From 4bbe4e5ebc209f9bef0c1538d711e4e7897d6613 Mon Sep 17 00:00:00 2001
From: Taylor Howell <taylorhowell@google.com>
Date: Mon, 22 Sep 2025 06:23:46 -0700
Subject: [PATCH] Zero actuator_velocity if actuation is disabled.

PiperOrigin-RevId: 809986353
Change-Id: Ie9fecda80864fef3377074042fd7829af8d03d64
---
 src/engine/engine_forward.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/engine/engine_forward.c b/src/engine/engine_forward.c
index e523cd6f..2a9e0bc5 100644
--- a/src/engine/engine_forward.c
+++ b/src/engine/engine_forward.c
@@ -214,6 +214,8 @@ void mj_fwdVelocity(const mjModel* m, mjData* d) {
   if (!mjDISABLED(mjDSBL_ACTUATION)) {
     mju_mulMatVecSparse(d->actuator_velocity, d->actuator_moment, d->qvel, m->nu,
                         d->moment_rownnz, d->moment_rowadr, d->moment_colind, NULL);
+  } else {
+    mju_zero(d->actuator_velocity, m->nu);
   }
 
   // com-based velocities, passive forces, constraint references