"ValueError: `x0` is infeasible." for least_squares.py

Question

I'm trying to use this code in Webots for one of the universal robots. The code works well until I try to the "ikResults" in line 49. The program is trying to use the least_squares.py but I'm getting the error for "'x0' is infeasible". This is the code I'm using:

import sys
import tempfile
try:
    import ikpy
    from ikpy.chain import Chain

import math
from controller import Supervisor

IKPY_MAX_ITERATIONS = 4

supervisor = Supervisor()
timeStep = int(4 * supervisor.getBasicTimeStep())

filename = None
with tempfile.NamedTemporaryFile(suffix='.urdf', delete=False) as file:
    filename = file.name
    file.write(supervisor.getUrdf().encode('utf-8'))
armChain = Chain.from_urdf_file(filename, active_links_mask=[False, True, True, True, True,
True, True, False, True, True, True])

motors = []
for link in armChain.links:
    if 'joint' in link.name and link.name !="wrist_3_link_gripper_joint":
        motor = supervisor.getDevice(link.name)
        motor.setVelocity(1.0)
        position_sensor = motor.getPositionSensor()
        position_sensor.enable(timeStep)
        motors.append(motor)
    
target = supervisor.getFromDef('TARGET')
arm = supervisor.getSelf()

while supervisor.step(timeStep) != -1:
    targetPosition = target.getPosition()
    armPosition = arm.getPosition()

    x = targetPosition[0] - armPosition[0]
    y = targetPosition[1] - armPosition[1]
    z = targetPosition[2] - armPosition[2]

    initial_position = [0] + [m.getPositionSensor().getValue() for m in motors] + [0]
    ikResults = armChain.inverse_kinematics([x, y, z], max_iter=IKPY_MAX_ITERATIONS,
    initial_position=initial_position)`

I've tried incrementing the iterations, changing the target's position, changing the status for the links in armChain (true or false), but nothing seemed to solve this issue. Reading other similar forums, it seems to do something with the bounds, not sure how to check on this.

Answer 1

Remove the limits from the urdf. You'll get an unbound chain, but it will likely solve