Hello Professor Hauser,

we are using Klampt to model and optimize a pick and place process using the provided tx90l.rob robot. Now we want to move the end effektor link to certain points given in cartesian coordinates. For that we tried to get the configuration out of the cartesian coordiantes x[0], x[1], x[2] by using the inverse kinematics solver:

```
link = robot.link(6)
obj = ik.objective(link, local=[1, 0, 0], world=[x[0], x[1], x[2]])
solver = ik.solver(obj)
solver.setJointLimits(*robot.getJointLimits()) # reinstantiate joint limits
solver.sampleInitial()
solver.solve()
```

For our application the direction (downwards at all times) of the end effector link has to be fixed. Are there suitable constrains to add to the inverse kinematics solver to enforce this direction constraint ?

Thanks for your great work!

I'm looking forward to your answer.