diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index 3e73ed060012fe3df80239f0adaff5e9e2d7ce76..c8cc39bd8bcda0ee9a3ffbb2204b12923f3849c9 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -511,11 +511,11 @@ class OhmPiHardware:
                 # ax.plot([0, vab_max], [0, vmn_upper_bound * vab_max / vab[k]], '-r', alpha=(k + 1) / n_steps)
                 # ax.plot([0, vab_max], [0, vmn_lower_bound * vab_max / vab[k]], '-g', alpha=(k + 1) / n_steps)
                 # bounds on rab
-                rab_lower_bound = vab_list[k] / iab_upper_bound
-                rab_upper_bound = vab_list[k] / iab_lower_bound
+                rab_lower_bound = np.min([0.1, vab_list[k] / iab_upper_bound])
+                rab_upper_bound = np.min([0.1, vab_list[k] / iab_lower_bound])
                 # bounds on r
-                r_lower_bound = vmn_lower_bound / iab_upper_bound
-                r_upper_bound = vmn_upper_bound / iab_lower_bound
+                r_lower_bound = np.min([0.01, vmn_lower_bound / iab_upper_bound])
+                r_upper_bound = np.min([0.01, vmn_upper_bound / iab_lower_bound])
                 # conditions for vab update
                 cond_vmn_max = rab_lower_bound / r_upper_bound * vmn_max
                 cond_p_max = np.sqrt(p_max * rab_lower_bound)