add backflip ckpts; update locomotion quaternion

examples/locomotion/backflip/readme.md

@@ -0,0 +1,15 @@
+# Go2 Backflips
+
+To try Go2 backflips, follow these steps:
+
+1. Download the checkpoints from the link below:
+    ```
+    https://drive.google.com/drive/folders/1ZxBaDP4_Br0ZhriQx_8A3JIwZZLnxix4?usp=drive_link
+    ```
+2. Place the downloaded checkpoints into the `backflip` directory.
+
+For advanced training code, including features like domain randomization and reference rewards for backflip, visit this repository:
+
+```
+https://github.com/ziyanx02/Genesis-backflip
+```

examples/locomotion/go2_backflip.py

@@ -0,0 +1,149 @@
+import argparse
+import os
+import pickle
+
+import torch
+from go2_env import Go2Env
+
+import genesis as gs
+
+
+def get_cfgs():
+    env_cfg = {
+        "num_actions": 12,
+        # joint/link names
+        "default_joint_angles": {  # [rad]
+            "FL_hip_joint": 0.0,
+            "FR_hip_joint": 0.0,
+            "RL_hip_joint": 0.0,
+            "RR_hip_joint": 0.0,
+            "FL_thigh_joint": 0.8,
+            "FR_thigh_joint": 0.8,
+            "RL_thigh_joint": 1.0,
+            "RR_thigh_joint": 1.0,
+            "FL_calf_joint": -1.5,
+            "FR_calf_joint": -1.5,
+            "RL_calf_joint": -1.5,
+            "RR_calf_joint": -1.5,
+        },
+        "dof_names": [
+            "FR_hip_joint",
+            "FR_thigh_joint",
+            "FR_calf_joint",
+            "FL_hip_joint",
+            "FL_thigh_joint",
+            "FL_calf_joint",
+            "RR_hip_joint",
+            "RR_thigh_joint",
+            "RR_calf_joint",
+            "RL_hip_joint",
+            "RL_thigh_joint",
+            "RL_calf_joint",
+        ],
+        # PD
+        "kp": 70.0,
+        "kd": 3.0,
+        # termination
+        "termination_if_roll_greater_than": 1000,  # degree
+        "termination_if_pitch_greater_than": 1000,
+        # base pose
+        "base_init_pos": [0.0, 0.0, 0.35],
+        "base_init_quat": [0.0, 0.0, 0.0, 1.0],
+        "episode_length_s": 20.0,
+        "resampling_time_s": 4.0,
+        "action_scale": 0.5,
+        "simulate_action_latency": True,
+        "clip_actions": 100.0,
+    }
+    obs_cfg = {
+        "num_obs": 60,
+        "obs_scales": {
+            "lin_vel": 2.0,
+            "ang_vel": 0.25,
+            "dof_pos": 1.0,
+            "dof_vel": 0.05,
+        },
+    }
+    reward_cfg = {"reward_scales": {},}
+    command_cfg = {
+        "num_commands": 3,
+        "lin_vel_x_range": [0, 0],
+        "lin_vel_y_range": [0, 0],
+        "ang_vel_range": [0, 0],
+    }
+
+    return env_cfg, obs_cfg, reward_cfg, command_cfg
+
+
+class BackflipEnv(Go2Env):
+
+    def get_observations(self):
+
+        phase = torch.pi * self.episode_length_buf[:, None] / self.max_episode_length
+        self.obs_buf = torch.cat(
+            [
+                self.base_ang_vel * self.obs_scales['ang_vel'],  # 3
+                self.projected_gravity,  # 3
+                (self.dof_pos - self.default_dof_pos) * self.obs_scales['dof_pos'],  # 12
+                self.dof_vel * self.obs_scales['dof_vel'],  # 12
+                self.actions,  # 12
+                self.last_actions,  # 12
+                torch.sin(phase),
+                torch.cos(phase),
+                torch.sin(phase / 2),
+                torch.cos(phase / 2),
+                torch.sin(phase / 4),
+                torch.cos(phase / 4),
+            ],
+            axis=-1,
+        )
+
+        return self.obs_buf
+
+    def step(self, actions):
+        super().step(actions)
+        self.get_observations()
+        return self.obs_buf, None, self.rew_buf, self.reset_buf, self.extras
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-e", "--exp_name", type=str, default="single")
+    args = parser.parse_args()
+
+    gs.init()
+
+    env_cfg, obs_cfg, reward_cfg, command_cfg = get_cfgs()
+
+    if args.exp_name == "single":
+        env_cfg["episode_length_s"] = 2
+    elif args.exp_name == "double":
+        env_cfg["episode_length_s"] = 3
+    else:
+        raise RuntimeError
+
+    env = BackflipEnv(
+        num_envs=1,
+        env_cfg=env_cfg,
+        obs_cfg=obs_cfg,
+        reward_cfg=reward_cfg,
+        command_cfg=command_cfg,
+        show_viewer=True,
+    )
+
+    policy = torch.jit.load(f"./backflip/{args.exp_name}.pt")
+    policy.to(device="cuda:0")
+
+    obs, _ = env.reset()
+    with torch.no_grad():
+        while True:
+            actions = policy(obs)
+            obs, _, rews, dones, infos = env.step(actions)
+
+
+if __name__ == "__main__":
+    main()
+
+"""
+# evaluation
+python examples/locomotion/go2_eval.py -e go2-walking -v --ckpt 100
+"""

examples/locomotion/go2_train.py

@@ -96,7 +96,7 @@ def get_cfgs():
         "termination_if_pitch_greater_than": 10,
         # base pose
         "base_init_pos": [0.0, 0.0, 0.42],
-        "base_init_quat": [0.0, 0.0, 0.0, 1.0],
+        "base_init_quat": [1.0, 0.0, 0.0, 0.0],
         "episode_length_s": 20.0,
         "resampling_time_s": 4.0,
         "action_scale": 0.25,