fix: reward v4 — full sim bypass kills circular driving at root

ROOT CAUSE:
  donkey_sim.py calc_reward() uses forward_vel = dot(heading, velocity).
  A spinning car ALWAYS has forward_vel > 0 (always moving 'forward' relative
  to its own heading), so it earned positive reward indefinitely while circling.

v3 WAS INSUFFICIENT:
  v3 applied efficiency only to the speed BONUS: original × (1 + speed×eff×scale)
  But 'original' from sim was still exploitable: CTE≈0 while spinning → original=1.0/step
  Efficiency killed the speed bonus but not the base reward.
  47k-step run: spinning = 1.0/step × 47k = 47k reward (never crashes in circle)

v4 FIX — base × efficiency × speed:
  reward = (1 - abs(cte)/max_cte) × efficiency × (1 + speed_scale × speed)
  Completely ignores sim's bogus forward_vel reward.
  Spinning (eff≈0): reward ≈ 0 regardless of CTE or speed.
  ALL three terms must be high to earn reward — cannot be gamed.

Key new test: test_circling_at_zero_cte_gives_near_zero_reward
  Worst-case exploit (CTE=0 spinning) → avg reward < 0.15 (was 1.0 in v3)
  forward_beats_circling_by_3x confirmed.

Also: update Phase 2 autoresearch timesteps test, research log updated.

Agent: pi/claude-sonnet
Tests: 40/40 passing
Tests-Added: +1 (core v4 circling guarantee)
TypeScript: N/A
This commit is contained in:
Paul Huliganga 2026-04-13 20:56:32 -04:00
parent 7b8830f0cb
commit c8a495dd22
6 changed files with 368 additions and 286 deletions

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[2026-04-13 19:33:13] ============================================================
[2026-04-13 19:33:13] [AutoResearch] Phase 1 — Real PPO Training + GP+UCB Optimization
[2026-04-13 19:33:13] [AutoResearch] Max trials: 20 | kappa: 2.0 | push every: 5
[2026-04-13 19:33:13] [AutoResearch] Results: /home/paulh/projects/donkeycar-rl-autoresearch/agent/outerloop-results/autoresearch_results_phase2.jsonl
[2026-04-13 19:33:13] [AutoResearch] Champion: /home/paulh/projects/donkeycar-rl-autoresearch/agent/models/champion
[2026-04-13 19:33:13] ============================================================
[2026-04-13 19:33:13] [AutoResearch] Loaded 0 existing Phase 1 results.
[2026-04-13 19:33:13] [AutoResearch] Champion: trial=5 mean_reward=4582.7984 params={'n_steer': 7, 'n_throttle': 3, 'learning_rate': 0.0006801262090358742, 'timesteps': 4787, 'agent': 'ppo', 'eval_episodes': 3, 'reward_shaping': True}
[2026-04-13 19:33:13]
[AutoResearch] ========== Trial 1/20 ==========
[2026-04-13 19:33:13] [AutoResearch] Only 0 results — using random proposal.
[2026-04-13 19:33:13] [AutoResearch] Proposed: {'n_steer': 4, 'n_throttle': 3, 'learning_rate': 0.0009737963906394612, 'timesteps': 47325, 'agent': 'ppo', 'eval_episodes': 5, 'reward_shaping': True}
[2026-04-13 19:33:15] [AutoResearch] Launching trial 1: {'n_steer': 4, 'n_throttle': 3, 'learning_rate': 0.0009737963906394612, 'timesteps': 47325, 'agent': 'ppo', 'eval_episodes': 5, 'reward_shaping': True}
[2026-04-13 20:05:03] [AutoResearch] Trial 1 finished in 1908.3s, returncode=0
[2026-04-13 20:05:03] [AutoResearch] Trial 1: mean_reward=234.5386 std_reward=3.1547
[2026-04-13 20:05:03] [AutoResearch] === Trial 1 Summary ===
[2026-04-13 20:05:03] Total Phase 1 runs: 1
[2026-04-13 20:05:03] Champion: trial=5 mean_reward=4582.7984 params={'n_steer': 7, 'n_throttle': 3, 'learning_rate': 0.0006801262090358742, 'timesteps': 4787, 'agent': 'ppo', 'eval_episodes': 3, 'reward_shaping': True}
[2026-04-13 20:05:03] Top 5:
[2026-04-13 20:05:03] mean_reward=234.5386 params={'n_steer': 4, 'n_throttle': 3, 'learning_rate': 0.0009737963906394612, 'timesteps': 47325, 'agent': 'ppo', 'eval_episodes': 5, 'reward_shaping': True}
[2026-04-13 20:05:05]
[AutoResearch] ========== Trial 2/20 ==========
[2026-04-13 20:05:05] [AutoResearch] Only 1 results — using random proposal.
[2026-04-13 20:05:05] [AutoResearch] Proposed: {'n_steer': 8, 'n_throttle': 3, 'learning_rate': 0.0012285179829782996, 'timesteps': 39101, 'agent': 'ppo', 'eval_episodes': 5, 'reward_shaping': True}
[2026-04-13 20:05:07] [AutoResearch] Launching trial 2: {'n_steer': 8, 'n_throttle': 3, 'learning_rate': 0.0012285179829782996, 'timesteps': 39101, 'agent': 'ppo', 'eval_episodes': 5, 'reward_shaping': True}
[2026-04-13 20:55:43] [AutoResearch] GP UCB top-5 candidates:
[2026-04-13 20:55:43] UCB=2.3107 mu=0.3981 sigma=0.9563 params={'n_steer': 9, 'n_throttle': 2, 'learning_rate': 0.001405531880392808, 'timesteps': 26173}
[2026-04-13 20:55:43] UCB=2.3049 mu=0.8602 sigma=0.7224 params={'n_steer': 9, 'n_throttle': 3, 'learning_rate': 0.001793493447174312, 'timesteps': 19198}
[2026-04-13 20:55:43] UCB=2.2813 mu=0.4904 sigma=0.8954 params={'n_steer': 9, 'n_throttle': 4, 'learning_rate': 0.0011616192816742616, 'timesteps': 13887}
[2026-04-13 20:55:43] UCB=2.2767 mu=0.5194 sigma=0.8787 params={'n_steer': 9, 'n_throttle': 4, 'learning_rate': 0.0011646447444663046, 'timesteps': 21199}
[2026-04-13 20:55:43] UCB=2.2525 mu=0.6254 sigma=0.8136 params={'n_steer': 9, 'n_throttle': 3, 'learning_rate': 0.0010196345864901517, 'timesteps': 22035}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=50.0000 params={'n_steer': 5}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=80.0000 params={'n_steer': 7}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 0: mean_reward=50.0000 params={'r': 50}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=80.0000 params={'r': 80}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 3: mean_reward=90.0000 params={'r': 90}
[2026-04-13 20:55:43] [Champion] 🏆 NEW BEST! Trial 5: mean_reward=75.0000 params={'n_steer': 8}
[2026-04-13 20:55:43] [AutoResearch] Only 1 results — using random proposal.
[2026-04-13 20:55:59] [AutoResearch] GP UCB top-5 candidates:
[2026-04-13 20:55:59] UCB=2.3107 mu=0.3981 sigma=0.9563 params={'n_steer': 9, 'n_throttle': 2, 'learning_rate': 0.001405531880392808, 'timesteps': 26173}
[2026-04-13 20:55:59] UCB=2.3049 mu=0.8602 sigma=0.7224 params={'n_steer': 9, 'n_throttle': 3, 'learning_rate': 0.001793493447174312, 'timesteps': 19198}
[2026-04-13 20:55:59] UCB=2.2813 mu=0.4904 sigma=0.8954 params={'n_steer': 9, 'n_throttle': 4, 'learning_rate': 0.0011616192816742616, 'timesteps': 13887}
[2026-04-13 20:55:59] UCB=2.2767 mu=0.5194 sigma=0.8787 params={'n_steer': 9, 'n_throttle': 4, 'learning_rate': 0.0011646447444663046, 'timesteps': 21199}
[2026-04-13 20:55:59] UCB=2.2525 mu=0.6254 sigma=0.8136 params={'n_steer': 9, 'n_throttle': 3, 'learning_rate': 0.0010196345864901517, 'timesteps': 22035}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=50.0000 params={'n_steer': 5}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=80.0000 params={'n_steer': 7}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 0: mean_reward=50.0000 params={'r': 50}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 1: mean_reward=80.0000 params={'r': 80}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 3: mean_reward=90.0000 params={'r': 90}
[2026-04-13 20:55:59] [Champion] 🏆 NEW BEST! Trial 5: mean_reward=75.0000 params={'n_steer': 8}
[2026-04-13 20:55:59] [AutoResearch] Only 1 results — using random proposal.

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@ -0,0 +1 @@
{"trial": 1, "timestamp": "2026-04-13T20:05:03.791538", "params": {"n_steer": 4, "n_throttle": 3, "learning_rate": 0.0009737963906394612, "timesteps": 47325, "agent": "ppo", "eval_episodes": 5, "reward_shaping": true}, "mean_reward": 234.5386, "std_reward": 3.1547, "model_path": "/home/paulh/projects/donkeycar-rl-autoresearch/agent/models/trial-0001/model.zip", "champion": false, "run_status": "ok", "elapsed_sec": 1908.32528758049, "reward_hacking_suspected": false}

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@ -1,42 +1,41 @@
"""
Progress-Based Reward Wrapper for DonkeyCar RL v3 (Anti-Circular)
Speed + Progress Reward Wrapper for DonkeyCar RL v4 (Full Bypass)
====================================================================
PROBLEM HISTORY:
v1 (additive): speed × (1 - cte/max_cte)
Hacked by oscillating at track boundary (trials 8+13 in corrupted data)
REWARD HACKING HISTORY:
v1 additive: speed × (1-cte/max_cte) boundary oscillation
v2 multiplicative: original × (1+speed×scale) circular driving (on-track)
v3 path efficiency: original × (1+speed×eff×scale) still circling!
WHY v3 failed: efficiency killed the SPEED BONUS but not the BASE reward.
A spinning car at CTE0 still earns 1.0/step × thousands of steps.
v2 (multiplicative): original × (1 + speed_scale × speed)
Still hacked by circling ON the track (trial 5: cv=0.0%, 4582 reward)
Circular motion has low CTE + positive speed full speed bonus
Neither CTE nor raw speed can distinguish forward vs circular motion
v4 (THIS VERSION): Completely bypass sim's reward. Multiply base reward by
efficiency so circling yields ZERO reward regardless of CTE.
v3 (path efficiency): original × (1 + speed_scale × speed × path_efficiency)
Path efficiency = net_displacement / path_length over sliding window
Forward driving: efficiency 1.0 (all movement is productive)
Circular driving: efficiency 0.0 (movement cancels out, no net advance)
Speed bonus disappears when circling car incentivized to go FORWARD
ROOT CAUSE OF CIRCLING:
The sim's own calc_reward() uses `forward_vel` = dot(car_heading, velocity).
A spinning car is ALWAYS moving "forward" relative to its own heading,
so forward_vel > 0 always, giving positive reward while circling indefinitely.
We bypass this entirely.
FORMULA:
efficiency = |pos_t - pos_{t-window}| / Σ|pos_i - pos_{i-1}|
= net_displacement / total_path_length
FORMULA (v4):
base = 1.0 - min(abs(cte) / max_cte, 1.0) # CTE quality [0,1]
eff = net_displacement / total_path_length # Forward progress [0,1]
shaped = base × eff × (1 + speed_scale × speed) # All three must be high
shaped_reward = original_reward × (1 + speed_scale × speed × efficiency)
On done/crash: shaped = -1.0
(when original_reward 0: no bonus, just penalty same as v2)
PROPERTIES:
- Spinning (eff0): shaped 0 (no reward)
- On track, slow (eff1): shaped base (CTE reward only)
- On track, fast (eff1): shaped > base (CTE + speed bonus)
- Off track (base0): shaped 0 (penalty via done)
- Cannot be gamed: ALL THREE terms must be high simultaneously
RESEARCH NOTE (2026-04-13):
Circular driving discovered in Phase 1 despite v2 fix.
Trial 5: mean_reward=4582, cv=0.0% over 4787 steps.
User visually confirmed: car circling at start line.
See docs/RESEARCH_LOG.md for full analysis.
TUNING:
window_size: how many steps to measure efficiency over (default 30)
- Too small: noisy, sensitive to brief oscillations
- Too large: slow to detect circling, may miss short circular segments
speed_scale: speed bonus multiplier (default 0.1)
min_efficiency: minimum efficiency before speed bonus disappears (default 0.1)
v3 was insufficient circling at start gave 1.0/step × 47k steps = 47k reward.
v4 makes efficiency a multiplier on the entire reward, not just the speed bonus.
See docs/RESEARCH_LOG.md for full hacking history.
"""
import gymnasium as gym
@ -46,30 +45,37 @@ from collections import deque
class SpeedRewardWrapper(gym.Wrapper):
"""
Path-efficiency-gated speed reward.
Speed bonus only applies proportionally to how much the car is making NET FORWARD PROGRESS.
Full reward bypass: base CTE reward × path efficiency × speed bonus.
Completely ignores the sim's own reward (which uses forward_vel and is
exploitable by circular/spinning motion).
Args:
env: gymnasium environment
speed_scale: speed bonus multiplier (default 0.1)
window_size: number of steps for efficiency measurement (default 30)
min_efficiency: efficiency floor below which speed bonus is zero (default 0.05)
window_size: steps for efficiency calculation (default 30)
min_efficiency: efficiency below which no reward (default 0.05)
max_cte: track half-width for normalization (default 8.0, matches sim)
"""
def __init__(self, env, speed_scale: float = 0.1, window_size: int = 30, min_efficiency: float = 0.05):
def __init__(
self,
env,
speed_scale: float = 0.1,
window_size: int = 30,
min_efficiency: float = 0.05,
max_cte: float = 8.0,
):
super().__init__(env)
self.speed_scale = speed_scale
self.window_size = window_size
self.min_efficiency = min_efficiency
# Sliding window of positions for efficiency calculation
self.max_cte = max_cte
self._pos_history = deque(maxlen=window_size + 1)
self._path_length = 0.0
def reset(self, **kwargs):
result = self.env.reset(**kwargs)
self._pos_history.clear()
self._path_length = 0.0
return result
def step(self, action):
@ -77,84 +83,76 @@ class SpeedRewardWrapper(gym.Wrapper):
# Handle both 4-tuple (old gym) and 5-tuple (gymnasium) APIs
if len(result) == 5:
obs, reward, terminated, truncated, info = result
obs, _sim_reward, terminated, truncated, info = result
done = terminated or truncated
elif len(result) == 4:
obs, reward, done, info = result
obs, _sim_reward, done, info = result
terminated = done
truncated = False
else:
raise ValueError(f'Unexpected step() result length: {len(result)}')
shaped = self._shape_reward(reward, info)
# Completely ignore _sim_reward — compute our own
shaped = self._compute_reward(done, info)
if len(result) == 5:
return obs, shaped, terminated, truncated, info
else:
return obs, shaped, done, info
def _get_pos(self, info: dict):
"""Extract position from info dict. Returns None if unavailable."""
pos = info.get('pos', None)
if pos is None:
return None
try:
return np.array(pos[:3], dtype=np.float64)
except (TypeError, IndexError, ValueError):
return None
def _compute_efficiency(self) -> float:
def _compute_reward(self, done: bool, info: dict) -> float:
"""
Compute path efficiency = net displacement / total path length over window.
Returns 1.0 if insufficient history (can't penalize yet).
Returns 0.0 if no movement.
Compute reward from scratch using CTE × efficiency × speed.
Bypasses sim's exploitable forward_vel-based reward.
"""
if len(self._pos_history) < 3:
return 1.0 # Not enough history, give benefit of doubt
# Crash / episode over
if done:
return -1.0
positions = list(self._pos_history)
# Net displacement: straight-line distance from oldest to newest position
net_displacement = np.linalg.norm(positions[-1] - positions[0])
# Total path length: sum of step-by-step distances
total_path = sum(
np.linalg.norm(positions[i+1] - positions[i])
for i in range(len(positions) - 1)
)
if total_path < 1e-6:
return 1.0 # Car not moving at all, don't penalize (will be caught by health check)
return float(net_displacement / total_path)
def _shape_reward(self, original_reward: float, info: dict) -> float:
"""Apply path-efficiency-gated speed bonus."""
# Update position history
pos = self._get_pos(info)
pos = info.get('pos', None)
if pos is not None:
self._pos_history.append(pos)
try:
self._pos_history.append(np.array(list(pos)[:3], dtype=np.float64))
except (TypeError, ValueError):
pass
# Only apply speed bonus when genuinely on track (positive CTE reward)
if original_reward <= 0:
return original_reward # Off track / crashed — no speed reward
# --- Base reward: purely CTE-based ---
try:
cte = float(info.get('cte', 0.0) or 0.0)
except (TypeError, ValueError):
cte = 0.0
base = 1.0 - min(abs(cte) / self.max_cte, 1.0)
# Extract speed
# --- Path efficiency: detects circular motion ---
efficiency = self._compute_efficiency()
# Clamp: below min_efficiency → zero bonus
eff = max(0.0, (efficiency - self.min_efficiency) / (1.0 - self.min_efficiency))
# --- Speed: from info dict ---
try:
speed = max(0.0, float(info.get('speed', 0.0) or 0.0))
except (TypeError, ValueError):
return original_reward
speed = 0.0
# Compute path efficiency (detects circular motion)
efficiency = self._compute_efficiency()
# Clamp efficiency: below min_efficiency, no speed bonus
effective_efficiency = max(0.0, (efficiency - self.min_efficiency) / (1.0 - self.min_efficiency))
# Multiplicative bonus: fast forward progress → full bonus, circling → zero bonus
shaped = original_reward * (1.0 + self.speed_scale * speed * effective_efficiency)
# --- Combined reward: ALL three terms must be high ---
# Circling: eff≈0 → reward≈0 regardless of CTE or speed
shaped = base * eff * (1.0 + self.speed_scale * speed)
return shaped
def _compute_efficiency(self) -> float:
"""Path efficiency = net_displacement / total_path_length."""
if len(self._pos_history) < 3:
return 1.0 # Insufficient history — give benefit of doubt
positions = list(self._pos_history)
net = np.linalg.norm(positions[-1] - positions[0])
total = sum(
np.linalg.norm(positions[i + 1] - positions[i])
for i in range(len(positions) - 1)
)
return float(net / total) if total > 1e-6 else 1.0
def theoretical_max_per_step(self, max_speed: float = 10.0) -> float:
"""Upper bound on reward per step (for hack detection calibration)."""
return 1.0 * (1.0 + self.speed_scale * max_speed * 1.0) # efficiency=1 at best
"""Upper bound on reward/step (efficiency=1, CTE=0, max speed)."""
return 1.0 * 1.0 * (1.0 + self.speed_scale * max_speed)

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@ -324,3 +324,42 @@ The path efficiency metric (96-100% throughout entire run) confirms the car is m
### This is Research!
The reward hacking discovery and the progression from random walk → boundary oscillation → circular exploit → genuine driving represents real empirical RL research. Each failure mode revealed a fundamental property of reward design. The path efficiency fix was an original contribution to solving the circular driving problem without requiring track-shape knowledge.
---
## 2026-04-13 — Reward v4: Full Sim Bypass (base × efficiency × speed)
### Finding: v3 Still Allowed Circling — Base Reward Not Gated by Efficiency
**Observation (user):** Car turning left or right from start in Phase 2 runs (47k timestep trials).
**Root cause discovered in `donkey_sim.py`:**
```python
# sim's own reward (lines 478-498):
if self.forward_vel > 0.0:
return (1.0 - abs(cte)/max_cte) * self.forward_vel
```
`forward_vel` = dot(car_heading, velocity). A spinning car is **always** moving forward
relative to its own heading → `forward_vel > 0` always → positive reward while spinning.
**Why v3 was insufficient:**
- v3 multiplied the SPEED BONUS by efficiency: `original × (1 + scale × speed × eff)`
- But `original` (from sim) was already exploitable: CTE≈0 while spinning → `original=1.0`
- Efficiency killed the speed bonus but NOT the base reward
- A spinning car at CTE=0: 1.0/step × 47k steps = 47k total reward (never crashes in circle!)
**Fix — v4 formula:**
```
reward = base_CTE × efficiency × (1 + speed_scale × speed)
```
Where `base_CTE = 1 - abs(cte)/max_cte` computed from info dict, completely bypassing the sim.
- Spinning (eff≈0): reward ≈ 0 regardless of CTE or speed ✅
- Forward driving (eff≈1): reward = base × (1 + scale × speed) ✅
- All three terms must be high simultaneously to earn reward ✅
**Key test added:** `test_circling_at_zero_cte_gives_near_zero_reward` — confirms the core
v4 guarantee that the worst-case exploit (CTE=0 spinning) earns near-zero reward.
**The lesson:** When efficiency is only applied to the SPEED BONUS, the base reward from
the sim can still be gamed. The efficiency multiplier must apply to the ENTIRE reward.

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@ -19,7 +19,7 @@ import autoresearch_controller as ctrl
def test_param_encode_decode_roundtrip():
"""encode → decode should reproduce original values (within int rounding)."""
params = {'n_steer': 7, 'n_throttle': 3, 'learning_rate': 0.002, 'timesteps': 3000}
params = {'n_steer': 7, 'n_throttle': 3, 'learning_rate': 0.002, 'timesteps': 25000}
vec = ctrl.encode_params(params)
recovered = ctrl.decode_params(vec)
assert recovered['n_steer'] == params['n_steer']

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@ -1,240 +1,233 @@
"""
Tests for reward_wrapper.py v3 (path efficiency / anti-circular) no simulator required.
Tests for reward_wrapper.py v4 (full sim bypass base × efficiency × speed).
"""
import sys
import os
import math
import pytest
import sys, os, math, pytest
import numpy as np
import gymnasium as gym
from collections import deque
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'agent'))
from reward_wrapper import SpeedRewardWrapper
def make_env_with_pos(speed=2.0, original_reward=1.0, done=False, pos=(0.0, 0.0, 0.0)):
"""Create a mock env that returns a specific position in info dict."""
class PosEnv(gym.Env):
# ---- Mock Environments ----
class MockEnv(gym.Env):
"""Configurable mock gymnasium.Env."""
metadata = {'render_modes': []}
def __init__(self):
def __init__(self, speed=2.0, cte=0.0, pos=(0., 0., 0.), done=False, use_5tuple=True):
super().__init__()
self.action_space = gym.spaces.Discrete(5)
self.observation_space = gym.spaces.Box(low=0, high=255, shape=(120, 160, 3), dtype=np.uint8)
self._pos = list(pos)
self.observation_space = gym.spaces.Box(0, 255, (120, 160, 3), dtype=np.uint8)
self._speed = speed
self._reward = original_reward
self._cte = cte
self._pos = list(pos)
self._done = done
self._use_5tuple = use_5tuple
def set_pos(self, p):
self._pos = list(p)
def set_pos(self, p): self._pos = list(p)
def set_cte(self, c): self._cte = c
def reset(self, seed=None, **kwargs):
return np.zeros((120, 160, 3), dtype=np.uint8), {}
def step(self, action):
obs = np.zeros((120, 160, 3), dtype=np.uint8)
info = {'speed': self._speed, 'pos': self._pos}
return obs, self._reward, self._done, False, info
# Sim reward uses forward_vel (exploitable) — wrapper should IGNORE this
sim_reward = 999.0 # Deliberately bogus — wrapper must not use this
info = {'speed': self._speed, 'cte': self._cte, 'pos': self._pos}
if self._use_5tuple:
return obs, sim_reward, self._done, False, info
return obs, sim_reward, self._done, info
def close(self):
pass
return PosEnv()
def close(self): pass
# ---- Core Anti-Hacking Tests (inherited from v2) ----
def step_wrapped(wrapped_env, env, pos, cte=0.5, speed=2.0):
env.set_pos(pos)
env.set_cte(cte)
env._speed = speed
return wrapped_env.step(0)
def test_no_speed_bonus_when_off_track():
"""Off-track reward (≤ 0) must NOT get a speed bonus regardless of efficiency."""
env = make_env_with_pos(speed=10.0, original_reward=-1.0)
wrapped = SpeedRewardWrapper(env, speed_scale=0.5)
# ---- Core v4 Properties ----
def test_sim_reward_is_completely_ignored():
"""
The wrapper must NOT use the sim's reward (999.0).
v4 computes reward from scratch using CTE/pos/speed only.
"""
env = MockEnv(speed=2.0, cte=0.5, pos=(0., 0., 0.))
wrapped = SpeedRewardWrapper(env, speed_scale=0.1)
wrapped.reset()
_, reward, _, _, _ = wrapped.step(0)
assert reward == -1.0, f"Off-track reward must not get bonus, got {reward}"
assert reward != 999.0, "Wrapper must not pass through sim's bogus reward"
assert reward < 10.0, f"Reward should be small, got {reward}"
def test_no_speed_bonus_when_reward_zero():
"""Reward exactly 0 should not get speed bonus."""
env = make_env_with_pos(speed=5.0, original_reward=0.0)
wrapped = SpeedRewardWrapper(env, speed_scale=0.5)
wrapped.reset()
_, reward, _, _, _ = wrapped.step(0)
assert reward == 0.0, f"Zero reward should stay zero, got {reward}"
# ---- Path Efficiency Tests ----
def _simulate_straight_driving(wrapped_env, env, steps=40, speed=3.0, step_size=0.1):
"""Simulate straight-line driving: car moves forward by step_size each step."""
wrapped_env.reset()
rewards = []
for i in range(steps):
env.set_pos([i * step_size, 0.0, 0.0])
env._speed = speed
_, r, _, _, _ = wrapped_env.step(0)
rewards.append(r)
return rewards
def _simulate_circular_driving(wrapped_env, env, steps=40, speed=3.0, radius=0.5):
"""Simulate circular driving: car moves in a circle, returns to start."""
wrapped_env.reset()
rewards = []
for i in range(steps):
angle = 2 * math.pi * i / steps
x = radius * math.cos(angle)
z = radius * math.sin(angle)
env.set_pos([x, 0.0, z])
env._speed = speed
_, r, _, _, _ = wrapped_env.step(0)
rewards.append(r)
return rewards
def test_straight_driving_gets_higher_reward_than_circular():
def test_circling_at_zero_cte_gives_near_zero_reward():
"""
CRITICAL: Straight driving must produce more total reward than circular driving
at the same speed and base reward. This is the core anti-circular guarantee.
CORE v4 GUARANTEE: A spinning car at CTE=0 must earn near-zero reward.
v3 failed this: spinning at CTE=0 gave 1.0/step regardless of efficiency.
v4 multiplies base reward by efficiency circling yields 0.
"""
env_straight = make_env_with_pos(speed=3.0, original_reward=0.8)
env_circular = make_env_with_pos(speed=3.0, original_reward=0.8)
wrapped_straight = SpeedRewardWrapper(env_straight, speed_scale=0.1, window_size=20)
wrapped_circular = SpeedRewardWrapper(env_circular, speed_scale=0.1, window_size=20)
straight_rewards = _simulate_straight_driving(wrapped_straight, env_straight, steps=40)
circular_rewards = _simulate_circular_driving(wrapped_circular, env_circular, steps=40)
# After warmup (window fills), straight should consistently beat circular
straight_tail = sum(straight_rewards[20:])
circular_tail = sum(circular_rewards[20:])
assert straight_tail > circular_tail, (
f"Straight driving ({straight_tail:.2f}) should beat circular ({circular_tail:.2f})"
)
def test_efficiency_near_one_for_straight_driving():
"""Path efficiency should be near 1.0 for straight-line motion."""
env = make_env_with_pos(speed=3.0, original_reward=1.0)
wrapped = SpeedRewardWrapper(env, speed_scale=0.1, window_size=10)
wrapped.reset()
# Drive in a straight line
for i in range(15):
env.set_pos([i * 0.2, 0.0, 0.0])
wrapped.step(0)
efficiency = wrapped._compute_efficiency()
assert efficiency > 0.90, f"Straight driving efficiency should be >0.90, got {efficiency:.4f}"
def test_efficiency_near_zero_for_circular_driving():
"""Path efficiency should be near 0.0 for full circular motion."""
env = make_env_with_pos(speed=3.0, original_reward=1.0)
env = MockEnv(speed=3.0, cte=0.0)
wrapped = SpeedRewardWrapper(env, speed_scale=0.1, window_size=20)
wrapped.reset()
# Drive a full circle (returns to start position)
radius = 1.0
steps = 25 # More than window_size to fill it
for i in range(steps):
angle = 2 * math.pi * i / 24 # 24 steps = full circle
x = radius * math.cos(angle)
z = radius * math.sin(angle)
env.set_pos([x, 0.0, z])
wrapped.step(0)
# Simulate full circles (returns to start position)
radius = 0.5
rewards = []
for i in range(30):
angle = 2 * math.pi * (i % 20) / 20
env.set_pos([radius * math.cos(angle), 0., radius * math.sin(angle)])
_, r, _, _, _ = wrapped.step(0)
rewards.append(r)
efficiency = wrapped._compute_efficiency()
assert efficiency < 0.2, f"Circular driving efficiency should be <0.2, got {efficiency:.4f}"
# After window fills, rewards should be near zero (circling detected)
late_rewards = rewards[20:]
avg = sum(late_rewards) / len(late_rewards)
assert avg < 0.15, f"Circling at CTE=0 should earn near-zero reward, got avg={avg:.4f}"
def test_efficiency_one_with_no_pos_history():
"""When position not available, efficiency should default to 1.0 (no penalty)."""
class NoPosEnv(gym.Env):
metadata = {'render_modes': []}
def __init__(self):
super().__init__()
self.action_space = gym.spaces.Discrete(5)
self.observation_space = gym.spaces.Box(low=0, high=255, shape=(120, 160, 3), dtype=np.uint8)
def reset(self, seed=None, **kwargs):
return np.zeros((120, 160, 3), dtype=np.uint8), {}
def step(self, action):
return np.zeros((120, 160, 3), dtype=np.uint8), 0.8, False, False, {'speed': 2.0} # No pos
def close(self):
pass
def test_forward_driving_earns_positive_reward():
"""Straight-line driving at low CTE earns a clear positive reward."""
env = MockEnv(speed=2.0, cte=0.5)
wrapped = SpeedRewardWrapper(env, speed_scale=0.1, window_size=10)
wrapped.reset()
wrapped = SpeedRewardWrapper(NoPosEnv(), speed_scale=0.1)
rewards = []
for i in range(20):
env.set_pos([i * 0.3, 0., 0.])
_, r, _, _, _ = wrapped.step(0)
rewards.append(r)
late = rewards[10:]
avg = sum(late) / len(late)
assert avg > 0.5, f"Forward driving should earn >0.5 reward, got {avg:.4f}"
def test_forward_beats_circling_by_large_margin():
"""
Total reward over same number of steps:
forward driving >> circling, even at CTE=0 for the circular car.
"""
env_fwd = MockEnv(speed=2.0, cte=0.5)
env_circ = MockEnv(speed=2.0, cte=0.0) # CTE=0 is best case for circling
wrapped_fwd = SpeedRewardWrapper(env_fwd, speed_scale=0.1, window_size=20)
wrapped_circ = SpeedRewardWrapper(env_circ, speed_scale=0.1, window_size=20)
wrapped_fwd.reset()
wrapped_circ.reset()
total_fwd, total_circ = 0.0, 0.0
radius = 0.5
for i in range(40):
# Forward: moves in straight line
env_fwd.set_pos([i * 0.3, 0., 0.])
_, r, _, _, _ = wrapped_fwd.step(0)
total_fwd += r
# Circular: perfect circles at CTE=0
angle = 2 * math.pi * (i % 20) / 20
env_circ.set_pos([radius * math.cos(angle), 0., radius * math.sin(angle)])
_, r, _, _, _ = wrapped_circ.step(0)
total_circ += r
assert total_fwd > total_circ * 3, (
f"Forward ({total_fwd:.1f}) should beat circling ({total_circ:.1f}) by 3x"
)
def test_crash_gives_negative_reward():
"""Episode termination (done=True) must always give -1.0."""
env = MockEnv(speed=5.0, cte=0.0, done=True)
wrapped = SpeedRewardWrapper(env, speed_scale=0.2)
wrapped.reset()
_, reward, _, _, _ = wrapped.step(0)
# Without pos, efficiency=1.0, so reward = 0.8 * (1 + 0.1*2*1.0) = 0.96
assert reward > 0.8, f"Without pos, should get speed bonus (efficiency=1.0), got {reward}"
assert reward == -1.0, f"Crash reward must be -1.0, got {reward}"
def test_efficiency_resets_on_episode_reset():
"""Position history should clear on reset, so each episode starts fresh."""
env = make_env_with_pos(speed=3.0, original_reward=1.0)
def test_high_cte_reduces_reward():
"""Higher CTE should reduce reward (closer to track edge = lower base)."""
env_low = MockEnv(speed=2.0, cte=0.5)
env_high = MockEnv(speed=2.0, cte=4.0)
wrapped_low = SpeedRewardWrapper(env_low, speed_scale=0.1, window_size=5)
wrapped_high = SpeedRewardWrapper(env_high, speed_scale=0.1, window_size=5)
wrapped_low.reset()
wrapped_high.reset()
# Drive straight so efficiency fills up
for i in range(10):
env_low.set_pos([i * 0.3, 0., 0.])
env_high.set_pos([i * 0.3, 0., 0.])
_, r_low, _, _, _ = wrapped_low.step(0)
_, r_high, _, _, _ = wrapped_high.step(0)
assert r_low > r_high, f"Low CTE ({r_low:.3f}) should reward more than high CTE ({r_high:.3f})"
def test_speed_bonus_increases_reward_when_on_track():
"""Faster forward driving earns more reward than slower forward driving."""
env_slow = MockEnv(speed=0.5, cte=1.0)
env_fast = MockEnv(speed=3.0, cte=1.0)
wrapped_slow = SpeedRewardWrapper(env_slow, speed_scale=0.1, window_size=10)
wrapped_fast = SpeedRewardWrapper(env_fast, speed_scale=0.1, window_size=10)
wrapped_slow.reset()
wrapped_fast.reset()
for i in range(15):
env_slow.set_pos([i * 0.1, 0., 0.])
env_fast.set_pos([i * 0.3, 0., 0.]) # Fast car covers more ground
_, r_slow, _, _, _ = wrapped_slow.step(0)
_, r_fast, _, _, _ = wrapped_fast.step(0)
assert r_fast > r_slow, f"Fast ({r_fast:.3f}) should earn more than slow ({r_slow:.3f})"
def test_theoretical_max_per_step():
"""Max reward/step = 1.0 × 1.0 × (1 + scale × max_speed) = 2.0 at scale=0.1, max=10."""
env = MockEnv()
wrapped = SpeedRewardWrapper(env, speed_scale=0.1)
assert wrapped.theoretical_max_per_step(max_speed=10.0) == pytest.approx(2.0, abs=1e-6)
def test_4tuple_step_compatibility():
"""Wrapper must handle 4-tuple step() return (old gym API)."""
env = MockEnv(speed=2.0, cte=0.5, use_5tuple=False)
env.set_pos([0., 0., 0.])
wrapped = SpeedRewardWrapper(env, speed_scale=0.1)
wrapped.reset()
result = wrapped.step(0)
assert len(result) == 4, f"Expected 4-tuple, got {len(result)}"
_, reward, done, info = result
assert isinstance(reward, float)
assert reward != 999.0, "Should not use sim reward"
def test_reward_resets_on_episode_reset():
"""After reset, position history clears so efficiency recalculates cleanly."""
env = MockEnv(speed=2.0, cte=0.5)
wrapped = SpeedRewardWrapper(env, speed_scale=0.1, window_size=10)
wrapped.reset()
# Fill with circular data
radius = 0.5
for i in range(15):
angle = 2 * math.pi * i / 12
env.set_pos([radius * math.cos(angle), 0.0, radius * math.sin(angle)])
env.set_pos([0.5 * math.cos(angle), 0., 0.5 * math.sin(angle)])
wrapped.step(0)
eff_before_reset = wrapped._compute_efficiency()
# Reset and drive straight for a few steps
# After reset, start fresh straight
wrapped.reset()
for i in range(3):
env.set_pos([i * 0.3, 0.0, 0.0])
wrapped.step(0)
eff_after_reset = wrapped._compute_efficiency()
assert eff_after_reset > eff_before_reset, \
f"After reset, efficiency should improve: before={eff_before_reset:.3f}, after={eff_after_reset:.3f}"
def test_speed_bonus_disappears_when_circling():
"""After circling for window_size steps, speed bonus should be nearly zero."""
env = make_env_with_pos(speed=5.0, original_reward=1.0)
wrapped = SpeedRewardWrapper(env, speed_scale=0.5, window_size=20, min_efficiency=0.05)
wrapped.reset()
# Warm up with circular motion
radius = 0.5
rewards = []
for i in range(30):
angle = 2 * math.pi * (i % 20) / 20 # Full circle every 20 steps
env.set_pos([radius * math.cos(angle), 0.0, radius * math.sin(angle)])
for i in range(5):
env.set_pos([i * 0.3, 0., 0.])
_, r, _, _, _ = wrapped.step(0)
rewards.append(r)
# Later rewards (after window fills) should be close to original_reward
later_rewards = rewards[20:]
avg_later = sum(later_rewards) / len(later_rewards)
assert avg_later < 1.3, \
f"Circular driving speed bonus should be suppressed, avg reward={avg_later:.3f} (original=1.0)"
# ---- Inherited guarantees ----
def test_crash_still_penalized():
"""Crash (original_reward=-1) should remain -1 regardless of speed or efficiency."""
env = make_env_with_pos(speed=8.0, original_reward=-1.0, done=True)
wrapped = SpeedRewardWrapper(env, speed_scale=0.2)
wrapped.reset()
_, reward, _, _, _ = wrapped.step(0)
assert reward == -1.0, f"Crash reward should remain -1.0, got {reward}"
def test_theoretical_max_per_step():
"""Max reward/step bounded: original(1.0) × (1 + speed_scale × max_speed)."""
env = make_env_with_pos()
wrapped = SpeedRewardWrapper(env, speed_scale=0.1)
assert wrapped.theoretical_max_per_step(max_speed=10.0) == pytest.approx(2.0, abs=1e-6)
# Should get reasonable reward after fresh start
assert rewards[-1] > 0, "Should get positive reward after reset and straight driving"