5.444793, 17.301618, 0],  baseOrientation=orientation,  linkMasses=link_Masses,  linkCollisionShapeIndices=linkCollisionShapeIndices,  linkVisualShapeIndices=linkVisualShapeIndices,  linkPositions=linkPos,  linkOrientations=linkOrientations,  linkInertialFramePositions=linkInertialFramePositions,  linkInertialFrameOrientations=linkInertialFrameOrientations,  linkParentIndices=indices,  linkJointTypes=jointTypes,  linkJointAxis=axis,  useMaximalCoordinates=True)p.setGravity(0, 0, -9.8)dt = 1./120.p.setRealTimeSimulation(1)for i in range(1000000):    p.stepSimulation()    time.sleep(dt)exit()

Statistics: Posted by camnelson — Mon Mar 02, 2020 4:55 pm

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