Roblox Script Generated by ScripterAI

"Can you make physics based animation system for R15 players using constraints and CFrames to animate arms and legs to move realistically?"

Creating a physics-based animation system for R15 players using constraints and CFrames is a complex task and would require a deep understanding of Roblox constraints, CFrames, and character rigging. However, I can provide you with a basic example of how to use Motor6D and CFrame to animate a character's arm.

This script should be placed in a LocalScript inside the StarterPlayerScripts folder.

```lua
local Players = game:GetService("Players")

local function animateCharacter(character)
    local humanoid = character:WaitForChild("Humanoid")
    local leftArm = character:WaitForChild("Left Arm")
    local rightArm = character:WaitForChild("Right Arm")
    local leftShoulder = character:WaitForChild("Left Shoulder")
    local rightShoulder = character:WaitForChild("Right Shoulder")

local leftShoulderC0 = leftShoulder.C0
    local rightShoulderC0 = rightShoulder.C0

while true do
        -- Animate left arm
        leftShoulder.C0 = leftShoulderC0 * CFrame.Angles(0, 0, math.rad(30))
        rightShoulder.C0 = rightShoulderC0 * CFrame.Angles(0, 0, math.rad(-30))
        wait(0.5)

-- Reset left arm
        leftShoulder.C0 = leftShoulderC0
        rightShoulder.C0 = rightShoulderC0
        wait(0.5)
    end
end

local function onCharacterAdded(character)
    animateCharacter(character)
end

local function onPlayerAdded(player)
    player.CharacterAdded:Connect(onCharacterAdded)
    if player.Character then
        onCharacterAdded(player.Character)
    end
end

Players.PlayerAdded:Connect(onPlayerAdded)
for _, player in ipairs(Players:GetPlayers()) do
    onPlayerAdded(player)
end
```

This script will animate the character's arms to move back and forth. You can expand on this concept to create a more realistic animation system using additional constraints and CFrames for other body parts.

Keep in mind that this is just a starting point, and creating a full physics-based animation system will require a lot of experimentation and fine-tuning.