[aQuestion]

замени

		this.xmov = bot_speed*Math.cos(ang);
		this.ymov = bot_speed*Math.sin(ang);
		this._x += this.xmov;
		this._y += this.ymov;

на

		this.xmov = bot_speed*Math.cos(ang*Math.PI/180);
		this.ymov = bot_speed*Math.sin(ang*Math.PI/180);
		this._x -= this.xmov;
		this._y -= this.ymov;